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Numrering	Referens	Omslagsbild	Hitta
1.	Lundberg, Daniel, et al. (författare) The Chemical Side of SLU : Book of Abstracts 2011 Annan publikation (övrigt vetenskapligt/konstnärligt)
2.	Swerin, Agne, et al. (författare) Formulation of superhydrophobic pigment coatings 2015 Ingår i: Formulation of superhydrophobic pigment coatings. - : TAPPI Press. - 9781510818873 ; , s. 1410-1424 Konferensbidrag (refereegranskat)
3.	Börjesson, Karl, 1982, et al. (författare) Conjugated anthracene dendrimers with monomer-like fluorescence 2014 Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:38, s. 19846-19850 Tidskriftsartikel (refereegranskat)abstract Two generations of highly emissive conjugated anthracene dendrimers containing up to 9 anthracene units are presented. In these dendrimers, anthracene-like absorption and emission properties are preserved due to the relatively weak electronic coupling between the anthracene units, while evidence of fast crosstalk within the molecular framework is still observed.
4.	Nicholls, Ian A., et al. (författare) Rational design of biomimetic molecularly imprinted materials : theoretical and computational strategies for guiding nanoscale structured polymer development 2011 Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 400:6, s. 1771-1786 Forskningsöversikt (refereegranskat)abstract In principle, molecularly imprinted polymer science and technology provides a means for ready access to nano-structured polymeric materials of predetermined selectivity. The versatility of the technique has brought it to the attention of many working with the development of nanomaterials with biological or biomimetic properties for use as therapeutics or in medical devices. Nonetheless, the further evolution of the field necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. The rapid growth in computer power and software over the past decade has opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers.
5.	Wiklander, Jesper G., 1974-, et al. (författare) Towards a synthetic avidin mimic 2011 Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 400:5, s. 1397-1404 Tidskriftsartikel (refereegranskat)abstract A series of streptavidin-mimicking molecularly imprinted polymers has been developed and evaluated for their biotin binding characteristics. A combination of molecular dynamics and NMR spectroscopy was used to examine potential polymer systems, in particular with the functional monomers methacrylic acid and 2-acrylamidopyridine. The synthesis of copolymers of ethylene dimethacrylate and one or both of these functional monomers was performed. A combination of radioligand binding studies and surface area analyses demonstrated the presence of selectivity in polymers prepared using methacrylic acid as the functional monomer. This was predicted by the molecular dynamics studies showing the power of this methodology as a prognostic tool for predicting the behavior of molecularly imprinted polymers.
6.	Swerin, Agne, et al. (författare) Probing molecular, nanoscale and adhesive forces related to fiber-fiber bonding and optimized surface interactions 2009 Ingår i: International Conference on Nanotechnology for the Forest Products Industry 2009. - Edmonton Canada. - 9781615679812 ; , s. 229-283 Konferensbidrag (refereegranskat)
7.	Nyström-Larsson, Ingalill, 1969, et al. (författare) Materialanalys av sydsvenskt bonadsmåleri 2007 Ingår i: Rapport: Sammanfattning av Riksantikvarieämbetets seminarieserie 2007 kring pågående FoU-projekt. ; , s. 23-24 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Bonadsmåleriet hade sin storhetstid 1750-1850, och var influerat av medeltida kalkmåleri och bildvävnad i kyrkorna. Bonaderna var temporära och prydde stugorna till fest. Motiven kan vara både bibliska och profana. Materialet är tyger (återanvända och hopfogade) och senare även papper. Mot slutet av perioden övergår hantverket i massproduktion. Tidigare har bonaderna framför allt studerats inom humaniora (exempelvis etnologi) och ett naturvetenskapligt perspektiv har saknats. Därför finns mycket knapphändiga uppgifter om materialet. Syftet med projektet är att: • Kartlägga materialanvändningen • Tolka och förstå materialutvecklingen • Klarlägga innehållet i de otydliga trivialnamnen • Bygga upp ett referensmaterial Genomförande Ett antal frågeställningar har satts upp inför studiet: • Vilka materialval har man gjort? • Skiljer måleriteknik, färg, materialval mellan bonader, och går det att urskilja geografiska skillnader eller är det en tidsmässig utveckling? • Kan bonader attribueras utifrån materialval och färgval? • Vad är det för pigment som döljs i trivialnamnen? Skriftliga källor räcker inte för att svara på dessa frågor utan måste komplet-teras med naturvetenskapliga analyser. Diskussion kring RÄA-seminariets specifika frågeställningar På vad sätt bidrar ert projekt till kunskapsuppbyggnaden inom ert område? • Projektet är också ett pilotprojekt och den kunskap som vinns kan också appliceras på annat än bonadsmåleri. Utifrån resultaten kan man också gå vidare och titta på handelsvägar, infrastruktur etc. • En referensdatabas byggs upp och kan kanske också användas för an-nat material. På vilket sätt skulle resultaten från ert projekt kunna tillämpas mer konkret inom kulturmiljösektorn? • Ett viktigt mål är att hitta analysmetoder som inte förstör materialet, och som helst kan göras på plats så att materialet inte behöver flyttas (Raman spektroskopi). • Som konstaterades ovan kan resultaten från den kemiska analysen visa att en sådan kan komplettera traditionella historiska metoder också inom andra områden än bonadsmåleri. Frågor och öppen diskussion • Ännu har man inte hittat några speciella pigment eller färger, men analysen är inte klar. • Analysmaterialet som valts ut är signerade bonader. • Eftersom uppbyggandet av referensdatabaser är centralt i konserva-torns arbete är det viktigt att sprida resultaten av projektet.
8.	Asfaw, Habtom Desta, Dr. 1986-, et al. (författare) Facile synthesis of hard carbon microspheres from polyphenols for sodium-ion batteries : insight into local structure and interfacial kinetics 2020 Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 18 Tidskriftsartikel (refereegranskat)abstract Hard carbons are the most promising negative active materials for sodium ion storage. In this work, a simple synthesis approach is proposed to produce hard carbon microspheres (CMSs) (with a mean diameter of ~1.3 μm) from resorcinol-formaldehyde precursors produced via acid-catalyzed polycondensation reaction. Samples prepared at 1200, 1400, and 1500 oC showed different electrochemical behavior in terms of reversible capacity, initial coulombic efficiency (iCE), and the mechanism of sodium ion storage. The specific capacity contributions from the flat voltage profile (<0.1 V) and the sloping voltage region (0.1–1 V) showed strong correlation to the local structure (and carbonization temperature) determined by the interlayer spacing (d002) and the Raman ID/IG ratio of the hard carbons (HCs) and the rate of cycling. Electrochemical tests indicated that the HC synthesized at 1500 oC performed best with an iCE of 85–89% and a reversible capacity of 300–340 mAh g−1 at 10 mA g−1, with the majority of charge stored below 0.1 V. The d002 and the ID/IG ratio for the sample were ~3.7 Å and ~1.27, respectively, parameters indicative of the ideal local structure in HCs required for optimum performance in sodium-ion cells. In addition, galvanostatic tests on three-electrode half-cells cells revealed that sodium metal plating occurred as cycling rates were increased beyond 80 mA g−1 leading to considerably high capacity and poor coulombic efficiency, a point that must be considered in full-cell batteries. Pairing the hard CMS electrodes with Prussian white positive electrode, a proof-of-concept cell could provide a specific capacity of almost 100 mAh g−1 maintained for more than 50 cycles with a nominal voltage of 3 V.
9.	Benselfelt, Tobias, 1989- (författare) Design of Cellulose-based Materials by Supramolecular Assemblies 2019 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Due to climate change and plastic pollution, there is an increasing demand for bio-based materials with similar properties to those of common plastics yet biodegradable. In this respect, cellulose is a strong candidate that is already being refined on a large industrial scale, but the properties differ significantly from those of common plastics in terms of shapeability and water-resilience.This thesis investigates how supramolecular interactions can be used to tailor the properties of cellulose-based materials by modifying cellulose surfaces or control the assembly of cellulose nanofibrils (CNFs). Most of the work is a fundamental study on interactions in aqueous environments, but some material concepts are presented and potential applications are discussed.The first part deals with the modification of cellulose by the spontaneous adsorption of xyloglucan or polyelectrolytes. The results indicate that xyloglucan adsorbs to cellulose due to the increased entropy of water released from the surfaces, which is similar to the increased entropy of released counter-ions that drives polyelectrolyte adsorption. The polyelectrolyte adsorption depends on the charge of the cellulose up to a limit after which the charge density affects only the first adsorbed layer in a multilayer formation.Latex nanoparticles with polyelectrolyte coronas can be adsorbed onto cellulose in order to prepare hydrophobic cellulose surfaces with strong and ductile wet adhesion, provided the glass transition of the core is below the ambient temperature.The second part of the thesis seeks to explain the interactions between different types of cellulose nanofibrils in the presence of different ions, using a model consisting of ion-ion correlation and specific ion effects, which can be employed to rationally design water-resilient and transparent nanocellulose films. The addition of small amounts of alginate also creates interpenetrating double networks, and these networks lead to a synergy which improves both the stiffness and the ductility of the films in water.A network model has been developed to understand these materials, with the aim to explain the properties of fibril networks, based on parameters such as the aspect ratio of the fibrils, the solidity of the network, and the ion-induced interactions that increase the friction between fibrils. With the help of this network model and the model for ion-induced interactions, we have created films with wet-strengths surpassing those of common plastics, or a ductility suitable for hygroplastic forming into water-resilient and biodegradable packages. Due to their transparency, water content, and the biocompatibility of cellulose, these materials are also suitable for biomaterial or bioelectronics applications.
10.	Kolavali, Reddysuresh, 1983, et al. (författare) The sorption of monovalent cations onto wood flour and holocelluloses of Norway spruce: molecular interactions during LiCl impregnation 2017 Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 1437-434X .- 0018-3830. ; 71:5, s. 373-381 Tidskriftsartikel (refereegranskat)abstract Active functional groups and interactions involved in the sorption of Li+ ions from an aqueous LiCl solution onto the Norway spruce sapwood (sW) flour have been investigated. To this purpose, sW was delignified by peracetic acid (PAA) treatments and the resulting holocelluloses (HC6 h, HC24 h, HC51 h, HC72 h, where the lower case data indicate the PAA treatment time) with various lignin contents were immersed in aqueous solution of LiCl and the sorption effects were studied by flame atomic emission spectroscopy (FAES), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The Brunauer- Emmett-Teller (BET) specific surface area increased from 1.5±0.0 m2g−1 to 2.4±0.1 m2g−1 for HC6 h, and from 1.6±0.03 m2g−1 to 2.7±0.6 m2g−1 for HC72 h upon LiCl treatment. It was found that Li+/Cl− retention occurs predominantly via O-containing functionalities and the carbohydrate-rich samples sorbed more Li+. Upon LiCl treatment, the mobility and accessibility of the wood matrix was enhanced, possibly by interference of the introduced ions with the existing intermolecular bonds.
11.	Fan, Qunping, 1989, et al. (författare) High-performance all-polymer solar cells enabled by a novel low bandgap non-fully conjugated polymer acceptor 2021 Ingår i: Science in China Series B. - : Springer Nature. - 1674-7291 .- 1869-1870. ; 64, s. 1380-1388 Tidskriftsartikel (refereegranskat)abstract Anon-fully conjugated polymer as a new class of acceptor materials has shown some advantages over its small molecular counterpart when used in photoactive layers for all-polymer solar cells (all-PSCs), despite a low power conversion efficiency (PCE) caused by its narrow absorption spectra. Herein, a novel non-fully conjugated polymer acceptor PFY-2TS with a low bandgap of similar to 1.40 eV was developed, via polymerizing a large pi-fused small molecule acceptor (SMA) building block (namely YBO) with a non-conjugated thioalkyl linkage. Compared with its precursor YBO, PFY-2TS retains a similar low bandgap but a higher LUMO level. Moreover, compared with the structural analog of YBO-based fully conjugated polymer acceptor PFY-DTC, PFY-2TS shows similar absorption spectrum and electron mobility, but significantly different molecular crystallinity and aggregation properties, which results in optimal blend morphology with a polymer donor PBDB-T and better device physical processes in all-PSCs. As a result, PFY-2TS-based all-PSCs achieved a PCE of 12.31% with a small energy loss of 0.56 eV enabled by the reduced non-radiative energy loss (0.24 eV), which is better than that of 11.08% for the PFY-DTC-based ones. Our work clearly demonstrated that non-fully conjugated polymers as a new class of acceptor materials are very promising for the development of high-performance all-PSCs.
12.	Karlsson, Therese, 1987, et al. (författare) Hyperspectral imaging and data analysis for detecting and determining plastic contamination in seawater filtrates 2016 Ingår i: Journal of Near Infrared Spectroscopy. - Chichester, England : SAGE Publications. - 0967-0335 .- 1751-6552. ; 24:2, s. 141-149 Tidskriftsartikel (refereegranskat)abstract One possible way of monitoring plastic particles in sea water is by imaging spectroscopic measurements on filtrates. The idea is that filters from seawater sampling can be imaged in many wavelengths and that a multivariate data analysis can give information on (1) spatial location of plastic material on the filter and (2) composition of the plastic materials. This paper reports on simulated samples with spiked reference plastic particles, and real seawater filtrates containing microplastic pollutants. These real samples were previously identified through visual examination in a microscope. The samples were imaged using three different imaging systems. The different wavelength ranges were 375–970nm, 960–1662nm and 1000–2500nm. Data files from all three imaging systems were analysed by hyperspectral image analysis. The method using the wavelength span 1000–2500nm was shown to be the most applicable to this specific type of samples and gave a 100% particle recognition on reference plastic, above 300 µm and an 84% pixel recognition on household polyethylene plastic. When applied to environmental samples the technique showed an increase in identified particles compared with visual investigations. These initial tests indicate a potential underestimation of microplastics in environmental samples. This is the first study to demonstrate that hyperspectral imaging techniques can be used to study microplastics down to 300µm, which is a common size limit used in microplastic surveys.
13.	Valencia, Luis, et al. (författare) Multivalent ion-induced re-entrant transition of carboxylated cellulose nanofibrils and its influence on nanomaterials' properties 2020 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 12:29, s. 15652-15662 Tidskriftsartikel (refereegranskat)abstract In this work, we identify and characterize a new intriguing capability of carboxylated cellulose nanofibrils that could be exploited to design smart nanomaterials with tuned response properties for specific applications. Cellulose nanofibrils undergo a multivalent counter-ion induced re-entrant behavior at a specific multivalent metal salt concentration. This effect is manifested as an abrupt increase in the strength of the hydrogel that returns upon a further increment of salt concentration. We systematically study this phenomenon using dynamic light scattering, small-angle X-ray scattering, and molecular dynamics simulations based on a reactive force field. We find that the transitions in the nanofibril microstructure are mainly because of the perturbing actions of multivalent metal ions that induce conformational changes of the nanocellulosic chains and thus new packing arrangements. These new aggregation states also cause changes in the thermal and mechanical properties as well as wettability of the resulting films, upon water evaporation. Our results provide guidelines for the fabrication of cellulose-based films with variable properties by the simple addition of multivalent ions.
14.	An, N., et al. (författare) Mechanistic insight into self-propagation in organo-mediated Beckmann rearrangement: A combined experimental and computational study. 2013 Ingår i: Journal of Organic Chemistry. - 0022-3263 .- 1520-6904. ; 78:9, s. 4297-4302 Tidskriftsartikel (refereegranskat)abstract Organo-mediated Beckmann rearrangement in the liquid phase, which has the advantage of high efficiency and straightforward experimental procedures, plays an important role in the synthesis of amides from oximes. However, the catalytic mechanisms of these organic-based promoters are still not well understood. In this work, we report a combined experimental and computational study on the mechanism of Beckmann rearrangement mediated by organic-based promoters, using TsCl as an example. A novel self-propagating cycle is proposed, and key intermediates of this self-propagating cycle are confirmed by both experiments and DFT calculations. In addition, the reason why cyclohexanone oxime is not a good substrate of the organo-mediated Beckmann rearrangement is discussed, and a strategy for improving the yield is proposed.
15.	Andersson Trojer, Markus, et al. (författare) Elastic strain-hardening and shear-thickening exhibited by thermoreversible physical hydrogels based on poly(alkylene oxide)-grafted hyaluronic acid or carboxymethylcellulose 2020 Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 22:26, s. 14579-14590 Tidskriftsartikel (refereegranskat)abstract The formation of strongly elastic physical gels based on poly(alkylene oxide)-grafted hyaluronan or carboxymethylcellulose, exhibiting both shear-thickening and strain-hardening have been studied using rheometry and explained using a slightly different interpretation of the transient network theory. The graft copolymers were prepared by a quantitative coupling reaction. Their aqueous solutions displayed a thermoreversible continuous transition from Newtonian fluid to viscoelastic solid which could be controlled by the reaction conditions. The evolution of all material properties of the gel could be categorized into two distinct temperature regimes with a fast evolution at low temperatures followed by a slow evolution at high temperatures. The activation energy of the zero shear viscosity and the relaxation time of the graft inside the interconnecting microdomains were almost identical to each other in both temperature regimes. This suggests that the number of microdomains remained approximately constant whereas the aggregation number inside the microdomains increased according to the binodal curve of the thermosensitive graft.
16.	Asfaw, Habtom Desta, et al. (författare) Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries Annan publikation (övrigt vetenskapligt/konstnärligt)
17.	Asfaw, Habtom Desta (författare) Multifunctional Carbon Foams by Emulsion Templating : Synthesis, Microstructure, and 3D Li-ion Microbatteries 2017 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Carbon foams are among the existing electrode designs proposed for use in 3D Li-ion microbatteries. For such electrodes to find applications in practical microbatteries, however, their void sizes, specific surface areas and pore volumes need be optimized. This thesis concerns the synthesis of highly porous carbon foams and their multifunctional applications in 3D microbatteries. The carbon foams are derived from polymers that are obtained by polymerizing high internal phase water-in-oil emulsions (HIPEs).In general, the carbonization of the sulfonated polymers yielded hierarchically porous structures with void sizes ranging from 2 to 35 µm and a BET specific surface area as high as 630 m2 g-1. Thermogravimetric and spectroscopic evidence indicated that the sulfonic acid groups, introduced during sulfonation, transformed above 250 oC to thioether (-C-S-) crosslinks which were responsible for the thermal stability and charring tendency of the polymer precursors. Depending on the preparation of the HIPEs, the specific surface areas and void-size distributions were observed to vary considerably. In addition, the pyrolysis temperature could also affect the microstructures, the degree of graphitization, and the surface chemistry of the carbon foams.Various potential applications were explored for the bespoke carbon foams. First, their use as freestanding active materials in 3D microbatteries was studied. The carbon foams obtained at 700 to 1500 oC suffered from significant irreversible capacity loss during the initial discharge. In an effort to alleviate this drawback, the pyrolysis temperature was raised to 2200 oC. The resulting carbon foams were observed to deliver high, stable areal capacities over several cycles. Secondly, the possibility of using these structures as 3D current collectors for various active materials was investigated in-depth. As a proof-of-concept demonstration, positive active materials like polyaniline and LiFePO4 were deposited on the 3D architectures by means of electrodeposition and sol-gel approach, respectively. In both cases, the composite electrodes exhibited reasonably high cyclability and rate performance at different current densities. The syntheses of niobium and molybdenum oxides and their potential application as electrodes in microbatteries were also studied. In such applications, the carbon foams served dual purposes as 3D scaffolds and as reducing reactants in the carbothermal reduction process. Finally, a facile method of coating carbon substrates with oxide nanosheets was developed. The approach involved the exfoliation of crystalline VO2 to prepare dispersions of hydrated V2O5, which were subsequently cast onto CNT paper to form oxide films of different thicknesses.
18.	Asfaw, Habtom Desta, 1986-, et al. (författare) Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries : a study of structure and electrochemical performance 2014 Ingår i: Nanoscale. - Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 6:15, s. 8804-8813 Tidskriftsartikel (refereegranskat)abstract In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.
19.	Hosseini, Seyedehsan, 1994 (författare) Additive-Driven Improvements in Interfacial Properties and Processing of TMP-Polymer Composites 2023 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Efforts to address environmental concerns have resulted in new regulations designed to plan the reduction of plastic and synthetic polymer usage, necessitating the search for sustainable natural alternatives with comparable cost-effectiveness and mechanical performance. Thermomechanical pulp (TMP) fibres are one of the most affordable natural fibres that have no chemical refining in production, production have a high yield of 90-98% and TMP fibres have been demonstrated to improve the mechanical characteristics (strength, stiffness and toughness) of wood-polymer composites (WPCs) compared to the pure polymer. The integration of TMP fibres with non-polar synthetic polymers remains a challenge due to surface polarity differences. This PhD thesis aims to ease the processing of TMP fibre composites through the incorporation of additives. The hypothesis posits that incorporating magnesium stearate (MgSt), molybdenum disulfide (MoS2) and alkyl ketene dimer (AKD) as additives in TMP composites will enhance interfacial properties, resulting in improved processability and flow behaviour at high temperatures. MoS2 is known for its interaction with lignin, which exists in TMP and MgSt is recognised for its ability to improve flow in pharmaceutical processing when combined with cellulose, also a component of TMP. AKD modifies the hydrophilic properties of lignocellulosic surfaces. The experimental work explores the effect of these additives on the properties of TMP composites of ethylene acrylic acid copolymer (EAA) and polypropylene (PP) matrices. The dynamic mechanical analysis (DMA) and mechanical analysis results reveal that MoS2 exhibits superior interaction with TMP fibres, yielding enhanced interfacial properties compared to MgSt in between EAA and TMP fibres. Rheological studies elucidate the transition from a fluid-like state to a network-like structure upon the incorporation of TMP into the PP matrix. The incorporation of AKD with C18 reduces the viscosity of TMP-PP composites and PP itself, and, as determined through theoretical Hansen solubility parameter (HSP) calculations, increases compatibility between cellulose in TMP fibres and PP. The addition of AKD influences both the colour (lighter) and shape (smoother surface) of the extrudate filaments in the TMP-PP composites, indicative of improved processing. In addition, frictional analysis demonstrates the reduction of the coefficient of friction (COF) between metal and TMP fibre by MgSt and AKD treatments.
20.	Hosseini, Seyedehsan, 1994, et al. (författare) Alkyl ketene dimer modification of thermomechanical pulp promotes processability with polypropylene 2024 Ingår i: Polymer Composites. - 1548-0569 .- 0272-8397. ; 45:1, s. 825-835 Tidskriftsartikel (refereegranskat)abstract Alkyl ketene dimers (AKDs) are known to efficiently react with cellulose with a dual polarity in their structure: a polar component and a nonpolar component. AKD of three different carbon chain lengths, 4, 10, and 16 carbons have been synthesized, and thermomechanical pulp (TMP) fibers were modified by them. The modification of TMP fibers with AKD resulted in an increased water contact angle, showing the presence of the AKDs on the TMP fibers and a new carbonyl peak in the IR spectra, suggesting modification of the TMP fibers with AKD groups. Calculating the Hansen solubility parameters of AKD and AKD conjugated to TMP in polypropylene (PP) indicates improved compatibility, especially of longer chain AKD and TMP AKD. The rheological studies of the composites showed that the AKD with the longest carbon chain decreases the melt viscosity of the PP-TMP-AKD composite, which combined with the shape and the color of the extruded composite filaments indicates improved flow properties and reduced stress build up during processing. The research findings demonstrate the ability of AKD to enhance the dispersibility and compatibility of natural fibers with PP.
21.	Liu, Shungang, et al. (författare) The role of connectivity in significant bandgap narrowing for fused-pyrene based non-fullerene acceptors toward high-efficiency organic solar cells 2020 Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 8:12, s. 5995-6003 Tidskriftsartikel (refereegranskat)abstract Great attention has been paid to developing low bandgap non-fullerene acceptors (NFAs) for matching wide bandgap donor polymers to increase the photocurrent and therefore the power conversion efficiencies (PCEs) of NFA organic solar cells, while pyrene-core based acceptor-donor-acceptor (A-D-A) NFAs have been mainly reported via the 2,9-position connection due to their bisthieno[3′,2′-b']thienyl[a,h]pyrene fused via a five-membered ring bridge at the ortho-position of pyrene as the representative one named FPIC5, which has prohibited further narrowing their energy gap. Herein, an acceptor FPIC6 was exploited by creating the 1,8-position connection through fusing as bisthieno[3′,2′-b′]thienyl[f-g,m-n]pyrene linked at the bay-position via a six-membered bridge, with enhanced push-pull characteristics within such A-D-A structure. As a structural isomer of FPIC5, FPIC6 exhibited a much lower bandgap of 1.42 eV (1.63 eV for FPIC5). Therefore, the photocurrent and PCE of PTB7-Th:FPIC6 cells were improved to 21.50 mA cm-2 and 11.55%, respectively, due to the balanced mobilities, better photoluminescence quenching efficiency and optimized morphology, which are both ∼40% better than those of PTB7-Th:FPIC5 cells. Our results clearly proved that a pyrene fused core with 1,8-position connection with electron-withdrawing end groups instead of 2,9-position connection is an efficient molecular design strategy to narrow the optical bandgap and improve the photovoltaic performance of NFA based OSCs.
22.	Londero, Elisa, 1982, et al. (författare) Desorption of n-alkanes from graphene: a van der Waals density functional study 2012 Ingår i: Journal of Physics Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 24:42, s. 424212- Tidskriftsartikel (refereegranskat)abstract A recent study of temperature-programmed desorption (TPD) measurements of small linear alkane molecules (n-alkanes, with formula CNH2N+2) from C(0001) deposited on Pt(111) shows a linear relationship of the desorption energy with increasing n-alkane chain length N. We here present a van der Waals density functional study of the desorption barrier energy of the ten smallest n-alkanes (of carbon chain length N = 1–10) from graphene. We find linear scaling with N, including a non-zero intercept with the energy axis, i.e. an offset at the extrapolation to N = 0. This calculated offset is quantitatively similar to the results of the TPD measurements. From further calculations of the polyethylene polymer we offer a suggestion for the origin of the offset.
23.	Nilsson, Robin, 1993 (författare) An Investigation of Mixed Cellulose Esters and Acyclic Polyacetates: Effects of Side-Chain Lengths and Degrees of Ring-Opening 2023 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Bio-based polymers produced from natural sources are gaining an increased interest as potential replacement for today’s conventional fossil-based plastic polymers. Their use is already wide in many large-scale industrial areas such as healthcare, personal care, and food. To widen the potential of biopolymers in new applications such as plastics, their properties need to be tuned by modification to handle factors like relative humidity, which is especially important for gas barriers in food packaging. This thesis explores the effect of two structural variations of cellulose esters, one where the average side-chain length is increased, going from cellulose acetate to cellulose acetate propionate and then cellulose acetate butyrate, and another where the polymer backbone of cellulose acetate is ring-opened. These two modifications affect the glass transition temperature, an important structural factor. The effect of the average side-chain length is explored to a greater extent where they are studied for impact on mechanical properties, water content, water sorption at different RH, the kinetics of water sorption at different RH, mechanical properties at different RH and oxygen permeation at different RH. The focus is on how water interacts with the different esters with regard to the average side-chain length and how water affects their properties. An increase of average sidechain length and the ring-opening were shown to decrease the glass transition temperature. Together with the water sorption and Hansen solubility parameter, it was concluded that longer average side-chain length screens out hydrogen bonding between the polymers. The studies on the average side-chain length and water sorption indicated that water entering the cellulose acetate creates clusters. These formed water clusters create cavities in the polymer which makes the polymer hold more water than before introducing of the water clusters. Oxygen permeation studies on prewetted films prove that these cavities created by water clustering are still present after drying the material at 0% RH and thus resulted in a higher oxygen permeation compared to films that had not been exposed to higher than 50% RH.
24.	Nilsson, Robin, 1993 (författare) Interactions Between Water and Cellulose Esters 2022 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Biopolymers, which are produced from natural sources, are gaining interest as a potential replacement for fossil-based polymers. As such, they are already widely used in several industries, including the food, healthcare, and personal care industries. To harness the full potential of biopolymers as materials in new products designed for specific tasks, an ability to accurately predict their properties and how these properties change in different environments, is desirable. Hansen Solubility Parameters (HSP) combine dispersive, polar, and hydrogen bonding energies to understand interactions between molecules. This thesis explores the potential use of HSP as predictors of glass transition temperatures (Tg) and water interactions. It also focuses on elucidating the effect of an increased side-chain length of cellulose esters on their thermal properties, structural properties, and water interactions, together with how these properties are affected by the absorption of water. The cellulose esters studied here were cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. The HSP showed that the dispersive energy dominates the total cohesive energy, followed by the hydrogen bonding and then the polar energy. Counter-intuitively, the Tg decreased with an increased total cohesive energy. The HSP explained this phenomenon, namely, that the increased length of the substituents screened the short-range hydrogen bonds. A similar effect was observed for water solubility and penetration into the cellulose esters, which decreased with increasing side-chain lengths despite the approximately constant hydrogen bonding energies. This indicates the importance of focusing on each of the different interaction parameters instead of only the total HSP.
25.	Palma, Carlos-Andres, et al. (författare) Photo-induced C-C reactions on insulators towards photolithography of graphene nanoarchitectures 2014 Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 136, s. 4651-4658 Tidskriftsartikel (refereegranskat)abstract On-surface chemistry for atomically precise sp2 macromolecules requires top-down lithographic methods on insulating surfaces in order to pattern the long-range complex architectures needed by the semiconductor industry. Here, we fabricate sp2-carbon nm-thin films on insulators and under ultra-high vacuum (UHV) conditions from photo-coupled brominated precursors. We reveal that covalent coupling is initiated by C-Br bond cleavage through photon energies exceeding 4.4 eV, as monitored by laser desorption ionization (LDI) mass spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) gives insight into the mechanisms of C-Br scission and C-C coupling processes. Further, unreacted material can be sublimed and the coupled sp2-carbon precursors can be graphitized by e-beam treatment at 500°C, demonstrating promising applications in photolithography of graphene nanoarchitectures. Our results present UV-induced reactions on insulators for the formation of all sp2-carbon architectures, thereby converging top-down lithography and bottom-up on-surface chemistry into technology.
26.	Pipertzis, Achilleas, 1992, et al. (författare) Ion transport, mechanical properties and relaxation dynamics in structural battery electrolytes consisting of an imidazolium protic ionic liquid confined into a methacrylate polymer 2023 Ingår i: Energy Materials: Materials Science and Engineering for Energy Systems. - 1748-9237. ; 3 Tidskriftsartikel (refereegranskat)abstract The effect of confining a liquid electrolyte into a polymer matrix was studied by means of Raman spectroscopy, differential scanning calorimetry, temperature-modulated differential scanning calorimetry, dielectric spectroscopy, and rheology. The polymer matrix was obtained from thermal curing ethoxylated bisphenol A dimethacrylate while the liquid electrolyte consisted of a protic ionic liquid based on the ethyl-imidazolium cation [C2HIm] and the bis(trifluoromethanesulfonyl)imide [TFSI] anion, doped with LiTFSI salt. We report that the confined liquid phase exhibits the following characteristics: (i) a distinctly reduced degree of crystallinity; (ii) a broader distribution of relaxation times; (iii) reduced dielectric strength; (iv) a reduced cooperativity length scale at the liquid-to-glass transition temperature (Tg); and (v) up-speeded local Tg-related ion dynamics. The latter is indicative of weak interfacial interactions between the two nanophases and a strong geometrical confinement effect, which dictates both the ion dynamics and the coupled structural relaxation, hence lowering Tg by about 4 K. We also find that at room temperature, the ionic conductivity of the structural electrolyte achieves a value of 0.13 mS/cm, one decade lower than the corresponding bulk electrolyte. Three mobile ions (Im+, TFSI-, and Li+) contribute to the measured ionic conductivity, implicitly reducing the Li+ transference number. In addition, we report that the investigated solid polymer electrolytes exhibit the shear modulus needed for transferring the mechanical load to the carbon fibers in a structural battery. Based on these findings, we conclude that optimized microphase-separated polymer electrolytes, including a protic ionic liquid, are promising for the development of novel multifunctional electrolytes for use in future structural batteries.
27.	Santos, Denys E. S., et al. (författare) Conformational Dynamics and Responsiveness of Weak and Strong Polyelectrolyte Brushes : Atomistic Simulations of Poly(dimethyl aminoethyl methacrylate) and Poly(2-(methacryloyloxy)ethyl trimethylammonium chloride) 2019 Ingår i: Langmuir. - Washington : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 35:14, s. 5037-5049 Tidskriftsartikel (refereegranskat)abstract The complex solution behavior of polymer brushes is key to control their properties, including for biomedical applications and catalysis. The swelling behavior of poly(dimethyl aminoethyl methacrylate) (PDMAEMA) and poly(2-(methacryloyloxy)ethyl trimethylammonium chloride) (PMETAC) in response to changes in pH, solvent, and salt types has been investigated using atomistic molecular dynamics simulations. PDMAEMA and PMETAC have been selected as canonical models for weak and strong polyelectrolytes whose complex conformational behavior is particularly challenging for the development and validation of atomistic models. The GROMOS-derived atomic parameters reproduce the experimental swelling coefficients obtained from ellipsometry measurements for brushes of 5–15 nm thickness. The present atomistic models capture the protonated morphology of PDMAEMA, the swollen and collapsed conformations of PDMAEMA and PMETAC in good and bad solvents, and the salt-selective response of PMETAC. The modular nature of the molecular models allows for the simple extension of atomic parameters to a variety of polymers or copolymers.
28.	Spiliopoulos, Panagiotis, 1987, et al. (författare) Cellulose modified to host functionalities via facile cation exchange approach 2024 Ingår i: Carbohydrate Polymers. - 0144-8617. ; 332 Tidskriftsartikel (refereegranskat)abstract Properties of cellulose are typically functionalized by organic chemistry means. We progress an alternative facile way to functionalize cellulose by functional group counter-cation exchange. While ion-exchange is established for cellulose, it is far from exploited and understood beyond the most common cation, sodium. We build on our work that established the cation exchange for go-to alkali metal cations. We expand and further demonstrate the introduction of functional cations, namely, lanthanides. We show that cellulose nanocrystals (CNCs) carrying sulfate-half ester groups can acquire properties through the counter-cation exchange. Trivalent lanthanide cations europium (Eu3+), dysprosium (Dy3+) and gadolinium (Gd3+) were employed. The respective ions showed distinct differences in their ability of being coordinated by the sulfate groups; with Eu3+fully saturating the sulfate groups while for Gd3+ and Dy3+, values of 82 and 41 % were determined by compositional analysis. CNCs functionalized with Eu3+ displayed red emission, those containing Dy3+ exhibited no optical functionality, while those with Gd3+revealed significantly altered magnetic relaxation times. Using cation exchange to alter cellulose properties in various ways is a tremendous opportunity for modification of the abundant cellulose raw materials for a renewable future.
29.	Swensson, Beatrice, 1992 (författare) Dissolution of cellulose in aqueous hydroxide base solvents 2022 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract As we move towards a circular bioeconomy, new and advanced materials based on cellulose are constantly developed. Unlike most plastics or metals, cellulose cannot be melted, and therefore dissolution is an important tool for processing of cellulose but also for analytical purposes. There is, however, both a knowledge gap in understanding the mechanisms behind dissolution as well as a continued search for new and improved solvents. Aqueous solutions of hydroxide bases are a group of solvents with considerable variation in both dissolution capacity and stability of cellulose solutions, and their properties need to be improved to be useful solvents. Despite this, they are interesting because they have the potential to be cheap and non-toxic, depending on the base of choice. Therefore, the purpose of this thesis has been to further understand the interactions governing cellulose dissolution and properties in aqueous solutions of hydroxide bases, so that in the future, new and improved solvents can be designed. In order to achieve this, cellulose dissolution at low temperatures in aqueous solutions of NaOH and selected quaternary ammonium hydroxide bases has been investigated. The effect of combining NaOH with a quaternary ammonium hydroxide was also investigated, along with the influence of the commonly used additive urea. Results based on light scattering measurements revealed that dissolution in NaOH(aq) is poor, with relatively large aggregates present already at very dilute concentrations and a fraction of undissolved cellulose always present. Upon comparing NaOH to more hydrophobic quaternary ammonium hydroxides, it was observed that the dissolution capacity of the bases increased with increasing hydrophobicity of the cation, alongside their ability to act as hydrogen bond acceptors. Rheology measurements showed that compared to pure NaOH(aq) or pure tetramethylammonium hydroxide (TMAH)(aq), combining NaOH with TMAH improved the stability of the solutions over time and against increasing temperature. It was therefore proved that combining bases can have a similar effect as an additive, but the results were highly dependent on the base pair employed and indicated that both bases need to be able to dissolve cellulose on their own, within the same temperature interval and be miscible with each other in order to improve solution properties.
30.	Xu, Husen, et al. (författare) Synergistically boosting performances of organic solar cells from dithieno[3,2-b]benzo[1,2-b;4,5-b′]dithiophene-based copolymers via side chain engineering and radical polymer additives 2024 Ingår i: Journal of Materials Chemistry C. - 2050-7526 .- 2050-7534. ; 12:10, s. 3644-3653 Tidskriftsartikel (refereegranskat)abstract As a notable analogue of benzo[1,2-b:4,5-b′]dithiophene (BDT), dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene (DTBDT) is expected to be a more promising building block for polymer photovoltaic donor materials due to its larger coplanar core and extended conjugation length as well as a similar electron donor ability to BDT. However, the performance of organic solar cells (OSCs) from DTBDT-based copolymers is much lower than that of OSCs from BDT-based copolymers, which is attributed to the higher voltage loss of the OSCs from DTBDT-based polymers as compared to that from BDT-based polymers. In this study, approaches such as increasing the donor (D) and acceptor (A) spacing by lengthening the side chains of the polymer donors and use of radical conjugated polymer additives are synergistically employed in OSCs from 2-alkyl-3-chlorothiophene flanked DTBDT-alt-1,3-bis(thiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) polymers paired with Y6. Compared to the OSCs from the DTBDT-alt-BDD polymer with 2-ethylhexyl side chains (PBDT-Cl) paired with Y6, the power conversion efficiencies (PCEs) of the counterpart OSCs from the DTBDT-alt-BDD polymer with 2-butyloctyl side chains (PDBT-Cl-BO) increased from 12.67% to 14.58%, with a remarkable improvement of the open circuit voltage (VOC). The reduction of non-radiative energy loss of the OSCs from PBDT-Cl-BO:Y6, ascribed to the increase of the DA spacing by lengthening the side chains, is supported through detailed studies such as Fourier-transform photocurrent spectroscopy external quantum efficiency (FTPS-EQE), electroluminescence (EL), electroluminescence external quantum efficiency (EQEEL), and molecular dynamics simulations (MD). Afterwards, the PCEs of the OSCs from the blends of PDBT-Cl-BO:Y6 were further improved from 14.58% to 15.93% with a notable improvement of short circuit densities (JSCs) and fill factors (FFs), along with a small improvement in VOC upon the addition of the radical conjugated polymer GDTA as an additive. For comparison, the PCEs of the OSCs from the blends of PDBT-Cl:Y6 remained almost unchanged upon the addition of GDTA. This work suggests a wise strategy to synergistically utilize side-chain engineering and radical conjugated polymer additives to reduce the non-radiative energy loss, thus improving the performance of OSCs from DTBDT-based polymer donors.
31.	Yang, Yi, et al. (författare) Using an ionomer as a size regulator in γ-radiation induced synthesis of Ag nanocatalysts for oxygen reduction reaction in alkaline solution 2023 Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 646, s. 381-390 Tidskriftsartikel (refereegranskat)abstract Ag nanoparticles (Ag NPs) are among the most promising candidates to replace Pt as the catalyst for the oxygen reduction reaction (ORR) in anion exchange membrane fuel cells (AEMFCs). However, synthesizing size-controlled Ag NPs with efficient catalytic performance is still challenging. Herein, uniform Ag NPs are produced through a γ-radiation induced synthesis route in aqueous solutions, using the ionomer PTPipQ100 as both an efficient size regulator in the synthesis and a conductor of hydroxide ions during the ORR process. The origin of the size control is mainly attributed to the affinity of the ionomer to metallic silver. The resulting Ag NPs covered with ionomer layers can be applied as model catalysts for ORR. The nanoparticles that were prepared using 320 ppm ionomer in the reaction solution turned out to be coated with a ∼1 nm thick ionomer layer and exhibited superior ORR activity as compared to other Ag NPs of similar size studied here. The improved electrocatalytic performance can be attributed to the optimal ionomer coverage that enables fast oxygen diffusion, as well as interactions at the Ag-ionomer interface which promote the desorption of OH intermediates from the Ag surface. This work demonstrates the advantage of using an ionomer as the capping agent to produce efficient ORR catalysts.
32.	Zhuang, Wenliu, 1979, et al. (författare) Molecular Orbital Energy Level Modulation through Incorporation of Selenium and Fluorine into Conjugated Polymers for Organic Photovoltaic Cells 2013 Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 1:43, s. 13422-13425 Tidskriftsartikel (refereegranskat)abstract We demonstrated an effective chemical approach to modulate the energy levels of conjugated polymers by synergistically combining fluorine substitution and thiophene-selenophene exchange. Such modifications from TQ1 resulted in a significantly enhanced open-circuit voltage up to 1.0 V while retaining high photovoltaic performance.
33.	Bandara, T M W J, 1968, et al. (författare) Characterization of poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) nanofiber membrane based quasi solid electrolytes and their application in a dye sensitized solar cell 2018 Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 266, s. 276-283 Tidskriftsartikel (refereegranskat)abstract The electrolyte plays a major role in dye sensitized solar cells (DSSCs). In this work a quasi-solid state (gel) electrolyte has been formed by incorporating a liquid electrolyte made with KI dissolved in ethylene carbonate (EC) and propylene carbonate (PC) co-solvent in poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) co-polymer nanofiber membrane prepared by electrospinning. SEM images of the electrolyte membrane showed the formation of a three-dimensional network of polymer nanofibers with diameters between 100 and 300 nm and an average membrane thickness of 14 mu m. The electrolyte was characterized by FTIR and differential scanning calorimetry (DSC) measurements. The DSSCs fabricated with this electrolyte were characterized by current-voltage and Electrochemical Impedance Spectroscopy (EIS) measurements. DSC thermograms revealed that the crystallinity of the PVdF-HFP nanofiber is 14% lower than that of the pure PVdF-HFP polymer while the FTIR spectra showed a reduced polymer-polymer interaction in the nano fiber based gel electrolyte. The DSSCs fabricated with nanofiber based gel electrolyte showed an energy conversion efficiency of 5.36% under 1.5 a. m. solar irradiation, whereas the efficiency of the DSSC made with the liquid electrolyte based cell was 6.01%. This shows the possibility of replacing the liquid electrolyte in DSSCs by electro-spun polymer nanofiber based gel electrolyte and thereby minimizing some major drawbacks associated with liquid electrolyte based solar cells while maintaining a reasonably high efficiency.
34.	Iurchenkova, Anna A., 1997-, et al. (författare) MWCNT buckypaper/polypyrrole nanocomposites for supercapasitor application 2020 Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 335 Tidskriftsartikel (refereegranskat)abstract In this work MWNT/polypyrrole nanocomposites were synthesized and investigated as electrode materials for supercapasitor application. The MWNT were synthesized by CCVD-method and precipitated as buckypaper film (NTBP). The polypyrrole was precipitated on the NTBP surface by chemical (sample NTBP_PPy_Chem) and electrochemical (sample NTBP_PPy_Elect) polymerization. The morphology and functional composition of individual and hybrid materials were investigated by microscopic and spectroscopic methods. It was obtained that the deposition method and presence of NTBP affects the polymer morphology. It was shown that PPy chemical deposition leads to the precipitation of a large amount of an amorphous polymer on a buckypaper surface. At the same time electrochemical deposition method promotes the synthesis of uniform polymer layers. In the second case, the mass of the precipitated polymer is smaller. It was found that both deposition methods are suitable for the polypyrrole deposition and can increase the buckypaper capacity almost twice. The material long cycling showed that the NTBP_PPy_Elect sample has the greatest stability. Thus, in this study, the relationship between morphology, functional composition and electrochemical properties of materials was studied. It was shown that the synthesis method allows controlling the morphology and/or functional composition of the materials. Also it was demonstrated that the synthesized structures are promising for use as supercapacitor electrodes due to the high specific capacitance and stability.
35.	Murto, Petri Henrik, 1984 (författare) Synthesis of Conjugated Polymers and Small Molecules for Organic Light-Emitting Devices and Photodetectors 2018 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Production cost and environmental impact are the two major concerns that are related to the conventional optoelectronic devices. It is desirable for the modern semiconductors that they are free of toxic/costly metals, they can be processed with low-cost solution-based methods, and their optical, electronic, and mechanical properties can be easily tuned depending on the target application. In this thesis, a range of different conjugated polymers and small molecules are designed and synthesized as semiconductors for organic light-emitting diodes (OLEDs), light-emitting electrochemical cells (LECs), and organic photodetectors (OPDs). In organic light-emitting devices, the emissive molecule is commonly mixed with a charge transporting host matrix, which can be either a small molecule or a conjugated polymer. The latter is beneficial since it does not require deposition of the emitter and matrix components in high vacuum and high temperature conditions. The polymeric materials can be dissolved and printed on a substrate of any desired size and production scale, at room temperature, and even under ambient air. The specific wavelength range of near-infrared (NIR) at λ >700 nm is of interest for a wide range of applications spanning from optical communication to biosensing. However, the low energy of NIR range poses challenges for the materials design, in terms of emission efficiency and light intensity, which are further addressed in this thesis, allowing the fabrication of high-performance NIR-OLEDs and NIR-LECs. For photodetectors, absorption of a wide spectrum of light is beneficial in biosensing and imaging applications. Low noise and fast charge extraction are necessary for the detection of light at high speeds even at low intensities. These aspects are studied in this thesis by designing new polymers with different absorption, charge transport, and morphological properties in the photoactive layer. Two polymers enabled the fabrication of visible (red) OPDs with a low dark current (the main constituent in the noise), high detectivity, and high photoresponse speed.
36.	Andersson, John, 1993 (författare) Functional polymer brush coatings for nanoscale devices 2022 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Nanobiotechnology is an interdisciplinary field that has garnered considerable attention for offering exciting new opportunities of studying and manipulating biomolecules at the nanoscale. This prospect bears large potential benefits in the field of medicine and the whole life science sector in general. Fabrication of different nanostructure devices that can handle liquids at the scale of biomolecules, such as nanochannels or nanopores, provide a good basis within nanobiotechnology. However, the materials of nanostructures tend to not interact with complex biomolecules in ways that are sufficiently specific or controlled. This issue can be avoided by functionalising the surface of nanostructures with different organic coatings, and polymer brushes have shown a diverse range of functionality in this regard. This thesis summarises efforts towards designing functional polymer brush coatings for nanoscale devices. Surface sensitive techniques are used to characterise the grafting of dense poly(ethylene glycol) brushes to various noble metals and silicon dioxide. The new functionalisation protocol for polymer brushes on silicon dioxide provides excellent biofunctionality and is demonstrated to be compatible with two different nanostructures. The specific hydrogen-bond mediated interaction between a poly(ethylene glycol) brush and poly(methacrylic acid) in solution at low pH is shown to make the polymer brush reversibly stimuli-responsive. Preliminary results further demonstrate how this interaction can be controlled electrochemically and indicates its suitability as a macromolecular gating mechanism for nanosized openings. Finally, characterisation and fabrication of plasmonic nanopore arrays with separately functionalisable compartments using electron beam lithography techniques is presented.
37.	Bergenstråhle, Malin, 1977-, et al. (författare) Dynamics of Cellulose-Water Interfaces : NMR Spin-Lattice Relaxation Times Calculated from Atomistic Computer Simulations 2008 Ingår i: Journal of Physical Chemistry B. - Washington : ACS Publications. - 1520-6106 .- 1520-5207. ; 112:9, s. 2590-2595 Tidskriftsartikel (refereegranskat)abstract Solid-state nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy has often been used to study cellulose structure, but some features of the cellulose NMR spectrum are not yet fully understood. One such feature is a doublet around 84 ppm, a signal that has been proposed to originate from C4 atoms at cellulose fibril surfaces. The two peaks yield different T1, differing by approximately a factor of 2 at 75 MHz. In this study, we calculate T1 from C4-H4 vector dynamics obtained from molecular dynamics computer simulations of cellulose Iβ-water interfacial systems. Calculated and experimentally obtained T1 values for C4 atoms in surface chains fell within the same order of magnitude, 3-20 s. This means that the applied force field reproduces relevant surface dynamics for the cellulose-water interface sufficiently well. Furthermore, a difference in T1 of about a factor of 2 in the range of Larmor frequencies 25-150 MHz was found for C4 atoms in chains located on top of two different crystallographic planes, namely, (110) and (10). A previously proposed explanation that the C4 peak doublet could derive from surfaces parallel to different crystallographic planes is herewith strengthened by computationally obtained evidence. Another suggested basis for this difference is that the doublet originates from C4 atoms located in surface anhydro-glucose units with hydroxymethyl groups pointing either inward or outward. This was also tested within this study but was found to yield no difference in calculated T1.
38.	Bylin, Susanne, 1982 (författare) Mechanisms of Biopolymer Solvation: Development of a two-component ionic liquid solvent system 2014 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Ionic liquids are of potential interest in the processing of lignocellulosic biomass, and/or its components, for the purpose of producing renewable and value-added biomaterials. An understanding of how solvation can be achieved and the way in which the feedstock biopolymers are affected, however, needs to be gained prior to a viable implementation. In this thesis, the solvation of the wood biopolymers cellulose, xylan and lignin in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIMAc) in a novel combination with the second system component 1-methylimidazole (MIM) have been investigated:The solvation of dissolving pulp, beech xylan and LignoBoost lignin model materials, was studied using FBRM (focused beam reflectance measurements) particle characterization in combination with microscopic analysis (cellulose and xylan), determination of molecular weights (xylan and lignin) and 13C- and 31P-NMR (nuclear magnetic resonance spectroscopy) of lignin.It was concluded that the most efficient solvation of cellulose and xylan occurred using 3-4% and 9% IL (n/n anhydroglucose units and n/n anhydroxylose Units), respectively, while polymer integrity was maintained. Cellulose solvation was found to be greatly dependent on the IL to AGU ratio whereas xylan solvation varied greatly with temperature. Moreover, a theoretical model was developed for the solvation of cellulose in the present system. The solvation of lignin was achieved at ~20% lignin loading (w/w), in any combination of MIM/EMIMAc. Regeneration of lignin resulted in two sets of fractions; one exhibiting a general and higher apparent molecular weight (Mw) along with an enrichment of condensed/aliphatic ether linkages and aliphatic hydroxyls, and the other exhibiting a lower apparent Mw and an enrichment of carboxylic and phenolic groups. The knowledge of biopolymer solvation gained in the present solvent system provides future opportunities of tuning extraction and/or fractionation processes to suite the specifications of a particular biomass-derived product.
39.	Dunér, Gunnar, et al. (författare) Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films 2008 Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:14, s. 7559-7564 Tidskriftsartikel (refereegranskat)abstract Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.
40.	Ferrand-Drake Del Castillo, Gustav, 1990 (författare) Polyelectrolyte Brush Electrodes for Protein Capture and Release 2020 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Stimuli-responsive polyelectrolyte brushes switch as a function of pH between a charged and neutral state that affects their electrostatic interactions with other charged molecules like proteins. Adjustment of the pH results in the binding of large quantities of proteins making polyelectrolyte brushes widely used as biointerfaces. However, the interaction between proteins and polyelectrolyte brushes remains poorly understood. Protein binding to brushes despite net repulsion indicates that the mechanism is determined by more than electrostatic effects. In this thesis polyelectrolyte brushes, and protein-polyelectrolyte interactions were characterized using new methods. The results show that non-electrostatic interactions play an important role in protein binding to pH-responsive polyelectrolyte brushes. Active switching of polyelectrolyte brushes requires control of the pH. However, controlled pH switching that is convenient and non-invasive has proven difficult to achieve. In this thesis electrochemistry was used to generate local pH gradients, that resulted in reversible switches of polyelectrolyte brushes, even in highly buffered liquids and in biological solutions like serum. Reversible electrochemical switching of polyelectrolyte brushes was accomplished by employing diazonium salt surface functionalization. Electrochemical switching was used to control protein-polyelectrolyte interactions to create polyelectrolyte brush electrodes that captured and released high quantities of proteins on-demand. Our method for electronic control of protein immobilization should increase the utility of pH-stimuli-responsive polymer brushes in applications such as bioanalytics, protein purification, and protein drug-delivery.
41.	Füchtbauer, Anders Foller, 1984, et al. (författare) Lighting Up DNA with the Environment-Sensitive Bright Adenine Analogue qAN4 2020 Ingår i: Chempluschem. - : Wiley. - 2192-6506. ; 85:2, s. 319-326 Tidskriftsartikel (refereegranskat)abstract The fluorescent adenine analogue qAN4 was recently shown to possess promising photophysical properties, including a high brightness as a monomer. Here we report the synthesis of the phosphoramidite of qAN4 and its successful incorporation into DNA oligonucleotides using standard solid-phase synthesis. Circular dichroism and thermal melting studies indicate that the qAN4-modification has a stabilizing effect on the B-form of DNA. Moreover, qAN4 base-pairs selectively with thymine with mismatch penalties similar to those of mismatches of adenine. The low energy absorption band of qAN4 inside DNA has its peak around 358 nm and the emission in duplex DNA is partly quenched and blue-shifted (ca. 410 nm), compared to the monomeric form. The spectral properties of the fluorophore also show sensitivity to pH; a property that may find biological applications. Quantum yields in single-stranded DNA range from 1-29 % and in duplex DNA from 1-7 %. In combination with the absorptive properties, this gives an average brightness inside duplex DNA of 275 M-1 cm(-1), more than five times higher than the most used environment-sensitive fluorescent base analogue, 2-aminopurine. Finally, we show that qAN4 can be used to advantage as a donor for interbase FRET applications in combination with adenine analogue qA(nitro) as an acceptor.
42.	Janewithayapun, Ratchawit, 1998, et al. (författare) Nanostructures of etherified arabinoxylans and the effect of arabinose content on material properties 2024 Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 331 Tidskriftsartikel (refereegranskat)abstract To further our understanding of a thermoplastic arabinoxylan (AX) material obtained through an oxidation-reduction-etherification pathway, the role of the initial arabinose:xylose ratio on the material properties was investigated. Compression molded films with one molar substitution of butyl glycidyl ether (BGE) showed markedly different tensile behaviors. Films made from low arabinose AX were less ductile, while those made from high arabinose AX exhibited elastomer-like behaviors. X-ray scattering confirmed the presence of nanostructure formation resulting in nano-domains rich in either AX or BGE, from side chain grafting. The scattering data showed variations in the presence of ordered structures, nano-domain sizes and their temperature response between AX with different arabinose contents. In dynamic mechanical testing, three transitions were observed at approximately −90 °C, −50 °C and 80 °C, with a correlation between samples with more structured nano-domains and those with higher onset transition temperatures and lower storage modulus decrease. The mechanical properties of the final thermoplastic AX material can therefore be tuned by controlling the composition of the starting material.
43.	Karlsson, Ola, et al. (författare) Particle Analysis: Particle Size, Particle Shape and Structure and Surface Characterisation 2013 Ingår i: Chemistry and Technology of Emulsion Polymerisation. - : Wiley. - 9781118638521 - 9781119953722 ; , s. 213-251 Bokkapitel (refereegranskat)
44.	Liu, Yanfeng, et al. (författare) In Situ Optical Spectroscopy Demonstrates the Effect of Solvent Additive in the Formation of All-Polymer Solar Cells 2022 Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 13:50, s. 11696-11702 Tidskriftsartikel (refereegranskat)abstract 1-Chloronaphthalene (CN) has been a common solvent additive in both fullerene- A nd nonfullerene-based organic solar cells. In spite of this, its working mechanism is seldom investigated, in particular, during the drying process of bulk heterojunctions composed of a donor:acceptor mixture. In this work, the role of CN in all-polymer solar cells is investigated by in situ spectroscopies and ex situ characterization of blade-coated PBDB-T:PF5-Y5 blends. Our results suggest that the added CN promotes self-aggregation of polymer donor PBDB-T during the drying process of the blend film, resulting in enhanced crystallinity and hole mobility, which contribute to the increased fill factor and improved performance of PBDB-T:PF5-Y5 solar cells. Besides, the nonradiative energy loss of the corresponding device is also reduced by the addition of CN, corresponding to a slightly increased open-circuit voltage. Overall, our observations deepen our understanding of the drying dynamics, which may guide further development of all-polymer solar cells.
45.	Liu, Yanfeng, et al. (författare) In Situ Optical Studies on Morphology Formation in Organic Photovoltaic Blends 2021 Ingår i: Small Methods. - : John Wiley & Sons. - 2366-9608. ; 5:10, s. 1-12 Tidskriftsartikel (refereegranskat)abstract The efficiency of bulk heterojunction (BHJ) based organic solar cells is highly dependent on the morphology of the blend film, which is a result of a fine interplay between donor, acceptor, and solvent during the film drying. In this work, a versatile set-up of in situ spectroscopies is used to follow the morphology evolution during blade coating of three iconic BHJ systems, including polymer:fullerene, polymer:nonfullerene small molecule, and polymer:polymer. the drying and photoluminescence quenching dynamics are systematically study during the film formation of both pristine and BHJ films, which indicate that the component with higher molecular weight dominates the blend film formation and the final morphology. Furthermore, Time-resolved photoluminescence, which is employed for the first time as an in situ method for such drying studies, allows to quantitatively determine the extent of dynamic and static quenching, as well as the relative change of quantum yield during film formation. This work contributes to a fundamental understanding of microstructure formation during the processing of different blend films. The presented setup is considered to be an important tool for the future development of blend inks for solution-cast organic or hybrid electronics.
46.	Ma, Z. F., et al. (författare) Structure-Property Relationships of Oligothiophene-Isoindigo Polymers for Efficient Bulk-Heterojunction Solar Cells 2014 Ingår i: Energy and Environmental Sciences. - 1754-5692 .- 1754-5706. ; 7:1, s. 361-369 Tidskriftsartikel (refereegranskat)abstract A series of alternating oligothiophene (nT)–isoindigo (I) copolymers (PnTI) were synthesized to investigate the influence of the oligothiophene block length on the photovoltaic (PV) properties of PnTI:PCBM bulk-heterojunction blends. Our study indicates that the number of thiophene rings (n) in the repeating unit alters both polymer crystallinity and polymer–fullerene interfacial energetics, which results in a decreasing open-circuit voltage (Voc) of the solar cells with increasing n. The short-circuit current density (Jsc) of P1TI:PCBM devices is limited by the absence of a significant driving force for electron transfer. Instead, blends based on P5TI and P6TI feature large polymer domains, which limit charge generation and thus Jsc. The best PV performance with a power conversion efficiency of up to 6.9% was achieved with devices based on P3TI, where a combination of a favorable morphology and an optimal interfacial energy level offset ensures efficient exciton separation and charge generation. The structure–property relationship demonstrated in this work would be a valuable guideline for the design of high performance polymers with small energy losses during the charge generation process, allowing for the fabrication of efficient solar cells that combine a minimal loss in Voc with a high Jsc.
47.	Movahedi, Alireza, 1983, et al. (författare) One-pot synthesis of TBTA-functionalized coordinating polymers 2014 Ingår i: Reactive and Functional Polymers. - : Elsevier BV. - 1381-5148. ; 82, s. 1-8 Tidskriftsartikel (refereegranskat)abstract A one-pot method for the functionalization of polyvinylbenzyl chloride with a tris-(benzyltriazolylmethyl)amine (TBTA) ligand via the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC) is reported, where the ligand is constructed simultaneously with its attachment to the polymer backbone. A hydrophobic TBTA polymer as well as co-polymers containing TBTA ligands were also prepared to demonstrate the possibility of tailoring the properties of the polymers. The polymers were characterized with FT-IR and NMR spectroscopy, elemental analysis, contact angle measurement, differential scanning calorimetry and thermal gravimetric analysis. The metal coordinating properties of films prepared from the polymers was also demonstrated using X-ray photoelectron spectroscopy and their structures inspected by scanning electron microscopy.
48.	Nilsson, Fritjof, Docent, 1978-, et al. (författare) Nanocomposites and polyethylene blends: two potentially synergistic strategies for HVDC insulation materials with ultra-low electrical conductivity 2021 Ingår i: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 204 Tidskriftsartikel (refereegranskat)abstract Among the various requirements that high voltage direct current (HVDC) insulation materials need to satisfy, sufficiently low electrical conductivity is one of the most important. The leading commercial HVDC insulation material is currently an exceptionally clean cross-linked low-density polyethylene (XLPE). Previous studies have reported that the DC-conductivity of low-density polyethylene (LDPE) can be markedly reduced either by including a fraction of high-density polyethylene (HDPE) or by adding a small amount of a well dispersed, semiconducting nanofiller such as Al2O3 coated with a silane. This study demonstrates that by combining these two strategies a synergistic effect can be achieved, resulting in an insulation material with an ultra-low electrical conductivity. The addition of both HDPE and C8–Al2O3 nanoparticles to LDPE resulted in ultra-insulating nanocomposites with a conductivity around 500 times lower than of the neat LDPE at an electric field of 32 kV/mm and 60–90 °C. The new nanocomposite is thus a promising material regarding the electrical conductivity and it can be further optimized since the polyethylene blend and the nanoparticles can be improved independently.
49.	Peterson, Anna, 1988, et al. (författare) Dynamic Nanocellulose Networks for Thermoset-like yet Recyclable Plastics with a High Melt Stiffness and Creep Resistance 2019 Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 20:10, s. 3924-3932 Tidskriftsartikel (refereegranskat)abstract Many polymers, including polyethylene, feature a relatively low melting point and hence must be cross-linked to make them viable for applications that demand a high stiffness and creep resistance at elevated temperatures. The resulting thermoset plastics cannot be recycled, and therefore alternative materials with a reconfigurable internal network structure are in high demand. Here, we establish that such a thermoset-like yet recyclable material can be realized through the addition of a nanocellulose reinforcing agent. A network consisting of cellulose nanocrystals, nano- or microfibrils imparts many of the characteristics that are usually achieved through chemical cross-linking. For instance, the addition of only 7.5 wt % of either nanocellulose material significantly enhances the melt stiffness of an otherwise molten ethylene-acrylate copolymer by at least 1 order of magnitude. At the same time, the nanocellulose network reduces the meltcreep elongation to less than 10%, whereas the neat molten matrix would rupture. At high shear rates, however, the molten composites do not display a significantly higher viscosity than the copolymer matrix, and therefore retain the processability of a thermoplastic material. Repeated re-extrusion at 140 °C does not compromise the thermomechanical properties, which indicates a high degree of recyclability. The versatility of dynamic nanocellulose networks is illustrated by 3D printing of a cellulose composite, where the high melt stiffness improves the printability of the resin.
50.	Rahm, Martin, 1982, et al. (författare) Polymorphism and electronic structure of polyimine and its potential significance for prebiotic chemistry on Titan 2016 Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113, s. 8121-8126 Tidskriftsartikel (refereegranskat)abstract The chemistry of hydrogen cyanide (HCN) is believed to be central to the origin of life question. Contradictions between Cassini–Huygens mission measurements of the atmosphere and the surface of Saturn’s moon Titan suggest that HCN-based polymers may have formed on the surface from products of atmospheric chemistry. This makes Titan a valuable “natural laboratory” for exploring potential nonterrestrial forms of prebiotic chemistry. We have used theoretical calculations to investigate the chain conformations of polyimine (pI), a polymer identified as one major component of polymerized HCN in laboratory experiments. Thanks to its flexible backbone, the polymer can exist in several different polymorphs, which are relatively close in energy. The electronic and structural variability among them is extraordinary. The band gap changes over a 3-eV range when moving from a planar sheet-like structure to increasingly coiled conformations. The primary photon absorption is predicted to occur in a window of relative transparency in Titan’s atmosphere, indicating that pI could be photochemically active and drive chemistry on the surface. The thermodynamics for adding and removing HCN from pI under Titan conditions suggests that such dynamics is plausible, provided that catalysis or photochemistry is available to sufficiently lower reaction barriers. We speculate that the directionality of pI’s intermolecular and intramolecular =N–H…N hydrogen bonds may drive the formation of partially ordered structures, some of which may synergize with photon absorption and act catalytically. Future detailed studies on proposed mechanisms and the solubility and density of the polymers will aid in the design of future missions to Titan.

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