| 1. |
- Araujo, Rafael B., et al.
(författare)
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Assessing the electrochemical properties of polypyridine and polythiophene for prospective applications in sustainable organic batteries
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:4, s. 3307-3314
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Tidskriftsartikel (refereegranskat)abstract
- Conducting polymers are being considered promising candidates for sustainable organic batteries mainly due to their fast electron transport properties and high recyclability. In this work, the key properties of polythiophene and polypyridine have been assessed through a combined theoretical and experimental study focusing on such applications. A theoretical protocol has been developed to calculate redox potentials in solution within the framework of the density functional theory and using continuous solvation models. Here, the evolution of the electrochemical properties of solvated oligomers as a function of the length of the chain is analyzed and then the polymer properties are estimated via linear regressions using ordinary least square. The predicted values were verified against our electrochemical experiments. This protocol can now be employed to screen a large database of compounds in order to identify organic electrodes with superior properties.
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| 2. |
- Araujo, Rafael B., et al.
(författare)
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Designing strategies to tune reduction potential of organic molecules for sustainable high capacity battery application
- 2017
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 5:9, s. 4430-4454
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Tidskriftsartikel (refereegranskat)abstract
- Organic compounds evolve as a promising alternative to currently used inorganic materials in rechargeable batteries due to their low-cost, environmental friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of the density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, and pi bonds, as well as carboxyl groups on the formal potential, have been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.
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| 3. |
- Carlsson, Daniel O., et al.
(författare)
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Cooxidant-free TEMPO-mediated oxidation of highly crystalline nanocellulose in water
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:94, s. 52289-52298
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Tidskriftsartikel (refereegranskat)abstract
- Selective oxidation of C6 hydroxyls to carboxyls through 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, where the oxidizing species (TEMPO+) is generated by cooxidants, such as NaBrO, NaClO or NaClO2, has become a popular way to modify the surfaces of nanocellulose fibrils in aqueous solutions. Employing highly crystalline nanocellulose from Cladophora sp. algae we demonstrate that the same degree of oxidation (D.O.) can be achieved within approximately the same time by replacing the cooxidants with electrogeneration of TEMPO+ in a bulk electrolysis setup. The D.O. is controlled by the oxidation time and the maximum D.O. achieved (D.O. 9.8%, 0.60 mmol g-1 of carboxylic acids and 0 mmol g-1 aldehydes) corresponds to complete oxidation of the surface-confined C6. This shows that TEMPO+ is not sterically hindered from completely oxidizing the fibril surface of Cladophora nanocellulose, in contrast to earlier hypotheses that were based on results with wood-derived nanocellulose. The oxidation does not significantly affect the morphology, the specific surface area (>115 m2 g-1) or the pore characteristics of the water-insoluble fibrous particles that were obtained after drying, but depolymerization corresponding to ∼20% was observed. For extensive oxidation times, the product recovery of water-insoluble fibrils decreased significantly while significant amounts of charge passed through the system. This could indicate that the oxidation proceeds beyond the fibril surface, in contrast to the current view that TEMPO-mediated oxidation is confined only to the surface.
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| 4. |
- Katsiotis, Christos S.
(författare)
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Additive Manufacturing and Mesoporous Materials for Pharmaceutical Applications
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Additive Manufacturing (AM), over the past decade, has evolved into a versatile technology with significant applications in pharmaceutical research. This technology enables the production of drug formulations tailored to individual patients, offering customization in both dosage and dissolution profiles. While challenges in mass production persist, 3D printing, particularly through techniques like Fused Deposition Modeling (FDM) and Semi Solid Extrusion (SSE), proves ideal for crafting smaller batches of personalized dosage forms.A prevalent issue in drug development revolves around poor water solubility, impacting bioavailability upon oral administration. To combat this, the integration of mesoporous materials emerges as a promising strategy to enhance the dissolution of poorly water-soluble drugs. Here, the applicability of mesoporous materials is explored, as well as their incorporation with various AM techniques. Overall, the thesis dives into the investigation of combinatorial formulations, incorporating at least one 3D printed component to address specific requirements in drug delivery. By combining FDM with Selective Laser Sintering (SLS), a hybrid two-compartmental formulation is developed. The durable FDM-printed shell regulates buffer medium access to the contained SLS-produced inserts loaded with the drug. Varying printing parameters and insert combinations within the shell showcase the adjustability and flexibility of this hybrid approach.Tablets with different infill percentages, containing drug-loaded mesoporous materials, are developed. Poorly water-soluble drugs are successfully amorphized within mesoporous material pores, formulated into filaments through Hot Melt Extrusion (HME), and printed via FDM. These tablets exhibit improved dissolution compared to the crystalline drug, with the dissolution behavior regulated also by the infill percentage.The study explores the impact of drug-loaded mesoporous materials on HME-produced filament properties, studying their effect on maximum tensile strength and Young’s modulus. The relationship between these properties and filament printability is investigated. Additionally, a protective effect of mesoporous materials on drugs from thermal degradation is revealed.For Semi Solid Extrusion (SSE) manufactured formulations, a paste is developed, comprising mesoporous material loaded with a poorly water-soluble drug and an excipient. This paste demonstrates favorable rheological properties and easy extrudability via a syringe. The formulation proves versatile for printing dosage forms for both oral and rectal administration, with the printed tablet and suppository exhibiting effective drug release.In conclusion, this work presents valuable strategies for developing patient-tailored dosage forms, addressing specific pharmaceutical challenges like poor solubility. The integration of mesoporous materials and various 3D printing techniques showcases a promising direction for personalized medicine in the pharmaceutical field.
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| 7. |
- Zhou, Shengyang, et al.
(författare)
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A mechanically robust spiral fiber with ionic-electronic coupling for multimodal energy harvesting
- 2024
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Ingår i: Materials Horizons. - : ROYAL SOC CHEMISTRY. - 2051-6347 .- 2051-6355.
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Tidskriftsartikel (refereegranskat)abstract
- Wearable electronics are some of the most promising technologies with the potential to transform many aspects of human life such as smart healthcare and intelligent communication. The design of self-powered fabrics with the ability to efficiently harvest energy from the ambient environment would not only be beneficial for their integration with textiles, but would also reduce the environmental impact of wearable technologies by eliminating their need for disposable batteries. Herein, inspired by classical Archimedean spirals, we report a metastructured fiber fabricated by scrolling followed by cold drawing of a bilayer thin film of an MXene and a solid polymer electrolyte. The obtained composite fibers with a typical spiral metastructure (SMFs) exhibit high efficiency for dispersing external stress, resulting in simultaneously high specific mechanical strength and toughness. Furthermore, the alternating layers of the MXene and polymer electrolyte form a unique, tandem ionic-electronic coupling device, enabling SMFs to generate electricity from diverse environmental parameters, such as mechanical vibrations, moisture gradients, and temperature differences. This work presents a design rule for assembling planar architectures into robust fibrous metastructures, and introduces the concept of ionic-electronic coupling fibers for efficient multimodal energy harvesting, which have great potential in the field of self-powered wearable electronics. In this work, a concept of ionic-electronic coupling fibers by integrating a 2D MXene and a polymer electrolyte to fabricate spiral metastructures is proposed to realize multimodal power generation from various sources simultaneously.
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