| 1. |
- Gazzotti, Stefano, et al.
(författare)
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DOX mediated synthesis of PLA-co-PS graft copolymers with matrix-driven self-assembly in PLA-based blends
- 2022
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 170, s. 111157-
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Tidskriftsartikel (refereegranskat)abstract
- Intriguing phase morphology was formed through self-assembly of polylactide-polystyrene (PLA-co-PS) graft copolymers blended with polylactide (PLA). PLA-co-PS graft copolymers were synthesized by exploiting a styrene-functionalized 1,3-Dioxolan-4-one (StyDOX) monomer through a two-step procedure and their structure was confirmed. Different amounts of PLA-co-PS and commercial PLA were solution cast to blend films. Etching of amorphous PLA revealed the presence of spherical micrometer sized domains dispersed within the films, arising from the self-assembly behavior of PLA-co-PS caused by the immiscibility of PS-grafts in the PLA matrix. EDS and IR imaging analyses further revealed that these microspheres were characterized by a PS-rich core opposed to the PLA-rich outer shell, which is expected to be miscible and able to form favorable interactions with the PLA matrix. PLA/PS blends were also prepared with different loadings of PLA-co-PS. The ability of PLA-co-PS to compatibilize the two phases was assessed through rheological analyses. Finally, the possibility to chemically recycle the copolymer was evaluated.
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| 2. |
- Gustavsson, Lotta H., et al.
(författare)
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Thermoplastic "All-Cellulose" Composites with Covalently Attached Carbonized Cellulose
- 2020
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 21:5, s. 1752-1761
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Tidskriftsartikel (refereegranskat)abstract
- Thermoplastic "all-cellulose" composites were synthesized by covalent functionalization of cellulose acetate (CA) with oxidized carbonized cellulose (OCC). The OCC were manufactured via microwave-assisted hydrothermal carbonization (HTC) of cellulose followed by oxidation and dialysis. The OCC were of micrometer-size, had plane morphology and contained a variety of oxygen functionalities, enabling transformation into acyl chlorinated OCC under moderate reaction conditions. The synthesis of OCC-modified CA composites and neat CA were performed in the recyclable ionic liquid 1-allyl-3-methylimidazolium chloride. The degree of acetylation and amount of OCC were varied to establish their influence on thermal and physical properties of the composites. The OCC-modified CA composites displayed a notably enhanced film-forming ability, which led to improved optical and mechanical properties compared to neat CA. In addition, it was shown that OCC-modified CA composites can be synthesized from waste products, such as paper tissues. The OCC-modification was demonstrated to be a promising route to transparent and strong thermoplastic "all-cellulose" composites with moderate flexibility.
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| 3. |
- Adolfsson, Karin H., et al.
(författare)
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Importance of Surface Functionalities for Antibacterial Properties of Carbon Spheres
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley. - 2366-7486.
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Tidskriftsartikel (refereegranskat)abstract
- Carbon spheres (CS) are interesting materials for antibacterial applications. Herein, CS are produced by a green process utilizing microwave-assisted hydrothermal treatment of cellulose. The CS are then postmodified in acidic and basic solutions to evaluate the influence of different functionalities on antibacterial properties. CS contain OH/COOH, C Symbol of the Klingon Empire C, and C Symbol of the Klingon Empire O functionalities, while O-CS produced by acid treatment of CS have additional COOH, and NH/NH2 groups, resulting in carbon spheres with negatively and positively charged groups in dispersion. Treatment with base (Na-CS) removes low molecular weight species with oxygen and results in carbon spheres with the highest C/O ratio. CS, O-CS, and Na-CS have nonporous morphology and are in micro/nanometer sizes, although, smaller sized spheres, hollow spheres, and fragments are also attained in the case of O-CS. O-CS show antibacterial activity toward both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa). The minimum inhibitory concentration is 200 and 400 mu g mL(-1) for S. aureus and P. aeruginosa, respectively, and is achieved only after 3 h of incubation. Neither CS nor Na-CS exhibit antibacterial activity. The antibacterial activity is suggested to originate from electrostatic interactions between O-CS and the bacteria.
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| 4. |
- Adolfsson, Karin H., et al.
(författare)
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In Vivo Versus In Vitro Degradation of a 3D Printed Resorbable Device for Ligation of Vascular Tissue in Horses
- 2021
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Ingår i: Macromolecular Bioscience. - : Wiley. - 1616-5187 .- 1616-5195. ; 21:10
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Tidskriftsartikel (refereegranskat)abstract
- A resorbable 3D printed polydioxanone (PDO) device is manufactured to facilitate ligation of vascular tissue during surgery. The device must provide sufficient mechanical performance throughout the healing period. Therefore, degradation and mechanical performance of the device are investigated as a function of in vivo and in vitro aging. During aging the PDO device released cyclic and linear water-soluble products. In vivo aging resulted in higher relative number of linear oligomers in comparison to in vitro aging. A major loss of mechanical performance is observed after only 10 days in vivo and the Young’s modulus (E) and tensile strength at break (σb) decreased by 28% and 54%, respectively. This is in contrast to in vitro aging, where no loss of mechanical properties is observed during the same period. The in vivo aged devices exhibit clear holes in the matrices after 28 days, while apparent cracks are observed first after 140 days in vitro. These results highlight the sensitivity of the degradation process of resorbable devices with regards to the interactions of the device with the surrounding environment (tissues) and demonstrate the importance of in vivo testing as compliment to in vitro testing before clinical use of devices.
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| 5. |
- Adolfsson, Karin H., et al.
(författare)
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Microwave Assisted Hydrothermal Carbonization and Solid State Postmodification of Carbonized Polypropylene
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 6:8, s. 11105-11114
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Tidskriftsartikel (refereegranskat)abstract
- Functional carbon materials produced through a hydrothermal treatment of waste products have gained interest. Particularly, the method is considered more facile and green compared to conventional decomposition methods. Here, we demonstrated an upcycling of polypropylene (PP) waste to carbon materials by a microwave assisted hydro thermal treatment. The solid product obtained from the hydrothermal treatment was analyzed by multiple techniques to reveal the structure and the influence of processing conditions on PP degradation and hydrothermal carbonization. Chemical analyses showed the presence of carbonaceous material independent of acid amount (20 and 30 mL), temperature (210 and 250 degrees C), and time (20-80 min). A complete transformation of PP content to amorphous carbon required 60 min at 250 degrees C. The mass yield of the solid product decreased as a function of harsher processing conditions. At the same time, thermogravimetric analysis illustrated products with increasing thermal stability and a larger amount of remaining residue at 600 degrees C. The solid products consisted of irregular fragments and sheet-like structures. A solid state microwave process in air atmosphere was performed on a product with incomplete carbonization. The modification resulted in a decreased C/O ratio, and TGA analysis in nitrogen showed high thermal stability and degree of carbonization as indicated by the remaining residue of 86.4% at 600 degrees C. The new insights provided on the hydrothermal carbonization, and postmodification in air atmosphere, can catalyze effective handling of plastic waste by enabling transformation of low quality waste into functional carbon materials.
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| 6. |
- Adolfsson, Karin H., et al.
(författare)
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Oxidized Carbonized Cellulose-Coated Filters for Environmental Contaminant Adsorption and Detection
- 2020
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 59:30, s. 13578-13587
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Tidskriftsartikel (refereegranskat)abstract
- Cationized cellulose filters with coating of oxidized carbonized cellulose (OCC) were successfully fabricated. The OCC-coated filter was demonstrated as a combined surface for adsorption of environmental contaminants and their detection on the filter by surface-assisted desorption ionization-mass spectrometry (SALDI-MS). The cellulose filters were cationized by utilizing 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHTAC) and sodium hydroxide. It was shown that the degree of substitution increased with the CHTAC feed. OCC, synthesized by hydrothermal carbonization of cellulose with subsequent oxidation and dialysis, was attached onto the cationized filters by electrostatic interactions. The filters adsorbed the model contaminant methylene blue (MB) from aqueous solution, and the MB could subsequently be detected on the filter surfaces by SALDI-MS as [M](+) adduct. The OCC coating further improved the relative peak intensity of [M](+) with little background interferences. This work indicates great potential for the OCC-coated filters as a combined surface for rapid monitoring of environmental contaminants.
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| 7. |
- Adolfsson, Karin H., et al.
(författare)
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Scavenging of DPPH by Persistent Free Radicals in Carbonized Particles
- 2023
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Ingår i: Advanced Sustainable Systems. - : Wiley. - 2366-7486. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- Persistent free radicals (PFR) in carbonized particles may play a role in degradation of environmental compounds. The influence of PFR is evaluated in various carbonized particles on their radical scavenging efficiency upon the common radical indicator 2-2-diphenyl-1-picrylhydrazyl (DPPH). Carbonized particles are derived by hydrothermal carbonization of glucose (C-W) or glucose and urea (NC-W) and ionothermal carbonization of glucose and urea ionic liquid (IL) (NC-IL). The carbonized materials contain OH/COOH, C=C, and C-O functionalities. The addition of urea introduces NH/NH2 functionalities. The content of polar surface groups is lower in IL-processed NC-IL. The scavenging ability, measured as DPPH UV–vis absorption decline, increases with concentration and time for all particles, while the efficiency changes are in the order of C-W > NC-W > NC-IL. Electron paramagnetic resonance analysis reveals similar radical concentration in all carbonized materials studied. The difference in efficiency is, thus, not directly related to the PFR concentration but rather to the type of PFR, surface functionalities and/or scavenging mechanism. According to the g-values, radicals in these particles are carbon-centered. The minor variation in g-values suggests interactions between the radicals and their environmental functional groups. This provides insights into the influence of PFR in carbonized materials on their radical scavenging efficiency.
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| 8. |
- Adolfsson, Karin H., et al.
(författare)
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Valorization of cellulose and waste paper to graphene oxide quantum dots
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:34, s. 26550-26558
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Tidskriftsartikel (refereegranskat)abstract
- Biobased graphene oxide quantum dots (GOQD) were derived from cellulose via carbon nanospheres (CN) as intermediate products. Solid CN were synthesized from cellulose through microwave-assisted hydrothermal degradation of alpha-cellulose with H2SO4 as a catalyst at 160 degrees C. The obtained CN were further utilized for the synthesis of GOQD by a two-step reaction including 30 minutes of sonication followed by heating at 90 degrees C under O-rich acidic conditions (HNO3). This process broke down the 3D CN to 2D GOQD. The size of the synthesized GOQD was controlled by the heating time, reaching a dot diameter of 3.3 nm and 1.2 nm after 30 and 60 minutes of heating, respectively. The synthesis process and products were characterized by multiple analytical techniques including FTIR, TGA, SEM, TEM, XPS, XRD, BET, DLS and AFM. Interesting optical properties in aqueous solutions were demonstrated by UV/Vis and fluorescence spectroscopy. Finally we demonstrated that corresponding GOQD can be synthesized from waste paper. This production route thus uses renewable and cheap starting materials and relatively mild synthesis procedures leads to instant nanometric production of 2D dots. In addition it enables recycling of low quality waste to value-added products.
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| 9. |
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| 10. |
- Adolfsson, Karin H., et al.
(författare)
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Zero-Dimensional and Highly Oxygenated Graphene Oxide for Multifunctional Poly(lactic acid) Bionanocomposites
- 2016
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 4:10, s. 5618-5631
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Tidskriftsartikel (refereegranskat)abstract
- The unique strengths of 2D graphene oxide nanosheets (GONSs) in polymer composites are thwarted by nanosheet agglomeration due to strong intersheet attractions. Here, we reveal that shrinking the planar size to 0D graphene oxide quantum dots (GOQDs), together with the intercalation of rich oxygen functional groups, reduces filler aggregation and enhances interfacial interactions with the host polymer. With poly(lactic acid) (PLA) as a model matrix, atomic force microscopy colloidal probe measurements illustrated that a triple increase in adhesion force to PLA was achieved for GOQDs (234.8 nN) compared to GONSs (80.4 nN), accounting for the excellent exfoliation and dispersion of GOQDs in PLA, in contrast to the notable agglomeration of GONSs. Although present at trace amount (0.05 wt %), GOQDs made a significant contribution to nucleation activity, mechanical strength and ductility, and gas barrier properties of PLA, which contrasted the inferior efficacy of GONSs, accompanied by clear distinction in film transparency (91% and 50%, respectively). Moreover, the GOQDs with higher hydrophilicity accelerated the degradation of PLA by enhancing water erosion, while the GONSs with large sheet surfaces gave a higher hydrolytic resistance. Our findings provide conceptual insights into the importance of the dimensionality and surface chemistry of GO nanostructures in the promising field of bionanocomposites integrating high strength and multifunction (e.g., enhanced transparency, degradation and gas barrier).
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| 11. |
- B. Erdal, Nejla, et al.
(författare)
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Green Strategy to Reduced Nanographene Oxide through Microwave Assisted Transformation of Cellulose
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:1, s. 1245-1255
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Tidskriftsartikel (refereegranskat)abstract
- A green strategy for fabrication of biobased reduced nanographene oxide (r-nGO) was developed. Cellulose derived nanographene oxide (nGO) type carbon nanodots were reduced by microwave assisted hydrothermal treatment with superheated water alone or in the presence of caffeic acid (CA), a green reducing agent. The carbon nanodots, r-nGO and r-nGO-CA, obtained through the two different reaction routes without or with the added reducing agent, were characterized by multiple analytical techniques including FTIR, XPS, Raman, XRD, TGA, TEM, AFM, UV-vis, and DLS to confirm and evaluate the efficiency of the reduction reactions. A significant decrease in oxygen content accompanied by increased number of sp2 hybridized functional groups was confirmed in both cases. The synergistic effect of superheated water and reducing agent resulted in the highest C/O ratio and thermal stability, which also supported a more efficient reduction. Interesting optical properties were detected by fluorescence spectroscopy where nGO, r-nGO, and r-nGO-CA all displayed excitation dependent fluorescence behavior. r-nGO-CA and its precursor nGO were evaluated toward osteoblastic cells MG-63 and exhibited nontoxic behavior up to 200 μg mL-1, which gives promise for utilization in biomedical applications.
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| 12. |
- Benyahia Erdal, Nejla, et al.
(författare)
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In vitro and in vivo effects of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A
- 2018
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Ingår i: Clinical and experimental optometry. - : WILEY. - 0816-4622 .- 1444-0938. ; 101:3, s. 354-362
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Tidskriftsartikel (refereegranskat)abstract
- Background: Acuvue Oasys silicone hydrogel contact lenses (Senofilcon A) are used as bandage lenses and often combined with ophthalmic solutions in the treatment of ocular diseases. Concerns have been raised regarding the compatibility and effect of eye-drop solutions on the bandage lenses, which have led to frequent replacement of lenses causing clinical problems. Some patients experience pain or discomfort during treatments and the accumulation of drugs and preservatives in lenses has been suggested as a possible reason. The aim with this study was to investigate the effect of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A in vitro and in vivo. Methods: The effect of three common ophthalmic solutions Isopto-Maxidex, Timosan and Oftaquix on Acuvue Oasys (Senofilcon A) bandage lenses was evaluated. An in vitro model method was developed where drug and preservative uptake by Acuvue Oasys was monitored with ultraviolet-visible spectroscopy and laser desorption ionisation mass spectrometry. Surface morphology changes of the lenses were evaluated using scanning electron microscopy. The method was then implemented for the in vivo pilot study evaluating lenses worn by patients. Results: In vitro model study monitoring the drug and preservatives uptake showed that the active ingredients from all the eye drops together with preservatives were taken up by the lenses in significant amounts. For the in vivo study no traces of active ingredients or preservatives could be found on the worn and treated lenses regardless of time being worn or dosage profiles. The surface morphology changes in the in vivo study were also minor in contrast to the changes observed in the in vitro scanning electron microscopy images. Conclusion: The in vivo results demonstrate minor effects of the ophthalmic solutions on the worn lenses. These results do not support the building up of preservatives and drugs on the contact lenses as the cause of pain or discomfort experienced by some patients, which is encouraging for the use of bandage lenses in combination with ophthalmic solutions.
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| 13. |
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| 14. |
- De Lima, S., et al.
(författare)
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Rupture and chemical accumulation in contact lenses with dexamethasone eye drop administration after congenital cataract surgery
- 2021
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Ingår i: Acta Ophthalmologica. - : John Wiley and Sons Inc. - 1755-375X .- 1755-3768.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate whether contact lenses used after surgery for congenital cataracts act as a depot for dexamethasone, which would allow the prescribed amount of drops to be reduced, and to examine whether the preservative benzalkonium chloride accumulates in the contact lens matrix, which would suggest a need for more frequent replacements. Methods: Contact lenses (n = 10) worn by infants treated with dexamethasone eye drops after congenital cataract surgery were analysed with scanning electron microscopy, UV-vis, 1H-NMR and LDI-MS for chemical deposits and for changes on the contact lens surface. Unused lenses (n = 5) and lenses (n = 4) from patients with no eye drop treatment were analysed as reference. Results: The treated contact lenses displayed ruptured surfaces in comparison with unused and reference lenses. Dexamethasone and BAK were not detected in any of the lenses. A polyethylene oxide component was found in the treated lenses, likely originating from the dexamethasone eye drops or the contact lens solution. Conclusion: Dexamethasone and BAK do not accumulate in the contact lenses, and a depot effect of any clinical significance is unlikely. Therefore, the number of drops given after surgery should remain the same regardless of whether the child has contact lenses. The ruptured surface may both decrease the child’s comfort and increase the risk of microbial adhesion, and so it is recommended that contact lenses should be replaced once a month throughout the course of anti-inflammatory eye drop treatment after surgery for congenital cataract.
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| 15. |
- Delekta, Szymon Sollami, et al.
(författare)
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Fully inkjet printed ultrathin microsupercapacitors based on graphene electrodes and a nano-graphene oxide electrolyte
- 2019
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 11:21, s. 10172-10177
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Tidskriftsartikel (refereegranskat)abstract
- The advance of miniaturized and low-power electronics has a striking impact on the development of energy storage devices with constantly tougher constraints in terms of form factor and performance. Microsupercapacitors (MSCs) are considered a potential solution to this problem, thanks to their compact device structure. Great efforts have been made to maximize their performance with new materials like graphene and to minimize their production cost with scalable fabrication processes. In this regard, we developed a full inkjet printing process for the production of all-graphene microsupercapacitors with electrodes based on electrochemically exfoliated graphene and an ultrathin solid-state electrolyte based on nano-graphene oxide. The devices exploit the high ionic conductivity of nano-graphene oxide coupled with the high electrical conductivity of graphene films, yielding areal capacitances of up to 313 mu F cm-2 at 5 mV s-1 and high power densities of up to 4 mW cm-3 with an overall device thickness of only 1 mu m.
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| 16. |
- Duch, J., et al.
(författare)
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Work function modifications of graphite surface via oxygen plasma treatment
- 2017
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 419, s. 439-446
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Tidskriftsartikel (refereegranskat)abstract
- The surface modification of graphite by oxygen plasma was investigated experimentally (X-ray diffraction, nanoparticle tracking analysis, laser desorption ionization mass spectrometry, thermogravimetry, water contact angle) and by molecular modelling (Density Functional Theory). Generation of surface functional groups (mainly –OHsurf) leads to substantial changes in electrodonor properties and wettability gauged by work function and water contact angle, respectively. The invoked modifications were analyzed in terms of Helmholtz model taking into account the theoretically determined surface dipole moment of graphite—OHsurf system (μ = 2.71 D) and experimentally measured work function increase (from 0.75 to 1.02 eV) to determine the –OH surface coverage (from 0.70 to 1.03 × 1014 groups cm−2). Since the plasma treatment was confined to the surface, the high thermal stability of the graphite material was preserved as revealed by the thermogravimetric analysis. The obtained results provide a suitable quantitative background for tuning the key operating parameters of carbon electrodes: electronic properties, interaction with water and thermal stability.
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| 17. |
- Feng, Zhaoxuan, et al.
(författare)
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Carbon dot/polymer nanocomposites : From green synthesis to energy, environmental and biomedical applications
- 2021
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Ingår i: Sustainable Materials and Technologies. - : Elsevier BV. - 2214-9937. ; 29
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Tidskriftsartikel (refereegranskat)abstract
- Carbon dots (CDs), a novel family of multifunctional carbon-nanomaterials, has the potential to revolutionize several important fields supporting the transformation to sustainable bioeconomy. CDs are characterized by attractive properties such as tunable optoelectronic and fluorescence properties, low toxicity, good biocompatibility, bioactivity and superior water solubility. Diverse methods and precursors have been applied for the synthesis of CDs. The possibility to scale-up the synthesis of CDs by employing Green Chemistry principles is a current research hotspot and a prerequisite for large-scale production and applications. Incorporation of CDs into polymer matrices, is another emerging research area with wide potential application range. This approach endows additional desirable functions and enables easy handling and reuse. This review summarizes recent progress regarding the green synthesis of CDs, the fundamental strategies for the construction of CD/polymer nanocomposites and the state-of-art applications of the CD/polymer nanocomposites in the realm of energy storage, environment and biomedicine. Finally, the outlook including challenges and future potential of CDs and CD/polymer composites are discussed.
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| 18. |
- Feng, Zhaoxuan, et al.
(författare)
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Recent progress in the use of graphene/polymer composites to remove oil contaminants from water
- 2021
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Ingår i: Xinxing tancailiao. - : Elsevier BV. - 1007-8827. ; 36:2, s. 235-252
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Forskningsöversikt (refereegranskat)abstract
- Frequent oil spill accidents and the massive discharge of industrial oily sewage have destroyed the ecological balance and threatened marine life. Graphene (G) and graphene oxide (GO) have emerged as important materials in the field of oil/water separation because of their remarkable physicochemical properties including high specific surface area, low density, high porosity and tailorable surface functionality. To take full advantage of G and GO, their incorporation with polymers to build functional G/polymer and GO/polymer composites has recently gained increasing popularity because of their improved oil clean-up capability, outstanding mechanical performance, relatively low cost and adjustable surface chemical composition. Tremendous efforts have contributed to the development of G/polymer and GO/polymer composite oil clean-up sorbents and filtration membranes in 3D structural forms such as aerogels, foams, sponges and membranes. In this review, a comprehensive picture from the basic theory of the surface wettability to the recent advances in G/polymer and GO/polymer composite oil clean-up sorbents and filtration membranes are highlighted. The strategies for oil recovery and regeneration of the sorbents are also summarized. Current challenges and future research directions in this topic are provided, aimed at providing new perspectives for in-depth exploration in this field.
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| 19. |
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| 20. |
- Gazzotti, Stefano, et al.
(författare)
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One-Pot Synthesis of Sustainable High-Performance Thermoset by Exploiting Eugenol Functionalized 1,3-Dioxolan-4-one
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:11, s. 15201-15211
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Tidskriftsartikel (refereegranskat)abstract
- 1,3-Dioxolan-4-one (DOX) chemistry was explored for production of "one-pot" biobased polyester thermosets. DOX monomer was first functionalized by naturally occurring eugenol to introduce a structural element, which could induce cross-linking reaction through cationic polymerization of the double bond. The feasibility of polymerizing DOX monomers bearing bulky side groups was proven by model phenol-substituted DOX monomer (PhDOX). Once the reaction was shown to be effective, the same protocol was applied to eugenol-substituted monomer (EuDOX). A brief screening of the optimal catalyst concentration was performed, to obtain a highly cross-linked product. The synthesized thermoset showed good thermal resistance and high mechanical strength probably due to the rich aromatic content. The obtained thermoset was further subjected to microwave-assisted hydrothermal degradation test, which demonstrated complete recyclability to water or methanol soluble products. NMR and matrix-assisted laser desorption/ionization-mass spectroscopy analyses of the obtained degradation products unveiled the structure of the thermoset, strongly indicating that the polymerization of eugenol-functionalized DOX monomer resulted in polylactide-like chains connected with aromatic aliphatic segments resulting from the reaction of the eugenol double bonds. The presence of free hydroxyl and carboxyl groups sheds light on the mechanism behind the observed shape-memory and self-healing properties.
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| 21. |
- Hassanzadeh, Salman, et al.
(författare)
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Controlling the cooperative self-assembly of graphene oxide quantum dots in aqueous solutions
- 2015
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Ingår i: RSC Advances. - : RSC Publishing. - 2046-2069. ; 5:71, s. 57425-57432
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Tidskriftsartikel (refereegranskat)abstract
- Fascinating 3D cooperative self-assembly behavior was observed for 2D graphene oxide quantum dots (GOQDs) in dilute and semi dilute aqueous solutions. In addition the optical properties could be tuned by controlling the supramolecular structures. While the electrostatic interactions between the charged single sheets were assigned as the main secondary interactions that were responsible for the supramolecular fine structures, the concentration, temperature, salt concentration and pH could tune the repulsive/attractive forces and the molecular binding between the GOQD sheets. The morphological studies combined with UV-Vis and fluorescence evaluations proved that after a slow nucleation step, elongation preceded radially by H-aggregate self-association of the GOQD monomers, forming the final porous spheres by radial growth of rods. The quenching properties of the self-associated-assembled GOQDs together with the excitation wavelengths of the GOQD solutions enabled tuning of the fluorescence intensity and color of the final solutions, which could be utilized for e.g. bioimaging and smart spectroscopy.
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| 22. |
- Hassanzadeh, Salman, et al.
(författare)
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Supramolecular Assembly of Biobased Graphene Oxide Quantum Dots Controls the Morphology of and Induces Mineralization on Poly(epsilon-caprolactone) Films
- 2016
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 17:1, s. 256-261
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Tidskriftsartikel (refereegranskat)abstract
- Biobased 2D graphene oxide quantum dots (GOQDs) were synthesized from waste paper via carbon nanosphere intermediates and evaluated as property-enhancing additives for poly(epsilon-caprolactone) (PCL). The morphology of PCL films was controlled by supramolecular assembly of the small, 2D GOQDs in the polymer matrix. Phase behavior studies of PCL-GOQD in the solid state indicated concentration-dependent self-association of GOQD sheets, which was confirmed by SEM observations. Depending on the GOQD concentration, the formation of, e.g., spheres and stacked sheets was observed. GOQDs also induced mineralization on the surface of the films. A calcium phosphate (CaP) mineralization test revealed that the density of growing CaP crystals was controlled by the type of GOQD aggregates formed. Thus, utilization of the aggregation behavior of small GOQD sheets in polymeric matrices paves the way for tuning the morphology and properties of nanocomposites.
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| 23. |
- Magnusson, Mikael, et al.
(författare)
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Bioconversion of food waste to biocompatible wet-laid fungal films
- 2022
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Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 216
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Tidskriftsartikel (refereegranskat)abstract
- The fungus Rhizopus delemar was grown on bread waste in a submerged cultivation process and wet-laid into films. Alkali or enzyme treatments were used to isolate the fungal cell wall. A heat treatment was also applied to deactivate biological activity of the fungus. Homogenization of fungal biomass was done by an iterative ultrafine grinding process. Finally, the biomass was cast into films by a wet-laid process. Ultrafine grinding resulted in densification of the films. Fungal films showed tensile strengths of up to 18.1 MPa, a Young's modulus of 2.3 GPa and a strain at break of 1.4%. Highest tensile strength was achieved using alkali treatment, with SEM analysis showing a dense and highly organized structure. In contrast, less organized structures were obtained using enzymatic or heat treatments. A cell viability assay and fluorescent staining confirmed the biocompatibility of the films. A promising route for food waste valorization to sustainable fungal wet-laid films was established. © 2022 The Authors
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| 24. |
- Melilli, Giuseppe, et al.
(författare)
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Intriguing Carbon Flake Formation during Microwave-Assisted Hydrothermal Carbonization of Sodium Lignosulfonate
- 2020
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Ingår i: Global Challenges. - : Wiley. - 2056-6646. ; 4:8
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Tidskriftsartikel (refereegranskat)abstract
- Elongated carbon structures, here denoted as carbon flakes (CF), are revealed after microwave-assisted hydrothermal carbonization of sodium lignosulfonate. The morphology of formed CF is investigated by transmission electron microscopy and atomic force microscopy. Interestingly, a wide range of length distributions (between 100 and 700 nm) and a relatively constant aspect ratio and thickness are observed, indicating structures clearly different from the carbon spheres commonly formed during hydrothermal carbonization of lignocellulosic biomass. Moreover, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy provide further information of the chemical structure, which consist mainly of nanographitic domains with a high degree of defects such as oxygenated functional groups, hybridized sp(3) carbon, and aliphatic side chains. Furthermore, new insights into the formation mechanisms are uncovered and the formation is speculated to proceed through the combined effect of microwave irradiation and a heterogeneous solid-solid conversion. The formed CF are anticipated as highly interesting products for a variety of material applications.
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| 25. |
- Mohammadkhani, Ghasem, et al.
(författare)
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New Solvent and Coagulating Agent for Development of Chitosan Fibers by Wet Spinning
- 2021
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 13:13
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Adipic acid was evaluated as a novel solvent for wet spinning of chitosan fibers. A solvent with two carboxyl groups could act as a physical crosslinker between the chitosan chains, resulting in improved properties of the fibers. The performance of adipic acid was compared with conventional solvents, i.e., lactic, citric, and acetic acids. Chitosan solutions were injected into a coagulation bath to form monofilaments. Sodium hydroxide (NaOH) and its mixture with ethanol (EtOH) were used as coagulation agents. Scanning electron microscopy confirmed the formation of uniform chitosan monofilaments with an even surface when using adipic acid as solvent. These monofilaments generally showed higher mechanical strength compared to that of monofilaments produced using conventional solvents. The highest Young’s modulus, 4.45 GPa, was recorded for adipic acid monofilaments coagulated in NaOH-EtOH. This monofilament also had a high tensile strength of 147.9 MPa. Furthermore, taking advantage of chitosan insolubility in sulfuric acid (H2SO4) at room temperature, chitosan fibers were successfully formed upon coagulation in H2SO4-EtOH. The dewatering of fibers using EtOH before drying resulted in a larger fiber diameter and lower mechanical strength. Adipic acid fibers made without dehydration illustrated 18% (for NaOH), 46% (for NaOH-EtOH), and 91% (for H2SO4-EtOH) higher tensile strength compared to those made with dehydration.
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| 26. |
- Svensson, Sofie, et al.
(författare)
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Fungal textiles : Wet spinning of fungal microfibers to produce monofilament yarns
- 2021
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Ingår i: Sustainable Materials and Technologies. - : Elsevier BV. - 2214-9937. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- The cell wall of a zygomycetes fungus was successfully wet spun into monofilament yarns and demonstrated as a novel resource for production of sustainable textiles. Furthermore, the fungus could be cultivated on bread waste, an abundant food waste with large negative environmental impact if not further utilized. Rhizopus delemar was first cultivated in bread waste in a bubble column bioreactor. The fungal cell wall collected through alkali treatment of fungal biomass contained 36 and 23% glucosamine and N-acetyl glucosamine representing chitosan and chitin in the cell wall, respectively. The amino groups of chitosan were protonated by utilizing acetic or lactic acid. This resulted in the formation of a uniform hydrogel of fungal microfibers. The obtained hydrogel was wet spun into an ethanol coagulation bath to form an aggregated monofilament, which was finally dried. SEM images confirmed the alignment of fungal microfibers along the monofilament axis. The wet spun monofilaments had tensile strengths up to 69.5 MPa and Young's modulus of 4.97 GPa. This work demonstrates an environmentally benign procedure to fabricate renewable fibers from fungal cell wall cultivated on abundant food waste, which opens a window to creation of sustainable fungal textiles.
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| 27. |
- Svensson, Sofie, et al.
(författare)
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Turning food waste to antibacterial and biocompatible fungal chitin/chitosan monofilaments
- 2022
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 209, s. 618-630
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Tidskriftsartikel (refereegranskat)abstract
- Here, cell wall of a zygomycete fungus, Rhizopus delemar, grown on bread waste was wet spun into monofilaments. Using the whole cell wall material omits the common chitosan isolation and purification steps and leads to higher material utilization. The fungal cell wall contained 36.9% and 19.7% chitosan and chitin, respectively. Solid state NMR of the fungal cell wall material confirmed the presence of chitosan, chitin, and other carbohydrates. Hydrogels were prepared by ultrafine grinding of the cell wall, followed by addition of lactic acid to protonate the amino groups of chitosan, and subsequently wet spun into monofilaments. The monofilament inhibited the growth of Bacillus megaterium (Gram+ bacterium) and Escherichia coli (Gram- bacterium) significantly (92.2% and 99.7% respectively). Cytotoxicity was evaluated using an in vitro assay with human dermal fibroblasts, indicating no toxic inducement from exposure of the monofilaments. The antimicrobial and biocompatible fungal monofilaments, open new avenues for sustainable biomedical textiles from abundant food waste.
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| 28. |
- Wersäll, Johan H, 1975, et al.
(författare)
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Relative poverty is associated with increased risk of diabetic ketoacidosis at onset of type 1 diabetes in children. A Swedish national population-based study in 2014-2019
- 2024
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Ingår i: DIABETIC MEDICINE. - : WILEY. - 0742-3071 .- 1464-5491.
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The aim of the study was to estimate the effect of household relative poverty on the risk of diabetic ketoacidosis at diagnosis of children with type 1 diabetes using an international standard measurement of relative poverty.Methods: A national population-based retrospective study was conducted. The Swedish National Diabetes Register (NDR) was linked with data from Sweden's public statistical agency (Statistics Sweden). Children who were diagnosed with new-onset type 1 diabetes in the period of 2014-2019 were common identifiers. The definition of diabetic ketoacidosis was venous pH <7.30 or a serum bicarbonate level <18 mmol/L. The exposure variable was defined according to the standard definition of the persistent at-risk-of-poverty rate used by the statistical office of the European Union (Eurostat) and several other European public statistical agencies. Univariate and multi-variable analyses were used to calculate the effect of relative poverty on the risk of diabetic ketoacidosis.Results: Children from households with relative poverty had a 41% higher risk of diabetic ketoacidosis (1.41, CI 1.12-1.77, p = 0.004) and more than double the risk of severe diabetic ketoacidosis (pH <7.10) (RR 2.10, CI 1.35-3.25, p = 0.001), as compared to children from households without relative poverty.Conclusions: Relative poverty significantly increases the risk of diabetic ketoacidosis at onset of type 1 diabetes in children, even in a high-income country with publicly reimbursed health care.
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| 29. |
- Wijayarathna, E.R. Kanishka B., et al.
(författare)
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Fungal textile alternatives from bread waste with leather-like properties
- 2022
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Ingår i: Resources, Conservation and Recycling. - : Elsevier. - 0921-3449 .- 1879-0658. ; 179
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Tidskriftsartikel (refereegranskat)abstract
- Food waste and fashion pollution are two of the most prominent global environmental issues. To alleviate the problems associated with food waste, while simultaneously contributing to sustainable fashion, the feasibility of making an alternative textile material with leather-like properties from fungal biomass cultivated on bread waste was investigated. The filamentous fungus, Rhizopus delemar, was successfully grown on waste bread in a submerged cultivation process, and fungal biomass was treated with vegetable tannin of chestnut wood. NMR and FTIR confirmed interactions between tannin and fungal biomass, while OM, SEM and AFM visualised the changes in the hyphae upon the tannin treatment. Thermal stability was assessed using TGA analysis. The wet-laid technique commonly utilised for paper-making was used to prepare sheets of hyphae. Some of the sheets were treated with glycerol and/or a biobased binder as post-treatment. Overall, three of the produced materials exhibited leather-like properties comparable to that of natural leather. Sheets from untreated biomass with only glycerol post-treatment showed a tensile strength of 7.7 MPa and an elongation at break of 5%. Whereas sheets from untreated biomass and tannin treated biomass with both glycerol and binder treatments led to tensile strengths of 7.1 MPa and 6.9 MPa, and the elongation at break of 12% and 17%, respectively. The enhancement of hydrophobicity after the binder treatment, helped to preserve the absorbed glycerol within the sheet and thereby the flexibility was retained when in contact with moisture. These findings demonstrate that bread waste-derived fungal sheets have great potential as environmentally friendly materials with leather-like properties.
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| 30. |
- Wijayarathna, E.R. Kanishka B., et al.
(författare)
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Tunable Fungal Monofilaments from Food Waste for Textile Applications
- 2024
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Ingår i: Global Challenges. - : John Wiley & Sons. - 2056-6646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- A fungal biorefinery is presented to valorize food waste to fungal monofilaments with tunable properties for different textile applications. Rhizopus delemar is successfully grown on bread waste and the fibrous cell wall is isolated. A spinnable hydrogel is produced from cell wall by protonation of amino groups of chitosan followed by homogenization and concentration. Fungal hydrogel is wet spun to form fungal monofilaments which underwent post-treatments to tune the properties. The highest tensile strength of untreated monofilaments is 65 MPa (and 4% elongation at break). The overall highest tensile strength of 140.9 MPa, is achieved by water post-treatment. Moreover, post-treatment with 3% glycerol resulted in the highest elongation % at break, i.e., 14%. The uniformity of the monofilaments also increased after the post-treatments. The obtained monofilaments are compared with commercial fibers using Ashby's plots and potential applications are discussed. The wet spun monofilaments are located in the category of natural fibers in Ashby's plots. After water and glycerol treatments, the properties shifted toward metals and elastomers, respectively. The compatibility of the monofilaments with human skin cells is supported by a biocompatibility assay. These findings demonstrate fungal monofilaments with tunable properties fitting a wide range of sustainable textiles applications.
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| 31. |
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| 32. |
- Yadav, Nisha, et al.
(författare)
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Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate
- 2021
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 22:5, s. 2211-2223
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Tidskriftsartikel (refereegranskat)abstract
- Chemical modification of biopolymers, before use in thermo-plastic applications, can reduce the susceptibility to open environment degradation. We demonstrate carbon dots (CDs) as green photocatalytic triggers that can render the common cellulose derivative, cellulose acetate (CA), degradable under open environment relevant conditions. CD-modified cellulose acetate (CA + CD) films were subjected to UV-A irradiation in air and simulated sea water, and the degradation process was mapped by multiple spectroscopic, chromatographic, and microscopy techniques. The addition of CDs effectively catalyzed the deacetylation reaction, the bottleneck preventing biodegradation of CA. The photocatalytically activated degradation process led to significant weight loss, release of small molecules, and regeneration of cellulose fibers. The weight loss of CA + CD after 30 days of UV-A irradiation in air or simulated sea water was 53 and 43%, respectively, while the corresponding values for plain CA films were 12 and 4%. At the same time the weight average molar mass of CA + CD decreased from 62,000 to 11,000 g/mol and 15,000 g/mol during UV-A irradiation in air and simulated sea water, respectively, and the degree of substitution (DS) decreased from 2.2 to 1.6 both in air and in water. The aging in water alone did not affect the weight average molar mass, but the DS was decreased to 1.9. Control experiments confirmed the generation of hydrogen peroxide when aqueous CD dispersion was subjected to UV-A irradiation, indicating a free radical mechanism. These results are promising for the development of products, such as mulching films, with photocatalytically triggered environmental degradation processes.
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| 33. |
- Yiga, Vianney Andrew, et al.
(författare)
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Combustion, kinetics and thermodynamic characteristics of rice husks and rice husk-biocomposites using thermogravimetric analysis
- 2023
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer Nature. - 1388-6150 .- 1588-2926. ; 148:21, s. 11435-11454
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis of rice husk (RH), alkali-treated cellulose-rich rice husk (RHC), chemically modified RHC (RHCM) and RH-biocomposites by thermogravimetric analysis was carried out to determine combustion and kinetic parameters at three different heating rates of 20, 40 and 50 degrees C min-1. Combustion performance was analyzed from results of ignition temperature, burnout temperature, combustion rates, flammability index and combustion characteristic index. Increase in heating rate from 20 to 40 and further to 50 degrees C min-1 increased the onset of degradation, burnout and peak temperatures as observed by curve shifts to the right. Maximum combustion rates were around 0.57-0.59% min-1, 1.03% min-1 and 0.63-0.69% min-1 for RH, RHC and RHCM, respectively. For the RH-biocomposites, the maximum combustion rates were in a 0.76-0.97% min-1 range. Their average pre-exponential factors using KAS method were in the 2.24E-03-8.07E-03 range, respectively, while those for OFW method were in the 7.75E + 04-4.55E + 06 range, respectively. Average activation energies of RH-biocomposites were in the 41.0-58.2 kJ mol-1 and 48.3-67.7 kJ mol-1 ranges for KAS and OFW methods, respectively. The data were well fitting with coefficient of determination (R2) values close to 1. Average Delta G value ranges for RH-biocomposites ranged between 148.2 and 161.7 kJ mol-1. The low-energy barrier (<= 5.4 kJ mol-1) between activation energy and enthalpy changes indicated that reaction initiation occurs easily.
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