| 1. |
- Hatti-Kaul, Rajni, et al.
(författare)
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Designing Biobased Recyclable Polymers for Plastics
- 2020
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Ingår i: Trends in Biotechnology. - : Elsevier BV. - 0167-7799. ; 38:1, s. 50-67
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Forskningsöversikt (refereegranskat)abstract
- Several concurrent developments are shaping the future of plastics. A transition to a sustainable plastics system requires not only a shift to fossil-free feedstock and energy to produce the carbon-neutral building blocks for polymers used in plastics, but also a rational design of the polymers with both desired material properties for functionality and features facilitating their recyclability. Biotechnology has an important role in producing polymer building blocks from renewable feedstocks, and also shows potential for recycling of polymers. Here, we present strategies for improving the performance and recyclability of the polymers, for enhancing degradability to monomers, and for improving chemical recyclability by designing polymers with different chemical functionalities.
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| 2. |
- Sayed, Mahmoud, et al.
(författare)
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5-Hydroxymethylfurfural from fructose : An efficient continuous process in a water-dimethyl carbonate biphasic system with high yield product recovery
- 2020
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 22:16, s. 5402-5413
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Tidskriftsartikel (refereegranskat)abstract
- Bio-based 5-hydroxymethylfurfural (5-HMF) and its derivatives have attracted enormous attention due to their valuable market potential. Production of pure 5-HMF is challenging owing to the high reactivity of its functional groups and formation of by-products. In this study, an efficient continuous process for 5-HMF production in a biphasic system and its recovery at high yield and selectivity was developed. After an initial screening of different solvents, a water/dimethyl carbonate (DMC) system was selected for acid catalyzed fructose dehydration in a continuous mode using 0.23 M HCl as a catalyst. Effects of various reaction parameters on substrate conversion, product yield and selectivity, were determined. The process using 30% (w/v) fructose in water with three times the volume of DMC at 1 min residence time in a tube reactor at 200 °C provided 96.5% fructose conversion and 87.2% 5-HMF yield with a selectivity of 85.5% and 95.8% in aqueous and organic phases, respectively. Increasing the fructose concentration in the water phase to 52% gave 96.4% conversion and 74% 5-HMF yield. Using a fructose-glucose mixture as substrate had no effect on fructose conversion but affected slightly the selectivity of 5-HMF in the aqueous phase. Recovery of 5-HMF with ≥93% purity from DMC was achieved by solvent evaporation under vacuum, and improved by prior treatment with activated carbon, especially together with Na2CO3. Evaluation of the purified 5-HMF in a reaction with pentaerythritol showed comparable performance to the commercial 5-HMF in the production of a spirocyclic diol, a monomer for the production of polyesters and polyurethane.
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| 3. |
- Wang, Ping, et al.
(författare)
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Synthesis, molecular docking simulation and enzymatic degradation of AB-type indole-based polyesters with improved thermal properties
- 2020
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 21:3, s. 1078-1090
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Tidskriftsartikel (refereegranskat)abstract
- We report the facile synthesis of a series of indole-based hydroxyl-carboxylate (AB-type) monomers by a one-step procedure. These monomers were successfully polymerized by melt-polycondensation to yield AB-type polyesters with a varied number of flexible methylene units in the backbones. These indole-based AB-polyesters showed decent thermal stability according to the TGA results (onset thermal degradation temperature >330 °C), and their glass transition temperatures are dependent on the length of the methylene bridge (Tg ~ 62-102 °C) according to the DSC results. Furthermore, DSC and WAXD measurements revealed that these polymers did not crystalize from melt, but the ones with flexible structures could crystalize from solution. Molecular docking simulations showed favorable interactions between indole-based polyester and polyethylene terephthalate hydrolase (PETase) from Idonella sakaiensis. This was corroborated by the experimental results, which indicated that the PETase enzyme has degrading activity on the indole-based AB polyesters except for the one with the highest degree of crystallinity.
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