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This research aims to investigate nonionic hyperbranched polyesters (HBPs) derived from indole and lignin resources as new nontoxic antimicrobial coatings. Three nonionic HBPs with zero to two methoxy ether substituents on each benzene ring in the polymer backbones were synthesized by melt-polycondensation of three corresponding AB 2 monomers. The molecular structures and thermal properties of the obtained HBPs were characterized by gel permeation chromatography, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry analyses. These HBPs were conveniently spin-coated on a silicon substrate, which exhibited significant antibacterial effect against Gram-negative ( Escherichia coli and Pseudomonas aeruginosa ) and Gram-positive bacteria ( Staphylococcus aureus and Enterococcus faecalis ). The presence of methoxy substituents enhanced the antimicrobial effect, and the resulting polymers showed negligible leakage in water. Finally, the polymers with the methoxy functionality exhibited excellent biocompatibility according to the results of hemolysis and MTT assay, which may facilitate their biomedical applications.

A new B3‐type blocked isocyanate core and AB2‐type building block molecules containing bis‐indole moiety were synthesized via a scalable synthetic routes. Starting with these molecules, amine‐ and blocked isocyanate‐terminated polyurethane dendrimers up to third generation were build‐up using (i) a simple urethane interchange reaction, (ii) deprotection of amine and (iii) efficient conversion of amine into blocked isocyanate groups. The structural integrity of the core, building block and their intermediates were verified using FT‐IR, 1H‐NMR, and 13C‐NMR spectroscopy and HR‐MS technique. The structure and molecular weight of blocked isocyanate‐terminated dendrimers were confirmed using 1H‐NMR spectra and size exclusion chromatography with multi angle laser light scattering detector (SEC‐MALLS) technique respectively whereas the structure of all other dendrimers were confirmed using FT‐IR, 1H‐NMR, and 13C‐NMR spectroscopy. Dye‐sensitized solar cells (DSSC) were fabricated using these dendrimers as electrolytes; the DSSC fabricated with G3 dendrimer yielded an overall energy conversion efficiency (η) of 6.32 % upon illumination with 1 sun visible light.

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An amine‐terminated hyperbranched poly(aryl‐ether‐urea) (HBPEU) was prepared from an AB2‐type blocked isocyanate monomer and then its end groups were modified into urea (M‐HBPEU) by reaction with phenyl isocyanate. Both of the polymers were doped with N3‐dye along with KI/I2 to work as efficient polymer electrolytes in nanocrystalline dye sensitized solar cell. The increment in the conductivity of doped HBPEU and doped M‐HBPEU was very significant and reached its value at 8.2 × 10−3 and 4.1 × 10−2 S/cm, respectively. The current–voltage (I–V) characteristics of these two doped polymers measured under simulated sunlight with AM 1.5 at 60 mW/cm2 generate photocurrent of 2.5 and 3.6 mA/cm2, together with a photo voltage of 690 and 750 mV, and fill factor of 0.55 and 0.61 yielding a overall energy conversion efficiency of 2.4% and 4.1%, respectively. These results suggest that M‐HBPEU show better cell performance and conductance properties than the HBPEU. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40408.

Unfortunately, due to crosslinked molecular structure, traditional thermoset cannot be thermally reprocessed leading to in best case downcycling or incineration of the materials at the end of use phase. [4,5] Research focused on development of circular thermosets is, therefore, critical for reaching sustainability goals.Associative and dissociative covalent adaptable networks [6] utilize different dynamic covalent chemistries (DCC) to combine the desired properties of thermosets with the properties typical of thermoplastics, such as thermal reprocessability. Additionally, these materials can often be chemically recycled back to original building blocks under facile conditions compared to traditional polymer materials. Leibler et al. first introduced epoxy vitrimers by using transesterification in 2011. [6] After that many DCC reactions have been utilized including transesterification, trans alkylation, transamination, olefin metathesis, Diels-Alder reactions, disulfide exchange, transcarbamoylation and imine exchanges, [7] exploiting, for example, ester, [8][9][10] disulfide, [11,12] vinylogous urethane, [13,14] and imine bonds [5,[15][16][17] Most synthetic thermosets are produced from fossil-based resources. Epoxy-thermosets are at the forefront of biobased thermoset materials, but still >90% of epoxy thermosets are obtained from fossil based resources. [18] Epoxy-thermosets have high performance and enable many products and technologies used in day to day life. [19][20][21][22][23][24] However, many epoxy-thermoset precursors, such as bisphenol A (BPA), are both fossil-based and toxic and hazardous to the living organisms. [18,25] As an example BPA exhibits estrogenic activity and is suspected as human endocrine disruptor.Schiff base chemistry involving a reaction between aldehyde or ketone with amine has been widely used in biological and medical applications, in catalysis, photo and analytical chemistry. In recent years, it appeared as an attractive DCC for synthesis thermosets containing the imine bond (CN) capable of participating in both dissociative and associative exchange reactions. [26] These imine bonds can rearrange at higher temperatures, resulting thermally reprocessable thermosets. [27,28] Furthermore, Schiff-base/imine bond is unstable under acidic conditions enabling chemical recycling under mild conditions. [29] Furthermore several aromatic aldehydes, such as vanillin and hydroxymethyl furfural, can be derived from biobasedThe paradigm shift from traditional petroleum-based non-recyclable thermosets to biobased repeatedly recyclable materials is required to move toward circular bioeconomy. Here, two mechanically and chemically recyclable extended vanillin-derived epoxy thermosets are successfully fabricated by introduction of Schiff-base/imine covalent dynamic bonds. Thermoset 1 (T1) is based on linear monomer 1 (M1) with two alcohol end groups and one imine bond, while thermoset 2 (T2) is based on branched monomer 2 (M2) with three alcohol end-groups and three imine-groups. Thermosets are ...

Detrimental effect of counter electrode corrosion, electrolyte leakage problem, and sublimation of iodine ions affect the performance and stability of dye-sensitized solar cells (DSSCs) based on a liquid redox electrolyte system. TEMPO/TEMPO + is the most desirable one to replace the existing redox couples in liquid electrolyte owing to its rapid and reversible one electron kinetics, high diffusion coefficient, and electrochemical stability. In the present study, a fifth generation polyurethane dendrimer end-capped with 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) was prepared and employed as an active redox mediator to replace up to 75% of iodine ions in the standard liquid iodide electrolyte system to elucidate the effect of a quick selfexchange reaction in DSSCs. In this concern, quasi-gel type electrolytes were prepared by incorporating different amounts of a newly prepared TEMPO radical dendrimer to a liquid I − /I 3 − redox system and were used as a dual redox mediator for DSSCs. Blending of 50 wt % of I − /I 3 − electrolyte with 50 wt % of the radical dendrimer improved the device performance (η) unprecedentedly from 6.56 to 9.54% upon illumination with 1 sun intensity. Thorough electrochemical characterization of cells was carried out and all such parameters authenticated this remarkable enhancement. Stability of the device was also found to be good, which retained its >80% efficiency after 30 days.

2,5-furandicarboxylic acid (FDCA) has gained great industrial interest as a renewable alternative to terephthalic acid (TPA) in the generation of bioplastics. However, chemical production of FDCA involves harsh reaction conditions not aligned with sustainable manufacturing. Herein, we demonstrate the use of whole-cell mediated synthesis of FDCA from 2-furoic acid (FA) as substrate. Our approach moves away from the use of isolated enzymes by supplementing the UbiDÀ UbiX system in E. coli with the gene of P. thermopropionicum HmfF (PtHmfF) known to generate FDCA. The resulting whole-cell system allows for production of FDCA under mild conditions by carboxylation of FA. We show how the enzymatically produced FDCA can be used to generate FDCA-based biopolymers along with a terpene-based diol monomer by enzymatic polycondensation catalyzed by Candida antarctica lipase B (CALB). This work highlights how underutilized hemicellulose-derived C5 building blocks can be converted into renewable platform chemicals and materials by a simple cell factory in a CO 2 sequestration process.