Bacterial cellulose (BC) exhibits beneficial properties for use in biomedical applications but is limited by its lack of tunable transparency capabilities. To overcome this deficiency, a novel method to synthesize transparent BC materials using an alternative carbon source, namely arabitol, was developed. Characterization of the BC pellicles was performed for yield, transparency, surface morphology, and molecular assembly. Transparent BC was produced using mixtures of glucose and arabitol. Zero percent arabitol pellicles exhibited 25% light transmittance, which increased with increasing arabitol concentration through to 75% light transmittance. While transparency increased, overall BC yield was maintained indicating that the altered transparency may be induced on a micro-scale rather than a macro-scale. Significant differences in fiber diameter and the presence of aromatic signatures were observed. Overall, this research outlines methods for producing BC with tunable optical transparency, while also bringing new insight to insoluble components of exopolymers produced by Komagataeibacter hansenii.

ADVERTISEMENT RETURN TO ISSUESpecial Issue Prefac...Special Issue PrefaceNEXTTribute to Hellmut EckertLuis SmithLuis SmithMore by Luis Smith and Leo van WüllenLeo van WüllenMore by Leo van Wüllenhttp://orcid.org/0000-0002-2493-7258Cite this: J. Phys. Chem. C 2021, 125, 17, 8919–8920Publication Date (Web):May 6, 2021Publication History Published online6 May 2021Published inissue 6 May 2021https://pubs.acs.org/doi/10.1021/acs.jpcc.1c02995https://doi.org/10.1021/acs.jpcc.1c02995introductionACS PublicationsCopyright © 2021 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views669Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (1 MB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Amorphous materials,Chalcogenides,Coupling reactions,Nuclear magnetic resonance spectroscopy,Resonance structures Get e-Alerts

Increasing the stability of zeolites in liquid, near-critical, and supercritical water at temperatures greater than 200 degrees C is required for many important chemical processes, notably including hydrothermal liquefaction. Extending ZSM-5 stability under these conditions was studied using silylation, hydrothermal carbonization, and sequential hydrothermal carbonization and pyrolysis treatments. Coatings resulting from silylation and hydrothermal carbonization were not hydrothermally stable at temperatures greater than 300 degrees C. In comparison, the coating formed by sequential hydrothermal carbonization and pyrolysis was thermally stable at temperatures as great as 550 degrees C and hydrothermally stable in the presence of a supercritical water phase at 400 degrees C. The carbon-coated ZSM-5 (termed C-ZSM-5) was studied for stability and activity for dodecane cracking in supercritical water. C-ZSM-5 exhibited similar cracking activity compared with ZSM-5 while retaining more crystallinity and Bronsted acid sites (BAS) density. The C-ZSM-5 failure mechanism is the disruption of the carbon-zeolite interface during use. C-ZSM-5 has the potential for extending zeolite stability in liquid water at more severe conditions than previously examined.

Zeolites have recently attracted attention for upgrading renewable resources in the presence of liquid water phases; however, the stability of zeolites in the presence of liquid-phase water is not completely understood. Accordingly, the stability of the ZSM-5 framework and its acid sites was studied in the presence of water at temperatures ranging from 250 to 450 °C and at pressures sufficient to maintain a liquid or liquid-like state (25 MPa). Treated samples were analyzed for framework degradation and Al content and coordination using a variety of complementary techniques, including X-ray diffraction, electron microscopy, N2 sorption, 27Al and 29Si NMR spectroscopy, and several different types of infrared spectroscopy. These analyses indicate that the ZSM-5 framework retains >80% crystallinity at all conditions, and that 300-400 °C are the most aggressive. Decrystallization appears to initiate primarily at crystal surfaces and share many characteristics in common with alkali promoted desilication. Liquid water treatment promotes ZSM-5 dealumination, following a mechanism analogous to that observed under steaming conditions: initiation by Al-O hydrolysis, Al migration to the surface, and finally deposition as extra framework Al or possibly complete dissolution under some conditions. As with the framework, dealumination is most aggressive at 300-400 °C. Several models were evaluated to capture the non-Arrhenius effect of temperature on decrystallization and dealumination, the most successful of which included temperature dependent values of the water auto-ionization constant. These results can help interpretation of previous studies on ZSM-5 catalysis in hot liquid water and suggest future approaches to extend catalyst lifetime.

Dion-Jacobson layered niobates have been extensively researched in recent years because of a variety of useful properties such as dielectric behavior, proton conduction, and solid acid catalysis. The behavior of these materials is strongly dependent on the elemental composition and, more specifically, the interlayer surface environment. A novel method of partial grafting of n-alcohols into the interlayer of HSr2Nb3O10 with approximately 40% conversion has been developed using microwave irradiation to generate high temperatures. This method has reduced the grafting reaction time by more than 97% while maintaining conversion rates consistent with previous methods.

Highly conductive solid polymer electrolytes were generated by blending linear poly(ethyleneimine)-graft-poly(ethylene glycol) with linear poly(ethyleneimine) bearing lithium N-propylsulfonate groups as the lithium source. The effect of polymer backbone structure on Li+ conductivity was determined by comparing a series of blends made from the PEI-based materials with those from polymethacrylate backbone analogues. The use of PEI backbones promoted ion-pair dissociation, stabilized the macromolecular mix and generated blends with ionic conductivities up to 2 orders of magnitude higher than those of the polymethacrylate-based systems. Blends containing the PEI-bound lithium sulfonates exhibited lithium conductivities higher than those measured for PEG doped with lithium bis(trifluoromethyl)sulfonimide. Shifts in the v(s)(SO3) IR absorption band suggest that the solvation environment for the lithium sulfonates changes with polymer structure. The PEI-based blends are thermally stable up to 200 degrees C , electrochemically stable in the +/- 5 V range, and showed unparalleled ionic conductivities (0.4 mS/cm at room temperature and 5 mS/cm at 80 degrees C) for solvent-free systems with polymer-bound anions.