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The incorporation of TEMPO-oxidized cellulose nanofibers (TOCNs) derived from wood pulp resulted in an improvement in the characteristics of polymeric membranes made up of poly (methyl vinyl ether maleic acid)/PMVEMA and poly (ethylene glycol)/PEG. The membranes were constructed, and TOCNs were included in the formulation at a rate of 5 wt%. TOCNs were categorized as either short or long, depending on the aspect ratio measurement. According to the findings of the research, the various lengths of TOCNs resulted in variances in the optical transmittance properties, contact angles, and whiteness level of the membranes, in addition to a little variation in the tensile and thermal properties of the material. When compared to short TOCNs, long TOCNs offer somewhat improved performance in terms of optical transmittance, whiteness level, tensile characteristics, and thermal stability. The results of this study reveal the significance of the morphology of nanocellulose in determining the properties of the composite that includes it. Thus, the characteristics of the target membrane were greatly influenced by nanocellulose morphology. [ABSTRACT FROM AUTHOR]

Nanocellulose made by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-catalyzed oxidation, described as TEMPO-oxidized cellulose nanofibers (TOCNs), has a high density of negative charges on its surface. Its use in microbial fermentation systems is expected to benefit microbial process stability. In particular, microbial stability is strongly required in acetone-butanol-ethanol (ABE) fermentation associated with the solvent-extraction process of butanol production. Here, TOCNs derived from oil palm empty fruit bunches pulp were added to extractive ABE fermentation media containing glucose as a main source, which can be potentially obtained from biomass by saccharification. Then, microbial fermentation was carried out using free or immobilized bacterial cells, to produce butanol from glucose. The presence of TOCNs induced higher total butanol production in broth by improving the growth environment of Clostridium saccharoperbutylacetonicum N1-4, which was used as the butanolproducing strain. Microscopic analysis revealed that the spider-web-like TOCN network helped to entrap bacterial cells in alginate beads, by ionic crosslinking of TOCNs and alginates via Ca2+ ions, to increase stability of bacterial cells in the composite gel beads. The addition of TOCNs to fermentation media had significant positive effects on the total butanol yield. [ABSTRACT FROM AUTHOR]

2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofbers (TOCNs), which have a high-density of exposed carboxylic acid groups on their crystalline surfaces, efectively act as acid catalysts in acetal hydrolysis. Carboxy-free cellulose nanofbers, polymeric carboxylic acids, and homogeneous acetic acid do not show signifcant catalytic activity under the same reaction conditions. Mercerized TOCNs difering from the original TOCNs in a crystalline structure were also inefective, which suggests that the unique nanoarchitectural features of TOCNs, such as regularly aligned carboxylic acid groups, large specifc surface areas, and structural rigidity, must be major factors in the acceleration of acetal hydrolysis. Kinetic analysis suggested that substrates and/or acid catalyst species were concentrated on the TOCN crystalline surfaces, which signifcantly enhanced the catalytic activity. [ABSTRACT FROM AUTHOR]

DFT studies were carried out to clarify the reaction mechanism and the stereocontrolling elements in the addition reaction of vinylindoles with azlactones catalyzed by a chiral phosphoric acid. The results suggest that the reaction proceeds via a six-membered transition state that is composed of the vinyl group of vinylindole and the enol moiety of azlactone. [ABSTRACT FROM AUTHOR]