Mesoporous Polymer Loading Heteropolyacid Catalysts: One-Step Strategy To Manufacture High Value-Added Cellulose Acetate Propionate

Abstract

Cellulose esters are cellulose derivatives with broad application in plastics, films, fibers, coatings, textiles industries, and so forth. Taking cellulose acetate propionate (CAP) as an example, high-viscosity CAP products are widely used in printing inks, hot-melt dip coatings and lacquer coatings, and so forth. However, it was and remains to be a great challenge to manufacture high-viscosity CAP derivatives because of the overuse of sulfuric acid as catalyst that can degrade cellulose and then affect the viscosity and molecular weight of the product. Herein, with use of the copolymer of divinylbenzene with 4-vinylbenzyl chloride (PDVB–VBC) as support, imidazole-containing ionic liquid (IM) as linker, and polyoxometalates (POMs) as catalytic active sites, novel solid acid catalysts of PDVB–VBC–IM–POMs are prepared and fully characterized by Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, nuclear magnetic resonance, Brunauer–Emmett–Teller, thermogravimetry-differential scanning calorimetry, and X-ray photoelectron spectroscopy. Application of the as-prepared catalysts for CAP shows the following advantages: (1) high viscosity and high molecular weight (Mw) of CAP can be achieved; (2) partially substituted CAP product (degree of substitution, 2.18–2.77) can be obtained without necessity of the hydrolysis step, in which the relatively higher substitution degree of cellulose takes place at the C6 position. This work shows the great potential of new designed solid acid catalyst for high value-added cellulose derivatives.