Core–shell Assembly of Heteropolyacids and Polymer: Efficient Preparation of Cellulose Acetate Propionate and Its Processed Products

As a biomass-derived polymer, cellulose acetate propionate (CAP) is widely used in food packaging, plastics and coatings, and so forth. In order to produce CAP in a green and environmentally benign way, we fabricated a novel solid acid PS@PMA-ZrO 2 -PW 12 (PS = polystyrene, PMA = poly(methyl acrylate), PW 12 = H 3 PW 12 O 40 · x H 2 O) with core–shell structure, in which the ZrO 2 -modified PMA shell was constructed by a Si–O–Zr framework, phosphotungstic acid (PW 12 ) was immobilized on the shell via strong interaction between PW 12 and ZrO 2, and PS was used as the core. The as-prepared PS@PMA-ZrO 2 -PW 12 showed excellent catalytic performance for the preparation of CAP with a M w of 100 644, DS of 2.73, and viscosity of 320 mPa·s. Compared with well-known Amberlyst-15 and H 2 SO 4 under the same reaction conditions, the PS@PMA-ZrO 2 -PW 12 exhibited the advantages of the controllable reaction process with CAP of higher viscosity and M w . In addition, we processed the CAP into the film without addition of any plasticizers and investigated its optical and mechanical properties. It is found that the CAP film displayed optically transparent property with transmittance >90%, high flexibility with 32.67% for elongation at the break, and easy dyeability. As such, the designed heteropolyacids immobilized on the ZrO 2 -modified polymer catalyst with a core–shell structure can act as a promising candidate for the manufacture of CAP.