“Grafting-From” Synthesis of Cellulose Acetate-graft-Poly(propylene carbonate) and Evaluation of Its Physical Properties

Poly(propylene carbonate) (PPC) is synthesized through the alternating copolymerization of propylene oxide (PO) and carbon dioxide (CO2) and has been widely studied as a sustainable polymer material. Although PPC is known for its biodegradability, biocompatibility, high optical transparency, and gas-barrier property, its relatively low thermal stability and limited mechanical strength restrict its broader practical applications. To address these limitations, we designed a graft copolymer that integrates PPC with a mechanically robust and biodegradable backbone. Cellulose acetate (CA), a high-performance thermoplastic widely utilized in fiber and film applications, was employed as the backbone, and PPC segments were covalently introduced as side chains to construct CA-graft-PPC. The designed CA-graft-PPC was synthesized by the “grafting-from” strategy, in which the PO/CO2 alternating copolymerization was conducted using CA as a macro-chain transfer agent. The molecular weight of the PPC side chains and the grafting density were systematically tuned by adjusting the monomer feed ratio and the degree of substitution of CA. Thermogravimetric analysis revealed a two-step degradation behavior corresponding to the PPC side chains and the CA backbone. Compared with neat PPC, CA-graft-PPC exhibited enhanced thermal stability. Tensile tests of PPC/CA-graft-PPC blend films demonstrated a slight improvement in tensile strength. The reinforcement effect depended strongly on the grafting density and side-chain length, reflecting the balance between chain entanglement and interfacial interactions.