Biodegradable Superabsorbent Polymer from CO2-Based Polycarbonate

Superabsorbent polymers (SAPs) are widely used but remain dominated by nondegradable poly(acrylic acid)-based networks, creating sustainability concerns. Natural polymer-based alternatives often require acrylic acid grafting to achieve high absorbency, compromising degradability and structural uniformity. Synthetic biodegradable polymers offer molecular-level designability, but most backbones struggle to combine high-density hydrophilic functionalization with rapid swelling. Here, we demonstrate CO2-based polycarbonates derived from functional epoxides as a programmable platform for high-performance biodegradable SAPs. A lightly cross-linked poly(vinyl cyclohexene carbonate)-derived network with rigid backbones and two pendant sodium carboxylate groups per repeat unit combines high hydrophilicity with mechanical strength, delivering high absorption in deionized water (237 g·g–1), saline (∼41 g·g–1), and under load (∼12 g·g–1). It also exhibits ultrafast early-stage swelling dominated by Fickian diffusion, reaching 102 g·g–1 within 1 min, retaining ∼85% of its absorbency after 5 swelling–deswelling cycles, and achieving 61% biodegradation over 51 days, which falls within the reported range for polyhydroxybutyrate (PHB). These findings underscore the promise of CO2-derived polycarbonates as a customizable platform for producing high-performance, biodegradable superabsorbent materials.