Green Fabrication of Degradable Poly(butylene succinate-co-butylene adipate) Foams: Effect of Ionic Monomers on In-Situ Polymerization and Microwave-Assisted Foaming

Degradable poly(butylene succinate- co -butylene adipate- co -butylene 5-sodiosulfoisophthalate) (PBSAS) incorporating sodium dimethyl isophthalate-5-sulfonate (SIPM) units were synthesized via an optimized two-step melt transesterification polycondensation. The introduced ionic groups enhanced polarity for microwave heating, while simultaneously reducing crystallinity and broadening the melting range from 23 to 35°C. They also acted as cross-links, improving melt strength and mechanical properties. Consequently, PBSAS5 foam achieved exceptional stability (25.3 times), a tunable bimodal cell structure, superior compression performance, and an ultralow thermal conductivity of 35.2 mW/m·K. Furthermore, SIPM imparted pronounced hydrophilicity and pH-responsive degradation, resulting in an accelerated degradation rate of PBSAS foams under acidic conditions. This integrated strategy of efficient polymerization and microwave-assisted foaming enables the fabrication of ultralight PBSAS foams, providing a universal method for the sustainable production of degradable materials.