Cationic copolymerization of furfural and furfural-derived 3,4-dihydropyran: biobased and biodegradable polyacetals with high glass transition temperatures

This study addresses the challenge of directly polymerizing furfural, a renewable platform chemical, by cationic copolymerization of furfural and 3,4-dihydro-2H-pyran (DHP), which can be derived from furfural, using GaCl₃/EtSO₃H/1,4-dioxane. This approach achieves higher yields (up to 72 %) and improved dispersity (M_w/M_n = 1.29–1.45) compared to BF₃·OEt₂, yielding fully bio-based, predominantly alternating poly(furfural-co-DHP) copolymers with high glass transition temperatures (T_g > 160 °C). These materials, thoroughly characterized by ¹H, ¹³C NMR and FTIR spectroscopy, GPC, TGA, and DSC, demonstrate a new pathway towards sustainable polyacetals. Further, we show that the materials undergo acid-triggered degradation, facilitated by the acetal linkages, and exhibit biodegradation in activated sludge (wastewater treatment) of ca. 52 % after 28 days (following OECD 301F), indicating their potential for reducing plastic waste accumulation and environmental persistence.