Catalyst-free synthesis of high-strength, reprocessable, degradable, and shape memory biobased Poly(β-hydroxyurethane)s

Poly(β-hydroxyurethane) (PHU) derived from five-membered cyclic carbonates and amines, is a promising alternative to conventional polyurethanes. However, common PHUs relying on hydroxyl/carbamate exchange exhibit poor reprocessing efficiency and non-degradability. This study addresses these limitations by developing high-performance, reprocessable, and degradable PHUs from renewable feedstocks, advancing sustainable chemistry. Therefore, novel cross-linked PHU networks with vinylogous urethane bonds were prepared. Thereinto, a five-membered dicyclic carbonate was synthesized via the reaction of diglycerol with dimethyl carbonate, and diglycerol tetraacetoacetate was prepared and used as a crosslinker. They reacted with 1,6-diaminohexane to synthesize a series of biobased crosslinked PHUs (PDGVU6s). The obtained PDGVU6s with dual dynamic covalent bonds exhibited relatively low activation energy (27.66 kJ/mol) and significant reprocessing efficiency (~100%, 30 min at 150 °C). Notably, the introduction of vinylogous urethane bonds not only enabled efficient material recycling but also enhanced mechanical properties, achieving tensile strength up to 53.4 MPa. In addition, the presence of dynamic β-hydroxyurethane and vinylogous urethane bonds realized network rearrangement without additional catalysts. Therefore, the obtained PDGVU6s possessed rapid shape memory behavior and self-healing properties (2 h at 70 °C). And the obtained PDGVU6s demonstrated degradation in acidic solutions while achieving a balance between highlyefficient self-healing and excellent mechanical properties. This study presents an efficient method for synthesizing PDGVU6s from renewable resources, which enriches synthetic diversity and holds a promise for further exploration in sustainable chemistry.