Stable N,O-acetal covalent adaptable networks: bio-based, highly dynamic and fully recyclable materials

Abstract

A new exchangeable platform for catalyst-free covalent adaptable networks (CANs), trifluoromethylated tertiary N,O-acetal, is reported. Its exchangeability was first demonstrated on model compounds and then exploited to design a highly bio-based CAN (92% C): HMF-P. The network was prepared from Priamine™ 1074 and hydroxymethylfurfural (HMF) via the synthesis of a putative A₂B₂ monomer that readily homopolymerized. This material exhibited high gel content (97%) and fast dynamic kinetics (short relaxation times: 80 s at 140 °C). HMF-P was reprocessable under relatively mild conditions (1 h, 120 °C, and 10 bars) without any major changes in its properties after 5 reprocessing cycles. Closed-loop chemical recycling of the material was performed by complete depolymerization in n-butanol and re-polymerization, with no major alterations in properties. Finally, this material appeared to be highly stable towards hydrolysis at different pH values (1, 7 and 14) with a maximum weight loss of 8% observed after 16 h of refluxing in HCl (100 °C).