Bio-based anhydride crosslinked furan-derived vitrimeric epoxy networks with intrinsic flame retardancy, self-healing capacity and recyclability

To address the depletion of petroleum resources and the challenge of recycling epoxy resin, the development of green and recyclable bio-based alternatives to bisphenol A-type epoxy resins is urgently needed. In this study, a furan-derived epoxy monomer (diglycidyl furfurylamine, DGFA) was synthesized from furfurylamine, and a flame-retardant curing agent (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-maleic anhydride adduct, DOPO-MA) containing ester bonds was prepared via the addition of DOPO and maleic anhydride. Furan-derived epoxy vitrimers based on transesterification were fabricated by curing DGFA with a proportional mixture of DOPO-MA and glutaric anhydride. Compared with the neat vitrimer (DGFA-D 0 G 1 ), the flame-retardant composites (DGFA-D 1 G 1 , DGFA-D 1 G 1.5 , DGFA-D 1 G 2 ) all achieved a UL-94 V-0 rating, with the limiting oxygen index (LOI) increasing from 23.0 % to 32.0 %, 30.0 %, and 29.0 %, respectively. The peak heat release rate (PHRR) and total heat release (THR) were reduced by up to 48.6 % and 56.4 %, respectively. With the incorporation of DOPO-MA, the glass transition temperature (Tg) and rigidity of the flame-retardant vitrimers significantly increased. Notably, these composites exhibited excellent solvent resistance, even under strongly acidic conditions, and their degradation rate could be tailored by adjusting the temperature and mixed solution ratio to achieve on-demand removal. The DGFA-D 1 G 2 sample demonstrated superior self-healing and recyclability: surface scratches were almost completely healed after heating at 150 °C for 25 min, and the tensile strength of the recycled sample retained 77.8 % of the original value, indicating well-preserved mechanical properties.