Self-Healing Biobased Thermoreversible Polymer Networks by Photo-Diels-Alder Chemistry

Abstract

Poly(furfuryl methacrylate) (poly(FMA)) homopolymers with controlled molecular weights made via ICAR ATRP undergo photo-crosslinking (λ = 254 nm) with 1,1′-(methylenedi-4,1-phenylene)bismaleimide (BM) by Diels-Alder (DA) chemistry, and are compared to the same DA reaction under non-UV initiated, ambient conditions (RT-DA). FTIR and DSC analysis confirm DA adduct formation and the retro-DA reaction. Co- and terpolymers of FMA with C13MA (alkyl methacrylate with average side length = 13) and isobornyl methacrylate (IBOMA) are prepared to enhance mechanical properties. Poly(C13MA-co-FMA) samples are used to study curing condition effects and BM loading on crosslinking density and thermal behavior. Varying BM loading (0.05–0.2 BM: FMA) in samples cured by photo-DA and RT-DA, UV cured samples showing higher gel content (50% versus 25% for 0.2 BM loading) and two endothermic peaks in the first heating run, unlike RT cured samples which display a single peak. Subsequently, poly(C13MA-co-IBOMA-co-FMA) are crosslinked with BM via photo-DA with resulting networks indicating self-healing/recyclability. FTIR and DSC results confirm DA and retro-DA reactions, while scratched samples of crosslinked terpolymers exhibit self-healing upon heating. Microscopic images show complete scratch healing in just 20 min due to furan-maleimide adduct formation, facilitated by the presence of flexible low T _g poly (C13MA) segments and rigid poly (IBOMA) repeating units.