Self‐Healing Biobased Thermoreversible Polymer Networks by Photo‐Diels‐Alder Chemistry
Masa Alrefai, Milan Marić
Abstract
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.