Thermo-reversible self-healing in a fluorous crosslinked copolymer

Abstract

Thermo-reversible self-healing of a partially fluorinated crosslinked polymer was achieved by utilizing reversible Diels–Alder (DA) chemistry. Copolymers (PHFBA-co-PFMA) of perfluorobutyl acrylate (HFBA) and furfurylmethacrylate (FMA) with controlled stoichiometric ratios were synthesized by microwave-assisted radical polymerization by controlling the individual components. The microstructures and stoichiometries of these copolymers of PHFBA and PFMA were analyzed by ¹H, ¹⁹F, ¹³C, and DOSY NMR spectroscopy and their molecular weights were analyzed by GPC. The glass transitions (T_g) of the different stoichiometric copolymers correlate well with the estimated T_g values from the Fox equation. A thermo-reversible crosslinked polymer network was achieved via Diels–Alder (DA) and retro-DA reactions between the furan moiety of the copolymer (PHFBA-co-PFMA) and bismaleimide; the self-healing ability of this network was investigated using ¹H NMR, DSC and solution experiments. The self-healing process and recovery of the crosslinked polymers was screened by microscopic visualization and stress–strain tensile studies. The surface properties of the fluorous copolymers and crosslinked polymers were studied by water contact angle measurements, and their mechanical properties were investigated by nanoindentation and DMA.