Synthesis and properties of de-cross-linkable acrylate polymers based on hexaarylbiimidazole

The radical polymerization of 4-(4,5-diphenyl-1H-imidazol-yl)-phenyl acrylate (DPIPA) was carried out in N,N-dimethylformamide at 60 °C for 24 h by using 2,2′-azobis(isobutyronitrile) (5 mol%) as an initiator to give a poly(DPIPA) (1) as a homopolymer. Poly(DPIPA-co-MMA) (2) was obtained by the radical copolymerization of DPIPA with methyl methacrylate (MMA) in a good yield. Moreover, copolymeriztion parameters of DPIPA were evaluated by the copolymerization of MMA. The cross-linking reaction of the obtained 2 proceeded with K3[Fe(CN)6] and KOH. The resulting cross-linked poly(DPIPA-co-MMA) (3) was de-cross-linked by pressurization or visible light irradiation. Consequently, the thiol-capped de-cross-linked poly(DPIPA-co-MMA) (4) was obtained in a good yield.