Photoresponsive behavior of two well-defined azo polymers with different electron-withdrawing groups on push–pull azo chromophores

•Two well-defined azo polymers were synthesized by RAFT polymerization.•The polymers were functionalized with strong push–pull azo chromophores.•The polymers exhibited different photoresponsive properties on all motion levels.•Photoinduced motion at large scales was severely restrained by hydrogen bonding.•Birefringence decay can be reduced with the existence of the hydrogen bonding.

Two well-defined methacrylate-based azo polymers bearing strong push–pull azo chromophores were synthesized by RAFT polymerization. The polymers contain cyano and carboxyl as electron-withdrawing groups at 4-positions of the azo chromophores. The polymers exhibited significantly different photoresponsive properties on all light-driven motion levels. When irradiated with a linearly polarized laser beam at 532 nm, the cyanoazobenzene-containing polymer showed rapid birefringence growth relative to that of the carboxylazobenzene-containing polymer. When the light was switched off, a much lower orientation decay was observed for the carboxylazobenzene-containing polymer compared with its counterpart. Upon irradiation with the interfering laser beams at these two wavelengths, surface-relief-grating amplitude formed on the film of the cyanoazobenzene-containing polymer and was substantially larger than that for the carboxyl substituted polymer. When the polymer films were irradiated with a homogenous laser beam at 488 and 532 nm, self-structured surface pattern was only detected for the cyanoazobenzene-containing polymer with the 532 nm light irradiation.