Effects of hydrogen bonding on photo-responsive behavior of healable azobenzene-containing polyurea elastomers

Photo-responsive polymers, obtained by incorporation of photochromic azobenzene groups into polymer, can display reversible photoactuation behavior. However, the damage can cause a reduction in their service scope or service lifetime. It remains a challenge to design healable and reprocessable azobenzene-containing polymers. The polyaddition of isophorone diisocyanate (IPDI) with p-diaminoazobenzene (DAAB) and amino-terminated poly(propylene glycol) (D2000) was performed to prepare the main-chain polyurea elastomer. The hydrogen bonding between urea groups can enhance self-healing of polyurea elastomer, but its influence on photo -responsive behavior of polyurea elastomer is not clear. The proportion of ordered hydrogen bonds was regu-lated by changing azobenzene content and the ratio of hard/soft segments. The ordered hydrogen bonds played a fundamental role in the maximum peak intensity of polyurea, while they had no direct effect on the photo -responsive efficiency of polyurea. This study provides a feasible way to obtain healable and reprocessable azobenzene-containing polymers.