A first study on copolymers of a methacrylate containing the 2-(hydroxyimino)aldehyde group and OEGMA. RAFT polymerization and assessment of thermal and photoresponsive polymer behavior

Abstract

We report the first synthesis of 4-[(hydroxyimino)aldehyde]butyl methacrylate and its RAFT copolymerization with oligo(ethylene glycol) monomethylether methacrylate. For comparison, 6-(hydroxyimino)hexyl methacrylate, containing a free oxime group, and 6-oxohexyl methacrylate, with an aldehyde group, are also synthesized and subjected to RAFT copolymerization with OEGMA. DP(GPC) values of all polymers are in the 18–33 range with PDI < 1.2. Interestingly, the thermal behavior of aqueous solutions of the 2-(hydroxyimino)aldehyde-containing copolymers exhibit a lower cloud point than their analogs, which comprise only a CN(OH) or CHO functionality. This effect can be ascribed to the simultaneous presence of a hydrogen donor and acceptor in the 2-(hydroxyimino)aldehyde group. Moreover, we present evidence for the thermally reversible E/Z photoisomerism of the 2-(hydroxyimino)aldehyde group (HIA) both in HIABMA and in its copolymers.