Facile synthesis, sequence-tuned thermoresponsive behaviours and reaction-induced reorganization of water-soluble keto-polymers

Abstract

We report facile synthesis, sequence-tuned thermoresponsive behaviours and reaction-induced reorganization of ketone-based hydrophilic reactive polymers. The well-controlled and living RAFT polymerisation of commercially-available diacetone acrylamide (DAAM), in methanol media on irradiation with visible light at 25 °C, leads to well-defined keto-polymers over wide degrees of polymerisation from 50–1000 and a block copolymer with poly(N,N-dimethyl acrylamide) (PDMA). Statistical copolymerisation with DMA gives a gradient copolymer, P(DAAM-grad-DMA), whose aqueous solubility can be finely tuned. Binary copolymers that have the tailored structures of PDMA-b-P(DAAM-grad-DMA) can be achieved via a one-pot iterative process. Aqueous solutions of the P(DAAM-grad-DMA) copolymers exhibit typical thermoresponsive behaviours on heating, with cloud points that can be widely tuned from 16 °C to permanently water-soluble. Adjusting the sequence from gradient, “short-block”-gradient, “middle-block”-gradient, “long-block”-gradient to block structures can induce diversity in the dehydration, heating-triggered phase transition, assembly and reaction-induced dynamic reorganization. These water-soluble reactive keto-polymers are thus promising for emerging biological applications on demand in physiological aqueous solution.