Thermoresponsive dynamic BAB block copolymer networks synthesized by aqueous PISA in one-pot

Abstract

We report a straightforward process to produce well-defined dynamic networks of associative BAB triblock copolymers through two successive polymerization steps conducted in one-pot and exclusively in water. The copolymers are composed of a hydrophilic poly(N,N-dimethylacrylamide) A block extended in a typical RAFT-PISA dispersion formulation with two lateral associative statistical poly(diacetone acrylamide-co-N,N-dimethylacrylamide) B blocks. The viscosity of the samples is strongly modified by the N,N-dimethylacrylamide (DMAc) content in the B block. This is attributed to the formation of a transient network for which the exchange dynamics of the B blocks between micelles and/or the number of bridges within the network depend on the DMAc content. Rheology analyses showed that transient networks are formed that exhibit a thermoresponsive behavior with a maximum viscosity as a function of temperature, presumably caused by a maximum of bond lifetime and/or number of elastically active chains.