Control over the assembly and rheology of supramolecular networks via multi-responsive double hydrophilic copolymers

Abstract

Stimuli-responsive double hydrophilic diblock copolymers have been prepared that consist of poly(N-isopropylacrylamide)-block-poly(2-(dimethylamino)ethyl methacrylate) sequences terminated by a terpyridine ligand. These building blocks are assembled in aqueous media in a stepwise manner, by first forming metallo-supramolecular ABA triblock copolymers and then gels by thermo-induced micellar aggregation. This study sheds light on the subtle interplay that exists between the responsive behaviour of the core and corona forming blocks. Due to the intrinsic sensitivity of the constituting polymer chains and the non-covalent interactions between them, supramolecular gels respond to specific external triggers. These stimuli allow the manipulation of numerous rheological aspects of the assembled materials, including network formation and dynamics. Interestingly, an independent control over the network formation and dynamics is notably achieved via an appropriate choice of the metal ions and of the length of the associating block. By playing with the architecture of the associating copolymers and the nature of the metal ions, this work further demonstrates the possibility to build materials possessing either a mono or dual relaxation mechanism via a unique approach.