Synthesis, thermoresponsivity and multi-tunable hierarchical self-assembly of multi-responsive (AB)mC miktobrush-coil terpolymers

Abstract

Despite tremendous progress in self-assembly, it remains a challenge to achieve multi-tunable reversible low-dimensional nano-objects. Given the crucial role of macromolecular architectures in self-assembly, this study aims at design of stimuli-responsive shape-variable toothbrushes to address this challenge. Four examples of miktobrush-coil terpolymers comprising thermoresponsive poly(N-isopropylacrylamide) and thermo/pH/oxidation-responsive poly(2-(dimethylamino)ethyl methacrylate) heterografts and hydrophilic poly(N,N-dimethyl acrylamide) were synthesized. Although compositions and external stimuli only slightly affected the cloud points, the transmittances under different conditions were significantly different due to the formation of distinct nanoparticles. Some factors such as composition, concentration, pH and temperature could induce intriguing hierarchical self-assembly via changing the degree of hydration and protonation and amphipathy. Intrinsic balances between competing interactions and tunable molecular shapes led to stepwise formation of a diversity of nanostructures such as spheres, disks, vesicles, disk-like compound vesicles, nanosheets, cylinders, nanoribbons and polyhedron micelles. Multi-tunable hierarchical self-assembly (MHSA) affords a versatile platform to directly fabricate on-demand low-dimensional nano-objects in aqueous solution. Our study underlies systematic research on shape-dependent properties and applications starting from the same precursor.