Dual-Gated Supramolecular Star Polymers in Aqueous Solution

Abstract

We introduce the formation of a dual responsive supramolecular star polymer system, displaying gated self-assembly behavior. The redox- and thermoresponsive star polymers are based on a 6-fold β-CD functionalized core molecule and RAFT-derived ferrocene end functionalized poly(N,N-dimethylacrylamide) (PDMA) and poly(N,N-diethylacrylamide) (PDEA) linear polymers. Complex formation is analyzed via various methods including dynamic light scattering (DLS). Chemical redox triggers, namely NaOCl and ascorbic acid, as well as electrochemical triggers can be utilized to shift the star polymers to the unbound state via CD/ferrocene complex dissociation. Moreover, heating above the lower critical solution temperature (approximately 34 °C) allows for a change from the coil to the globular state of the star polymers in the case of PDEA arms. For PDMA arms, heating to 70 °C allows shifting of the system to the unbound state. The response of the supramolecular star polymers is carefully studied via various methods including cyclic voltammetry (CV), DLS, and turbidimetry. Overall, the supramolecular star polymers can be transformed into predefined states via individually addressable temperature and/or redox stimuli, presenting a novel dual gated self-assembling supramolecular star polymer system in aqueous solution.