Multi-stimuli-responsive copolymers based on 1-pyrenol polyphotoacids

Abstract

In this work we present a set of multi-stimuli responsive copolymers based on the photoresponsive 1-pyrenol-based monomer N-(3-((6/8-hydroxypyrene)-1-sulfonamido)propyl)methacrylamide HPSAPMA and oligo(ethylene glycol) (OEGMA) comonomers of varying molecular weight. The copolymers with the general structure P[(OEG_aMA)_x-co-HPSAPMA_y] (a = 3, 5, 9) are prepared with varying functional comonomer compositions via reversible addition fragmentation chain transfer (RAFT) polymerization. The photo- and pH-responsiveness is introduced by the 1-pyrenol moiety as 1-pyrenol allows for excited state proton transfer (ESPT) upon irradiation, enabling the spatiotemporal manipulation of the materials protonation state and the respective proton concentration (pH) with visible light. The implementation of hydrophilic comonomers based on OEGMA, i.e. OEG₉MA, OEG₅MA and OEG₃MA, ensures applicability in aqueous media and simultaneously introduces a temperature-sensitive fragment, rendering these materials responsive to three different stimuli.