Temperature-Induced Control of Conformation and Conjugation Length in Water-Soluble Fluorescent Polythiophenes

Abstract

Application of fluorescent polythiophenes and related conjugated polymers as a platform for highly sensitive chemo- and biodetection can benefit from the possibility to effectively control their conformation and conjugation length by applying external stimuli. Temperature can be used as such a stimulus if a substantial effect can be achieved in a relatively narrow temperature range. To investigate the temperature-induced conformational switching, a series of polythiophenes with different degree of regioregularity were prepared and functionalized by grafting temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) side chains to their conjugated backbones. These highly water-soluble fluorescent brush-type copolymers featured almost complete lack of intermolecular electronic interactions even in aggregated state owing to remarkably insulating properties of the PNIPAm grafts. Therefore, these grafted copolymers provided an opportunity to study the effects originating from the conformational switching with...