Polymerization-induced emission of borinic acid towards stimuli-responsive luminescent polymers

Stimuli-responsive luminescent polymer is generally prepared by incorporation of both stimuli-responsive and luminescent moieties into polymer chain, which cause difficulties in molecular design and synthesis. The preparation of stimuli-responsive luminescent polymer from one moiety represents a time-saving approach and is highly desirable. Here, we demonstrate a simple approach to achieve stimuli-responsive luminescent polymers through polymerization-induced emission of nonemissive borinic acid moiety. Attributed to versatile borinic acid moiety, the prepared borinic acid polymer (PBA) exhibits upper critical solution temperature (UCST) type thermo-responsive behavior and chemical sensitivities. Interestingly, PBA is not only stimuli-responsive but also luminescent, while the repeating borinic acid moiety is nonemissive, indicating borinic acid is a novel PIE luminogen (PIEgen). This work therefore opens a new avenue to molecularly design stimuli-responsive luminescent polymer from nonemissive borinic acid moiety, which might cause inspirations to the fields of boron chemistry, stimuli-responsive polymer and luminescent polymer.