pH-responsive AIE-active Polyethylene-based Block Copolymers

A novel synthetic strategy towards pH-responsive aggregation-induced emission (AIE)-active tetraphenylethene (TPE)-functionalized polyethylene-based block copolymers is presented. Tris(3-(4-(1,2,2-triphenylvinyl)phenoxy)propyl)borane was used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined alpha-TPE-omega-OH linear polyethylenes (PE). The terminal hydroxyl groups were transformed to atom transfer radical polymerization (ATRP) initiating sites by esterification with alpha-bromoisobutyryl bromide, followed by polymerization of tert-butyl acrylate (tBA) to provide TPE-PE-b-PtBA block copolymers. After hydrolysis of the tBu group to COOH group, the corresponding pH-responsive TPE-PE-b-PAA block copolymers were obtained. All synthesized block copolymers revealed AIE behavior either in solution or bulk. Due to the pH-responsivity of PAA chains, the aggregation state at different pH and consequently the fluorescence intensity changed. Also, the synthesized block copolymers exhibited ion-specificity fluorescence properties.