Tetraphenylethene-Functionalized Polyethylene-Based Polymers with Aggregation-Induced Emission

A novel synthetic strategy toward a series of tetraphenylethene (TPE)-functionalized polyethylene-based homo/copolymers is presented. Tris(3-(4-(1,2,2-triphenylvinyl)phenoxy)propyl)borane, synthesized by hydroboration of (2-(4-(allyloxy)phenyl)ethene-1,1,2-triyl)tribenzene with BH₃, was used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined TPE-terminated linear polyethylene (PE). Combining this efficient strategy with ring-opening polymerization (ROP) or atom transfer radical polymerization (ATRP), TPE-functionalized PE-based block copolymers have been synthesized. All synthesized polymers showed aggregation-induced emission (AIE) behavior either in solution or in bulk. Self-assembly of the PE-based block copolymer in DMF resulted in strong emission due to the AIE effect of the aggregated TPE-PM core; the fluorescence intensity of the solution is directly related to the composition of block copolymers and the size of the micelle. The response of the AIE-operative fluorescence behavior in terms of concentration of the block copolymer solutions has also been used to locate the critical micelle concentration (CMC) value of the block copolymers. The nonemissive dilute solutions of block copolymers became fluorescent when increasing concentrations above the CMC.