Synthesis Of Functional Hyperbranched Polymers By Activated Internal Alkyne-based Polymerizations

Hyperbranched polymers(HBPs)have found wide applications in optoelectronics,chemical sensing,and biomedical fields,due to their unique structural characteristics and properties such as low viscosity,high degree of branching,and large number of terminal functional groups.Efficient synthesis of functional HBPs with new structures by new polymerizations is of academic interest and technological value.The polymerization reactions based on alkyne monomers have been widely used to prepare functional polymers with diverse structures.However,the internal alkyne-based polymerizations have been rarely reported to synthesize functional HBPs.In this thesis,a series of functional HBPs have been prepared through the catalyst-free activated internal alkyne?thiol click polymerization and Rh-catalyzed polycyclotrimerization of activated internal alkynes.Four ester-activated alkyne monomers were designed and synthesized,and the reaction conditions of the polymerization of trisbutynoate and dithiol were systematically optimized.Four soluble hyperbranched poly(β-thioacrylate)s(hb-PTAs)with high molecular weights were synthesized through such polymerization.The hb-PTAs could be degraded rapidly under alkaline conditions.Thanks to their contained sulfur atoms and benzene rings,the hb-PTAs show high refractive indices.Furthermore,the hb-PTAs are weakly emissive in dilute solution,but become highly emissive in aggregated state,showing aggregation-induced emission(AIE)properties.The nanoaggregates of tetraphenylethene(TPE)-containing hb-PTAs exhibit strong fluorescence,and can be utilized for highly sensitive detection of nitroaromatic explosives.The polycyclotrimerization reaction of 1,6-hexanediol-diphenylpropionate was explored.Through optimization of the polymerization conditions,a rhodium-catalyzed phenylpropionate polycyclotrimerization to prepare HBPs was developed,and three hyperbranched poly(triphenylbenzoate)s(hb-PTPBs)with high molecular weights and good solubility were prepared by such the polymerization.The polymer structures were characterized by FT-IR and NMR spectroscopic techniques,from which the regioregularities and degree of branching of the polymers were determined.The hb-PTPBs could be degraded rapidly under alkaline conditions.Moreover,they showed AIE properties due to the formed triphenylbenzene(TPB)units.The TPE-containing hb-PTPB exhibited intense fluorescence in aggregate state,which could work as chemosensors to detect nitroaromatic explosives sensitively.