Design,Synthesis And Structure-Property Relationship Study Of Typical Topological Polymers With Long Branched Subchain

Based on advances in polymer chemistry,controlled synthetic approaches enable to design and synthesize the polymer systems of various topology with diverse properties to meet specific needs of today's "smart world".Branched polymers mainly include dendrimers,hyperbranched and comb polymers,have been widely fascinated by academic and industrial circles in recent years because of highly branched structures providing the advantages of low viscosity and high density of terminal functional groups.Unquestionably,chain behavior and polymer properties are intensively influenced by chain size,topology,subchain length and degree of branching.The objective of this research work is to synthesize few novel typical topological polymer systems with long branched chains in order to study the structure-property relationship.In this dissertation,through rational design,a series of novel macromolecular precursors with regulated structures are first synthesized and then long subchain hyperbranched polymers(LHPs)and comb polymers are designed,synthesized and studied.Specifically,we used styrene,?-caprolactone,D,L-lactide and tris(ethylene glycol)monomethyl ether acrylate as starting materials to synthesize trifunctional AB2 type macromonomer with predefined topology and narrowly distributed controlled molar mass,where block composition includes:polystyrene(PS),polycaprolactone(PCL),polylactide(PLA)and polyethylene glycol(PEG).Furthermore,we constructed structure-controlled long subchain hyperbranched homopolymers,hyperbranched graft copolymers and comb copolymer systems.Using a variety of characterization techniques(SEC,NMR,FT-IR,etc.),we have accurately and comprehensively determined the structural and molecular parameters of the typical systems.The limits for biodegradation and crystallization of hypergraft copolymers based on semi-crystalline polycaprolactone were explored through laser light scattering(LLS)and differential scanning calorimetry.(DSC).By a combination of rational design,precise synthesis and careful analysis,we have not only controlled the average crystallinity of PCL-based polymers from-0(lowest limit)to-52%(highest limit),but also fine-tuned the biodegradation time of hypergraft self-assemblies from few hours to few days.On the other hand,by measuring the ionic conductivity,lithium ion transfer efficiency,electrochemical-thermal properties and interface stability of the solid polymer electrolyte(SPE),we investigated the applicability of the prepared hyperbranched and comb copolymers in all-solid-state lithium metal batteries(ASSLBs).The facile manufacturing techniques,high ionic conductivity,good cycling and rate performance of the hyperbranched PCL/PS copolymer and PLA/PEG-SPE making them promising SPE host materials toward the next generation ASSLBs with high energy density and improved safety.In general,through the study of several typical long-chain branched polymer systems,we have clarified some important intrinsic relationships between structures and properties.