Shen Kaihua

Synthesis methodology of dendrigraft functionalpolymer

Structuralization, functionalization and integration are efficient pathways to improve the properties of synthetic rubber and elastomer, and the living anionic polymerization is an effective method to prepare polymer chain with topological structure and functional groups. Recently, the dendrigraft polymers attracted more and more attentions in the macromolecular chemistry, owing to their unique structure and properties. Herein, the synthesis methodology of dendrigraft functional polymers was summarized. On the basis of epoxidized polybutadiene/polyisoprene with different structures, novel dendrigraft star-comb polymers were precisely synthesized by the iterative epoxidation-coupling reactions with coupling groups in the polymer chain. High vacuum technique in the living anionic polymerization was explored, establishing the efficient synthesis strategy for the preparation of dendrigraft star-comb polymers. Aiming to achieve in-chain functionalized polymers with the goal of “definite function”, “accurate quantity” and “precise position”, the precise synthesis of in-chain functional polymers with complex topological structure was researched and the relationship between the polymer structure and performance was probed. These dendrigraft functional polymers were prepared by introducing different target functionalized groups into polymer chain via copolymerization, group transfer reaction, hydrosilylation and click chemistry. A series of functionalized DPE derivatives with complex structures were designed and the corresponding synthesis pathway and purification method for the monomers were examined. The copolymerization of DPE derivatives possessing different functional groups with butadiene, isoprene and styrene were also illustrated. Based on the synthesis of a series of liquid crystal macromolecules with alkenyl-teminated units, dendrigraft liquid crystal polystyrene was prepared with hydrosilylation reactions. Based on the synthesis of a series liquid crystal macromolecules with SiH-teminated units, the dendrigraft liquid crystal polybutadiene/polyisoprene were prepared, resolving the difficulty caused by the self-crosslinking reaction in the polymerization of functionalized conjugated dienes with hydrosilylation reaction. This work illustrated the influences of topological structure toward the liquid crystal properties of the dendrigraft polymers. Based on the preparation fluorescent compounds (alkynyl-teminated coumarin) and photochromic compounds (alkynyl-teminated spiropyrane), fluorescent polybutadiene and photochromic polybutadiene with dendrigraft topology were obtained by click chemistry, respectively. This work demonstrated the influences of complex topological structure toward the fluorescence and photochromism characteristics of the dendrigraft polymers. With copolymerization, group transfer reaction, hydrosilylation and click chemistry, dendrigraft functional polymers with polybutadiene main chain were attained, which expanded the characteristic of rubber and proposed the novel pathway for green rubber synthesis. The green rubber could be further designed based on the revealed relationship between topological structure and properties within functional polymers.