Synthesis and Applications of Chain End Functionalized Polyolefins

Abstract

Chain end functionalized polyolefins( Cef-POs) are of great importance in macromolecular design and polyolefin modifications. By utilizing self-induced chain transfer reactions( to β-H,e. g.) or using chain transfer agents such as borane, phosphine and styrene( and its derivatives) / H 2 in olefin coordination polymerization,unsaturated bond and reactive group terminated polyolefins can be obtained,respectively. Successive chemical modification of chain-end group results in various Cef-POs. Given the status of "one polymer chain per catalyst"in living coordination polymerization of olefin,Cef-POs can also be obtained by endcapping living chains and / or applying functionalized living catalysts. The problem of low catalyst efficiency encountered in living coordination polymerization can be w ell solved by coordinative chain transfer polymerization( CCTP),a process involving rapid and reversible chain transfer reactions betw een the catalyst( active species) and the chain transfer agent( usually in the form of a main group metal alkyl). CCTP generates polyolefin capped by carbon-metal bond,w hich is highly reactive and can be modified into versatile terminal groups. In addition,living polymerization of Ylides,living anionic polymerization of butadiene and ring-opening metathesis polymerization of cycloolefine are alternative approaches to synthesize( analogues of) Cef-PEs. The applications of Cef-POs,featured by transformation reaction from metallocene to other polymerization( living anionic polymerization,"controlled / living " radical polymerization,ring-opening polymerization,etc.) and combination w ith click chemistry,include tw o main aspects: polymer modification and synthesis of topological polymer.