Living Cationic Cyclopolymerization of Divinyl Ether with Bulky Substituents: Synthesis of High-Molecular-Weight Cyclopolymers and Star-Shaped Cyclopolymers

Abstract

synthesis of star - shaped cyclopolymers. Living cationic cyclopolymerization of 1,2 - bis ( 2 - vinyloxyethoxy )- 3,5 - di - tert - butylbenzene ( 1 ) was investigated with the CH 3 CH ( O i Bu )-OCOCH 3 / Et 1.5 AlCl 1.5 / CH 3 COOEt initiating system in toluene at 0 ° C. All the reactions proceeded quantitatively to give gel - free polymers, soluble in organic solvents. The number - average molecular weight ( M n ) of the polymers increased in direct proportion to monomer conversion and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that living cyclopolymerization of 1 occurred. The content of unreacted vinyl groups in the produced soluble polymers was less than ³ 2mol%, and therefore, the degree of cyclization of the polymers was determined to be over ³ 98%. Preparation of high - molecular - weight cyclopoly ( 1 ) was achieved by sequential monomer addition to the living polymerization system and polymer linking reaction of living cyclopoly ( 1 ) leading to star - shaped polymers. Glass transition temperature ( T g ) of linear cyclopoly ( 1 ) ( M n = 18,500 ) was 134 ° C and T g of star - shaped cyclopoly ( 1 ) ( M n = 95,900 ) was 132 ° C, and thermal decomposition temperatures ( T d s ) of these cyclopoly ( 1 ) were over 350 ° C, indicating their high thermal stability.