Living Cationic Cyclopolymerization of Divinyl Ether: Synthesis of High-Molecular-Weight Cyclopolymers by Sequential Monomer Addition and Formation of Star-Shaped Polymer

Abstract

Living cationic cyclopolymerization of 1,2-bis(2-vinyloxyethoxy)-benzene (1) was investigated with the CH₃CH(OiBu)OCOCH₃/Et_1.5AlCl_1.5/CH₃COOEt initiating system in toluene at 0°C. All the reactions proceeded quantitatively to give gel-free, soluble polymers 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 contents of unreacted vinyl groups in the produced soluble polymers were less than ~5 mol%, and therefore, the degrees of cyclization of the polymers were determined to be over ~95%. Preparation of high-molecular-weight cyclopoly(1) was achieved by sequential monomer addition to the living polymerization system and linking reaction of living cyclopoly(1) leading to star-shaped polymers. Glass transition temperature (T_g) of linear cyclopoly(1) (M_n = 19,000) was 106°C and T_g of star-shaped cyclopoly(1) (M_n = 96,100) was 112°C, and thermal decomposition temperatures (T_ds) of these cyclopoly(1) were over 370°C, indicating their high thermal stability.