Synthesis and Characterization of Alternating and Multiblock Copolymers from Ethylene and Cyclopentene

Abstract

The synthesis and characterization of copolymers from ethylene and cyclopentene are reported. Polymerization of ethylene and cyclopentene using a living bis(phenoxyimine)titanium catalyst yields copolymers with cis-1,2 cyclopentane units, high molecular weights, and low polydispersities. The effects of cyclopentene concentration, ethylene pressure, and reaction temperature on cyclopentene incorporation were determined; under the optimal reaction conditions 47 mol % cyclopentene was incorporated to give a nearly perfectly alternating copolymer. The glass-transition temperatures of the polymers, ranging from −27.3 °C (27 mol % cyclopentene) to 10.1 °C (47 mol % cyclopentene), were found to be linearly dependent on the mole percent cyclopentene content. Synthesis of atactic and isotactic model poly(ethylene-alt-(cis-1,2-cyclopentane))s using ring-opening metathesis polymerization allowed the assignment of the fine structure of 13C NMR spectra of atactic polymers made from ethylene and cyclopentene. Finally, polymers containing blocks with varying ratios of ethylene/cyclopentene were synthesized. By repetitively raising and lowering the ethylene pressure of a cyclopentene/ethylene polymerization, polymers with multiple blocks were synthesized.