Activity of Epoxide Chain Transfer Agents on the Ring-Opening Metathesis Polymerization of Cyclopentene

Abstract

Ring-opening metathesis polymerizations (ROMP) pave a way to synthesizing polymers with tunable molecular weights and narrow distributions. However, as a type of living polymerization, ROMP requires one molecule of initiator for every chain formed. This clearly presents a disadvantage when the initiator is costly, and polymers of low molecular weight are desired. Chain transfer agents (CTAs) provide a solution by increasing the number of chains generated per initiator molecule and a method to control end group functionality. This thesis examines the reactivity and regioselectivity of epoxide containing CTAs on the ROMP of cyclopentene (CP) using a Mo-based Schrock’s initiator. The CTAs employed herein are allyl glycidyl ether (AGE) and 1,2-epoxy-5-hexene (EH). Using the chain transfer equation, the chain transfer activity of AGE (CT = 2.80 ± 0.20) and EH (CT = 0.53 ± 0.01) were quantified. Proton nuclear magnetic resonance (1H NMR) was used to assess end group fraction and to obtain a values for and the percentage of chains containing the epoxide-functional end group. Matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) analysis revealed molecular weights of the individual chains. Though this technique, AGE was found to be at least 97% and EH to be at least 98% regioselective. Synthesis of a 5-star polymer containing an amine core with PCP arms was attempted, but yielded no conclusive results.