Ring-Opening Metathesis Copolymerization of Bicyclic and Monocyclic Olefins

Abstract

In this thesis the kinetics of the ROMP copolymerization of cyclopentene and norbornene using a molybdenum-based Schrock-type initiator are studied. In particular, this thesis explores how the high equilibrium concentration of cyclopentene, and its associated depolymerization, impacts the incorporation of cyclopentene into the copolymer. The effectiveness of the standard Skeist model was compared to a reversible copolymerization model in describing the kinetics of the reaction over a range of different starting monomer concentrations and ratios. Both models have the capacity to effectively predict the results of a copolymerization at relatively high monomer concentrations, where cyclopentene propagation is strongly favored over depropagation, but the reversible model has an edge in predictive power when the reverse reaction rate of the cyclopentene monomer is significant relative to the forward reaction rate of both cyclopentene and norbornene. The reactivity ratios for this copolymerization for cyclopentene and norbornene, respectively, are found to be r\(_{C}\)=0.0041±0.0007 and r\(_{N}\)=85±7 (± one standard deviation) with the particular Mo-based initiator examined. In addition, polymerizations wherein the concentration of cyclopentene was lower than its equilibrium monomer concentration were observed to incorporate cyclopentene units into the monomer until all the norbornene was consumed; at that point, the reaction stopped. With this knowledge of cyclopentene and norbornene reactivity ratios and proper inclusion of cyclopentene depropagation into the model, copolymers of these monomers with interesting and useful architectures can now be developed. Such polymers can be valuable both in research, where properties of block-like copolymers can be studied, and in industry, where it may become possible to produce a valuable product from a C5 stream that is currently relegated to making low-value products.