Ring‐Opening Metathesis Copolymerization of Cyclopentene Above and Below Its Equilibrium Monomer Concentration

Abstract

Cyclopentene (C) and norbornene (N) may both be enchained by ring‐opening metathesis polymerization (ROMP). N homopolymerizes to essential completion, but C has a significant equilibrium monomer concentration, [C]eq = 1.17 m at 30 °C. While C cannot homopolymerize below [C]eq, it can still be enchained in copolymerizations with N. A terminal kinetic model, where one monomer shows depropagation competitive with propagation, well represents experimental data for the “living” ROMP copolymerization of C and N with a Mo‐based “Schrock‐type” initiator, covering a broad range of monomer feed ratios, both above and below [C]eq. Incorporating a penultimate unit effect on C depropagation increases the model's accuracy when both the monomers are dilute. Below [C]eq, polymerization halts when all N is consumed; above [C]eq, a C homopolymer block forms once all N is consumed. As polycyclopentene may be hydrogenated to linear polyethylene, such copolymerizations offer a facile route to polyethylene‐containing block copolymers from a single charge of mixed‐monomer feed.

Long-Chain Branched Polypentenamer Rubber: Topological Impact on Tensile Properties, Chain Dynamics, and Strain-Induced Crystallization

“…Our reasoning is that DCPD is more reactive than CP and should add to the chain first. Similar observations have been made with other CP copolymerizations …”

“…Similar observations have been made with other CP copolymerizations. 35 Whether the reduced chain mobility is caused by branching points or by an unintended nanofiller effect cannot be distinguished from our current data. Therefore, in the remaining discussion, we will not attempt to deconvolute their individual effects but rather discuss branched PPR as rubber possessing decreased the chain mobility.…”

Highly active ruthenium metathesis catalysts enabling ring-opening metathesis polymerization of cyclopentadiene at low temperatures

“…The basic driving force for ROMP is the release of the strain energies of constrained monomers, such as norbornene and its derivatives (>20 kcal/mol) 6–8 . Cyclopentenes, however, have significantly lower ring strains (4.5–6.8 kcal/mol) than those of norbornene derivatives; consequently, fewer examples of ROMP involving cyclopentenes have been reported 9–15 . Notably, the ROMP of cyclopentadiene (CPD), which is easily obtained by the cracking of naphtha and rapidly dimerized to dicyclopentadiene (DCPD) even below 0 °C, has, to the best of our knowledge, never been achieved.…”

Single-End-Functionalized Polycyclopentene via Ring-Opening Metathesis Polymerization with Concurrent Chain Transfer

“…Figure 2a shows the evolution of the molecular weight distribution (MWD) during the ROMP of CP with no added CTA: the narrow primary peak increases in molecular weight progressively with time (conversion) and is accompanied by a shoulder at higher molecular weight that results from secondary metathesis reactions. 31 Note that the presence of these secondary metathesis reactions and the high equilibrium monomer concentration of CP ([M] eq = 1.17 mol/L at 30 °C) 36 mandate that the CP conversion be kept low; at 2 h, conversion is approximately 11%. Figure 2b shows the same progression when styrene is added as CTA, at [CTA]/[M] = 0.05.…”