Ring-opening metathesis polymerization (ROMP) is a powerful tool to create bottlebrush polymers that have high grafting density and pendant chains with low dispersity. Specifically, the grafting-through method allows for “perfectly grafted” bottlebrush polymers due to each monomer unit containing a pendant side chain. However, grafting-through is limited to bottlebrush polymers with relatively low molecular weight pendant chains as well as backbones with lower degrees of polymerization when compared to other bottlebrush polymer synthetic methods. The objective of this research is to optimize grafting-through ROMP by determining the ideal polymerization conditions, specifically how solvent choice and purity affect the propagation kinetics. To achieve this, a polystyrene macromonomer was synthesized, and ROMP was performed using Grubb’s third generation ruthenium catalyst (Figure 1), and six different solvents with varying levels of purity. This solvent study allowed us to identify solvents that enable the greatest “livingness” in ROMP as well as determining which solvents are usable as received and which need further purification. By optimizing grafting-through in ROMP, bottlebrush polymers with longer backbones and/or pendant chain lengths as well as materials with unique shapes could be synthesized.

Optimization of bottlebrush polymer synthesis by ring-opening metathesis polymerization

ACS Fall 2021

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