Ring-opening metathesis polymerization (ROMP) is a powerful tool for the design and synthesis of polymeric materials with diverse applications such as self-healing and medical uses. While much efforts were made towards synthesis and applications of polymers with controlled length and composition by ROMP, less attention was paid on the depolymerizability and repolymerizability of the system. Since ROMP is driven by release of ring strain, we hypothesized that monomers with less ring strain such as cyclopentene are promising candidates for tunable polymerizability by incorporating different substituents. Herein, we investigated ceiling temperature (Tc) of a series of cyclopentene derivatives both in solution and bulk to quantify their polymerizability. Varying the substituents at the b-position of the cyclopentene ring dramatically affects both solution and bulk Tc. By judiciously selecting liquid monomers with bulk Tc values that are slightly above room temperature, the corresponding polypentenamers readily depolymerize in the neat state at elevated temperatures to generate liquid monomers. Upon cooling, these monomers repolymerize to yield solid polymers. This depolymerization-repolymerization cycle is solely triggered by mild environmental temperature changes, which opens up new opportunities towards development of functional materials with reversible polymerizability.

Effects of substituents on the ceiling temperature of cyclopentene in ring-opening metathesis polymerization

253rd National Meeting (2017)

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