Cross-linked polydicyclopentadiene (PDCPD) is a light-weight material of superior mechanical strength. The cross-linked network is a result of ring-opening metathesis polymerization (ROMP) of the highly reactive C=C double bond of norbornene ring system in addition to the ring opening cross metathesis (ROCM) of the less reactive C=C double bond of the cyclopentene ring. We have demonstrated that under certain conditions, a 3<sup>rd</sup> generation Grubbs-type catalyst can be used to exclusively synthesize linear PDCPD, in particular when very low catalyst loadings were used to a degree that molecular weights were close those of a controlled polymerization. Some branching of the linear polymer as a result of ROCM was observed particularly at higher catalyst loadings. We developed two methods to terminate the ROMP reaction, 1) with PPh<sub>3</sub> which retains the Ru-alkylidene end group of the polymer and 2) ethyl vinyl ether which detaches the Ru-alkylidene from the polymer. The thermal properties of the isolated linear PDCPD materials were investigated and the materials containing Ru-alkylidene end groups exhibited later onset temperatures for decomposition. The addition of bromine resulted in a linear material in which the C=C double bonds of the linear PDCPD is partially brominated. Varying degrees of bromination affected the thermal properties of these materials which exhibited higher energies and onset temperatures of an endothermic dehydrobromination process with higher amounts of covalently bonded bromine in the polymer.

Synthesis and thermal properties of linear poly-dicyclopentadiene and linear polybrominated polydicyclopentadiene

2019 Spring National Meeting

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