Surface initiated ring-opening metathesis polymerization of norbornene onto Wang and Merrifield resins

Merrifield and Wang resins were successfully converted to supported vinyl-functionalized solid supports with excellent yields by reacting the Cl or OH functionality with an α,ω-difunctional spacer bearing a carboxylic acid group and a terminal alkene. The ruthenium initiator (PCy3)2Cl2Ru = CHPh (Grubbs I catalyst) was then immobilized on the resins via cross metathesis (alkylidene exchange) and was used to initiate ROMP of norbornene. Number-average molecular weight and polydispersity index of the grafted polymers were determined after cleavage of the ester link between the resin and the spacer. The results showed a competition between ROMP and intramolecular “ring-closing” metathesis and/or intermolecular “cross” metathesis, which leads to an overestimated ruthenium initiator loading.

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