Frontal polymerization using encapsulated catalysts

Abstract

Frontal polymerization involves the propagation of a thermally driven polymerization wave through a monomer solution to rapidly generate high-performance polymeric materials with little energy input. The balance between latent catalyst activation and sufficient reactivity to sustain a front can be difficult to achieve and often results in systems with poor storage lives. This is of particular concern for frontal ring-opening metathesis polymerization (FROMP) where gelation occurs within a single day of resin preparation due to the highly reactive nature of Grubbs-type catalysts. The invention uses encapsulated catalysts to provide remarkable latency to frontal polymerization systems, with negligible differences in frontal velocities or thermomechanical properties of the resulting polymeric materials. FROMP systems with encapsulated catalyst particles are shown with storage lives exceeding eight months and front rates that increase over a two month period. Moreover, the generality of this encapsulation method is demonstrated by encapsulating a platinum catalyst for the frontal polymerization of silicones using hydrosilylation chemistries.