Because you release ring strain, ring opening metathesis polymerization (ROMP) of strained cyclic olefins (norbornenes, cyclooctadiene, etc.) is an exothermic reaction, which means once initiated it generates heat, and the rate increases until the reaction fizzles out. If you’re interested in molding a large part, this can be problematic since you don’t want your resin to harden until your infusion is complete, and a number of tricks have been developed to slow this process down.
But sometimes a fast reaction is exactly what you want. A series of publications from Kenneth Caster and coworkers at Lord Corporation a few years back is an example of this. Termed “contact metathesis polymerization,” this process takes advantage of the spontaneous ROMP reaction to create a quick-setting adhesive.
They applied a ruthenium metathesis catalyst coating to a substrate surface (metal or elastomer). They then applied a layer of ROMP monomer (ethylidenenorbornene, methylidenenorbornene, dicyclopentadiene, or cyclooctene) to a rubber surface, and simply pressed the two together to create a strong bond. How strong? In many cases, they observed material tear prior to adhesive failure.
Caster, K. C.; Tokas, E. F.; Keck, C. G.; Hontz, M. E. J. Mol. Catal. A: Chem. 2002, 190, 65.
Caster, K. C.; Walls, R. D. Adv. Synth. Catal. 2002, 344, 764.
Keck, C. G.; Kendall, J. L.; Caster, K. C. Adv. Synth. Catal. 2007, 349, 165.