The present invention relates to certain ring open metathesis polymerized (ROMP) polymers encompassing polycycloolefinic monomers and a certain of olefinic monomers having thermally labile functional group. More specifically, the present invention relates to ROMP polymers under mass polymerization conditions of a series of functionalized norbornene-type monomers and at least one other olefinic monomer containing a thermally labile functional group such as, ether, acetal, ester, and the like. This invention also relates to reaction compositions containing a series of functionalized norbornene-type monomers and at least one other olefinic monomer containing a thermally labile functional group such as, ether, acetal, ester, and the like, which undergo ring open metathesis polymerization to produce materials which are useful as flame retardant materials having a variety of applications.