AQUEOUS RING-OPENING METATHESIS POLYMERIZATION OF CARBOXIMIDE-FUNCTIONALIZED 7-OXANORBORNENES

The ring-opening metathesis polymerization (ROMP) of exo-N-methyl-7-oxabicyclo[2.2.1]-hept-5-ene-2,3-dicarboximide (1) was accomplished in aqueous solution under mild conditions using the simple ruthenium(II) coordination complex Ru(II)(H2O)6(tos)2 (tos = P-toluenesulfonate) (2). The polymerization yield was nearly quantitative. The resultant high molecular weight polymer (poly-1)exhibited a glass transition temperature (T(g)) of 225-degrees-C and was thermally stable up to 402-degrees-C. The thermal and radiative stabilities of poly-1 were further investigated. Poly-1 was hydrogenated to yield its saturated analogue, which had a lower T(g) (170-degrees-C) but a higher temperature of decomposition (430-degrees-C). Complex 2 was deactivated by coordination of free maleimides formed during the polymerization of carboximide-functionalized monomers capable of undergoing retro Diels-Alder chemistry. The scope of this polymerization was therefore limited to carboximide-functionalized monomers that are stable toward retro Diels-Alder reactions at the polymerization temperature. Both ruthenium(II)-1 and ruthenium(II)-N-methylmaleimide olefin complexes were identified.