Interest and research activity in the photoinitiated cationic crosslinking polymerizations of multifunctional epoxide and oxetanes monomers have increased rapidly as this technology has found broad use in many industrial applications. However, while the synthesis of current epoxy-functional siloxanes yields monomers that undergo efficient cationic ring-opening photopolymerization to give crosslinked materials with excellent thermal and chemical resistance, they produce hard, brittle, glass-like materials with little elongation and flexibility. This invention is directed to new, highly reactive epoxy-silicone monomers and oligomers prepared by a simple, low cost route that, while useful in a wide range of conventional epoxy applications, are especially attractive for the formulation of rapid curing radiation curable coatings and composites.