Suitable photopolymerizable monomers for use in the compositions are selected from any of the free radically polymerizable ethylenically-unsaturated monomers, examples of which include one or more of the vinyl aromatic monomers such as styrene, ??-methylstyrene, 2- and 4-vinyl pyridine, and the like; a,??-unsaturated carboxylic acids and their derivatives such as acrylic acid, methacrylic acid, it