substituted dioxolanes are provided having the formula ## str1 ## wherein r 1 and r 2 are h or a phenyl group substituted with up to 5 substituents of lower alkyl or nitro , with the proviso that at least one of f 1 and r 2 is a phenyl group having an orthonitro substituent ; and r 3 and r 4 are each h or lower alkyl . these dioxolanes , as well as appropriate dioxanes , are used to intercalate a polyoxymethylene polymer to make such a polymer having thermally stable but photochemically sensitive and degradable random linkages ## str2 ## in the chain where n is 0 or 1 , r 3 and r 4 are h or lower alkyl and at least one of r 1 and r 2 is a phenyl group with an orthonitro substituent . by exposing a film of the polymer to light through a transparency followed by heating or a heated treatment with base , a relief image of the copy on the transparency is obtained .