Vinyl acetophenone-maleic anhydride copolymer

Light-sensitive polymers contain the recurring unit where n=0, 1, 2 or 3, Q is an aryl group of the benzene series, D is a single bond or an aryl group of the benzene or naphthalene series, and R is hydrogen or an alkyl group containing 1 to 5 carbon atoms. Specified are polymers and copolymers of vinyl cinnamal acetophenone, vinyl p-methoxy cinnamal acetophenone (particularly with vinyl benzal acetophenone) acetyl styrene and its a -n-amyl, p-chloro, m-nitro, o-chloro, p-methoxy, p-methyl and benzal derivatives, the p-chloro or p-methoxy cinnamal acetyl o-methoxy styrene, p-methyl cinnamal acetyl-o-chlorostyrene and cinnamal methyl vinyl ketone. The polymers may be prepared by condensing a polymer of an acylated vinyl benzene or-naphthalene with, preferably an excess of, a cinnamic aldehyde, alternatively a vinyl acetophenone (which may be prepared by depolymerizing polyvinylacetophenone) or acetonaphthone monomer may be polymerized or copolymerized with a compound containing the group -CH=C< and the resultant condensed with the cinnamic aldehyde. The condensation may be carried out in the presence of a dehydration catalyst, e.g. sulphuric acid, phosphoric acid, acetic anhydride, phosphoric pentoxide, toluene sulphonic acid, trimethyl benzyl or tetramethyl or tetraethyl ammonium hydroxides, trimethyl benzyl ammonium butoxide, sodium hydroxide or sodium methoxide in the presence of a solvent, e.g. 1,4-dioxane, benzophenone or a large excess of the aldehyde. Specified -CH=C< group containing compounds are styrene, acrylonitrile, acrylic and alkacrylic acids and esters, maleic anhydride and isobutylene. Partially acetylated polystyrene is prepared by treating a carbon disulphide solution of polystyrene with acetyl chloride in the presence of aluminium chloride. The preferred cinnamic aldehydes have the formula where R is hydrogen or an alkyl group containing 1 to 5 carbon atoms and Q is an aryl group of the benzene series, while mixtures may be used and may include such aldehydes as benzaldehyde. Specifications 695,197, [Group XX], 713,947, 717,708, 717,710, 717,711 and 717,712 and U.S.A. Specification 2,566,302 are referred to.