Abstract: The invention relates to a method of producing (meth)acryloylthio esters of general formula I ##STR1## where R represents hydrogen or methyl, and R.sup.1 represents a phenyl group, a substituted phenyl group, a C.sub.1-24 alkyl group, a substituted C.sub.1-24 alkyl group, a cyclic C.sub.3-24 alkyl group;comprising reacting (meth)acrylic acid anhydride (formula II) ##STR2## where R represents hydrogen or methyl, with at least the stoichiometric amount with a thiol or thiolate of formula IIIR.sub.1 --S--M, (III)where M represents hydrogen or a metal cation, andR.sub.1 is defined as above.

Abstract: The invention relates to sulfur-containing polymethacrylates P produced by radical polymerization of monomers of formula I: ##STR1## where Y represents a C.sub.2-12 alkyl group, a C.sub.2-12 branched alkyl group, a C.sub.3-12 cyclic alkyl group, a C.sub.6-14 aryl group, or a C.sub.7-26 alkaryl group, wherein the carbon chains of Y may be interrupted by one or more ether or thioether groups; andR represents hydrogen or methyl; andwherewith the polymer P contains, in addition to units of monomer(s) of formula I, units of at least one monomer of formula II: ##STR2## where R and Y have the same meanings as above; and n is an integer in the range 1 to 6.