A composition comprising: a. at least one copolymerizable (meth)acrylic monomer; b. optionally, at least one copolymerizable non-acrylic monomer; c. at least one copolymerizable photoinitiator; d. optionally, a solvent; and e. optionally, one or more non-copolymerizable thermal initiators; characterized in that the at least one copolymerizable photoinitiator (c) is a compound of formula wherein - X isS; - R 1, R 2 and R 3, each independently, are selected from hydrogen, C 1-6 alkyl groups, halogens, amino groups, nitro groups, nitrile groups, hydroxyl groups, C 1-6 alkoxide groups; - R 4 is selected from hydrogen, -COOH, -CH 2 CO 2 H and a methyl group, wherein said at least one copolymerizable (meth)acrylic monomers (a) is selected from: i. hydroxyalkyl acrylic or methacrylic acid esters, wherein alkyl groups have 2-18 carbon atoms, most preferably 2 to 10 carbon atoms, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and mixture thereof; ii. alkyl acrylic or methacrylic acid esters, wherein alkyl groups have preferably 2-18 carbon atoms, most preferably 2 to 10 carbon atoms, such as n-butyl acrylate, n-butyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate and mixture thereof; iii. alkoxyalkyl of acrylic or methacrylic acid esters, wherein alkyl groups have preferably 2-18 carbon atoms, most preferably 2 to 10 carbon atoms, such as methoxyethyl acrylate, methoxyethyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate and mixture thereof; iv. monomers of formula R 5 -(OCH 2 CHR 7) n L-O -CR 6 =CH 2 wherein R 5 is hydrogen or a C 1 -C 6 alkyl group, n is an integer from 1 to 100, L is a single bond or a divalent linking group, preferably a single bond or a C 1 -C 6 alkylene group and R 6 is hydrogen or a CH 3 group, and R 7 is a hydrogen or a methyl group; and mixtures thereof. a. at least one copolymerizable (meth)acrylic monomer; b. optionally, at least one copolymerizable non-acrylic monomer; c. at least one copolymerizable photoinitiator; d. optionally, a solvent; and e. optionally, one or more non-copolymerizable thermal initiators; - X isS; - R 1, R 2 and R 3, each independently, are selected from hydrogen, C 1-6 alkyl groups, halogens, amino groups, nitro groups, nitrile groups, hydroxyl groups, C 1-6 alkoxide groups; - R 4 is selected from hydrogen, -COOH, -CH 2 CO 2 H and a methyl group, i. hydroxyalkyl acrylic or methacrylic acid esters, wherein alkyl groups have 2-18 carbon atoms, most preferably 2 to 10 carbon atoms, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and mixture thereof; ii. alkyl acrylic or methacrylic acid esters, wherein alkyl groups have preferably 2-18 carbon atoms, most preferably 2 to 10 carbon atoms, such as n-butyl acrylate, n-butyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate and mixture thereof; iii. alkoxyalkyl of acrylic or methacrylic acid esters, wherein alkyl groups have preferably 2-18 carbon atoms, most preferably 2 to 10 carbon atoms, such as methoxyethyl acrylate, methoxyethyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate and mixture thereof; iv. monomers of formula R 5 -(OCH 2 CHR 7) n L-O -CR 6 =CH 2 wherein R 5 is hydrogen or a C 1 -C 6 alkyl group, n is an integer from 1 to 100, L is a single bond or a divalent linking group, preferably a single bond or a C 1 -C 6 alkylene group and R 6 is hydrogen or a CH 3 group, and R 7 is a hydrogen or a methyl group; and mixtures thereof.