A macro-photoinitiator comprising a polymer chain structure represented by the following general formula, Φ-[[- p -] x -Y-L-PI] z wherein, Φ is selected from linear or branched aliphatic compounds, cycloaliphatic compounds, heterocyclic compounds, aryl compounds, heteroaryl compounds, aralkyl compounds, sulfonyl compounds, sulfenyl compounds, esters of carboxylic acids, polymeric compounds, and mixtures thereof, M is a residue of at least one ethylenically unsaturated radically polymerizable monomer, p represents an average number of monomer residues occurring in a block of monomer residues, p, x, and z are each individually selected such that said macro-photoinitiator has a number average molecular weight of at least 400, p is, independently for each x, an integer from 1 to 5000, x is, independently for each z, an integer from 1 to 20, z from 1 to 10, Y, independently for each z, is selected from S and O, L, independently for each z, is a bond or a divalent linking group, said divalent linking group comprising at least one divalent organic moiety and optionally at least one divalent inorganic moiety selected from -O-, -C -, -O-C -, -O-C -O-, and combinations thereof, and PI, independently for each z, represents a photoinitiator residue said photoinitiator residue is selected from anthraquinone residues, thioxanthone residues, triazine residues, fluorenone residues, and photoinitiator residues represented by the following general formula, wherein, R is aryl, aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen and combinations thereof, C 3 -C 12 cycloalkyl or -CR 1 R 2 R 3, wherein R 1, R 2 and R 3 are each individually selected from hydrogen, hydroxyl, aryl, aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen, and combinations thereof, C 1 -C 20 hydroxylalkyl, C 1 -C 20 alkoxy, C 3 -C 12 cycloalkyl, and -C -R 5 wherein R 5 is aryl or aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen and combinations thereof, and R 4 in each instance is independently selected from hydrogen, halogen, linear, or branched C 1 -C 20 alkyl, C 3 -C 12 cycloalkyl, and aryl, and wherein said macro-photoinitiator has a number average molecular weight of from 400 to 500,000, and a polydispersity index of less than 1.8. Φ is selected from linear or branched aliphatic compounds, cycloaliphatic compounds, heterocyclic compounds, aryl compounds, heteroaryl compounds, aralkyl compounds, sulfonyl compounds, sulfenyl compounds, esters of carboxylic acids, polymeric compounds, and mixtures thereof, M is a residue of at least one ethylenically unsaturated radically polymerizable monomer, p represents an average number of monomer residues occurring in a block of monomer residues, p, x, and z are each individually selected such that said macro-photoinitiator has a number average molecular weight of at least 400, p is, independently for each x, an integer from 1 to 5000, x is, independently for each z, an integer from 1 to 20, z from 1 to 10, Y, independently for each z, is selected from S and O, L, independently for each z, is a bond or a divalent linking group, said divalent linking group comprising at least one divalent organic moiety and optionally at least one divalent inorganic moiety selected from -O-, -C -, -O-C -, -O-C -O-, and combinations thereof, and PI, independently for each z, represents a photoinitiator residue said photoinitiator residue is selected from anthraquinone residues, thioxanthone residues, triazine residues, fluorenone residues, and photoinitiator residues represented by the following general formula, wherein, R is aryl, aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen and combinations thereof, C 3 -C 12 cycloalkyl or -CR 1 R 2 R 3, wherein R 1, R 2 and R 3 are each individually selected from hydrogen, hydroxyl, aryl, aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen, and combinations thereof, C 1 -C 20 hydroxylalkyl, C 1 -C 20 alkoxy, C 3 -C 12 cycloalkyl, and -C -R 5 wherein R 5 is aryl or aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen and combinations thereof, and R 4 in each instance is independently selected from hydrogen, halogen, linear, or branched C 1 -C 20 alkyl, C 3 -C 12 cycloalkyl, and aryl, and wherein said macro-photoinitiator has a number average molecular weight of from 400 to 500,000, and a polydispersity index of less than 1.8. wherein, R is aryl, aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen and combinations thereof, C 3 -C 12 cycloalkyl or -CR 1 R 2 R 3, wherein R 1, R 2 and R 3 are each individually selected from hydrogen, hydroxyl, aryl, aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen, and combinations thereof, C 1 -C 20 hydroxylalkyl, C 1 -C 20 alkoxy, C 3 -C 12 cycloalkyl, and -C -R 5 wherein R 5 is aryl or aryl substituted with at least one substituent selected from C 1 -C 20 alkyl, halogen and combinations thereof, and R 4 in each instance is independently selected from hydrogen, halogen, linear, or branched C 1 -C 20 alkyl, C 3 -C 12 cycloalkyl, and aryl, and wherein said macro-photoinitiator has a number average molecular weight of from 400 to 500,000, and a polydispersity index of less than 1.8.