at least one photoinitiator which promotes {HEAD ~ free radical polymerization} by generating {TAIL ~ reactive specie} by way of unimolecular homolysis resulting from photoexcitation, said photoinitiator having the formula ##STR27## wherein A1 and A2 are the same or different and each is a benzenoid or nonbenzenoid aromatic radical 
at least one photoinitiator which promotes { HEAD ~ free radical polymerization } by generating { TAIL ~ reactive specie } by way of unimolecular homolysis resulting from photoexcitation , said photoinitiator having the formula # # STR27 # # wherein A1 and A2 are the same or different and each is a benzenoid or nonbenzenoid aromatic radical
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH