Photocrosslinking of polyethylene glycol (PEG) using exogenous agents is a convenient way to produce branched PEG from commercial sources thus avoiding the tricky synthesis of new reactive and functional polymers. In this study, we synthesized two series of new photocrosslinkers, i.e. bis-fluorophenyl azide and bis-trifluoromethyl diazirine, which under soft UV-irradiation produce reactive species