Describes polymerizing with actinic radiation a cationically polymerizable organic composition comprising (a) at least one polyfunctional thiirane having at least two groups represented by the following general formula (I), wherein X is selected from S and O, the number of functional groups wherein X is S constituting at least 50 percent of the total number of such functional groups present in said first polyfunctional thiirane, and R8, R9 and R10 are each independently selected from hydrogen and C1-C10 alkyl; and (b) at least one actinic radiation activated cationic polymerization initiator.
