Embodiments in accordance with the present invention encompass compositions comprising an organopalladium compound, a photoacid generator, a photosensitizer, one or more epoxy group containing olefinic monomers. The compositions of this invention may additionally contain one or more olefinic monomers and a stabilizer, such as for example a hindered amine. The compositions undergo simultaneous vinyl addition polymerization and cationic polymerization when exposed to a suitable actinic radiation to form a substantially transparent film. The compositions of this invention are stable at room temperature for several days to several months and undergo mass polymerization only when subjected to suitable actinic radiation. The monomers employed therein have a range of optical and mechanical properties, and thus these compositions can be tailored to form films having various opto-electronic properties. More specifically, the compositions of this invention undergo much faster mass polymerization and exhibit superior thermo-mechanical properties when compared with the compositions containing only the olefinic monomers. Accordingly, compositions of this invention are useful in various applications, including as coatings, encapsulants, fillers, leveling agents, sealants, adhesives, among others.