High performance holographic gratings formed with novel photopolymer films containing hyper-branched silsesquioxane

A transparent photopolymer film was prepared by embedding the epoxy cured octaaminophenylsilsesquioxane (hyper-branched POSS) into poly(vinyl chloride) (PVC) matrix containing vinyl monomers. Holographic gratings were successfully generated in that films by irradiation of laser light with 532 nm wavelength. The diffraction efficiency was increased with increasing the hyper-branched POSS concentration up to 15 wt%. DSC and TG analysis indicated the plasticizing effect of POSS in photopolymer that loosened the polymer matrix. This plasticizing effect made the monomer diffusion much more effective providing higher diffraction efficiency (D.E. ∼ 80%) compared to the film without hyper-branched POSS (D.E. ∼ 50%). The diffraction efficiency started to decrease with further higher concentration of POSS, because the polymer film became less transparent. Low volume shrinkage of 1.64% could be also obtained in recording of slanted holographic gratings.