Holographic Gratings in Photosensitive Acrylic Polymers with High Refractive Index Diphenyl Sulfide

To investigate the effects of polymer matrices on the diffraction efficiency of holographic grating, a series of chiral compounds of bornyl acrylate (BA), bornyl methacrylate (BMA), and their enantiomers derived from borneol were synthesized. Instead of conventional liquid crystals, in this investigation we used a high refractive index diphenyl sulfide (DS, n20D=1.6327) mixed with initiators, bornyl acrylate, bornyl methacrylate, and multifunctional monomers to prepare the photosensitive holographic grating films. Membranes having a large refractive index difference (Δn) between the cured grating arrays and revealing high diffraction efficiency (DE) were created by using the compositions. The dynamic formation of the holographic grating and the dependence of the diffracting efficiency on laser exposure time and intensity were carried out. It was found that the intensity of the writing laser may affect the polymerization rate leading to various results of holographic grating. Bragg grating and Raman–Nath grating depending on the incident writing angles were all obtained. We also investigated the plural recording function of the photosensitive films, the morphologies of the polymer matrices, and laser light grating through the holographic grating membranes. Thermogravimetric analyses of the photosensitive membranes were also estimated.