Thermo-stability of acrylate based holographic polymer dispersed liquid crystal gratings

The thermo-stability of acrylate based holographic polymer dispersed liquid crystal gratings has been evaluated with regard to their morphology, diffraction efficiency, Bragg angle and electro-optical tunable performance. Our studies indicate that the thermo-stability is closely related to the chemical structure of the monomers in the grating. Usually, a more rigid molecular structure forms a more stable morphology. Another important aspect, the reaction efficiency of the system, shows that a highly efficient photoreaction leads to a dense polymer network and high ene-conversion, thus promoting the phase separation of the liquid crystal and enhancing the thermo-stability. We also find that a higher average functionality of the monomers can improve grating thermo-stability due to denser crosslinked polymers and more complete phase separation.