Low driving voltage holographic polymer dispersed liquid crystals with chemically incorporated graphene oxide

A minute amount of allyl isocynate functionalized graphene oxide (MGO, 0.05-0.25%) has been covalently incorporated into the polyurethane acrylate based matrix of holographic polymer dispersed liquid crystals (HPDLC), and the effects were studied in terms of compound viscosity, grating kinetics and morphology, diffraction efficiency (DE), and electro-optical properties of the HPDLC films at two levels of laser writing power. MGO at very low content (0.05%, 0.10%) significantly reduced the compound viscosity, increased the polymerization rate, limited droplet coalescence, and increased the diffraction efficiencies (74%, 64%) over the MGO-free compound (48%). Polymer conductivity and local electrical field increased with increasing MGO content to give a large decrease in operating voltage in accordance with a theoretical prediction. With high laser intensity, well defined grating structure with small droplet size was seen from the SEM morphology to give a fast grating formation with high saturation diffraction.