Tuning the morphology and electro-optical properties of reverse mode PDLCs using multifunctional acrylates

Reverse-mode Polymer Dispersed Liquid Crystals (rev-PDLCs) are composite materials generally obtained by the phase separation of dispersions of liquid crystal/monomer mixtures and characterised by the possibility to change on-demand their transmittance in a continuous manner from an initial transparent state to an opaque one by application of an electric field. Rev-PDLCs have found applications in many fields, including large-area smart windows, automotive, and bifunctional devices. In this work, acrylate monomers with different functionality (from 3 to 6) and weight ratios (from 5 to 15%) were used to finely adjust the morphology and electro-optical properties of the rev-PDLCs obtained by photo-polymerisation of an aligned LC/LC monomer mixture. The doping of nematic liquid crystalline monomers with acrylate monomers allowed to finely tune the morphology of rev-PDLC films, which were characterised by highly transparent OFF-states (TOFF always larger than 60%), strongly opaque ON-states (TON always around or lower than 1%), but with contrast ratios, transmittance slopes, threshold and switching fields dependent on the amount and functionality of used monomers. Such results could represent a valid method to overcome the drawback of relatively low materials to be used as starting components in the fabrication of reverse mode dimming films.