Polymer-encapsulated liquid crystals comprising montmorillonite clay

摘要

The morphologies of polymer-dispersed liquid crystals (PDLCs) and holographic PDLC(HPDLC) composites consisting of nematic liquid crystals filled with inorganic nanoparticles ofeither pristine montmorillonite (MMT) clay or organically modified MMT (OMMT) clay inpolymer matrices are described. Different curing processes with ultraviolet irradiation and anAr+ laser were applied to make the PDLCs and HPDLCs, respectively. In order to gain someprior knowledge of the dispersion of the inorganic nanoparticles in the polymer-encapsulatedsystems, wide-angle x-ray diffraction patterns from an MMT clay suspension in liquid crystalwere observed at variable temperatures. Differential scanning photocalorimetry was carried outto observe the monomer conversion. The morphology of liquid-crystal droplets of the PDLCswas investigated by optical polarizing microscopy. The holographic nature of the HPDLCs wasconfirmed by both scanning electron microscopy and atomic force microscopy. It was foundthat the diffraction efficiency is markedly enhanced by doping a small amount of pristine clayplatelets in the HPDLC. This preliminary study demonstrates the potential of a new opticaldevice, which is made of MMT clay hybridized with liquid crystal in a PDLC system.