Polymer-dispersed liquid crystal/layered double hydroxide nanocomposite: A new emerging optical application

Abstract

Abstract This paper describes the preparation and characterization of polymer-dispersed liquid crystal (PDLC)/layered double hydroxides (LDHs) nanocomposites. In this study, Mg–Al LDH was applied as two-dimensional host material, with the unique properties of higher anionic exchange capacity (AEC) and higher aspect ratio. Preparation of nanomaterials with a uniform, higher crystalline and surface charge density could be performed by a hydrothermal method. SEM and particle diameter analysis measurement, successfully obtained affords smaller crystallites with a higher aspect ratio, having a very narrow distribution of crystallite size. The structure formula [ Mg 2 Al ( OH ) 6 ] NO 3 · 1.2 H 2 O were carried out by ICP-AES, EA and TGA. The major applications of LDHs based on the intercalation or exchange of specific guests as absorbents have been reported. However, it is seldom discussed to apply as optical materials. In this work, we have studied the Mg–Al LDH mixed with nematic liquid crystal and photo-polymer matrix. Photo-polymerization was induced by argon ion laser irradiation on the filled cells, which contain photo-initiator, monomers, liquid crystals and Mg–Al LDHs. Diffraction efficiency makes apparently increasing from 1.4 to 5.6%. When the sample was added 1 phr of Mg–Al LDH, the diffraction efficiency rise to 5.6 from 1.4%, compared with original PDLCs. Polymerization induced the phase separation of polymer and liquid crystal in the PDLC film. Higher diffraction efficiency was observed when PDLC hybridized with inorganic LDH, which will change the polymerization rate of PDLC, and help the formation of the grating effect; therefore, the diffraction efficiency of the whole system was improved. The noteworthy factor of improving diffraction efficiency will be discussed in this paper.