Comparative study on the electrooptical properties of polymer‐dispersed liquid crystal films with different mixtures of monomers and liquid crystals

Abstract

This article deals with the study of polymerdispersed liquid crystal (PDLC) films that consisted of microdroplets of liquid crystals (LCs) dispersed in a polymer matrix. The PDLC films were fabricated by the photoinduced phase separation method under room-temperature conditions. To determine the extent of the effects of the molecular structures and their physical properties of different mixtures of monomers and LCs on the morphology and electrooptical properties of the PDLC films, various mixtures were used. A detailed discussion of the obtained results is given.

New Polymer Networks for PDLC Films Application

“…The electrooptical properties of PDLC films prepared by the polymerisation induced phase separation (PIPS) method depend on a numbers of factors such as the type of liquid crystal, molecular structure of polymerisable monomers and polymeric conditions. These factors could seriously affect the microstructure of the polymer matrix, the size and the shapes of the LC domains and molecular interactions between the LC molecules and the polymer matrix (anchoring effect) 8,[18][19][20] . In general and in a simple way, in a nematic liquid crystal there is a relationship between the size and the shape of LC domains and the anchoring effect.…”

“…Smaller domain size can be achieved by higher viscosity of the systems and poor diffusion of free radicals of the polymerisable monomers during polymerisation and hence the reduced coalescence of LC domains. Therefore, small LC domains can be obtained 8,20 .…”

“…The electro-optical response of PDLC films is greatly influenced by molecular structure of the monomers to be incorporated as polymeric matrix 10,19,20 . In literature reports there is not a great variety of monomers used in research for applications for PDLC films, besides the most common commercial ones.…”

“…Optical microscopy pictures of monomers 7, 5, 22, 21 and 20 are present in figures [16][17][18][19][20]. The analysis of these figures revealed a birefringent texture in the solid state.…”

Investigation of liquid crystal dispersion and dielectric relaxation behavior in polymer dispersed liquid crystal composite films

“…PDLCs have found great significance because of their promising use in advanced optical device applications, such as switchable windows, large flexible displays, or paper like displays for e-books [6][7][8][9]. In industrial and institutional research, PDLC films are getting more consideration, as liquid crystal (LC) display devices using these films can be switched to an electrically visible state without the use of polarizer and alignment layer on an electrode and also due to various other advantages like low fabrication cost, ease of production and quick electrooptical response [10]. PDLCs are composed of micron-size droplets of LCs dispersed in solid polymer binder and are formed by phase separation of a primarily homogeneous LC-polymer mixture.…”