Liquid Crystal Alignment Effects for Nematic Liquid Crystal on Homeotropic Polyimide Surface Using New Ion-Beam Source

Abstract

We have studied the liquid crystal (LC) alignment and tilt angle generation of a nematic liquid crystal (NLC) on a homeotropic polyimide (PI) surface using a new ion beam source. The tilt angle of the NLC on the homeotropic PI surface for all incident angles is about 38 and this angle has a stabilization trend. A good LC alignment of the NLC on the homeotropic PI surface by to exposure ion beam of 45 incidence angle was observed. Also, the tilt angle of the NLC on the homeotropic PI surface by to exposure ion beam of 45 incidence angle had a tendency to decrease as ion beam energy density increased. Thus, we demonstrated that the tilt angle could be controlled from vertical to horizontal directions. Also, the alignment character of the NLC on the homeotropic PI surface with respect to ion beam energy was good at more than 1500 eV. Finally, a superior LC alignment thermal stability on the homeotropic PI surface subject to ion beam exposure was achieved.

Vertical Alignment of Liquid Crystals on Phenylphenoxymethyl-Substituted Polystyrene—PS Derivatives Structurally Similar to LC Molecules

“…For instance, the vertical alignment of LC molecules, wherein the direction of the LC molecules is oriented vertically relative to the surface, has been investigated for optical sensor applications owing to susceptibility to small perturbations [ 21 , 22 , 23 , 24 ]. It has been found that LC molecules could be oriented by the anisotropic properties of a surface via contact and non-contact methods, such as rubbing, lithography, stretching, polarized ultraviolet irradiation, and ion beam treatment [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Among these, the rubbing technique is the conventional contact method used to align LC molecules because of its simplicity and rapidity [ 33 , 34 ].…”

Vertical Orientation of Liquid Crystal on Comb-Like 4-(trans-4-alkylcyclohexyl)phenoxymethyl-substituted Polystyrene Containing Liquid Crystal Precursor

“…For example, the vertical orientation of nematic LCs, wherein the director of the nematic LCs is oriented vertically to the surface of the substrate, has been studied for sensor applications because of its susceptibility to small perturbations and binding events [ 15 , 16 , 17 , 18 ], which can be observed by an optical apparatus such as a polarized optical microscopy (POM) [ 19 , 20 ]. It has been demonstrated that LC molecules can be aligned by the anisotropic characteristics of a surface via numerous contact and noncontact methods, such as mechanical rubbing, stretching, lithography, polarized ultraviolet (UV) radiation, and ion beam treatment [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Among these, the mechanical rubbing of polymeric surfaces is the most commonly used contact method to obtain a uniform orientation of LC molecules because of its simplicity and rapidity [ 29 , 30 ].…”

Vertical Orientation of Liquid Crystal on Polystyrene Substituted with n-Alkylbenzoate-p-oxymethyl Pendant Group as a Liquid Crystal Precursor

“…The most well-known example of these efforts is the development of the liquid crystal display (LCD), which involves an orientation layer, and is widely used in portable display devices such as smartphones [ 10 , 11 ]. It has been found that liquid crystal (LC) molecules can be oriented by the anisotropic characteristics of a substrate surface via numerous contact and noncontact methods, such as mechanical rubbing, stretching, lithography, polarized ultraviolet (UV) radiation, and ion beam treatment [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Due to its simplicity and rapidity, the mechanical rubbing of polymeric surfaces is the most commonly used contact method for controlling not only the orientation direction, but also the pretilt angle of the LC molecules [ 20 , 21 ].…”