Orientating layers with adjustable pretilt angles for liquid crystals deposited by a linear atmospheric pressure plasma source

Abstract

A method for controlling the pretilt angles of liquid crystals (LC) was developed. Hexamethyldisiloxane polymer films were first deposited on indium tin oxide coated glass plates using a linear atmospheric pressure plasma source. The films were subsequently treated with the rubbing method for LC alignment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements were used to characterize the film composition, which could be varied to control the surface energy by adjusting the monomer feed rate and input power. The results of LC alignment experiments showed that the pretilt angle continuously increased from 0° to 90° with decreasing film surface energy.

Enhancement of Planar Orientation of Reactive Mesogen Molecules for Optical Retarder Film by Anisotropic Surface Plasma Treatment

“…Crystals 2021, 11, 1080 2 of 14 Meanwhile, there has been approaches to improve the alignment of LC molecules using plasma [19][20][21][22][23][24]. Yaroshchuk et al applied a vacuum plasma treatment for LC alignment [19].…”

“…Then, it was reported that the uniform LC orientation can be obtained by the atmospheric plasma treatment [21,22]. In addition, it was also reported that the continuous control of the LC pretilt angle could be achieved by the combination of the plasma treatment and a rubbing treatment [23,24]. The effect of plasma treatment conditions such as the irradiation energy and the incident angle has been studied in the previous literature [23,24].…”