Polymer dispersed liquid crystals devices: role of photopolymerisation to control defect orientation, optical and electro-optical properties

ABSTRACT

We are reporting the effect of polymer dispersion on liquid crystals (LCs) by examining their structural, morphological and electro-optic properties. Ultraviolet irradiation effect has been investigated through morphological and electro-optic characteristics and perceived structural behaviour transformation in the respective devices, which persuade topological restraints in the form of defects (photopolymerisation and chemical interaction provoke the development of frozen network which leads to packing of LC molecules in different orientations and defect geometries). We have observed the effect of temperature and voltage on morphological studies via optical micrographs under polarising optical microscopy. A significant effect of polymer concentrations and temperature has been observed on the physicochemical properties of polymer-dispersed liquid crystal (PDLC) systems. The development of defects can be understood via possible theoretical chemical interactions, polymerisation and anchoring energy. A relative optical transmittance and lower threshold voltage has been presented for all the respective PDLC devices in comparison to the pure LC. A higher anchoring (10⁻⁵ J/m²) and contrast (18.34 dB) have been noticed in the PDLC devices. Refractive indices and corresponding birefringence have also been measured and compared for pure and doped LC systems. Furthermore, these investigations offer an understanding of essential mechanisms to develop potential electronic materials and optical device applications.

GRAPHICAL ABSTRACT

KEYWORDS:

• Polymer-dispersed liquid crystal
• photopolymerisation
• transmittance
• anchoring
• contrast and threshold

Acknowledgments

Ashok Chaudhary is grateful to Director, NIT Jalandhar, for providing the experimental facility and for their valuable support and cooperation.

Disclosure statement

No potential conflict of interest was reported by the author(s).