Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/2717
Title: PREPARATION AND CHARACTERIZATION OF NORMAL AND REVERSE MODE POLYMER DISPERSED LIQUID CRYSTALS
Authors: SHARMA, VANDNA
Keywords: NORMAL AND REVERSE
POLYMER DISPERSED LIQUID CRYSTALS
Issue Date: Jan-2020
Publisher: Chitkara university, Punjab
Abstract: Polymer dispersed liquid crystals (PDLCs) have become an area of interdisciplinary research and developing their great scientific attention in this field. In PDLCs, liquid crystal (LC) is trapped as drops embedded within a polymeric matrix and LC molecules within droplets are randomly aligned parallel to the substrate and scattered light in OFF state. However, in reverse mode PDLC, LC is vertically aligned (VA) initially and transparent in OFF state. Thus, research work was focused to prepare normal and reverse mode PDLCs and studied their droplet morphology, electro-optic (EO) characteristics, threshold and operating voltages, contrast ratio (CR), response time and absorption behaviour as well as interdependency among all these parameters. Initially, Introduction of LC to PDLCs along with process cum formation of normal and reverse modes was studied and reviewed the advancements in the field extensively. Further, normal mode PDLCs for conventional (pure) and with the doping of silica nanoparticles (NPs) and multiwall carbon nano tubes (CNTs) were prepared and investigated in detail. Results have shown that NPs and multiwall CNTs in PDLC readily controlled the molecular orientation and dynamics of LC in droplets with reduced value of threshold electric field in addition to higher contrast. Further, work was continued with the effect of doping of azo orange dichroic dye having varied concentrations (0.0625%-1.0% of LC) in PDLCs were prepared and characterized. Experimental results showed that controlled amount of azo orange dichroic dye reduce the scattering with the alignment of the LC molecules along the director and showed enhanced EO characteristics as compared to conventional normal mode PDLCs. Moreover, the effect of NPs and dye in reverse mode PDLCs was also observed. Consequently, in reverse mode PDLCs, the POM study confirmed the development of VA of LC within the LC droplets. Droplet configuration varies with applied voltage and showed the scattering state with radially planar type textures. Doping of NPs, dye and (NPs + dye) reduced the threshold and operating voltages significantly, found 3.89 V & 12.7 V, 4.92 V & 13.3 V as well as 3.51 V & 11.3 V, respectively for NPs, dye and (NPs + dye) doped as compared with 6.09 V & 15.05 V required for conventional (without doping) reverse mode PDLC. In addition, CR was also found improved 25.18, 26.4 and 33.78 for NPs, dye and (NPs + dye) doped, respectively, compared with 14.5 for conventional reverse mode PDLC. Thus, the augmented performance of doped normal and reverse mode PDLCs with improved CR and low driving voltages will be of great interest of energy efficient display devic
URI: http://hdl.handle.net/123456789/2717
Appears in Collections:Doctoral Theses

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80_Recommendation.pdf379.75 kBAdobe PDFView/Open
Abstract Page.pdf7.76 kBAdobe PDFView/Open
Chapter 1.pdf4.07 MBAdobe PDFView/Open
Chapter 2.pdf801.3 kBAdobe PDFView/Open
Chapter 3.pdf1.03 MBAdobe PDFView/Open
Chapter 4.pdf2.16 MBAdobe PDFView/Open
Chapter 5.pdf1.7 MBAdobe PDFView/Open
Chapter 6.pdf1.43 MBAdobe PDFView/Open
Chapter 7.pdf259.15 kBAdobe PDFView/Open
Declaration and Certificate Pages.pdf431.92 kBAdobe PDFView/Open
Preliminary Pages.pdf809.43 kBAdobe PDFView/Open
References.pdf465.24 kBAdobe PDFView/Open
Title Page.pdf122.98 kBAdobe PDFView/Open


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