Synthesis and Electro-Optical investigation of Fluorine substituted Banana-Shaped Liquid Crystals Monomers

Lutfor Rahman, (2009) Synthesis and Electro-Optical investigation of Fluorine substituted Banana-Shaped Liquid Crystals Monomers. (Unpublished)

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Abstract

Six novel bent-shaped monomers viz. substituted 1,3-phenylene bis-{ 4-[ 4-(n-allyloxyalkyloxy) phenylazo ]benzoate} 5a-c and substituted 1,3-phenylene bis-{ 4-[ 4-(n-allyloxyalkyloxy)-3- fluorophenylazo]benzoate} 5d-f in which azobenzene moiety in the periphery and resorcinol as central unit and polymerizable double bonds at both ends of all the molecules were synthesized and characterized. Mesophase behavior was investigated using polarizing optical microscopy, DSC and XRD measurements. All six members of the family show an intercalated smectic (Smintercal) phase. One of these azo dyes has been Investigated for guest host effect in which liquid crystal is the guest and bent core azo dye is the host, 5% of this azo dye is mixed with 95 % of liquid crystal E7. The absorbance study as a function of wavelength at different time intervals with fixed UV intensity (intensity lmW/cm2). When the radiation is switched off and the sample is left In the dark, reverse isomerization takes place with the sample transforming in to the nematic phase from isotropic phase and consequently absorbance increases. Absorbance spectrum has been recorded at certain Intervals to check the thermal back relaxation process. After 50000 seconds (around 13 hours), system fully transforms to original nematic state. It takes very long time (almost 13 hours) to convert back to trans state which is useful for creation of optical image storage devices. Thus, one of azo dye is mixed with liquid crystal as a guest, showed greater increase in thermal back relaxation time which is useful for creation of optical image storage devices.

Item Type: Research Report
Uncontrolled Keywords: Bent-shaped monomers viz , phenylazo benzoate , azobenzene moiety
Subjects: Q Science > QD Chemistry
Depositing User: Noraini
Date Deposited: 30 Sep 2019 00:31
Last Modified: 30 Sep 2019 00:31
URI: http://eprints.ums.edu.my/id/eprint/23644

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