Synthesis and characterisation of thermotropic liquid crystalline monomer : 4-methylphenyl 4-[2-(vinyloxy) ethoxy]benzoate
This thesis is primarily concerned with the synthesis of a new thermotropic liquid crystalline monomer and its characterisation by using elemental analysis, spectroscopic analysis and thermal analysis techniques. A new thermotropic liquid crystalline monomer, 4-methylphenyl 4-[2- (vinyloxy)ethox...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2000
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/9084/1/FSAS_2000_18%20IR.pdf |
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| Summary: | This thesis is primarily concerned with the synthesis of a new thermotropic liquid
crystalline monomer and its characterisation by using elemental analysis,
spectroscopic analysis and thermal analysis techniques.
A new thermotropic liquid crystalline monomer, 4-methylphenyl 4-[2-
(vinyloxy)ethoxy]benzoate (4MP4VEB) was synthesised by reacting 4-
methylphenyl 4-hydroxybenzoate (4MP4HB) with 2-chloro-ethyl-vinyl ether in
acetonic solution. The compound 4MP4HB as a mesogenic group was prepared
from the reaction of p-hydroxybenzoic acid and p-cresol. The mesogenic group
(4MP4HB) was also used to synthesise the other thermotropic liquid crystalline
compound namely 4-methylphenyl 4-(3-hydroxypropoxy)benzoate (4MP4HPB)
but without a monomer terminal.The attempted synthesis of other liquid crystalline monomer with a varying
spacer length using a different approach only ended up with a precursor
compound. Two precursors, namely 4-[4-(allyloxy)butoxy]benzoic acid
(4ABBA) and 4-(allyloxy)benzoic acid (4ABA) were successfully synthesised
for the preparation of thermotropic liquid crystals with an allyl group as a
monomer terminal. The compound 4ABBA is a precursor that has a spacer
linkage, while 4ABA is without a spacer linkage.
The liquid crystalline compound and the synthesised precursors were
characterised by elemental, spectroscopic and thermal analyses. The observation
of thermal properties and liquid crystallinities under polarising microscope
revealed that the compound 4MP4VEB exhibited the like-mosaic defect texture
of nematic mesophase, while the compound 4MP4HPB exhibited the focal-conic
texture of smectic A mesophase. |
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