Phase behaviour of side-chain liquid-crystalline polymers
Phase behaviour of side-chain liquid-crystalline polymers
A number of homologous series of homo- and copolymers have been synthesised, by polymer modification methods, in which the following structural components were varied systematically:
(i) the terminal substituent of the rigid anisometric units (ii) the length and parity of the alkyl chains connecting the anisometric units to the polymer backbone (iii) the chemical constitution of the polymer backbone (iv) the molecular weights of the polymers (v) the concentration of mesogenic units in copolymers (vi) the chemical constitution of the non-mesogenic side-chain in copolymers
The clearing temperatures, glass transition temperatures and transition enthalpies and entropies were determined for all materials and compared.
The trends in transitional behaviour for the homopoymers are broadly similar to those observed in low molar mass liquid crystals. Smectic and nematic phases were observed and large odd-even effects were exhibited in transition temperatures and entropies alike. Relatively high glass transition temperatures were observed, inherited from the parent polymers. Copolymers of mesogenic and non-mesogenic components exhibited stable mesophases with little change in clearing temperatures to dilutions of mesogenic side-chains as low as 50. Deviations from ideal behaviour were also observed in the glass transition temperatures and transition entropies.
The behaviour has been rationalised in terms of virtual trimer model in which the polymer backbone plays an integral role in determining the mesogenic characteristics of the polymer.
University of Southampton
1994
Madden, Andrea
(1994)
Phase behaviour of side-chain liquid-crystalline polymers.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A number of homologous series of homo- and copolymers have been synthesised, by polymer modification methods, in which the following structural components were varied systematically:
(i) the terminal substituent of the rigid anisometric units (ii) the length and parity of the alkyl chains connecting the anisometric units to the polymer backbone (iii) the chemical constitution of the polymer backbone (iv) the molecular weights of the polymers (v) the concentration of mesogenic units in copolymers (vi) the chemical constitution of the non-mesogenic side-chain in copolymers
The clearing temperatures, glass transition temperatures and transition enthalpies and entropies were determined for all materials and compared.
The trends in transitional behaviour for the homopoymers are broadly similar to those observed in low molar mass liquid crystals. Smectic and nematic phases were observed and large odd-even effects were exhibited in transition temperatures and entropies alike. Relatively high glass transition temperatures were observed, inherited from the parent polymers. Copolymers of mesogenic and non-mesogenic components exhibited stable mesophases with little change in clearing temperatures to dilutions of mesogenic side-chains as low as 50. Deviations from ideal behaviour were also observed in the glass transition temperatures and transition entropies.
The behaviour has been rationalised in terms of virtual trimer model in which the polymer backbone plays an integral role in determining the mesogenic characteristics of the polymer.
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Published date: 1994
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Local EPrints ID: 462825
URI: http://eprints.soton.ac.uk/id/eprint/462825
PURE UUID: a07b57ec-fa04-4e84-80a2-275c10053139
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Date deposited: 04 Jul 2022 20:12
Last modified: 04 Jul 2022 20:12
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Author:
Andrea Madden
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