Transitions in a Spread Film of a Side-Chain Liquid Crystal Polymer
作者:
Chris Bower,
Sarah Froggatt,
Richard Laycock,
RupertJ Musgrove,
RobertM Richardson,
Greg Rozario,
Ali Zarbakhsh,
JohnP R Webster,
Oxii Oqx,
JonathanS Hill,
David Lacey,
Garry Nestor,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 261,
issue 1
页码: 437-451
ISSN:1058-725X
年代: 1995
DOI:10.1080/10587259508033488
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
A series of side-chain liquid crystal polymers have been screened for successhl deposition using the Langmuir Blodgett method. It was found that the best materials had glass transitions below room temperature. The behaviour of the spread film of one material was studied in detail using surface isotherms, surface potential, X-ray and neutron reflection techniques. It was found to undergo a phase transition from a thin, low density film to a thicker, more dense one as the surface pressure was increased. This corresponds to a reorientation of the mesogenic units so that about half of them point upwards. At higher pressure a transition to a multilayer occurs on the water surface. In the surface pressure range where deposition is possible, neutron reflection shows that the spread film has a stratum of close packed mesogenic units outermost and the total thickness (38 Å) agrees very well with the smectic layer spacing in the bulk. This similarity in structure could explain the ease of deposition.
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