Synthesis and monolayer formation of liquid crystal polysiloxanes having alateral side chain with a perfluoroalkyl chain

Citation
J. Mu et al., Synthesis and monolayer formation of liquid crystal polysiloxanes having alateral side chain with a perfluoroalkyl chain, COLL SURF A, 181(1-3), 2001, pp. 303-313
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
ISSN journal
0927-7757 → ACNP
Volume
181
Issue
1-3
Year of publication
2001
Pages
303 - 313
Database
ISI
SICI code
0927-7757(20010615)181:1-3<303:SAMFOL>2.0.ZU;2-L
Abstract
Liquid crystal polysiloxanes with a lateral 4-(4-cyanophenoxycarbonyl)pheny l 4-(2-perfluoroalkylethoxy)-2-propyleneoxybenzoate side group and a 4-decy loxy-2-propyleneoxy-benzoate hydrocarbon analogue were prepared, and the me somorphic properties were determined by the microscopic observation and dif ferential scanning calorimeter (DSC) thermogram, and the layer structure of the smectic A phase was characterized by an X-ray diffraction experiment. The introduction of the perfluoroalkyl chain to the polymer remarkably enha nces the smectic properties due to the strong fluorophilic interactions aro und the perfluoroalkyl chain. The effect of the perfluoroalkyl chain on the monolayer formation was studied at the air-water interface. The surface pr essure-area isotherms show that the perfluoroalkyl chain enhances the stabi lity of the monolayer versus surface pressure. In the condensed state the c yano group in the side chain is assumed to be anchored on the water surface and the mean axis of the liquid crystal core is approximately normal to th e water surface. The monolayers were easily deposited on a hydrophobic glas s slide, giving uniform Langmuir-Blodgett (LB) films by the vertical deposi tion method. The X-ray diffraction results indicate that the perfluorooctyl chain effectively stabilizes the layer structure in the multilayer LB film at room temperature. The side chain monomers also show a similar behavior to the polymers and give uniform LB films on hydrophobic glass slides. (C) 2001 Elsevier Science B.V. All rights reserved.