Dielectric properties of nematic liquid crystals in porous membranes

Stanislaw A. Rozanski; Friedrich Kremer

doi:10.1117/12.215567

2 August 1995 Dielectric properties of nematic liquid crystals in porous membranes

Stanislaw A. Rozanski, Friedrich Kremer

Proceedings Volume 2372, Liquid Crystals: Materials Science and Applications; (1995) https://doi.org/10.1117/12.215567
Event: Liquid Crystals: Materials Science and Applications, 1994, Zakopane, Poland

Abstract

Broadband dielectric spectroscopy (10² Hz-10⁹ Hz) is employed to study the molecular dynamics of the liquid crystal 4-n-pentyl-4'-cyanobiphenyl (5CB) in cylindrical channels of Anopore membranes having a diameter between 0.2 micrometers and 0.02 micrometers , and thickness about 60 micrometers . The surfaces of channels are modified using the coupling agent C₉H₁₉COOH. In the bulk 5CB two relaxation processes are observed: the hindered rotation of the molecules around their short molecular axis ((delta) -relaxation, and tambling of the molecules around short molecular axis. In untreated Anopore membranes the first process is only observed, which is nearly uninfluenced by the presence of the inner surfaces. In contrast, in treated Anopore membranes the second process connected with tambling of the molecules around their short molecular axis becomes detectable. This phenomenon is connected with a changing of the planar axial to planar radial alignment of the molecules. The relaxation rate in the isotropic phase is nearly uninfluenced by the presence of the inner surfaces, it is in the nematic phase by two orders of magnitude faster for the porous materials with modified surface as compared to the bulk. The dielectric strength of the (delta) -relaxation is considerably weakened for the 5CB/Anopore system.

Citation Download Citation

Stanislaw A. Rozanski and Friedrich Kremer "Dielectric properties of nematic liquid crystals in porous membranes", Proc. SPIE 2372, Liquid Crystals: Materials Science and Applications, (2 August 1995); https://doi.org/10.1117/12.215567

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available