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Issue 8, 2006
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Gelation of smectic liquid crystal phases with photosensitive gel forming agents

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Abstract

This paper studies the potential of 3 newly synthesized low molecular weight gelling agents (2 of them with azo groups) with the semicarbazide group as a H-bonding motif to gel the smectic phase of a commercial chiral smectic C* material. To detect gelation two methods were used: the stabilization of the director pattern, which measures the interaction of the physical gel network with the LC-director, and the suppression of the onset of electrohydrodynamic instabilities, which measures the increase of viscosity. Special emphasis was put on the influence of the photochemical transcis isomerization of the gelling agents on gelation.

From the stabilization of the director pattern an elastic component can be seen by the memory effect (two different switching times). Photochemical transcis isomerization destroys this memory effect. The increase of the threshold field for the onset of electrohydrodynamic instabilities in free-standing films measures the increase of viscosity and the supression of flow. Both methods detect the same melting temperature of the gel and the same reduction of the gelling ability upon transcis isomerization. This proves that the gelling abilities of the new azo-containing gelling agents can be reversibly switched on and off by photoisomerization.

Graphical abstract: Gelation of smectic liquid crystal phases with photosensitive gel forming agents

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Publication details

The article was received on 09 Mar 2006, accepted on 23 May 2006 and first published on 12 Jun 2006


Article type: Paper
DOI: 10.1039/B603562K
Soft Matter, 2006,2, 693-698

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    Gelation of smectic liquid crystal phases with photosensitive gel forming agents

    P. Deindörfer, A. Eremin, R. Stannarius, R. Davis and R. Zentel, Soft Matter, 2006, 2, 693
    DOI: 10.1039/B603562K

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