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Open AccessArticle

Richness of Side-Chain Liquid-Crystal Polymers: From Isotropic Phase towards the Identification of Neglected Solid-Like Properties in Liquids

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Laboratoire Léon Brillouin (CEA-CNRS), CE-Saclay, Gif-sur-Yvette 91191, France
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Structure et Propriétés d’Architectures Moléculaires, UMR 5819 SPrAM (CEA-CNRS-UJF), CEA-Grenoble, 17, avenue des Martyrs, Grenoble 38054, cedex 9, France
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Fachbereich Chemie, Philipps-Universität Marburg, D-35032 Marburg, Germany
*
Author to whom correspondence should be addressed.
Polymers 2012, 4(2), 1109-1124; https://doi.org/10.3390/polym4021109
Received: 6 March 2012 / Revised: 1 April 2012 / Accepted: 20 April 2012 / Published: 25 April 2012
(This article belongs to the Special Issue Liquid Crystalline Polymers)
Very few studies concern the isotropic phase of Side-Chain Liquid-Crystalline Polymers (SCLCPs). However, the interest for the isotropic phase appears particularly obvious in flow experiments. Unforeseen shear-induced nematic phases are revealed away from the N-I transition temperature. The non-equilibrium nematic phase in the isotropic phase of SCLCP melts challenges the conventional timescales described in theoretical approaches and reveal very long timescales, neglected until now. This spectacular behavior is the starter of the present survey that reveals long range solid-like interactions up to the sub-millimetre scale. We address the question of the origin of this solid-like property by probing more particularly the non-equilibrium behavior of a polyacrylate substituted by a nitrobiphenyl group (PANO2). The comparison with a polybutylacrylate chain of the same degree of polymerization evidences that the solid-like response is exacerbated in SCLCPs. We conclude that the liquid crystal moieties interplay as efficient elastic connectors. Finally, we show that the “solid” character can be evidenced away from the glass transition temperature in glass formers and for the first time, in purely alkane chains above their crystallization temperature. We thus have probed collective elastic effects contained not only in the isotropic phase of SCLCPs, but also more generically in the liquid state of ordinary melts and of ordinary liquids. View Full-Text
Keywords: isotropic phase; side-chain liquid crystal polymer; shear flow; intermolecular interactions; solid-like properties; ordinary melt; ordinary liquid isotropic phase; side-chain liquid crystal polymer; shear flow; intermolecular interactions; solid-like properties; ordinary melt; ordinary liquid
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Noirez, L.; Mendil-Jakani, H.; Baroni, P.; Wendorff, J.H. Richness of Side-Chain Liquid-Crystal Polymers: From Isotropic Phase towards the Identification of Neglected Solid-Like Properties in Liquids. Polymers 2012, 4, 1109-1124.

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