Calorimetric studies of poly (2-phenoxyethylacrylate)/5CB mixtures |
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Authors: | Tewfik Bouchaour Frédérick Roussel Jean-Marc Buisine Xavier Coqueret Mustapha Benmouna Ulrich Maschke |
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Institution: | 1. Laboratoire de Recherche sur les Macromolécules, Faculté des Sciences, Université Aboubakr Belka?d, Bel Horizon, 13000 Tlemcen, Algeria;2. Laboratoire de Thermophysique de la Matière Condensée, Equipe de I'UPRESA 8024 du CNRS, Université du Littoral--C?te d'Opale, MREID, F-59140 Dunkerque, France;3. Laboratoire de Chimie Macromoléculaire, UPRESA CNRS N°8009, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq Cedex, France |
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Abstract: | The thermophysical properties of mixtures of poly (2-phenoxyethylacrylate) and 4-cyano-4′-pentyl-biphenyl, 5CB, are investigated using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The polymer has a molar mass M w = 181 000 g mol -1 the low molecular mass liquid crystal exhibits a nematic to isotropic transition at 35.3°C and crystallizes below 23°C. The phase diagram exhibits miscibility gaps in certain regions of temperature and composition where coexisting nematic and isotropic phases are found. From a practical point of view when considering the electro-optical applications of these systems, it proves to be useful to know precisely the amount of small liquid crystal molecules dissolved in the polymer matrix and the concentration of polymer in the nematic phase. The former quantity has a mechanical impact due to a plasticizing effect, an optical impact since it changes the polymer refractive index, while the polymer in the nematic phase shifts the transition temperatures influencing the electro-optical response of the liquid crystal. The present work addresses these important aspects using POM and DSC. |
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Keywords: | liquids crystals ferroelectric phase antiferroelectric phase helical pitch helical twist sense |
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