Theory of microphase separation on side-chain liquid-crystalline polymers with flexible spacers |
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Authors: | M Hernández-Jiménez H Westfahl jr |
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Institution: | (1) Instituto de Fısica “Gleb Wataghin”, Universidade Estadual de Campinas, UNICAMP, CP 6165, 13083-970 Campinas, SP, Brazil;(2) Laboratório Nacional de Luz Sıncrotron, CP 6192, 13083-970 Campinas, SP, Brazil |
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Abstract: | We model a melt of monodisperse side-chain liquid-crystalline polymers as a melt of comb copolymers in which the side groups
are rod-coil diblock copolymers. We consider both excluded-volume and Maier-Saupe interactions. The first acts among any pair
of segments while the latter acts only between rods. Using a free-energy functional calculated from this microscopic model,
we study the spinodal stability of the isotropic phase against density and orientational fluctuations. The phase diagram obtained
in this way predicts nematic and smectic instabilities as well as the existence of microphases or phases with modulated wave
vector but without nematic ordering. Such microphases are the result of the competition between the incompatibility among
the blocks and the connectivity constraints imposed by the spacer and the backbone. Also the effects of the polymerization
degree and structural conformation of the monomeric units on the phase behavior of the side-chain liquid-crystalline polymers
are studied. |
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Keywords: | 61 30 Vx Polymer liquid crystals 64 70 Md Transitions in liquid crystals |
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