We study three monodomain (single-crystal) nematic elastomer materials, all side-chain siloxane polymers with the same mesogenic groups but with different types of crosslinking: (i) short flexible siloxane linkage affine to the network backbone, (ii) short flexible aliphatic crosslinks miscible with mesogenic side chain groups, and (iii) long segments of main-chain nematic polymer. Equilibrium physical properties of these three systems are very different, especially the spontaneous thermal expansion and anisotropic stress-strain response along and perpendicular to the uniform nematic director. In the latter case, we examine the soft elastic plateau during the director reorientation. We compare the nematic order-parameter [formula presented] provided primarily by the side mesogenic groups and relatively constant between the samples, and the average backbone chain anisotropy [formula presented] which is strongly affected by the crosslinking geometry. The experimental data is compared quantitatively with theoretical models of nematic elastomers.
|ジャーナル||Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics|
|出版ステータス||Published - 2001 1月 1|
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