Mechanical Properties of Monodomains Liquid Single Crystal Elastomers

2 Mechanical Properties of Monodomains Liquid Single Crystal Elastomers 

Strain-induced transitions of the director orientation in nematic LCEs were studied 

Nematic monodomains have been prepared using a variant of the method introduced by Kiipfer and Finkelmann [10, 18] instead of keeping the stress constant in the second crosslinking step the strain was held constant in the second crosslinking step [53]. As for the case studied by Kupfer and Finkelmann, it is found that the monodomain character is retained after heating the sample into the isotropic phase upon return into the nematic phase. Stress strain relation has been measured for two classes of poly-siloxane elastomers. 

Ultrasonic experiments using laser induced phonon spectroscopy have been performed in a nematic liquid single crystal elastomer [48]. The experiments reveal a dispersion step for the speed of sound and a strong anisotropy for the acoustic attenuation constant in the investigated frequency range (100 MHz -1 GHz). These results are consistent with a description of LCEs using macroscopic dynamics [54-56] and reflect a coupling between elastic effects and the nematic order parameter as analyzed in detail previously [48]. 

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Lebar A, Kutnjak Z, Zumer S, Finkelmann H, Sanchez-Ferrer A, Zalar B (2005) Evidence of supercritical behavior in liquid single crystal elastomers Phys Rev Lett 94 197801 1-4 Martinoty P, Stein P, Finkelmann H, Pleiner H, Brand HR (2004a) Mechanical properties of monodomain side-chain nematic elastomers. Eur Phys J E Soft Matter 14 311-321 Martinoty P, Stein P, Finkelmann H, Pleiner H, Brand HR (2004b) Reply to the commentary by Teientjev EM, Warner M on Mechanical properties of monodomain side chain nematic elastomers . Eur Phys J E 14 329-332... 

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