State of Order in Liquid Crystalline Elastomers

Schätzle, Joachim; Finkelmann, Heino

doi:10.1080/00268948708084595

Cited by 75 publications

(14 citation statements)

References 4 publications

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“…As described above the selectivity of a membrane is affected by the macroscopic homogeneity of the membrane structure. By stretching an LCSC-elastomer by applying a force F i t is possible to enhance the macroscopic homogeneity of the membrane by macroscopically aligning the mesogenic moieties in the LC-state and the pretransition region above the LC-state [6,7,20]. The alignment of the director (which represents the axis of the preferred orientation of the long axis of the cylindrical shaped mesogenic groups) with the axis of stress and with respect to the membrane surface, is analysed by X-ray investigations.…”

Section: Characterisation Of the Liquid Crystalline Elastomer Membranesmentioning

confidence: 99%

“…The alignment of the director (which represents the axis of the preferred orientation of the long axis of the cylindrical shaped mesogenic groups) with the axis of stress and with respect to the membrane surface, is analysed by X-ray investigations. The elastomers C30CH3-and the C40CH, (Table 1) have previously been characterized by Gleim [6] and Schatzle [20] (Fig. 4).…”

Section: Characterisation Of the Liquid Crystalline Elastomer Membranesmentioning

confidence: 99%

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Influence of the Phase Structure on the Gas Transport Behaviour Through Liquid Crystalline Side Chain Elastomer Membranes

Modler

Finkelmann

1990

Ber Bunsenges Phys Chem

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The dependence of hydrocarbon gas transport behaviour on the liquid crystalline (LC) and isotropic state of different liquid crystalline side chain elastometer membranes (LCSCE‐membranes) is investigated with respect to the LC‐phase structure of the membranes and the molecular shape of the gas molecules.—A distinct change of the transport behaviour at the phase transformation from the smectic to the nematic and from the nematic to the isotropic state is observed. Additionally, an odd‐even effect is detected determined by the spacer length of the mesogenic moieties at a temperature range a little above the phase transformation temperature from the LC‐ to the isotropic state. It is assumed that this odd‐even effect correlates with the stress temperature dependence of the LCSCE‐samples. An enhanced selectivity for linear shaped gases compared to spherical shaped gases occurs in a macroscopic ordered sample.—For these experiments the accuracy of the transport coefficient determination by a transport process through membranes is analysed with respect to the geometrical arrangement of the developed experimental apparatus. The experimental method of determing transport coefficients, already described by R. A. Pasternack, is discussed and further developed.—The LCSCE‐membranes are synthesized by adding a mesogenic side chain to a polymethylhydrogensiloxane network.

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Section: Characterisation Of the Liquid Crystalline Elastomer Membranesmentioning

confidence: 99%

Section: Characterisation Of the Liquid Crystalline Elastomer Membranesmentioning

confidence: 99%

Influence of the Phase Structure on the Gas Transport Behaviour Through Liquid Crystalline Side Chain Elastomer Membranes

Modler

Finkelmann

1990

Ber Bunsenges Phys Chem

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“…This feature evidences that the carbazole molecules do not tilt during the deformation process. As it is well known, nematic order in LSCEs increases upon stretching of the sample along the director direction . As a consequence, a more favorable overlap between both carbazole units and surrounding mesogen molecules should occur.…”

Section: Resultsmentioning

confidence: 90%

Optical Mechanotransduction with Carbazole‐Based Luminescent Liquid Single‐Crystal Elastomers

García-Amorós

Velasco

2015

Macromol. Rapid Commun.

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Carbazole-based liquid single-crystal elastomers (LSCEs) are valuable fluorescent flexible materials to perform optical mechanotransduction under ambient conditions. Indeed, the covalent incorporation of carbazole derivatives into nematic LSCEs allows to tune their luminescence on demand under mechanical control in a quick and reversible fashion. Specifically, the fluorescence intensity for these materials can be switched back and forth in less than a second. Moreover, such a process can be performed several times without detecting any sign of fatigue in the system. In addition, these materials show excellent resistance to aging; 2 years after their preparation they exhibit the very same mechanofluorescent behavior as when freshly prepared. In fact, the here reported fluorescent systems are highly sensitive; the application of a force of 70 mN decreases the fluorescence in the elastomeric material by 7%. Thus, mechanical forces are attractive external stimuli to modulate the fluorescence of nematic elastomers rapidly and reversibly enabling thereby mechanotransduction.

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“…The assembled nematic structure of the side-chain mesogens influences the network deformation. Various peculiar phenomena, such as electrically-induced shape changes, 26 mechanical and electrical molecular switching, 26,58 memory effects 9,59 and variations in phase behavior 9,60 have been observed and mainly arise from these interactions.…”

Section: Coupling Effect Between Mesogens and Polymer Networkmentioning

confidence: 99%