Cover Picture: Macromol. Rapid Commun. 1/2007

Komp, Ansgar; Finkelmann, Heino

doi:10.1002/marc.200790000

Cited by 17 publications

(27 citation statements)

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“…[9][10][11][12][13] There have been a few investigations on the reversible shape change of nematic elastomers; however, much less work has been carried out on that of smectic elastomers, in spite of their potentially useful mechanical properties, owing to their one-dimensional crystalline structure. [14][15][16][17][18][19][20][21][22] In 1997, Nishikawa et al [14] succeeded in preparing a smectic A single-crystal elastomer (SmA-LSCE) and reported that the elastic constant in the direction parallel to the layer normal was about two orders of magnitude larger than the elastic modulus in the direction parallel to the layer, becauseoftheone-dimensionalcrystalline structure and the two-dimensional liquid-like fluidity of the elastomer.…”

Section: Full Papermentioning

confidence: 99%

Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C^*Elastomers

Hiraoka

Tagawa

Baba

2008

Macro Chemistry & Physics

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We have investigated the shape‐memory effects of uniaxially‐deformed, chiral, smectic C (SmC*) elastomers for two different types of crosslinker, namely, a hydroquinone‐type crosslinker and a rod‐like crosslinker. Mesogens tilt with decreasing temperature from the SmA phase to the SmC* phase in SmC* elastomers synthesized with the hydroquinone‐type crosslinker. As for SmC* elastomers with the rod‐like crosslinker, however, not mesogens but smectic layers are tilted in the smectic phases, because the crosslinker is sufficiently rigid to hinder mesogens from tilting. Because the shape change of such elastomers is coupled to the transformation of molecular alignment, SmC* elastomers synthesized with the hydroquinone‐type crosslinker elongate with increasing temperature in SmC* because of the decrease in molecular‐tilt angle, whereas those with the rod‐like crosslinker have an almost constant sample length in the temperature range of the SmC* phase, despite the rearrangement of the layer structure. Both types of elastomer exhibit a reversible shape change that corresponds to the reversible change in molecular alignment during a heating and cooling process, within successive phase transitions between the isotropic phase and the smectic C* phase.magnified image

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Section: Full Papermentioning

confidence: 99%

Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C^*Elastomers

Hiraoka

Tagawa

Baba

2008

Macro Chemistry & Physics

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“…In smectic-A-elastomers, where the smectic layers are oriented perpendicular to the director, orientation of the director also results in a macroscopic orientation of the smectic layers. [18][19][20][21] In the case of the SmC-phase, both chiral and achiral, a uniaxial field is not sufficient anymore to obtain a liquid single crystal elastomer. In these liquid crystals, the smectic layer normal is not oriented parallel to the director but tilted by the angle θ.…”

Section: Introductionmentioning

confidence: 98%

Shear Deformation and Ferroelectricity in Chiral SmC* Main-chain Elastomers

Heinze

Finkelmann

2010

Macromolecules

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Ferroelectric smectic main-chain liquid crystalline elastomers were synthesized and subjected to simple shear deformation to achieve reorientation of the layer structure and the formation of a macroscopic spontaneous polarization. The phase behavior and structural parameters of these elastomers are investigated and discussed. A shear-induced splitting of the X-ray scattering intensity distribution is found. A splitting of the sample in domains of two director orientations that couple differently to the shear deformation is proposed. The smectic layers also move at different affinities depending on their initial orientation. The smectic layer spacing was found to be nearly constant even though the smectic tilt angle changes significantly. The realignment of the smectic layers indicates a migration process, where depending on their original orientation the layer normals are leaving or entering the X-ray scattering plane. The spontaneous polarization was found to be linearly dependent on the dopant concentration with Ps = 30 nC/cm 2 for a system doped with 11 wt % of chiral dopant.

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“…Recently, Komp and Finkelmann [8] and Stannarius et al [9] investigated S A -LSCEs which clearly differed from Nishikawa's system in their response to mechanical stress. Komp and Finkelmann used the same backbone, crosslinker and preparation technique but incorporated a side-on mesogen carrying fluorinated tails.…”

Section: Introductionmentioning

confidence: 99%

Breakdown of Layering in Frustrated Smectic‐A Elastomers

Kramer

Finkelmann

2007

Macromol. Rapid Commun.

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Smectic‐A elastomers combine the positional long‐range order of mesogenic molecules in one dimension with the rubber elasticity of a polymer network. Upon mechanical deformation, completely different responses of the phase structure have been reported. We present a highly distorted system which shows a breakdown of smectic layering but no reorientation under deformation along the layer normal, while the phase structure stays unaffected under uniaxial stress in the perpendicular direction. The thermoelastic properties, macroscopic dimensions and stress–strain behaviour are investigated parallel and perpendicular to the layer normal. SAXS measurements supply evidence for a breakdown of the macroscopically ordered layer structure indicated by the small angle intensities and correlation length, whereas the orientational order is preserved. We propose defects in the smectic layer structure to be the origin of the different responses of different smectic elastomers.magnified image

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Cover Picture: Macromol. Rapid Commun. 1/2007

Cited by 17 publications

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Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C^*Elastomers

Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C^*Elastomers

Shear Deformation and Ferroelectricity in Chiral SmC* Main-chain Elastomers

Breakdown of Layering in Frustrated Smectic‐A Elastomers

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Cover Picture: Macromol. Rapid Commun. 1/2007

Cited by 17 publications

References 0 publications

Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C*Elastomers

Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C*Elastomers

Shear Deformation and Ferroelectricity in Chiral SmC* Main-chain Elastomers

Breakdown of Layering in Frustrated Smectic‐A Elastomers

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Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C^*Elastomers

Shape‐Memory Effect Controlled by the Crosslinking Topology in Uniaxially‐Deformed Smectic C^*Elastomers