Polydomain–Monodomain Orientational Process in Smectic‐C Main‐Chain Liquid‐Crystalline Elastomers

Sánchez‐Ferrer, Antoni; Finkelmann, Heino

doi:10.1002/marc.201000590

Cited by 47 publications

(51 citation statements)

References 42 publications

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“…(17) derived from Eqs. (15) and (16) has one direction of anisotropy n 0 . It can be written using the following invariants of the Cauchy-Green strain tensor C = F T · F:…”

Section: A Methodsmentioning

confidence: 99%

Numerical study of stretched smectic-Aelastomer sheets

Brown

Adams

2013

Phys. Rev. E

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We present a numerical study of stretching monodomain smectic-A elastomer sheets, computed using the finite element method. When stretched parallel to their smectic layer normal the smectic layers are unstable to a transition to a buckled state. We model macroscopic deformations by replacing the microscopic energy with a coarse grained effective free energy that accounts for the fine-scale layer buckling. We augment this model with a term to describe the energy of deforming buckled layers, which is necessary to reproduce the experimentally observed Poisson ratios postbuckling. We examine the spatial distribution of the microstructure phases for various stretching angles relative to the layer normal and for different length-to-width aspect ratios. When stretching parallel to the layer normal the majority of the sample forms a bidirectionally buckled microstructure, except at the clamps where a unidirectionally buckled microstructure is predicted. When stretching at small inclinations to the layer normal the phase of the sample is sensitive to the aspect ratio of the sample, with the bidirectionally buckled phase persistent to large angles only for small aspect ratios. We relate these theoretical results to experiments on smectic-A elastomers.

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“…(17) derived from Eqs. (15) and (16) has one direction of anisotropy n 0 . It can be written using the following invariants of the Cauchy-Green strain tensor C = F T · F:…”

Section: A Methodsmentioning

confidence: 99%

Numerical study of stretched smectic-Aelastomer sheets

Brown

Adams

2013

Phys. Rev. E

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“…Polydomain smectic MCLCEs have been extensively studied [20,[60][61][62][63][64][65][66][67]. Sánchez-Ferrer et al [64] reported the polydomain to monodomain (P-M) transition caused by uniaxial strain in these materials.…”

Section: Polydomain Smectic-c Main Chain Liquid Crystal Elastomersmentioning

confidence: 99%

Soft Elasticity in Main Chain Liquid Crystal Elastomers

et al. 2013

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Main chain liquid crystal elastomers exhibit several interesting phenomena, such as three different regimes of elastic response, unconventional stress-strain relationship in one of these regimes, and the shape memory effect. Investigations are beginning to reveal relationships between their macroscopic behavior and the nature of domain structure, microscopic smectic phase structure, relaxation mechanism, and sample history. These aspects of liquid crystal elastomers are briefly reviewed followed by a summary of the results of recent elastic and high-resolution X-ray diffraction studies of the shape memory effect and the dynamics of the formation of the smectic-C chevron-like layer structure. A possible route to realizing auxetic effect at molecular level is also discussed.

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“…However, since the mesogens are chemically bound to the cross-linked polymer network, any change in their orientation will be coupled to changes in the mechanical properties of the bulk material. If there is an overall preferred direction for the mesogens (termed the liquid crystal director) and this direction is the same throughout the material, then this network can be termed a mono-domain LCE (in contrast to a poly-domain LCE, in which each domain inside the material has a different director, see [14][15][16][17][18] for a summary and details of poly-domain to mono-domain transition in LCE). As the mesogens undergo a phase transition from the liquid crystalline state to the isotropic state, mono-domain LCEs exhibit a significant change of their macroscopic shape due to the fact that motion of the polymer network is coupled to that of the mesogens bound to the polymer.…”

Section: Open Accessmentioning

confidence: 99%

Nanoparticle-Liquid Crystalline Elastomer Composites

Marshall

Terentjev

2012

Polymers

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Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including a uniquely high-stroke reversible mechanical actuation triggered by external stimuli. Fundamentally, all such stimuli affect the degree of liquid crystalline order in the polymer chains cross-linked into an elastic network. Heat and the resulting thermal actuation act by promoting entropic disorder, as does the addition of solvents. Photo-isomerization is another mechanism of actuation, reducing the orientational order by diminishing the fraction of active rod-like mesogenic units, mostly studied for azobenzene derivatives incorporated into the LCE composition. Embedding nanoparticles provides a new, promising strategy to add functionality to LCEs and ultimately enhance their performance as sensors and actuators. The motivation for the combination of nanoparticles with LCEs is to provide better-controlled actuation stimuli, such as electric and magnetic fields, and broad-spectrum light, by selecting and configuring the appropriate nanoparticles in the LCE matrix. Here we give an overview of recent advances in this area with a focus on preparation, physical properties and actuation performance of the resultant nanocomposites.

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Polydomain–Monodomain Orientational Process in Smectic‐C Main‐Chain Liquid‐Crystalline Elastomers

Cited by 47 publications

References 42 publications

Numerical study of stretched smectic-Aelastomer sheets

Numerical study of stretched smectic-Aelastomer sheets

Soft Elasticity in Main Chain Liquid Crystal Elastomers

Nanoparticle-Liquid Crystalline Elastomer Composites

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