A Liquid Crystalline Elastomer with a <i>p</i>‐Pentaphenyl Transverse Rod Laterally Attached to the Main Chain

Ren, Wanting; McMullan, Philip J.; Guo, Huina; Kumar, Satish; Griffin, Anselm C.

doi:10.1002/macp.200700431

Cited by 12 publications

(14 citation statements)

References 13 publications

(19 reference statements)

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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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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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“…Liquid crystalline network (LCN) polymers can show slow dimensional recovery (anelasticity) after removal of load if the strain recovery occurs at temperatures well below the mesophase – isotropic (clearing) temperature 1–5. For smectic (layered) LCNs a critical feature in this regard is the strain‐induced formation of a monodomain structure in which there is a uniform macroscopic orientation of the molecular (mesogen) units, typically parallel to the direction of applied tensile force.…”

Section: Introductionmentioning

confidence: 99%

Thermal strain recovery of anelastic monodomain liquid crystalline networks: Mechanically induced strains ratios

Ren¹,

Kline²,

McMullan³

et al. 2010

Physica Status Solidi (b)

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A series of smectic liquid crystalline network polymers was subjected to a large uniaxial stress at temperatures far below the clearing temperature. Their dimensional recovery is anelastic showing substantial retained strain. This process produced a temporally stable monodomain state. Upon heating this monodomain from room temperature, recovery of the original film dimensions occurs. The strain recovery (length) curves show a pronounced curvature as the temperature approaches the smectic-isotropic temperature. It is proposed that nanosegregation of netpoints in the smectic structure is responsible for the anelasticity and that the temperature dependence of the shape recovery is consistent with a balance between enthalpic and entropic forces with temperature. An interesting mechanically induced strains ratio (MISR) was observed on heating these prestressed films. Loss of the monodomain structure near the isotropization temperature is postulated to rationalize the shape of the MISR curves.

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“…Comparison of our work to a related study by Griffin et al is warranted 30. In their study of smectic networks containing “transverse” mesogens in the main chain, different changes in properties were observed after annealing samples at 70 °C 30.…”

Section: Resultsmentioning

confidence: 53%

“…However, “annealing” in ref. 30 was conducted in the isotropic state above T i , rather than in the smectic state below T i as in the present study, so a fair comparison of results cannot be made. It is noteworthy that both systems exhibited changes in mechanical behavior after applying thermal treatments, however.…”

Section: Resultsmentioning

confidence: 99%

Influence of thermal history on mesoscale ordering in polydomain smectic networks

Chen

Hedden

2012

J Polym Sci B Polym Phys

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Dramatic changes in mesoscale ordering and macroscopic mechanical behavior are observed in smectic polydomain networks after annealing at a temperature well above the glass transition temperature but below the clearing temperature. Tensile testing reveals gradual stiffening and loss of extensibility, and X-ray linewidth measurements confirm that stiffening is initially due to thickening of domains. At long annealing times, a more highly ordered smectic mesophase forms, further stiffening the networks and reducing their exten-sibility. Increasing the concentration of (flexible) crosslinkers hinders domain growth and suppresses formation of the higher order mesophase, a useful guideline for design of smectic networks that exhibit reduced sensitivity to thermal history.

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A Liquid Crystalline Elastomer with a p‐Pentaphenyl Transverse Rod Laterally Attached to the Main Chain

Cited by 12 publications

References 13 publications

Soft Elasticity in Main Chain Liquid Crystal Elastomers

Soft Elasticity in Main Chain Liquid Crystal Elastomers

Thermal strain recovery of anelastic monodomain liquid crystalline networks: Mechanically induced strains ratios

Influence of thermal history on mesoscale ordering in polydomain smectic networks

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