Molecular architecture dependence of mesogen rotation during uniaxial elongation of liquid crystal elastomers

Yasuoka, Haruka; Takahashi, Kazuaki Z.; Fukuda, Jun Ichi; Aoyagi, Takeshi

doi:10.1016/j.polymer.2021.123970

Cited by 8 publications

(9 citation statements)

References 38 publications

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“…A typical molecular architecture consists of soft-core Gay-Berne (SCGB) ellipsoidal particles 65 , Lennard-Jones (LJ) spherical particles, and harmonic bonds among particles (for details, see Ref. 34 ). This model makes it possible to build numerous molecular architectures for LCEs by setting the 20 design variables shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…1 and Table 1. A total of 220 main-and side-chain LCE molecules are modeled, corresponding to those considered in previous studies 34,35 . Note that the parameters for non-bonded interactions among SCGB and LJ particles, except the point charge q, are fixed to the same values as in Refs.…”

Section: Resultsmentioning

confidence: 99%

“…The mechanism of soft elasticity is closely related to the dynamics of mesogenic units embedded in polymer chains, and experiments have shown that a unidirectionally oriented polymer network with relatively low crosslink density is important for the realization of soft elasticity 6,26,27 . To clarify the coupling dynamics of mesogens and polymeric chains, theoretical studies have focused on the microscopic behavior of mesogens through molecular simulations [28][29][30][31][32][33][34][35][36] . These studies indicate the great potential of molecular simulations to uncover the mechanism of soft elasticity.…”

Section: Regression Analysis For Predicting the Elasticity Of Liquid ...mentioning

confidence: 99%

“…These studies indicate the great potential of molecular simulations to uncover the mechanism of soft elasticity. Our previous study on the effect of LCE molecular architectures on microscopic dynamics under uniaxial elongation demonstrated that side-chain-type LCEs, in which mesogens are embedded in the side chain, have a different mesogen rotation mechanism from main-chain-type LCEs, in which mesogens are embedded in the main chain 34 . Furthermore, we found a systematic and robust trade-off between the stress and strain ranges in soft elasticity 35 , indicating that the optimal set of output power and amount of deformation for LCE can be selected by tuning the crosslink density.…”

Section: Regression Analysis For Predicting the Elasticity Of Liquid ...mentioning

confidence: 99%

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Regression analysis for predicting the elasticity of liquid crystal elastomers

Doi

Takahashi

Yasuoka

et al. 2022

Sci Rep

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It is highly desirable but difficult to understand how microscopic molecular details influence the macroscopic material properties, especially for soft materials with complex molecular architectures. In this study we focus on liquid crystal elastomers (LCEs) and aim at identifying the design variables of their molecular architectures that govern their macroscopic deformations. We apply the regression analysis using machine learning (ML) to a database containing the results of coarse grained molecular dynamics simulations of LCEs with various molecular architectures. The predictive performance of a surrogate model generated by the regression analysis is also tested. The database contains design variables for LCE molecular architectures, system and simulation conditions, and stress–strain curves for each LCE molecular system. Regression analysis is applied using the stress–strain curves as objective variables and the other factors as explanatory variables. The results reveal several descriptors governing the stress–strain curves. To test the predictive performance of the surrogate model, stress–strain curves are predicted for LCE molecular architectures that were not used in the ML scheme. The predicted curves capture the characteristics of the results obtained from molecular dynamics simulations. Therefore, the ML scheme has great potential to accelerate LCE material exploration by detecting the key design variables in the molecular architecture and predicting the LCE deformations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Regression Analysis For Predicting the Elasticity Of Liquid ...mentioning

confidence: 99%

Section: Regression Analysis For Predicting the Elasticity Of Liquid ...mentioning

confidence: 99%

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Regression analysis for predicting the elasticity of liquid crystal elastomers

Doi

Takahashi

Yasuoka

et al. 2022

Sci Rep

Self Cite

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“…Their arrangement was, however, not perfect, as one can see from the fact that the microstructures do not appear completely dark when one of the polarizers is parallel to the mesogens alignment direction. This observation could have been a consequence of the molecular structures and the composition of the formulation 38 or a non-optimal alignment in the presence of the electric field generated by flat electrodes. It could also be a result of the high energy printing conditions typical of 2PP (which may disrupt the molecular packing locally).…”

Section: Resultsmentioning

confidence: 99%

Direct laser writing of liquid crystal elastomers oriented by a horizontal electric field

Carlotti¹,

Tricinci²,

Hoed³

et al. 2021

Open Res Europe

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Background: The ability to fabricate components capable of performing actuation in a reliable and controlled manner is one of the main research topics in the field of microelectromechanical systems (MEMS). However, the development of these technologies can be limited in many cases by 2D lithographic techniques employed in the fabrication process. Direct Laser Writing (DLW), a 3D microprinting technique based on two-photon polymerization, can offer novel solutions to prepare, both rapidly and reliably, 3D nano- and microstructures of arbitrary complexity. In addition, the use of functional materials in the printing process can result in the fabrication of smart and responsive devices. Methods: In this study, we present a novel methodology for the printing of 3D actuating microelements comprising Liquid Crystal Elastomers (LCEs) obtained by DLW. The alignment of the mesogens was performed using a static electric field (1.7 V/µm) generated by indium-tin oxide (ITO) electrodes patterned directly on the printing substrates. Results: When exposed to a temperature higher than 50°C, the printed microstructures actuated rapidly and reversibly of about 8% in the direction perpendicular to the director. Conclusions: A novel methodology was developed that allows the printing of directional actuators comprising LCEs via DLW. To impart the necessary alignment of the mesogens, a static electric field was applied before the printing process by making use of flat ITO electrodes present on the printing substrates. The resulting microelements showed a reversible change in shape when heated higher than 50 °C.

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