Stress-strain and thermomechanical characterization of nematic to smectic A transition in a strongly-crosslinked bimesogenic liquid crystal elastomer

Rešetič, Andraž; Milavec, Jerneja; Domenici, Valentina; Zupančič, Borut; Bubnov, Alexej; Zalar, Boštjan

doi:10.1016/j.polymer.2018.10.049

Cited by 25 publications

(20 citation statements)

References 27 publications

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“…The planar Grandjean texture of the N* mesophase is obtained similar to the planar texture in ordinary nematic, that is, by imposing boundary conditions such that the molecules in contact with the bonding surfaces are aligned parallel to these surfaces. The resulting texture is durable and can last for a long time, many months, or even years. − …”

Section: Resultsmentioning

confidence: 99%

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

Janeczek

Duale

Sikorska

et al. 2022

ACS Sustainable Chem. Eng.

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This paper presents the liquid crystal (LC) properties of poly( l -lactide) (PLLA). Mesophase behavior is investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The performed analyses confirm that pressed PLLA films exhibit the unique capability of self-assembling into a nematic mesophase under the influence of mechanical pressure, temperature, and time. It was originally demonstrated that the chiral nematic mesophase can be obtained by introducing fine powders into the polymer. Based on the research conducted, it was proved that the pressed PLLA films have a chiral nematic mesophase with a nematic-to-isotropic phase transition and a large mesophase stability range overlapping the temperature of the human body, which can persist for years at ambient temperature. The obtained films show tailor-made properties toward a nematic mesophase with a specific texture, including colored planar texture of the chiral nematic mesophase and blue-phase (BP) LC texture. The BP, described for the first time in plain PLLA, occurred over a wider than usual temperature range of stability between isotropic and chiral nematic thermotropic phases (Δ T ≈ 9 °C), which is an advantage of the obtained polymer material, in addition to ease of preparation. This opens up new prospects for advanced photonic green applications.

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Section: Resultsmentioning

confidence: 99%

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

Janeczek

Duale

Sikorska

et al. 2022

ACS Sustainable Chem. Eng.

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“…Furthermore, soft and light LCEs exhibit relatively fast and accurate reactions to these external stimuli. Therefore, LCEs are candidate materials for soft actuators [17][18][19][20][21] , and their mechanical properties have been extensively studied [22][23][24][25] . 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 .…”

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

confidence: 99%

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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“…In recent years, various self-oscillating systems based on diverse stimuli-responsive materials are reported, such as hydrogels [ 14 , 15 ], dielectric elastomers [ 16 ], ionic gels [ 17 ], liquid crystal elastomers (LCEs) [ 7 , 18 , 19 , 20 , 21 ], and thermally responsive polymer materials [ 22 ], etc. Furthermore, a variety of self-sustained motion modes have been constructed, such as bending [ 23 , 24 , 25 , 26 ], buckling [ 27 , 28 , 29 , 30 ], torsion [ 31 , 32 ], stretching and shrinking [ 33 , 34 ], rolling [ 35 , 36 ], swimming [ 9 ], swinging [ 37 , 38 ], vibration [ 39 , 40 , 41 ], jumping [ 42 , 43 , 44 ], rotation [ 45 ], eversion or inversion [ 46 , 47 ], and even synchronized motion of several coupled self-oscillators [ 48 ].…”

Section: Introductionmentioning

confidence: 99%

Self-Jumping of a Liquid Crystal Elastomer Balloon under Steady Illumination

Jin

Dai

et al. 2022

Polymers

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Self-oscillation capable of maintaining periodic motion upon constant stimulus has potential applications in the fields of autonomous robotics, energy-generation devices, mechano-logistic devices, sensors, and so on. Inspired by the active jumping of kangaroos and frogs in nature, we proposed a self-jumping liquid crystal elastomer (LCE) balloon under steady illumination. Based on the balloon contact model and dynamic LCE model, a nonlinear dynamic model of a self-jumping LCE balloon under steady illumination was formulated and numerically calculated by the Runge–Kutta method. The results indicated that there exist two typical motion regimes for LCE balloon under steady illumination: the static regime and the self-jumping regime. The self-jumping of LCE balloon originates from its expansion during contact with a rigid surface, and the self-jumping can be maintained by absorbing light energy to compensate for the damping dissipation. In addition, the critical conditions for triggering self-jumping and the effects of several key system parameters on its frequency and amplitude were investigated in detail. The self-jumping LCE hollow balloon with larger internal space has greater potential to carry goods or equipment, and may open a new insight into the development of mobile robotics, soft robotics, sensors, controlled drug delivery, and other miniature device applications.

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Stress-strain and thermomechanical characterization of nematic to smectic A transition in a strongly-crosslinked bimesogenic liquid crystal elastomer

Cited by 25 publications

References 27 publications

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

Regression analysis for predicting the elasticity of liquid crystal elastomers

Self-Jumping of a Liquid Crystal Elastomer Balloon under Steady Illumination

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