Polymer stabilization of the smectic C-alpha* liquid crystal phase—Over tenfold thermal stabilization by confining networks of photo-polymerized reactive mesogens

Abstract

The smectic C*-alpha (SmC a *) phase is one of the sub-phases of ferroelectric liquid crystals that has drawn much interest due to its electro-optical properties and ultrafast switching. Generally observed above the ferroelectric SmC* phase in temperature, the SmC a * commonly shows only very narrow phase temperature range of a few degree Celsius. To broaden the SmC a * phase, polymer stabilization was investigated for thermal phase stabilization. Two different reactive monomers were tested in three mixtures, and all three broadened the temperature range of the SmC a * phase from 3 C to 39 C. The current reversal method was used to determine the phase existence versus temperature. Moreover, the texture and network structure was studied by polarized optical microscopy and scanning electron microscopy, with the latter revealing the confinement of the smectic layer structure within the porous polymer network. V C 2015 AIP Publishing LLC.

Confinement of an antiferroelectric liquid crystal in a polymer nanonetwork: thermal and dielectric behaviour

“…by mesogenic monomers (Type B) would have a strong tendency to follow the ordering of the LC molecules. These differences do alter the physical properties substantially, as was demonstrated by Madhuri et al [15] and Labeeb et al [17]. In this article we demonstrate the effect of the polymer confinement on the dielectric properties of an LC exhibiting a direct transition from the paraelectric SmA to the antiferroelectric SmC * A phase.…”

Characterization of the Submicrometer Hierarchy Levels in the Twist-Bend Nematic Phase with Nanometric Helices via Photopolymerization. Explanation for the Sign Reversal in the Polar Response

“…This class of materials have been shown to aid in the liquid crystalline alignment [6][7][8][9] and may also extend the temperature range of the mesophases. 10 The twist-bend nematic phase has recently become one of the most topical areas of research in the field of LCs due to the presence of a complicated hierarchy of periodic structures. 11 The phase is observed in wide range of materials and mixtures containing either odd-hydrocarbon-chain-link dimers or bent-core mesogenic materials.…”

Molecular Dynamics and Kinetics of Isothermal Cold Crystallization in the Chiral Smectogenic 3F7FPhH6 Glassformer

“…The next phase transition upon cooling occurred at 372.5 K and lead to both the decrease of the fractal dimension and a change in texture color, indicating a more pronounced structural change. It is interpreted as a transition to the SmC * phase, where the tilt angle is larger than in SmC * α [32]. The results of the numerical analysis indicate two further transitions at 365 K and 361.5 K. There are possible sub-phases between the SmC * and SmC *…”

“…The Iso → SmA * transition is visible as the discontinuity in the fractal dimension at 379 K. In the 373-375 K range, the fractal dimension is much lower than in the SmA * phase, while the texture colour is almost the same. This implies a transition to the SmC * α phase, which is characterized by a small tilt angle and a very short helix pitch [31,32]. The next phase transition upon cooling occurred at 372.5 K and lead to both the decrease of the fractal dimension and a change in texture color, indicating a more pronounced structural change.…”