First photoresponsive liquid-crystalline materials with small layer shrinkage at the transition to the ferroelectric phase

Effect of alkyl chains length on properties of ferroelectric liquid crystals with the keto group attached to the molecule core

“…are often reasonable, in the range 30-70 C, and the LC phases can easily be supercooled well below room temperature and (iv) lactic acid-based LCs usually show no ageing, and are highly stable, thermally as well as chemically. Moreover, introduction of double bond or -OH polymerizable groups [9,[30][31][32] or adding the photosensitive azo group [15][16]20,32] in the molecular core can strongly increase the potential functionality of this class of chiral LC materials and can make them useful for photonics, telecommunications, non-linear optics, etc.…”

“…There are four main advantages of the lactic acid derivatives as a sub-class of chiral LCs that makes them attractive with respect to other materials, i.e. (i) forming of a broad variety of basic LC phases, including the cholesteric N*, paraelectric SmA* [10,11], ferroelectric SmC* [3,8,[12][13][14][15][16], antiferroelectric SmC Ã A [12,[17][18][19][20][21][22][23], polar hexatic phases [9,13,14,19,24] as well as frustrated ones like the twist grain boundary phases, namely TGB Ã A [1][2]7,12] and TGB Ã C [25] or SmQ* phase [12,26] or re-entrant SmA* [27][28][29] and re-entrant SmC* [9,13,24]; (ii) utilization of the lactic unit as a precursor of chiral centre minimizes the cost as the price ratio to the most commonly used chiral precursor material (S)-2-octanol is at least 1:100; (iii) melting points (m.p.) are often reasonable, in the range 30-70 C, and the LC phases can easily be supercooled well below room temperature and (iv) lactic acid-based LCs usually show no ageing, and are highly stable, thermally as well as chemically.…”

Self-Assembling Behavior of Smart Nanocomposite System: Ferroelectric Liquid Crystal Confined by Stretched Porous Polyethylene Film

“…Chiral liquid crystals derived from the lactic acid are intensively investigated due to definite advantages [19,25,26] with respect to other types of chiral molecular structures: chemical stability -no aging, reasonably low price, and a comprehensive variety of conventional and frustrated nematic and smectic phases stable in a broad temperature range. LC compounds with chiral part based on lactate group are actively used as: (i) chiral dopants while designing binary [27][28][29] and multicomponent functional mixtures [30,31]; (ii) reactive mesogens for macromolecular compounds used as side-chains for polymers [32][33][34] and elastomers [35,36]; (iii) functional dopants for organic photovoltaic cells [37][38][39] and matrices [40][41][42] for design of nanocomposite systems; and (iv) source of chirality for photosensitive low molar mass [21,[43][44][45] and macromolecular [20,34,[46][47][48] materials.…”

Functional Photochromic Methylhydrosiloxane‐Based Side‐Chain Liquid‐Crystalline Polymers

“…Photosensitive polymers are extensively studied due to their potential applications in devices for optical data storage. Important feature of these materials is a light‐induced change of the structure mostly owing to the presence of a photosensitive group . For example, E–Z ( trans–cis ) isomerization takes place upon UV light irradiation in azobenzene derivatives possessing a NN moiety.…”

“…Excitation converts a fraction of the molecules to the Z ‐isomer, which may relax back to the E ‐form either through photoexcitation or by thermal relaxation. In liquid crystals, the Z ‐form acts like a bent‐shaped impurity inside the calamitic LC matrix; therefore, the formation of Z ‐isomers strongly decreases the order parameter of the LC phase and can eventually lead to the transformation to the isotropic state . This transformation may occur even when a low‐intensity light source is used; for example, the light from a microscope is often sufficient to cause a phase transition.…”