Liquid-Crystalline Branched Polymers having Ionic Moieties

Abstract

Ionic LC-dendrimers were obtained by proton-transfer reaction of alkanoic acid and primary amino groups of poly(amidoamine) dendrimer in a 1:1 molar ratio. The ion complexes containing stearate, palmitate or myristate ions showed a smectic A phase. However, the ion complexes containing laurate and decanoate ions exhibited no liquid-crystalline phase. Oilystreak, maltese, and homeotropic textures were observed in the smectic A phase. The formation of the homeotropic structure is characterized by conoscopic observation. The Xray diffraction pattern in the smectic A temperatures consists of sharp inner reflections at the small angles and the wide-angle diffuse halo. Mixtures of the dendrimer and stearic acid [a molar ratio (x) of stearic acid against the primary amino groups of the dendrimer] were prepared; mixtures with x ¼ 0.11-1.5 showed a smectic A phase. However, the mixture with x ¼ 2.33 formed a disordered hexagonal columnar mesophase, characterized by an optical texture and X-ray diffraction measurement.

Ionic Liquid Crystalline Systems Consisting of Polyammonium and Counter Carboxylate Ions

“…Liquid crystalline ion complexes (ionic liquid crystalline systems) were prepared by mixing a carboxylic acid (CA) (16-hydroxyhexadecanoic acid (16hA), dicarboxylic acid (ndA); where "n" refers to the number of carbon atoms: n = 11, 13, 15) and branched polyethyleneimine (BP; MW = 1,800) ( Figure 1). The synthesis was carried out according to the literatures [15,16]. Solutions of CAs and BP (the rate of "CA: amine unit of BP" was weighed 1:4 molecular ratio) were prepared in tetrahydrofuran (THF) and methanol, respectively.…”

“…In ionic liquid crystalline systems, ionic groups such as ammonium, carboxylate, and sulfonate salts effectively form liquid crystals and enhance the thermal stability of the liquid crystalline alignment. Previously, ionic liquid crystalline systems without aromatic mesogenic groups were synthesized by ion complexation (a proton-transfer reaction) of polyethyleneimine and alkanoic acids [15,16]. These ionic liquid crystalline systems exhibited a smectic A phase with an oily-streak texture and a homeotropic alignment upon heating and cooling.…”

Key Developments in Ionic Liquid Crystals

“…More complex examples of this approach include the upcoming area of ionic liquid crystalline dendrimers in which the amine is not a simple aliphatic amine, but rather a amine terminated dendrimer [ 60 , 61 , 62 , 63 ]. The anions can be as straightforward as linear or branched carboxylic acids or complex and include entire mesogenic moieties.…”

Thermal Properties of Ionic Liquid Crystalline Copolymers and their Nonionic Family

“…The ionic liquid crystal systems usually exhibit a smectic layered structure, due to the micro-segregation of ionic and nonionic groups. We have already reported various types of liquid crystalline polymers having ionic units and described the properties of the ionic liquid crystalline polymers incorporating ammonium ion groups [6][7][8][9].…”