Mesomorphic phases of main‐chain liquid‐crystalline polymers with pendent sulfonic acid groups

Abstract

Some main-chain liquid-crystalline polymers were synthesized with pendent sulfonic acid groups (0-6 wt %) on the polymer backbone. The solution viscosity behavior, the chemical structures, and the liquid-crystalline (LC) properties were characterized with Fourier transform infrared spectroscopy, elemental analysis, 1 H-NMR, differential scanning calorimetry, polarizing optical microscopy, and X-ray measurements. All the polymers displayed a smectic mesophase with a mesogenic range of 142-1558C and good thermal stability. With an increasing concentration of sulfonic acid groups in the polymer systems, some of the polymers exhibited two kinds of mesophases, including smectic and nematic phases. The glass-transition temperatures and isotropic-transition temperature were elevated slightly, whereas the temperature of the smectic-nematic phase transition changed a little. For polymers with a few sulfonated benzene groups, the regular mesogen/soft matrix structures led to a smectic structure because of microdomains between the mesogenic moieties and the soft main-chain matrix, whereas for polymers with an increased number of sulfonic groups, the ionic groups were distributed in both the soft matrix and the LC microphase. Although the increased ionic interactions between mesogens led to more crystalline phases, the strong electrostatic interactions in the ionic group/mesogen/soft matrix systems may have been tangled in domains. Therefore, they disturbed the regular mesogen/soft matrix smectic phase structure, leading to the appearance of a smectic-nematic transition.

Sulfonated liquid crystalline polyesters as resin matrix for single wall carbon nanotube and nanodiamond composites

“…Although several research groups reported on the synthesis and characterization of sulfonated LCPs,31–41 their application in the preparation of LCP/CNT nanocomposites is rather limited,42 and LCP/ND nanocomposites have not been reported at all. Zhang and coworkers explored different methods to prepare main‐chain LCPs with pendant sulfonate groups.…”

“…In an extensive series of studies, they used dye molecules like Brilliant Yellow31–34 and Fast Yellow35 as the sulfonate‐containing monomer to prepare LCPs via interfacial polymerization. They also report on the synthesis of liquid crystalline polyesters (LCPEs) via a three‐step synthetic route that makes use of Brilliant Yellow36 and 2‐hydroxy‐5‐carboxy‐benzenesulfonic acid derivatives as one of the monomers 37, 38. Finally, dimethyl 5‐sodiosulfoisophthalate39 and sulfoterephthalic acid40 have been used in melt condensation reactions and very recently the post‐treatment (sulfonation) of an LCP was demonstrated 41.…”

“…Different sulfonate-based approaches have been explored, including the addition of sulfonated surfactants 25,26 or sulfuric acid, 27 blending with another (sulfonated) polymer, 28 and the sulfonation of nanomaterials and/or polymers. 29,30 Although several research groups reported on the synthesis and characterization of sulfonated LCPs, [31][32][33][34][35][36][37][38][39][40][41] their application in the preparation of LCP/CNT nanocomposites is rather limited, 42 and LCP/ND nanocomposites have not been reported at all. Zhang and coworkers explored different methods to prepare main-chain LCPs with pendant sulfonate groups.…”

“…They also report on the synthesis of liquid crystalline polyesters (LCPEs) via a three-step synthetic route that makes use of Brilliant Yellow 36 and 2-hydroxy-5carboxy-benzenesulfonic acid derivatives as one of the monomers. 37,38 Finally, dimethyl 5-sodiosulfoisophthalate 39 and sulfoterephthalic acid 40 have been used in melt condensation reactions and very recently the post-treatment (sulfonation) of an LCP was demonstrated. 41 None of these studies applied the sulfonated LC polymers for the preparation of (nano)composites.…”

Sulfonic acid supported on magnetic nanoparticle as an eco‐friendly, durable and robust catalyst for the synthesis of β‐amino carbonyl compounds through solvent free Mannich reaction

“…Therefore, due to the stringent environmental standards and economic pressures, much attention has been directed toward to immobilized sulfuric acid on solid support to reducing of waste, effective separation of catalyst and simple purification of the products. Toward this aim, many support materials such as polymers, amorphous and mesoporous carbon, mesoporous silica and amorphous silica are often used for immobilization of sulfuric acid, which can be separated by conventional separation techniques such as centrifugation and filtration.…”