Anisotropic assembly of a side chain liquid crystal polymer containing sulfoalkoxy groups for anhydrous proton conduction

Abstract

A side chain liquid crystal polymer containing pendant sulfonic acid groups has been synthesized by post-polymerization functionalization of a brominated mesogenic precursor. A macroscopic alignment was achieved by mechanical shearing of the liquid crystal polymer in the smectic phase. The uniaxial layered assembly exhibited anisotropic proton conductivities under anhydrous conditions and has potential applications in medium temperature fuel cells.Scheme 1 Synthesis of the mesogenic P2 containing sulfonic acid groups.

Hydrogen bonding and liquid crystallinity of low molar mass and polymeric mesogens containing benzoic acids: a variable temperature Fourier transform infrared spectroscopic study

“…This material design approach has been very widely adopted and remains an area of considerable research activity; recent examples of hydrogen-bonded systems have included both main chain [11][12][13] and side chain liquid crystal polymers (SCLCPs), [14,15] and new discotic systems. [16][17][18] Hydrogen bonding also plays a key role in driving liquid crystalline behaviour in a diverse range of other materials including commercially important high-performance fibres, [19] protonic conductors [20,21] and liquid crystal sugars. [22][23][24][25] Supramolecular SCLCPs have attracted particular attention and these have been assembled not only using hydrogen bonding (see, for example, [7,26,27]), but also by utilising other types of non-covalent interactions such as ionic bonding [28] and quadrupolar interactions.…”

Anhydrous proton‐conducting electrolyte based on a nematic poly(methyl acrylate) containing sulfonated side chains

“…POM observation suggested that P S45 preserved its original morphology when it was quenched using liquid nitrogen from the nematic phase. In contrast with the sample resulted from the smectic phase, the quenched nematic P S45 did not form uniformly patterned structures on a macroscopic scale even after shearing (Figure ).…”

“…4‐(6‐Bromohexoxy)−4′‐hydroxy biphenyl ( 1 ) and 4‐(6‐acryloyloxyhexyloxy)benzoyl chloride ( 2 ) were synthesized according to the procedures described previously . The brominated mesomorphic poly(methyl acrylate) ( P Br ) was prepared according to our previous report …”

Enhancing proton conduction via doping of supramolecular liquid crystals (4-alkoxybenzoic acids) with imidazole

“…Proton conduction has been achieved for smectic, columnar and cubic liquid crystals containing benzenesulfonic acid or sulfonate over 100 • C [8][9][10]. We succeeded in obtaining proton conductivity of 4.7 × 10 −3 S cm −1 at 200 • C in the layered side-chain liquid crystal polymers bearing sulfonic acids [11]. Styrenic comb polymers self-assembling into supramolecular structures with cylindrical imidazole-rich domains showed proton conductivity of 10 −3 S cm −1 at 200 • C [12].…”