Morphological studies of a hydrogen-bonded LC polymer obtained by photopolymerization in LC solvents

Abstract

Anisotropic morphologies and the phase behaviour of a hydrogen-bonded LC polymer obtained by photopolymerization in two kinds of LC solvent are discussed. The hydrogenbonded LC monomer, 4-(6-acryloyloxyhexyloxy) benzoic acid (A6OBA), was photopolymerized in 4-cyano-4'-hexyloxybiphenyl (6OCB) and in 4-cyano-4'-undecyloxybiphenyl (11OCB), which show a nematic phase and a smectic A phase, respectively. After photopolymerization, the LC media were removed by extraction and the pure polymer was observed by scanning electron microscopy. SEM images showed that the polymer possessed fibrous morphology with a fibre diameter of a few micrometers, based on polymerizationinduced phase separation. The overall geometries reflected typical LC characteristics such as schlieren and focal-conic fan textures. It was found that the hydrogen bond between benzoic acid groups in the monomer was rigid enough to fix the anisotropic phase-separated structure forming during the early stage of phase separation; however, it could not permanently maintain the fibre structure due to dissociation at elevated temperature. X-ray measurements revealed that a well developed layer structure of the hydrogen-bonded mesogen existed in the polymer obtained from the smectic phase of 11OCB, whereas a polymer layer structure could develop only partially from the nematic phase of 6OCB.

An Optically Active Polythiophene Exhibiting Electrochemically Driven Light‐Interference Modulation

“…Such a CLC reaction field has successfully been employed for the polymerization of polymerstabilized CLC materials. [11,12] The surface structures of polymers synthesized using CLC or smectic A (SmA) matrices have been observed after removal of the LC, [13][14][15] and it has been confirmed that the polymerization of helical polyacetylene in CLC, [16] and polyaniline [17,18] and poly(3,4-ethylenedioxythiophene) (PEDOT) in micellar lyotropic LC by an electrochemical method results in molecular imprinting. Optically active PEDOT has been synthesized using a LC solution of deoxyribonucleic acid (DNA), [19] and nanohybrids of PEDOT/ schizophyllan have been produced by template polymerization.…”

Polymer Architectures Consisting of Rotating Fibers Prepared by Photopolymerization in a Cholesteric Phase

“…The monomer, 4-(6-acryloyloxyhexyloxy)benzoic acid (1), was synthesized according to the method outlined by Broer et al [10] The thermal properties of 1 have been described in a previous paper. [8] The chiral dopant, (S)-(þ)-4-cyano-4 0 -(2-methylbutoxy)biphenyl (3), was prepared by etherification of 4-cyano-4 0 -hydroxybiphenyl and (S)-(þ)-1-bromo-2-methylbutane in the presence of K 2 CO 3 in a DMF solution. The molecular structure of 3 was confirmed by means of NMR spectroscopy and mass spectrometry.…”

“…[8] After UV irradiation, the samples were extracted with ethanol to remove the cyanobiphenyl derivatives and unreacted monomers. The resulting polymers remaining on the glass plates were observed with an SEM.…”

“…[7] Previously, we reported that oriented fibers consisting of a hydrogen-bonded LC polymer could be obtained by photopolymerization of the corresponding monomer in a nematic or a smectic A phase of alkoxy cyanobiphenyls. [8] The fiber formation is based on a polymerization-induced phase separation and requires, as a necessary condition, the immiscibility of the obtained polymer with the LC solvent. [9] The fibers were found to extend parallel to the LC director of the LC solvents and to have a diameter of a few micrometers.…”

Liquid crystal electropolymerisation under magnetic field and resultant linear polarised electrochromism

“…The surface structures of polymers synthesised in LC matrices using light-induced polymerisation methods have been studied. [12][13][14][15][16] A LC solvent was employed for the preparation of polyacetylenes using the Ziegler-Natta catalytic system over 20 years ago. [17][18][19] Syntheses of polyacetylene in NLC under an applied magnetic field [20] and using a gravity flow technique [21] were performed to obtain films with conductivity anisotropy.…”