[19a-211A-1~10] 12.3 Functional Materials and Novel Devices

[19a-211A-9] Orientation Control and Proton Conductivity of Smectic Phase of Random Copolymers with Photo-responsive Liquid Crystal and Acrylic acid

〇Kota Suetsugu¹, Ryosuke Goto¹, Mitsuo Hara¹, Shusaku Nagano², Takahiro Seki¹ (1.Nagoya Univ., 2.Nagoya Univ. VBL)

Keywords:liquid crystal, proton conduction, orientation control

Random copolymers with azobenzene acrylate (Az) and acrylic acid (AA) chains P(Az-co-AA) were synthesized by free radical polymerization. Differential scanning calorimetry (DSC), X-ray scattering (XRS) measurements and polarized optical microscopy (POM) measurements revealed that P(Az0.7-co-AA0.3) (The copolymerization ratio was estimated by absorbance ratio of solutions.) exhibited the smectic liquid crystal phase (SmB-70-SmA-115-Iso). The scattering due to the smectic layer spacing of the copolymer was observed at 2 theta = 1.2° (d = 7.4 nm) in XRS pattern. The spacing was larger than that in azobenzene homopolymer. These results suggested that the copolymers formed a hetero-smectic lamellar structure with phase separation between hydrophilic Az and hydrophobic AA layers. The single film of P(Az0.7-co-AA0.3) adopted homeotropic orientation in the thin film. On the other hand, the mixed film of P(Az0.7-co-AA0.3) added PDMS-b-PAz to 20% showed random planer orientation which is advantageous for in-plane alignment. When the mixed film was irradiated with linear polarization light (LPL) under the liquid crystal temperature of P(Az0.7-co-AA0.3) (110 degree), dichroism was observed in the absorption band of Az mesogen by a polarized absorption spectroscopy. By grazing incidence small angle X-ray scattering measurement, the scattering from the lamellar structure was observed in the in-plane direction only with the X-rays incidence parallel to the LPL electric field. These results suggested that the lamellar structure was monoaxially aligned in the in-plane direction. We evaluated proton conductivity of P(Az0.7-co-AA0.3) thin film of different orientation structure by AC impedance measurement. Based on those results, we will discuss the contribution of orientation structure of the proton conduction pass to the proton conductivity.