| 초록 |
The effect of the side chain length on structural change in side chain liquid crystalline polymers (SLCPs), poly[oxy(tetradecylsulfonylmethyl)ethylene] (14SEO) and pol[oxy(hexadecylsulfonylmethyl)ethylene] (16SEO) and poly[oxy(octadecylsulfonylmethyl)ethylene] (18SEO), was investigated by using FT-IR and synchrotron X-ray scattering measurements. For these SLCPs, the presence of sulfone groups near the polar backbone made it possible to show the evident mesophase stability due to its amphiphilic character. In contrast to 14SEO, however, it was found for both 16SEO and 18SEO that a broad reflection peak relating to ripple wavelength λ was observed at the low-angle region in small angle X-ray scattering (SAXS) measurements. From the peak analysis, the multiple reflections exhibited in 16SEO could be indexed as the 10, 01, 11 and 02 reflections of 2-dimensional tetragonal symmetry. This unique ripple structure suggested in conventional lipid bilayer is believed to occur due to the periodic undulation in PEO backbone chains. This is most probably caused by the energy penalties associated with conformational disordering in alkyl side chains. From the FT-IR measurements in CH2 stretching and bending region, the population of gauche conformation in alkyl side chain of 16SEO was found to increase compared with 14SEO. To enhance the bending rigidity in flexible PEO backbone, we prepared the 16SEO/LiClO4 complex system by simply mixing the 16SEO with LiClO4 in THF. Notably, ripple structure was changed into simple bilayer structure, indicating the enhanced the bending rigidity in PEO backbone and the cross-sectional area of sulfone group caused by complex Li ion with oxygens in polar parts. |
