X-RAY-DIFFRACTION STUDY OF THE SMECTIC-C MESOPHASE OF A SIDE-CHAIN POLYACRYLATE CONTAINING A SULFIDE SUBSTITUTED MESOGEN

An X-ray study was performed on powder specimen and oriented fibers of a side chain liquid-crystalline polyacrylate containing a sulfide substituent. The X-ray diffraction patterns showed the presence of a bilayer smectic C mesophase with the mesogenic groups tilted by an angle beta approximate to 40 degrees with respect to the layer normal. The electron density profile rho(z) along the direction normal to the smectic layers was calculated by Fourier inversion and the results suggest a minor interdigitation of the aliphatic chains. The positional smectic order parameter was also determined.