STRUCTURAL-CHANGES OF DIACETYLENE FATTY-ACID HETEROCYCLIC LANGMUIR-BLODGETT-FILMS BY POLYMERIZATION STUDIED BY X-RAY-DIFFRACTION

Hetero-structured Langmuir-Blodgett (LB) films of stearic acid (C18) a nd unpolymerized 10-12 pentacosadiynoic acid (CH3(CH2)11C=C-C=C(CH2)8C OOH : PD) were prepared and the structure of unpolymerized and photopo lymerized films were investigated by X-ray diffraction. The structural changes by photopolymerization were discussed. The order of depositio n was varied systematically. It is found that the interplanar spacings and molecular alignments of the hetero-structured films strongly depe nd on the order of deposition. For the 3 and 4 layer cycle films, ''pa rtially overturned'' structure was observed in some unpolymerized film s, which means that some molecules turns into Z or X films from Y type . Moreover, polymerized films returned to Y type structure. From the f ilms with rather thick periodicity as long as about 200 angstrom, sate llite reflections were observed suggesting that high order can be achi eved over large distances and the macroscopic molecular orientations a re highly ordered in spite of the microscopic inhomogeneity.