Self-assembled molecular patterns of fatty acid on graphite in the presence of metal ions
Dong, Wen-fei; Wang, Ruomiao; Mao, Guangzhao; Möhwald, Helmuth; Dong Wen-fei; Key Laboratory of Automobile Materials (Jilin University), Ministry of Education and Department of Materials Science and Engineering, Jilin University; Max Planck Institute of Colloids and Interfaces; Wang Ruomiao; Department of Chemical Engineering and Materials Science, Wayne State University; Mao Guangzhao; Department of Chemical Engineering and Materials Science, Wayne State University; Möhwald Helmuth; Max Planck Institute of Colloids and Interfaces
Журнал:
Soft Matter
Дата:
2006
Аннотация:
The stripe phase formed by long-chain alkane derivatives on the graphite lattice provides a unique opportunity for the study of molecular adsorption, aggregation, and reaction on patterns. Fatty acids, such as arachidic acid (AA), self-assemble on graphite into a sheet of parallel stripes with a periodicity of twice its molecular chain length. The molecular pattern is thus defined precisely by the size and functionality of the headgroup and tailgroup of the amphiphile. Complexation of metal ions to AA fixes the number and location of the ion, which can serve as a precursor to semiconductor nanocrystal arrays. In order to understand the effect of the ion complexation, we carry out atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) investigations of AA self-assembly in the presence of various metal ions. While the stripe orientation is dictated by the graphite lattice and the stripe periodicity is determined by the AA chain length, the size, shape, and degree of order of the stripe crystalline domain are influenced by the metal ion bond strength to the carboxylic ligand. The change of morphology in the self-assembled pattern shows a trend along the Irvingâ Williams series.
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