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Formation of Microscopic Ordering and Macroscopic Patterns in Solid Polyacrylate−Tetraoctylammonium Bromide Films
journal contribution
posted on 2006-04-04, 00:00 authored by Shuizhu Wu, Fang Zeng, Hongping Zhu, Zhen TongPreviously, we observed the rather unusual macroscopic patterns that formed in the solid films
cast from organic solutions containing a surfactant tetraoctylammonium bromide (TOAB) and a chromophore-containing polymer, and we proposed that the patterns resulted from the phase separation between the polymer-rich amorphous structures and the surfactant-rich mesomorphous structures (Macromolecules 2005, 38, 9266). In
this study, it was found that the mesomorphous structure and macroscopic patterns could also form in the solid
films cast from a mixture of toluene, TOAB, and polyacrylates with common polar groups like hydroxyl or
carboxyl. It was also found that the higher polymer chain mobility as well as the balanced interactions between
the three components in the system are crucial to the formation of mesomorphous structure and the macroscopic
patterns. The patterns and the ordered mesomorphous structures were found to be destroyed at the elevated
temperatures, further proving that the pattern formation needs the participation of solvent. The small-angle X-ray
scattering (SAXS) investigations shows that different polar groups in the polymer chains cannot make any difference
in SAXS profile in terms of peak position ratios, suggesting that the resultant mesomorphous structures do not
change with the type of the polar groups in the polymer chains. These results prove that the ordered supramolecular
structures can also be formed in the polymer−surfactant-organic solvent system, and the weak van der Waals
interactions can lead to the formation of mesomorphous structures and macroscopic patterns.