Formation of Microscopic Ordering and Macroscopic Patterns in Solid Polyacrylate−Tetraoctylammonium Bromide Films

Previously, 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.