Characterization and self-assembly of poly[sodium N-(11-acrylamidoundecanoyl)-l-alaninate] in water

A vesicle-forming amino acid derivatized surfactant, sodium N-(11-acrylamidoundecanoyl)-l-alaninate was polymerized to obtain a polysoap. The average molecular weight of the polysoap was determined by gel permeation chromatography. Rheological measurements suggested that the aqueous solution of the polysoap behaves as a non-Newtonian fluid. Fluorescence probe studies using pyrene as probe molecule indicated hydrophobic domain(s) (intra-chain aggregate) formation within a polymer chain. It has been found that the vesicular structure formed by surfactant monomers are retained after polymerization. The polymer forms inter-chain aggregates in concentrated solution. The dependence of fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene on temperature, pH, and urea concentration suggested strong inter-chain interactions of the polysoap. The pKa of the surfactant units of the polymer chain and the phase transition temperature were determined. Dynamic light scattering measurements were performed to determine the mean size of the aggregates. The size of the aggregates was found to increase with the increase in polymer concentration also suggesting formation of inter-chain aggregates. The transmission electron micrographs revealed closed vesicular structures in water.