Surprising effects of polymer-surfactant solutions on inorganic crystallization processes

Abstract

Polymer-surfactant solutions, in which the surfactant molecules interact strongly with the polymer chains forming polymerbound micelles above the critical association concentration, are used as media for inorganic precipitation reactions. The formation of PbS is used as a prototype reaction with unexpected results. Under a wide range of conditions, the PbS crystallites initially produced evolve into a range of metastable structures composed of PbS and lead dodecyl sulfate. X-ray diffraction and transmission electron microscopy serve as valuable tools to study the evolution of the crystallizing system in detail. The coexistence of three different colloidal particles (polymers, surfactant micelles and inorganic nanocrystals) leads to extremely complex behavior. The present work highlights the significance of coupling colloidal aggregation to ionic equilibria, and introduces polymersurfactant solutions as a new medium for the study of inorganic crystallization reactions and the production of organic-inorganic nanocomposite materials. © Springer-Verlag 2001.