Microstructure of Single Chain Quaternary Ammonium Cations Intercalated into Montmorillonite: A Molecular Dynamics Study

This study uses molecular dynamics (MD) modeling to examine the interlayer microstructures of montmorillonite intercalated with single chain QACs. Three types of QACs-tetramethylammonium (TMA), decyltrimethylammonium (DTMA), and hexadecyltrimethylammonium (HDTMA)-were selected to synthesize the organoclay complex, and the surfactant arrangement was analyzed quantitatively in systems in the absence of water. A series of arrangement patterns of interlayer QAC surfactant were observed, including lateral monolayers, lateral bilayers, pseudotrilayers, and paraffin monolayers, in agreement with previous experimental results. The effects of increasing one carbon chain length and amount of loading of QAC on the resultant QAC arrangement are summarized, yielding a model that provides insight into the prediction of synthesized QAC-clay microstructure and engineering behavior in practice.