Admicelles and adsolubilization using polymerizable surfactants onto solid oxide surface

Abstract

Various surfactant and solid surface systems have been evaluated for surface modification though surfactant adsorption and adsolubilization processes. However, surfactant-modified surfaces face the challenge of substantial losses due to desorption which is negatively impact the stability of that surfactant-modified surfaces. This research aims to minimize the amount of surfactant desorbed from the surface by polymerization of the admicelle (adsorbed surfactant aggregate/layer) including examines the ability of surfactant modified adsorbent to remove organic contaminant through the surfactant-based adsorption process. The objectives of this studies are extend to verify the presence of the polymer thin film formed via admicellar polymerization by atomic force microscopy (AFM) which allows the film to be studied at the nanometer scale. Along with the AFM examination, the contact angle of the admicellar-modified mica surface has been characterized to help examine these objectives. Surfactants used in this study were polymerizable gemini surfactant that is gemini surfactant containing of polymerizable group (double bond) in the tail structure. Furthermore, the comparison with conventional cationic non-polymerizable surfactant, DTAB, was additionally evaluated. Polymerizable gemini surfactant show the higher surfactant adsorption than the monomeric and conventional surfactant. The polymerizable gemini surfactant also reached its maximum adsorption capacity at a lower aqueous surfactant concentration. Styrene and phenylethanol were selected to represent as weak and strong polar organic solutes in adsolubilization study, respectively. Adsolubilization reaches its maximum when surfactant adsorbed onto the solid-liquid interface with the complete bilayer formation and/or maximum adsorption. The impact of polymerization process on the adsolubilization of styrene and phenylethanol was not observed. Styrene increases its adsolubilization capacity to the core where its can expand to facilitate more solute molecules. In the other hand, phenylethanol adsolubilization was preferential related to the palisade region of admicelle structure. Lower desorption of gemini over non-gemini surfactant were observed, and increased stability of polymerized admicelles as reflected by their resistance to desorption. In addition, it was apparent that conventional surfactant bilayer readily desorbs during washing.