The Adsorption of Mixed Surfactants at the Hydrophilic Silica Surface from Aqueous Solution: Studied by Specular Neutron Reflection

Specular neutron reflection has been used to determine the structure and composition of the mixed ionic-non-ionic surfactants adsorbed at the hydrophilic silica solid/water iInterface. Measurements on two different mixed surfactant systems are reported: the cationic/nonionic mixture of hexadecyltrimethyl ammonium bromide, C16TAB, and hexaethylene glycol monododecyl ether, C12E6, and the anionic/nonionic mixture of sodium dodecyl sulfate, and C12E6. For the C16TAB-C12E6 mixture, pH is shown to have a dramatic effect on the relative affinity for adsorption of the two surfactants at the iInterface.