Novel gelling structures based on polymer/surfactant systems

Our objective was to seek and characterize n w gelling compositions based on suitably chosen polymer/sur-factant pairs. In earlier work we reported unusual increases in viscosity when an anionic surfactant, such as SDS, was added to a cationic cellulosic polymer (Polyquaternium-10, medium MW). We have now found even greater increases in apparent viscosity and, indeed, formation of gels of good strength and clarity when a high-molecular-weight version of PQ-10 is used in combination with SDS. Gels are viscoelastic materials, i.e., possess both liquid and solid characteristics and are most appropriately characterized byoscillatory rheology measurements that yield such parameters a storage modulus (G'), loss modulus (G"), phase angle (8), and so on. Measurements, with data analysis, were carried out using the Bohlin VOR Rheometer. The results are interpreted in terms of the formation of "super " macromolecules through association f the alkyl groups of surfactant molecules bound to the ionic sites of different poly-meric molecules by strong electrostatic forces. It is shown that strong gels can be formed at quite low levels of polymer (--1%) and that there is an optimal level of SDS and other anionic surfactants o achieve maximum gel strength. Adjustment of the gel's properties, including liquefaction, can be achieved by suitable adjustment of the surfactant/polymer ratio or the addition of selected cationic materials. Preliminary information relevant to formulation is provided