The Effect of the Formation of Polymer /Surfactant Complexes on Selected Tribological Properties of Their Aqueous Solutions

Abstract

Aqueous solutions of sodium alkyl sulphate (surfactant) and polyvinylpyrrolidone (polymer) whose physicochemical properties, including complexing ability, have been widely described in the literature were proposed as a model lubricant. It has been assumed that aqueous solutions of these compounds will favourably modify lubricating properties of water under high load conditions. For this purpose, measurements were made on a four-ball apparatus (T-02 Tester) for aqueous solutions of these compounds. Two kinds of tests were carried out: at constant loads (2, 3, and 4 kN) and variable loads within the range of 0 to 7.2 kN. Unexpectedly, high decreases in motion resistance and wear as well as an increase in antiseizure properties were found in relation to water as a base. The results obtained are so promising that solutions with an optimized composition can find practical applications. The surprisingly high effectiveness of the additives used results from the formation of surfactant/polymer complexes. These adducts adsorb at the interface, and, under friction conditions, they form a lubricant film capable of carrying high loads.

Interfacial complexation of a neutral amphiphilic ‘tardigrade’ co-polymer with a cationic surfactant: Transition from synergy to competition

“…Polymer/surfactant complexation at interfaces and in the bulk [1,2] is important to many industrial applications such as foaming [3][4][5], detergency [6], solubilisation [7], flotation [8], encapsulation [9], lubrication [10], personal care products [11], pharmaceuticals [12,13], and oil industries [14]. Neutron reflectivity (NR) has played a key role in unravelling the polymer/surfactant interfacial structure (i.e.…”