Recent Advances in Surface Forces Measurement

Abstract

This article reviews recent advances in the surface forces measurements with an overview given in a table Measurements using a surface forces apparatus and an atomic force microscope are explained in a concise manner, and detailed researches on soft comlex systems are described. 1) The elastic compressibility modulus of polyelectrolyte (ionized poly (glutamic acid)) brush layers was determined by analysing the steric repulsion of the surface forces. Abrupt change in the modules was found at a critical density, which was accounted for in terms of the transition in the counterion binding to polyelectrolytes. 2) Two-dimensionally organized protein layers was prepared utilizing LB films which could bind His-tag (poly (histidine) tagged) proteins through specific interaction between metal-chelating lipids and poly (histidine) stretches via Cu (II) ions. An atomic force microscope was employed to measure the forces between these protein monolayers. 3) Nanorheological behavior of liquid crystal thin films was studied by a shear forces apparatus. Resonance curves of the mechanical system were monitored with changing film thickness and normal load. The rheological as well as tribological parameter, local viscosity and friction coefficient, were obtained from the amplitude and the phase of response signals around the resonance frequencies.