Tuning structural forces between silica surfaces by temperature-induced micellization of responsive block copolymers

Abstract

The aim of this study is to demonstrate a method to control interactions between two surfaces by the use of a responsive solution. This was done by performing AFM-based force measurements between two silica surfaces immersed in an aqueous solution of thermo-responsive Pluronics P85 block copolymers. For this system we demonstrate that one can switch between a situation where no long-range forces are acting between the surfaces to a situation where a long-range structural force, oscillating between attractive and repulsive force regimes, is controlling the surface interaction. This shift in behavior is caused by a long-range order introduced by temperature-induced micellization of the block copolymers and is thus simply achieved by changing the temperature from below to above the micellization temperature. We propose that the use of micelle-forming responsive block copolymers is a general method for reversibly controlling surface interactions by a temperature switch. Since the force control is achieved by changes occurring in bulk solution, the nature of the surfaces is expected to play only a relative minor role.