Adhesion and detachment Mechanism of Polymer Surfaces

With the development of nanotechnology and biotechnology during the last two decades, more and more people are interested in the surface interactions (adhesion, separation) between soft materials, such as lipid bilayers, cell membranes, ‘soft’ polymers, etc. The classical theories describe the adhesion and deformations of two elastic solid surfaces, and their static (equilibrium) models, which can not be directly applied to the surface interactions of the above soft materials. Understanding the adhesion and detachment mechanism of polymer surfaces is the main object of this study . The adhesion and separation of two polymer thin films was studied using a Surface Force Apparatus (SFA). The polymer thin films are prepared by spin-coating, characterized by atomic force microscope (AFM) and contact angle measurements prior to adhesion experiments. Interesting interfacial instabilities and patterns appear during both the adhesion and separation of two viscoelastic polymer films ; the patterns are highly ordered for the adhesion and coalescence process, and irregular for the detachment process. Film thickness, viscosity and other factors can affect the lifetime and appearance of the patterns. The appearance of the se patterns can be explained by both fluid mechanics theories, and inter molecular and surface forces. References: (1) Zeng, H. B.; Tian, Y.; Zhao, B. X.; Tirrell, M.; Israelachvili, J., Langmuir 2007, 23, 6126-6135. (2) Zeng, H. B.; Zhao, B. X.; Tian, Y.; Tirrell, M.; Leal, L. G.; Israelachvili, J. N., Soft Matter 2007, 3, 88-93. (3) Zeng, H. B.; Maeda, N.; Chen, N. H.; Tirrell, M.; Israelachvili, J., Macromolecules 2006, 39, 2350-2363.