Forming patterned films with tethered polymers

Abstract

We use numerical and analytical models to investigate polymer films formed by tethering chains to flat surfaces and immersing the system in a poor solvent. Since the ends of the chains are immobilized on the surface, the polymers avoid the unfavorable solvent by clustering together into aggregates, or pinned micelles, on the surface. These micelles have a uniform size and spacing and form a distinct pattern. We demonstrate that more complex surface patterns can be generated by tethering homopolymers to two surfaces (so that the chains bridge the interfaces) or anchoring copolymers onto one surface. Our numerical calculations reveal the morphology of the layer and the scaling arguments indicate how the dimensions of the patterns depend on the characteristics of the chains and solvent. Finally, we investigate how free copolymers in solution can be exploited to modify the patterns in the film. These results provide further guidelines for controlling the structure of the tethered layer. Overall, the patterned films are useful in the fabrication of adhesives, lubricants and ordered colloidal arrays. The surfaces can also be used to regulate the flow of molecules in channels and for selective filtration systems.