Modulable nanometer-scale surface architecture using spin-coating on an adsorbed collagen layer

A strategy was developed to create a modulable polymer surface architecture (topography, chemical composition) at the nanometer scale. Therefore, collagen was first adsorbed on a poly(methyl methacrylate) (PMMA) substrate and dried at high or low rate to produce continuous or discontinuous layers, respectively. Solutions of PMMA in chlorobenzene were then spin-coated on top of these collagen layers. The obtained surfaces were investigated using atomic force microscopy and X-ray photoelectron spectroscopy. Spin-coating with pure chlorobenzene on the continuous collagen layer produced pits in the PMMA substrate through the collagen layer; spin-coating with PMMA solutions of increasing concentrations progressively led to the formation of a surface covered by particles made of PMMA and collagen, resulting from a combination of dissolution of PMMA from the substrate and deposition of PMMA from the solution. Spin-coating with pure chlorobenzene on the discontinuous collagen layer led to dissolution of PMMA and to its redeposition on the collagen pattern, which served as a template. This provided a surface entirely composed of PMMA, with cavities in the range of 0.1-1 mum diameter and 50-250 nm depth. In this case, the surface relief was independent of the PMMA concentration of the spin-coated solution, the substrate PMMA dissolution and redeposition being the dominant processes.