Supramolecular organization of adsorbed collagen layers and nanoscale structure of polymer surfaces

The aim of this work is to achieve a better understanding of the nanoscale organization of adsorbed collagen layers. It includes the design and characterization of heterogeneous polymer surfaces that would possibly control the organization of protein adsorbed layers. On native poly(ethylene terephthalate) (PETn), under water, two morphologies for the adsorbed collagen layer were observed. At an adsorbed amount equal to the half of the plateau value of the isotherm, collagen form a granular layer which was attributed to the nodes of a network constituted by lying collagen molecules. At the adsorption plateau, the granular layer was covered by elongated structures attributed to segments of collagen molecules protruding into the solution. This leads to the formation of spindle-like particles after drying. Morphologies observed in the dried state after adsorption (up to 6 hours) on PETn and oxidized PET (PETox) from low concentration solutions were similar and compatible with a network of lying collagen molecules. On PETn after very short adsorption times, the adsorbed layer was damaged by the AFM tip, indicating that the protein interactions with PETn were weaker compared to PETox. In the presence of Pluronic PE6800, the amount of collagen adsorbed on PETn was greatly reduced due the rapid adsorption of the surfactant. Upon drying, the mixed Pluronic-collagen layer profoundly reorganized from a granular morphology (similar to those observed without Pluronic) to a sponge-like morphology. Heterogeneous polymer surfaceswere obtained by the controlled crystallization of PET. Surfaces were constituted by spherulites embedded in an amorphous matrix. This kind of heterogeneties is characterized by a nanoroughness, a higher stiffness and a lower swellability compared to the amorphous phase. The adsorption of t-PtBUMA-b-PDMAEMA block copolymer on silicon oxide (SiOH) and methyl-grafted silicon (SiOH3) was considered to obtain chemically heterogeneous surfaces. A layer of individual copolymer molecules was formed at both surfaces. The distribution of micelles on this layer depends on the processing conditions but also on the hydrophobicity of the support, wich onfluences the organization of the first adsobed molecules.Doctorat en sciences agronomiques - UCL, 200