Adsorption of polymer/solvent complexes on silica surfaces

In this work local chain conformation, polymer/solvent interactions and particle size of different PMMA/solvent or PMMA/surfactant/solvent systems were investigated by dynamic light scattering, infrared spectroscopy and capillary viscosimetry. Aggregation can be forced, in the chlorinated solvents, through mixing with a small amount of PEG non-ionic surfactants. Nano-gel particles can also be formed by stereocomplexation of i- and s-PMMA in certain solvents. The adsorption of stereoregular PMMA on silica was investigated by H-1 NMR. The strong relative lowering of the peak ascribed to isotactic sequences has provided evidence of a stereospecific adsorption of the isotactic segments. The conformation and the secondary structure induced by the PMMA stereoregularity may, therefore, be considered as a significant factor in the adsorption process. According to the miscibility of the components, PMMA/PEG mixtures are shown to increase the amount of polymer adsorbed and also to modify the stereoselectivity of the adsorption. Aggregative adsorption is assumed to deeply influence the organisation of the polymer at the silica/solvent interface. Finally, adsorption of aggregates of stereocomplexes can be used to pattern surfaces in thin Films.