Polystyrene layers grafted to epoxy-modified silicon surfaces

Carboxylic acid- and anhydride-terminated polystyrenes of different molecul ar weights from 4500 to 672 000 were grafted from melt onto silicon substra tes modified with epoxysilane monolayer. The grafted chains are densely pac ked with a density close to the known value for the bulk material. The teth ered polymer layers are very smooth, uniform, mechanically stable, and cove r homogeneously the modified silicon. At the degree of polymerization (N) c lose to the critical molecular weight, the grafting process is the most eff ective, resulting in the grafted unperturbed macromolecules. We suggest tha t the grafting from the reactive polymer melt is controlled by steric const raints through the minimum available free volume between the grafted macrom olecules, which is reachable by another reactive end. This volume correlate s with the size of monomeric unit and varies very Little with the molecular weight.