SPECIFIC ADSORPTION OF SOME STYRENE VINYLPYRIDINE DIBLOCKS FROM SELECTIVE SOLVENTS ONTO SOLID SUBSTRATES - AN NMR-STUDY

Interactions of styrene-b-4-vinylpyridine P(S-b-4VP) diblocks with various particulates were investigated. Proton nuclear magnetic resonance (H-1 NMR) was used to determine the quantities of copolymer diblocks in solution. The effects of both diblock chain length and of quantity of adsorbed diblock were investigated. It was found that surface interactions lead to preferential adsorption of the 4VP chain segments onto the particulates. Isotherms show that there is a direct correlation between the normalized equilibrium quantities of adsorbed copolymer diblocks and the length of the 4VP anchor. A linear relationship also was obtained between the equilibrium quantities per unit area of substrate and the acid/base properties of the particulates, as expressed by the ratio of acceptor number to donor number (as defined by the Gutmann theory). Using the scaling model of Marques, Joanny, and Leibler, good agreement was found between the experimental and predicted equilibrium quantities of adsorbed material. For these systems, it was demonstrated that the prefactor of the scaling law relation was directly related to the acid/base properties of the substrate, and that this prefactor could be calculated from the values of the acid/base surface indices obtained by inverse gas chromatography.