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 var ious 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 inter actions lead to preferential adsorption of the 4VP chain segments onto the particulates. Isotherms show that there is a direct correlation b etween the normalized equilibrium quantities of adsorbed copolymer dib locks and the length of the 4VP anchor. A linear relationship also was obtained between the equilibrium quantities per unit area of substrat e and the acid/base properties of the particulates, as expressed by th e 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 equilibriu m quantities of adsorbed material. For these systems, it was demonstra ted that the prefactor of the scaling law relation was directly relate d to the acid/base properties of the substrate, and that this prefacto r could be calculated from the values of the acid/base surface indices obtained by inverse gas chromatography.