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The thickness of copolymer layers adsorbed to track-etched mica pores was measured as a function of the molecular weight of the polymer when N/JNb < 0.2, where N\ and Nb are the number of monomers in the adsorbing and solvated blocks, respectively. Two polymers were studied: poly(2-vinylpyridine)/ polystyrene, P VP/PS, and poly(methacrylic acid)/poly (butyl methacrylate), PMAA/PBMA. The adsorbing blocks were PVP and PMAA, and JVa was constant for each copolymer series. The copolymers were adsorbed from dilute solution in a selective solvent so that the driving force for adsorption appeared to be primarily a lyophobic effect. The equivalent hydrodynamic thickness (Lh) of a layer was determined from the measured reduction in pressure-driven flow of polymer-free solvent after adsorption of a copolymer. The data for both series of copolymers are correlated by Lh/a ~Nb0-26, where a is the Stokes-Einstein radius of the solvated block and the prefactor depends on the monomer of the solvated block.

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