CAPILLARY WAVE STUDIES OF POLYSTYRENE-B-POLY(METHACRYLIC ACID) DIBLOCK COPOLYMER FILMS AT THE TOLUENE WATER INTERFACE

We have used both a mechanically generated capillary wave technique and surface light scattering to measure capillary wave properties of the toluene/water interface covered by polystyrene-b-poly(methacrylic acid) diblock copolymer (PS-PMAA) as a function of both the overall molecular weight M(w) and the interfacial concentration of the diblock copolymer. As interfacial polymer number density N is increased, surface pressure pi increases with a slope dependent on molecular weight and reaches a maximum value at a particular interfacial density (saturation density), beyond which density pi no longer changes appreciably. The slope of pi(N) indicates that all molecular weights show approximately the same areal compressibility at the lowest number densities. The saturation surface pressure increases with molecular weight.