Molecular dynamics simulations have been used to study the interaction of toluene, hexadecane, and water with the surfaces of thin films of a random copolymer of styrene and butadiene (SB) and a random copolymer of styrene, butadiene, and acrylonitrile (SBA). Qualitatively different behavior is seen with the three small molecules. The two hydrocarbons remain on the thin films of the copolymers, but water has little affinity for the surface. Toluene has a stronger tendency to penetrate into the film than does hexadecane, which remains at the surface of the thin him. The attractive interaction of the hydrocarbons with the surfaces is dominated by van der Waals interactions. The energy of the interaction of toluene with SB is slightly smaller than the heat of vaporization of toluene at the temperature of the simulation. When expressed on a weight basis, the interaction of toluene with SB is larger than the interaction of hexadecane with the same surface. Hexadecane interacts slightly more strongly with SB than with SBA.