A diblock copolymer of deuterated styrene and isoprene (dPS-PI) with a small volume fraction of isoprene was chemically modified to incorporate pendant fluorinated side chains ("fingers"). The composition distribution of the diblock copolymers within a high molecular weight polystyrene (PS) homopolymer was determined by forward recoil spectrometry. Surface segregation and interfacial segregation of the modified block copolymers from a polystyrene matrix are observed in as-spun films. Equilibrium segregation was achieved on annealing at 160 degrees C for several days. The segregation isotherms at the air-polymer interface are shown to be quantitatively described by a self-consistent mean field theory (SCMF), and these permit us to estimate an effective Flory parameter which describes the attraction of the fluorinated segments to the surface and their repulsion from the bulk. The change in the surface tension as a result of the adsorption of the block copolymers at the air-homopolymer interface was evaluated from the predictions of SCMF theory and compared with the changes in the water contact angle observed. Advancing water contact angle data are consistent with the presence of a nonuniform layer of PS, CF2, and CF3 segments on the surface of the segregated samples.