Effects of the casting solvent on the surface compositions of a series of polydimethylsiloxane (PDMS)-urethane-urea copolymers were investigated. The solvent pair investigated was tetrahydrofuran (THF) and mineral spirits (MS). Factors that determine solubility of a copolymer in a mixture of THF and MS include the solvent composition and the ratio between the sizes of the soft and the hard segments. The effectiveness of using mixed solvent to enhance surface PDMS enrichment varies with the copolymer composition. The benefits are maximized when the average molecular weight of the PDMS segments is 10,000.