A systematic study of the effect of casting solvent on the bulk properties of linear SBS block copolymers

Using a well-characterized series of styrene-butadiene triblock copolymers, a systematic study was carried out to determine the influence of casting solvent, used for film preparation, on the final mechanical properties. The results clearly indicate that in the range of styrene contents of 30–40 mole%, the modulus behavior varies greatly as the solubility parameter δ of the casting solvent is varied. Specifically, the modulus increases as δ increases. At lower or higher styrene content, the properties are influenced but to a much lesser degree. Interpretation of the measured mechanical behavior is given in light of morphological data obtained by rheo-optical methods.