Triblock copolymers containing polysulfone, poly(alkylene oxide), and poly(dimethylsiloxane) segments were obtained by addition of preformed ,-bis(hydrogensilyl) poly(dimethylsiloxane) oligomers to alyl end-capped poly(alkylene oxide)-b-polysulfone. Viscometric and UV absorption measurements were carried out in dilute 1,2-dichlorethane solutions, in the temperature range of 20-75 degrees C. The specific interactions exhibited by the block copolymers in a selective solvent are influenced by the copolymer composition and temperature. The results point to a conformational transition phenomenon, located around 55 degrees C, which is attributed to the transition from a segregated to a pseudo-Gaussian conformation through a compressed-segregated conformation. POLYM. ENG. SCI., 57:114-118, 2017. (c) 2016 Society of Plastics Engineers