Solubility parameter of a SBS triblock copolymer

The dissolution behavior of well-defined SBS triblock copolymer with 30 wt% of styrene block was characterized in terms of solubility parameter and its component parameters. Solubility tests in 30 kinds of organic solvents and intrinsic viscosity measurements yield the solubility parameters of 19.0 and 18.9 MPa(1/2), respectively. These results agree well with a value of 19.0 MPa(1/2) estimated by semi-empirical prediction of Hoy, but are found to deviate slightly from 17.2 MPa(1/2) determined by the Hoftyzer-Van Krevelen method. An analysis of the solubility parameter components based on the Hansen's theory confirmed that the SBS is soluble preferably in such solvents having delta(d) higher than 17.2 MPa(1/2), but are hardly soluble where delta(h) marks higher than 4.1 MPa(1/2). All the experimental data and theoretical predictions of solubility parameters for the SBS triblock copolymer lead to a conclusion that the solubility parameter lies in the range of 18.1 to 19.0 MPa(1/2).