MOLECULAR-WEIGHT STANDARDS FROM SULFONATION OF POLYSTYRENE

In the reported experiment, polystyrene was sulfonated with sulfur trioxide-triethyl phosphate complexes in dichloroethane, the object being to prepare polystyrene sulfonates substantially free of sulfone links between polymer chains. Variations in the sulfone content with reaction conditions were conveniently followed by exclusion chromatography, the sulfone peak appearing at about twice the molecular weights between 1. 1 multiplied by 10**5 and 8. 7 multiplied by 10**5 by using (at minus 20 to plus 25 degree C) a 5:1 excess of a 1. 5:1 complex, the last at a concentration of 0. 5M. Completely soluble polystyrene sulfonate was also obtained from polystyrene of molecular weight 2. 05 multiplied by 10**6. Requirements for the successful use of the 1. 5:1 complex include careful purification of the dichloroethane and, if 2 g or more polystyrene is to be sulfonated, formation of the complex at minus 20 degree C. A method is given for measuring the sulfonating capability of the reagent before adding the polymer.