Carbon Dioxide → Benzene, ethenyl-, polymer with 1,3-butadiene

Participants

Reaction Steps

A one-liter round bottom flask is equipped with a dry ice cooled reflux condenser and an agitator. The vessel is provided with a nitrogen atmosphere and charged with 318 grams of purified styrene and 170 grams of purified butadiene. The contents of the flask were at ambient temperature (about 22° C.). The polymerization was initiated by the addition of 2 milliliters of a 0.523 normal solution of n-butyllithium in hexane. The polymerization temperature in the flask varied from about 14° C. to 24° C. and was governed by the refluxing rate of the butadiene from the reaction mixture. The polymerization was terminated 5 hours after the addition of the n-butyllithium by the addition of about 0.2 milliliters of n-propanol. The polymer was recovered by precipitation with methanol to yield 45.5 grams of a rubbery styrene-butadiene polymer. The yield was 9.3 weight percent based on the weight of the initial monomers. Gel permeation chromatography was employed to determine the molecular weight using both an ultraviolet and refractive index detectors. The molecular weight was 187,000 grams per mole and the polymer contained 14.9 percent styrene and 85.1 percent butadiene, percentages being weight percentages. Employing the reactivity ratios reported by Hsieh and Glaze (Rubber Chem. Tech., 43, 22, 1970), wherein the reactivity ratio for styrene was taken at 0.1 and that for butadiene as 12.5, the calculated composition was 14.5 percent styrene and 85.5 percent butadiene.

Provenance & Evidence