Structure of Alkali Metal-Catalyzed Butadiene Polymers

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Abstract
The structures of various sodium and potassium-catalyzed butadiene polymers were determined from infrared absorption measurements. All of the polymers had a higher proportion of butadiene in the 1,2-configuration (45–80 per cent) than emulsion polybutadiene (18–23 per cent). Polybutadienes catalyzed by potassium had 15–20 per cent less butadiene in the 1,2-configuration than those in which sodium was the catalyst. When a mixture of sodium and potassium was used, the results were nearly the same as with the potassium catalyst alone. Polybutadienes made at 5° had 10 to 15 per cent more butadiene in the 1,2-configuration than those made at 45°. Diluent type had little or no effect on the structure of the polybutadienes. The butadiene portions of butadiene-styrene copolymers were found to have the same relative proportions of 1,2-, cis-1,4- and trans-1,4-configurations as the butadiene homopolymers. The second order transition temperature of sodium-catalyzed polybutadiene polymerized at 30° was −45°, whereas the 75° polybutadiene had a value of −64°.

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