Infrared Studies of 1,2- and Trans 1,4-Structure of Polybutadiene and Butadiene-Styrene Copolymers Polymerized at Various Temperatures

Abstract

Abstract Infrared methods have been used in determining 1,2- and trans-1,4-addition in polybutadiene polymerized in the temperature range −19° to 97° and butadiene-styrene copolymers prepared at −18°, 5° and 50°. trans-1,4-Addition increases and 1,2-addition decreases with decreasing temperature of polymerization. At −19°, substantially all of the 1,4-addition product is present in the trans-1,4-form. Approximately 20 per cent 1,2-addition occurs at this temperature and is concluded to account for the major part of the non-crystallizable portion of polymers made at low temperatures. The influence of styrene on 1,2- and trans-1,4-addition in butadiene-styrene copolymers is also discussed. Free energy, heat and entropy of activation are calculated for 1,4- vs. 1,2-addition and trans-1,4- vs. cis-1,4-addition in the polymerization process.