Study of terminal hydroxyl groups of tetrahydrofuran and propylene oxide linear copolymers

A study was made of the effect of glycols, a catalytic complex, and copolymerization conditions on the type of hydroxyl groups of tetrahydrofuran (THF) and propylene oxide linear copolymers. It was found that the content of primary hydroxyl groups in copolymers, where diethylene glycol (DEG) is used as co-catalyst, decreases on increasing molecular weight. The rate of incorporation of DEG in the polymer chain was determined and a mechanism proposed for chain breakage by the primary hydroxyl group of oligomer alcohol. The exchange reaction between the BF3· ·THF complex and glycols was examined. Heats of formation were found for BF3· ·glycol complexes. The highest rate of exchange reaction is observed for DEG. With increased concentration of the BF3·DEG complex in the reaction medium, the content of primary hydroxyl groups in the copolymers formed decreases from 50 to 13·7%.