| Popis: |
Styrene oxide (SO) and propylene oxide (PO) were copolymerized at temperatures between − 40 and +20° C using boron trifluoride etherate (BF3) as catalyst, 1,3-propanediol (DIOL) as cocatalyst, and ethylene dichloride (EC) as solvent. The initial rates of consumption of SO and PO varied as follows with the initial catalyst, cocatalyst, and comonomer concentrations: Computation of reactivity ratios yielded values of 0.1 for SO (M1) and 0.4 for PO (M2), indicating that the comonomers tend to alternate in the copolymer. SO yielded a cyclic dimer when homopolymerized with BF3 in EC. In the presence of THF, copolymerization did not take place; instead, homopolymerization of SO into higher molecular weight polymers was observed. In the presence of PO, mixtures of SO and THF gave rise to terpolymers. |
