The influence of initiator Diol-BF3 complex solubility and other factors on the induction period in BF3 catalyzed cationic ring opening polymerization of epichlorohydrin

Abstract

In this work, the effect of initiator diol-BF3 complex solubility on an induction period was investigated for BF3 catalyzed cationic ring opening polymerization of epichlorohydrin at various [BF3]/[initiator diol] ([C]/[I]) ratios, using on-line temperature and torque monitoring systems. Other factors influencing the induction period (reaction temperature: −5∼30 °C, [C]/[I] ratio, and monomer feed rate: 9.2×10−3–27.6×10−3 mol·min−1) were also investigated in order to optimize the polymerization condition in the presence of the diethylene glycol (DEG)-BF3 complex. A 5-L, triple-glass jacket reactor was customized for the monitoring system. 1,4-Butanediol (BD) and diethylene glycol (DEG) were used for the initiator diol. In the presence of the BD-BF3 complex, which is insoluble in methylene chloride solvent (MC), an uncontrollable and highly exothermic reaction occurred shortly after the long induction period. Although there was an induction period with the DEG initiator diol, the exothermic reaction which followed was much more controlled, and the resulting polymers showed relatively narrow polydispersities (1.31–1.34) using the DEG initiator diol, which is soluble in MC. The longer induction period, which was highly affected by the solvation effect of the reaction media, appeared at a lower reaction temperature and [C]/[I] ratio. The molecular weights and structural characterizations of PECHs were analyzed via GPC, 1H-NMR.