Bottleneck for reactive molar mass in the polymerization of propylene oxide initiated with potassium t-butoxide

• Published in: Journal of applied polymer science Vol. 113; no. 6; pp. 3656 - 3660
• Main Authors: Yang, Pengfei, Zhu, Xuwei, Yu, Yanhong, Xia, Yong mei, Li, Tianduo
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.09.2009; Wiley
• Subjects: Alkoxides; anionic polymerization; Applied sciences; Chain transfer; Exact sciences and technology; Fourier transforms; FTIR; Infrared spectroscopy; molecular weight distribution/molar mass distribution; NMR; Organic polymers; Oxides; Physicochemistry of polymers; polyethers; Polymerization; Potassium; Preparation, kinetics, thermodynamics, mechanism and catalysts; Propylene oxide; Ring opening polymerization; Priming activity; Experimental study; Solution polymerization; molecular weight distribution/molar mass distribution; NMR; polyethers; Cyclic ether polymer; Propylene oxide polymer; FTIR; Anionic catalyst; Alkoxide; Anionic polymerization; Kinetics
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.30360

The anionic polymerization of propylene oxide was investigated with potassium t-butoxide as an initiator, and the solvent hexamethyl phosphoric triamide was used in controlling experiments. The relative molar mass limit of the products was determined as about 2700, and the C==C double bond was found to exist by NMR. In situ Fourier transform infrared spectroscopy was used to monitor the whole polymerization process until the absorbance reached a constant value and the system reached equilibrium. However, propylene oxide still existed in the system, and alkoxide was detected in the reaction system by ²³Na-NMR. On the basis of these results, we deduced that the residual alkoxide was not active enough to initiate propylene oxide polymerization in the near end of the polymerization. Therefore, there might have been another factor that limited the increase of the relative molar mass of poly(propylene oxide) in addition to chain transfer.