用六甲基磷酰三胺作溶剂,叔丁醇钾作引发剂进行环氧丙烷的活性聚合反应,得到分子量分布系数为1.04的聚环氧丙烷,用红外光谱(IR)和核磁共振(~1H-NMR)表征产物结构,确定了~1H-NMR谱图中各峰的归属;用核磁共振法测定了产物的数均分子量,发现其存在2800的上限;同时,根据_1H-NMR数据计算出反应中的链转移常数,链转移常数的迅速增大是产生分子量上限的原因之一;最后,用在线红外技术研究环氧丙烷阴离子聚合过程,根据吸光度-浓度工作曲线求得聚合反应的活化能为38.0 kl/mol,动力学方程为r=dC/df=1.7×10~3exp(E_a/RT)C(mol·L~(-1)·min~(-1)).
The polymerization of propylene oxide in hexamethyl phosphorarnide (HMPT) was investigated with potassium t-butoxide as initiator. Monodisperse poly(propylene oxide) was obtained (PDI = 1.04), then infrared spectroscopic(1R) and hydrogen nuclear magnetic resonance spectrum(~1H-NMR) were used to characterize its structure, all the peaks in ~1H-NMR spectra was assigned as well. Number average molecular weight was calculated by ~1H-NMR and was limited to about 2800. Chain-transfer constants were calculated out and were found to increase with the molar ratio of propylene oxide to potassium t-butoxide, which may be lead to the upper limit of molecular weight. In-situ FT-IR spectroscopy was used to illustrate the anionic polymerization of propylene oxide. According to the calibration of absorbance to concentration, activation energy was worked out to be 38.0 kJ/mol and the kinetic equation was deduced to be.
参考文献
| [1] | Cyrille Billouard;Stephane Carlotti;Philippe Desbois;Alain Deffieux ."Controlled"High-Speed Anionic Polymerization of Propylene Oxide Initiated by Alkali Metal Alkoxide/Trialkylaluminum Systems[J].Macromolecules,2004(11):4038-4043. |
| [2] | 吴立传,余爱芳,张敏,陈立班.双金属催化环氧化物聚合动力学研究[J].高分子学报,2003(06):871-874. |
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