核磁共振磷谱在混合取代聚磷腈合成中的应用研究

MONITORING THE SYNTHESIS REACTION OF A MIXED SUBSTITUTED POLY(ORGANOPHOSPHAZENE) BY ^(31)P NMR

用核磁共振磷谱对具有 4 丙氧羰苯氧基和甘氨酸乙酯侧链的混合取代聚磷腈的合成过程进行监测 .实验结果表明 ,聚二氯磷腈与 4 丙氧羰苯氧基钠的反应及其中间产物与甘氨酸乙酯的反应分别需要 2 0h和 2 4h才能完成 .生成的最终产物中 ,既含有混合取代型链节 ,也含有单取代型链节 ,但从整个分子来看 ,两种取代基的相对含量之比为 0 .49∶0 .5 1 .这些结果对于深入了解此类高分子反应的机理 ,进一步优化混合取代聚磷腈的合成条件 。

Poly (organophosphazenes) possesses a backbone of alternating nitrogen and phosphorus atoms with two organic side groups attached to the phosphorus atoms. A unique property of poly (organophosphazenes) is that polymers with tailored physical and chemical properties can be prepared by using appropriate nuclephiles. This feature is useful in developing polymers that are good candidates for biomedical materials. In this study, a mixed substituted poly(organophosphazene) bearing propyl 4-oxybenzoate and glycine ethyl ester side groups was synthesized via macromolecular substitution reactions of poly (dichlorophosphazene) with sodium salt of propyl 4-hydroxybenzoate and glycine ethyl ester. The stepwise substitution reactions were monitored by ^(31)P NMR spectroscopy. ^(31)P NMR spectra were acquired repeatedly in a 4-hour interval during the synthetic reaction. The results showed that more than 20 hours and 24 hours were required, respectively, to complete the first step reaction and the second step reaction. Two types of skeleton phosphorus atoms existed in the final polymer product, one with the same two side groups (two -OC_6H_4COOCH_2CH_2CH_3 or two -NHCH_2COOEt) attached, and the other type of phosphorus atoms had two different side groups (one (-OC_6H_4COOCH_2CH_2CH_3) and one -NHCH_2COOEt). The relative content of the propyl 4-oxybenzoate substitute and the glycine ethyl ester substitute was 0.49∶0.51. The results obtained were of interest for understanding the mechanism of the macromolecular substitution reactions, for optimizing the reactive condition for synthesizing the mixed substituted poly(organophosphazene) and for increasing the yield of the polymer product.