Synthesis and protonation behavior of comblike poly(ethyleneimine)
Synthesis and protonation behavior of comblike poly(ethyleneimine)
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DOI：
10.1021/ma020819s
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发表时间：
2003-04-08
期刊：
影响因子：
5.5
通讯作者：
Borkovec, A
中科院分区：
文献类型：
--
作者：
Koper, GJM;van Duijvenbode, RC;Borkovec, A
采用保护基策略合成了以-(CH2CH2)N(CH2CH2NH2)-为重复单元的梳状聚乙烯亚胺(PEI)，并通过电位滴定法进行了分析。如果将质子化程度绘制为 pH 的函数，则滴定曲线显示由两个中间平台分隔的三个质子化步骤，即一个质子化程度为 1/2，第二个为 3/4。第一个质子化步骤发生在 pH 值约为 9.5 时，对应于侧链上伯胺基团的质子化。在第二次质子化步骤中，pH 值约为 4.5，每秒叔胺质子化一次。最后的质子化步骤，即剩余的叔胺质子化，被怀疑发生在接近 0 的 pH 范围内。后一点和详细的质子化机制是根据位点结合模型推导出来的。该模型已经根据低分子量胺的滴定数据进行了独立校准，能够以良好的精度定量预测滴定曲线。
Comblike poly(ethyleneimine) (PEI) with -(CH2CH2)N(CH2CH2NH2)- as the repeating unit has been synthesized by employing a protecting group strategy, and analyzed by potentiometric titration. If the degree of protonation is plotted as a function of pH, the titration curve shows three protonation steps separated by two intermediate plateaus, namely one at a degree of protonation of 1/2 and a second one at 3/4. The first protonation step occurring at pH around 9.5 corresponds to the protonation of the primary amine groups on the side chains. During the second protonation step at pH around 4.5 every second tertiary amine protonates. The final protonation step, where the remaining tertiary amines protonate, is suspected to occur in a pH range near 0. The latter point and the detailed protonation mechanism are deduced on the basis of a site-binding model. The model, which has been independently calibrated on titration data of low molecular weight amines, is capable to predict the titration curve quantitatively to a good degree of accuracy.