X-ray photoelectron spectroscopy analysis of di-(2-ethylhexyl) phosphoric acid activated membranes
X-ray photoelectron spectroscopy analysis of di-(2-ethylhexyl) phosphoric acid activated membranes
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DOI：
10.1006/jcis.2000.6805
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发表时间：
2000-06-01
影响因子：
9.9
通讯作者：
Oleinikova, M
中科院分区：
文献类型：
--
作者：
Ariza, MJ;Rodríguez-Castellón, E;Oleinikova, M
采用x射线光电子能谱（XPS）对含有不同量的二-（2-乙基己基）磷酸作为载体的聚酰胺/聚砜载体组成的活化复合膜进行了表面化学表征，以获得载体与膜顶层之间化学键的性质信息。聚合物载体（聚酰胺）顶层的XPS光谱显示出c1s、n1s、o1s和p2p区。聚酰胺层的N 1s和O 1s信号是不对称的，可以反卷积成两个峰，对应于自由和氢键聚酰胺共存。为了支持这一分配，我们还用XPS研究了苯酰胺和正丁酰胺等一级酰胺，它们可以相互结合形成氢键，而叔酰胺n-苯甲酰啉不能形成氢键。苯甲酰胺和正丁酰胺的N Is不对称信号在两个峰上反卷积，这是由于自由和氢键的共存，而N-苯甲酰啉的N Is信号是对称的，对应于自由酰胺的单独存在。在聚合物基体中加入二-（2-乙基己基）磷酸，N Is信号强度随着载流子浓度的增加而降低，而p2p信号强度随着载流子浓度的增加而增加，达到最大值，对应于表面位置饱和。在加入酸后，聚酰胺被质子化，并且由于氮原子正电荷的增加，观察到N Is信号向更高结合能的化学位移。另一方面，通过XPS测定的N和P的表面浓度表明，浇注溶液中400 mM的载体浓度足以使膜表面饱和。(C) 2000年学术出版社。
Surface chemical characterization of activated composite membranes, which consist of a polyamide/polysulfone support containing different amounts of di-(2-ethylhexyl) phosphoric acid as carrier, was performed by X-ray photoelectron spectroscopy (XPS) in order to obtain information about the nature of the chemical bonding between the carrier and the membrane top layer. XPS spectra of the top layer of the polymeric support (polyamide) show bands in the C 1s, N 1s, O 1s, and P 2p regions. The N 1s and O 1s signals of the polyamide layer were asymmetric and could be deconvoluted in two peaks that correspond to the coexistence of free and hydrogen bonded polyamide. To support this assignment, primary amides such as benzamide and n-butyramide, which can associate themselves forming hydrogen bonding, and a tertiary amide, N-benzoyl morpholine, unable to form hydrogen bonding, were also studied by XPS. The N Is asymmetric signals of benzamide and n-butyramide were deconvoluted in two peaks due to the coexistence of free and hydrogen bonded species, while the N Is signal of N-benzoyl morpholine is symmetric and corresponds to the existence of free amide alone. As a result of the addition of di-(2-ethylhexyl) phosphoric acid to the polymeric matrix, the N Is signal intensities decrease, while the P 2p signal intensities increase with carrier concentration to a maximum corresponding to surface site saturation. Upon acid addition, the polyamide was protonated and an expected chemical shift of the N Is signal to higher binding energies was observed due to the increase of the positive charge of the nitrogen atom. This type of chemical interaction allows to fix the carrier in the membrane without its complete immobilization, On the other hand, the surface concentration of N and P, determined by XPS, indicates that a concentration of 400 mM of the carrier in the casting solution is sufficient to saturate the surface of the membrane. (C) 2000 Academic Press.