Rotational Dynamics of Spin-Labeled Polyacid Chain Segments in Polyelectrolyte Complexes Studied by CW EPR Spectroscopy
Rotational Dynamics of Spin-Labeled Polyacid Chain Segments in Polyelectrolyte Complexes Studied by CW EPR Spectroscopy
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DOI：
10.1021/acs.macromol.5b00474
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发表时间：
2015-05
期刊：
影响因子：
5.5
通讯作者：
U. Lappan;Brigitte Wiesner;U. Scheler
中科院分区：
文献类型：
--
作者：
U. Lappan;Brigitte Wiesner;U. Scheler
将氮氧自旋标记物共价连接到弱多酸聚(乙烯-丙基-马来酸)(P(E-ALT-MA))上，研究了强阳离子聚(二烯丙基二甲基氯化铵)(PDADMAC)形成的聚电解质络合物(PEC)中多酸主链的旋转迁移率随分散体的pH值和温度的变化规律。用限制转动扩散的微观有序/宏观无序(MOMD)模型模拟了连续波(CW)电子顺磁共振(EPR)谱的线形，确定了多酸链段的转动迁移率。研究表明，在pH为4的低离解度时，表征多酸主链旋转运动的扩散系数明显小于在pH为7和pH为10时的高度离解时的扩散系数。
A nitroxide spin label has been covalently linked to the weak polyacid poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the rotational mobility of the polyacid backbone in polyelectrolyte complexes (PEC) formed with the oppositely charged strong polycation poly(diallyldimethylammonium chloride) (PDADMAC) in dependence on the pH of the dispersion and the temperature. The rotational mobility of the polyacid chain segments has been determined by simulation of the line shape of the continuous wave (CW) electron paramagnetic resonance (EPR) spectra using the microscopic order/macroscopic disorder (MOMD) model of restricted rotational diffusion. The study has shown that the diffusion coefficient characterizing the rotational motions of the polyacid backbone is significantly smaller at low degree of dissociation at pH 4 than at high degree of dissociation at pH 7 and pH 10.