Dissociation Behavior of Poly(maleic acid): Potentiometric Titrations, Viscometry, Pulsed Field Gradient NMR, and Model Calculations
Dissociation Behavior of Poly(maleic acid): Potentiometric Titrations, Viscometry, Pulsed Field Gradient NMR, and Model Calculations
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聚马来酸的解离行为：电位滴定、粘度测定、脉冲场梯度 NMR 和模型计算
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
J. D. Bleijser
中科院分区：
文献类型：
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作者：
J. D. Groot;G. Koper;M. Borkovec;J. D. Bleijser
对聚马来酸在不同离子强度的盐溶液中进行了电位滴定、脉冲场梯度核磁共振和粘度测定。滴定曲线的形状很大程度上取决于所用阳离子的类型，特别是在α=0.5后。在5倍以上的过量盐浓度下，电位滴定曲线可以满意地符合基于随机伊辛模型的方程，该方程使用三个自由参数： 本征离解常数K0和两个过剩自由能Er和Em，它们分别描述了外消旋和介晶键上的最近邻相互作用。PMA的立体化学模型使用一个额外的参数Pr，它是合成过程中外消旋传播的概率。该参数由~(13)C核磁共振仪测定。所得结果与其他聚羧酸S的结果相比较是有利的。除了聚合物线圈在充电后逐渐膨胀外，没有观察到构象变化。
Potentiometric titrations, pulsed field gradient NMR, and viscometry of poly(maleic acid) have been carried out in different salt solutions of varying ionic strength. The shape of the titration curve depends strongly on the type of cation used, especially beyond α = 0.5. Above 5 times excess salt concentration, the potentiometric titration curves can be fit satisfactorily to an equation derived on the basis of a random Ising model, using three free parameters: the intrinsic dissociation constant K0 and two excess free energies er and em describing the nearest-neighbor interaction across a racemic and mesomeric bond, respectively. The stereochemistry of PMA is modeled using an additional parameter Pr, which is the probability of racemic propagation during synthesis. This parameter was determined by 13C NMR. The results compare favorably with those obtained for other poly(carboxylic acid)s. Except for a gradual expansion of the polymer coil upon charging, no conformational changes are observed by PFG-NMR a...