A self-consistent mean-field model for polyelectrolyte gels
A self-consistent mean-field model for polyelectrolyte gels
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DOI：
10.1039/c6sm02825j
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发表时间：
2017-05-14
期刊：
影响因子：
3.4
通讯作者：
Kosovan, Peter
中科院分区：
文献类型：
--
作者：
Rud, Oleg;Richter, Tobias;Kosovan, Peter
我们提出了一种新的方法来模拟聚电解质凝胶，利用星形支化聚合物和聚合物网络之间的类比，作为一种计算廉价但可靠的全尺寸模拟替代方案。在星形聚合物的数值平均场模型中，我们修改了边界条件来表示一个无限网络。我们根据粗粒度模拟模型验证新模型的预测。我们还对现象学分析模型进行了验证，该模型先前已被证明在有限的参数范围内与模拟一致。平均场模型明确地考虑了局部密度梯度，并且在广泛的参数范围内与解析模型的模拟结果一致。最后，我们使用平均场模型来预测弱聚电解质凝胶在不同pH条件下的溶胀行为。我们证明了局部密度梯度是重要的，弱聚电解质凝胶的电离被显著抑制。在研究条件下，有效pK(A)比游离单体高1个单位左右。这种有效pK(A)的变化源于凝胶内外不同的pH值。
We present a novel approach to modeling polyelectrolyte gels, exploiting the analogy between star-branched polymers and polymer networks as a computationally inexpensive yet reliable alternative to full-scale simulations. In the numerical mean-field model of a star-like polymer we modify the boundary conditions to represent an infinite network. We validate the predictions of our new model against a coarse-grained simulation model. We also validate it against a phenomenological analytical model which has been previously shown to agree with simulations in a limited range of parameters. The mean-field model explicitly considers local density gradients and agrees with the simulation results in a broad range of parameters, beyond that of the analytical model. Finally, we use the mean-field model for predictions of the swelling behaviour of weak polyelectrolyte gels under different pH conditions. We demonstrate that the local density gradients are important and that the ionization of the weak polyelectrolyte gel is significantly suppressed. Under the studied conditions the effective pK(A) is about one unit higher than that of the free monomer. This shift in the effective pK(A) stems from the different pH values inside and outside the gel.