Comparison of the multiphasic model and the transport model for the swelling and deformation of polyelectrolyte hydrogels.
Comparison of the multiphasic model and the transport model for the swelling and deformation of polyelectrolyte hydrogels.
复制标题
DOI：
10.1016/j.jmbbm.2011.05.001
复制
发表时间：
2011-10
影响因子：
3.9
通讯作者：
Ligang Feng;Yuxi Jia;Xue Li-;L. An
中科院分区：
文献类型：
--
作者：
Ligang Feng;Yuxi Jia;Xue Li-;L. An
聚电解质水凝胶是水、聚合物网络和移动的离子的三元混合物。本文考察了两种常用的描述水凝胶溶胀和变形行为的模型，即多相模型和输运模型。多相流模型将水流、管网变形和离子扩散耦合起来，以流体压力梯度作为管网变形的驱动力。然而，在离子渗透压起流体压力作用的输运模型中忽略了水流。用这两个模型模拟了水凝胶球对外部盐溶液浓度变化的自由溶胀和水凝胶条在外电场作用下的弯曲变形两个简化实验。模拟结果表明，这两个模型导致相同的预测水凝胶球的溶胀平衡，但不同的预测水凝胶球的溶胀动力学和水凝胶条在外部电场下的变形。这是因为这两个模型在热力学平衡情况下是等价的，但在热力学非平衡情况下，传输模型不再适用，因为它忽略了水在水凝胶中的流动，并将离子渗透压作为力学参数来发挥溶胀压力的作用。本文的工作将有助于理解水凝胶的流体力学性质和两种模型的应用。
Polyelectrolyte hydrogel is a ternary mixture of water, polymer network and mobile ions. The present paper examined two popular models describing the swelling and deformation behaviors of polyelectrolyte hydrogels, i.e. the multiphasic model and the transport model. The water flow, the network deformation and the ionic diffusion are coupled in the multiphasic model, and the gradient of the fluid pressure is taken as the driving force for the network deformation. However, the water flow is neglected in the transport model with the ionic osmotic pressure taking the role of fluid pressure. Two simplified experiments, i.e. the free swelling of a hydrogel sphere in response to the concentration change of the external salt solution and the bending deformation of a hydrogel strip under an external electric field, are simulated by the two models. Simulation shows that the two models lead to the same predictions for the swelling equilibrium of the hydrogel sphere but different predictions for the swelling kinetics of the hydrogel sphere and the deformation of the hydrogel strip under the external electric field. These are due to the fact that the two models are equivalent in thermodynamic equilibrium situations, but in thermodynamic non-equilibrium situations, the transport model is no longer applicable as it neglects the water flow in the hydrogel and takes the ionic osmotic pressure as a mechanical parameter to play the role of swelling pressure. The present work will be helpful for understanding the hydrodynamics of polyelectrolyte hydrogels and the application of the two models.