Water diffusion in polymer composites is not only affected by the chemical nature of the materials but also by their internal structures. To enable the design of polymer composites with controlled diffusion kinetics, we investigate the effect of hydrogel particle networks on the water transport. The composites in this study comprise hydrogel particles based on sodium poly(acrylic acid), which are incorporated at different concentrations into a soft and sticky polymer matrix. Through the use of X-ray micro computed tomography, the internal structure of the polymer composites is examined and the interparticle distances are calculated. The structure of the composites is then related to the water diffusion kinetics upon exposure to saline solution as well as humid air. Even though the hydrogel particles are isolated and the interparticle distances are in the order of several micrometers, a sudden increase in the water diffusion kinetics is observed above a critical concentration. Due to the low water permeability of the matrix, such a change in the water diffusion kinetics is indicative of network formation. During hydration, swelling enables the hydrogels to overcome the interparticle distances and form a network for water transport.

中文翻译：

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聚合物复合材料中的水通过溶胀诱导的水凝胶颗粒网络传输。

聚合物复合材料中的水扩散不仅受材料的化学性质影响，还受其内部结构影响。为了能够设计具有受控扩散动力学的聚合物复合材料，我们研究了水凝胶颗粒网络对水传输的影响。本研究中的复合材料包含基于聚丙烯酸钠的水凝胶颗粒，将其以不同的浓度掺入柔软且粘稠的聚合物基质中。通过使用X射线计算机断层扫描，检查了聚合物复合材料的内部结构并计算了颗粒间的距离。然后，复合材料的结构与暴露于盐溶液和潮湿空气中时的水扩散动力学有关。即使分离了水凝胶颗粒并且颗粒间的距离在几微米的数量级，但观察到超过临界浓度的水扩散动力学突然增加。由于基质的低水渗透性，水扩散动力学的这种变化指示网络的形成。在水合过程中，溶胀使水凝胶能够克服颗粒间的距离并形成水传输网络。