Friction between polymer chains and water is considered to govern the water retention and permeation in hydrogels. This concept has been examined by means of water permeation measurements through hydrogels. Previous studies used hydrogels in the equilibrium swollen state and supported the scaling relationship between the friction coefficient (f) and the blob size (ξ) proposed by Tanaka and de Gennes (f ∼ ξ^–2). However, the experiments on equilibrium-swollen hydrogels are not enough, and those on as-prepared hydrogels are needed to fully examine the validity of the scaling relationship. In this study, we established a novel water permeation apparatus, which well prevented the swelling of gels and enabled the water permeation experiments on gels in the as-prepared state. Using this novel apparatus, we measured f of a model polymer network system, i.e., Tetra-PEG gels. By comparing f measured by the water permeation experiment and ξ measured by a small-angle neutron scattering experiment, we confirmed the scaling relationship f ∼ ξ^–2 even in the as-prepared state. This result strongly supports the availability of the current model in the equilibrium swollen state and thus strengthens the validity of the model.

中文翻译：

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水通过具有可控网络结构的水凝胶的渗透

聚合物链与水之间的摩擦被认为可控制水凝胶中的保水性和渗透性。已经通过水凝胶对水的渗透性测量来检验该概念。以前的研究中使用的平衡溶胀状态的水凝胶和支持的摩擦系数（之间的比例关系˚F）和斑点大小（ξ）提出由Tanaka和德热纳（˚F〜ξ ^-2）。然而，对平衡溶胀的水凝胶进行的实验还不够，需要对准备好的水凝胶进行的实验才能充分检验比例关系的有效性。在这项研究中，我们建立了一种新型的水渗透装置，该装置可以很好地防止凝胶溶胀，并可以按准备好的状态对凝胶进行水渗透实验。使用这种新颖的仪器，我们测量了模型聚合物网络系统的f，即Tetra-PEG凝胶。通过比较˚F由透水试验测定，ξ由小角中子散射实验中测量，我们证实了比例关系˚F〜ξ ^-2即使在准备好的状态下 这一结果有力地支持了当前模型在平衡溶胀状态下的可用性，从而增强了模型的有效性。