서강대학교

초록

The thesis presents a combined experimental and theoretical investigation of the dynamics of water imbibition through soft porous materials. Water-absorbing porous materials such as papers and porous hydrogels are widely used in engineering applications. Microfluidic paper-based analytical devices (μPADs) have been emerged as a novel platform for various point-of-care diagnostics. Porous hydrogel materials are widely used for agricultural substrates, hygienic products, drug delivery systems, and microfluidic devices. The Washburn equation has been widely used to describe the dynamics of water imbibition in various soft porous materials, but its prediction of water imbibition speed has been reported to be inaccurate since the solid matrix of soft porous materials absorbs water with swelling, crucially affecting the imbibition dynamics. In this study, based on the experimental observations on water absorption and swelling of paper and hydrogel, we suggest mathematical models for water imbibition through paper channels and porous structures made of hydrogel considering the effects of both absorption and swelling. Our model is in good agreement with the measurements of the water flow rate through paper channels and hydrogel-coated capillary tubes. By introducing parameters that characterize the absorption and swelling of the materials, our model elucidates how the absorption and swelling regulate the capillary flow through the interconnected pores. The results provide not only a theoretical background for understanding the dynamics of capillary flow through soft porous materials, but also new insights into the engineering applications of these materials.