MOE Key Laboratory of Hydrodynamic Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, P. R. China.
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China.
J Phys Chem Lett. 2021 Mar 18;12(10):2587-2592. doi: 10.1021/acs.jpclett.1c00034. Epub 2021 Mar 9.
The water-vapor transition is critical for hydrogels in a collection of applications. However, how the polymer-water interaction along with the nature of the structure affect the macroscopic water-vapor transition remains a challenging question to answer. In this work, we tested the moisture transfer behaviors of a series of hydrogels at different humidities and found some hydrogels capable of lowering their surface vapor pressure to stop dehydration at low humidity and absorbing water from ambient air to recover toward initial states at high humidity. Through molecular dynamic simulations, we demonstrate that water inside these hydrogels undergoes increasing intensive intermolecular bonding during evaporation. The increased intermolecular bonding reduces the vapor pressure of the hydrogels and leads to the self-regulation. More interestingly, we demonstrate the self-regulation is closely related to the Young's modulus of hydrogels. These results provide further insight into the mechanism of the water-vapor transition in hydrogels and show potential in a broad range of future applications.
水蒸汽转变对于一系列应用中的水凝胶至关重要。然而，聚合物-水相互作用以及结构的性质如何影响宏观水蒸汽转变仍然是一个具有挑战性的问题。在这项工作中，我们测试了一系列水凝胶在不同湿度下的水分传递行为，发现一些水凝胶能够降低其表面蒸汽压，以在低湿度下阻止脱水，并从周围空气中吸收水分以恢复到高湿度时的初始状态。通过分子动力学模拟，我们证明了这些水凝胶内部的水在蒸发过程中经历了越来越强烈的分子间键合。增加的分子间键合降低了水凝胶的蒸汽压，导致了自我调节。更有趣的是，我们证明了自我调节与水凝胶的杨氏模量密切相关。这些结果进一步深入了解了水凝胶中水蒸气转变的机制，并在广泛的未来应用中显示出潜力。
