发表机构
ETH Zürich（苏黎世联邦理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用水凝胶颗粒在冰中因低温抽吸而移动的现象，以皮升级体积高分辨率测量其渗透率、压缩性和多孔弹性扩散系数，并发现经典预测模型不适用于真实水凝胶。
AI 中文摘要
引人注目的是，当水凝胶颗粒嵌入处于温度梯度中的冰内时，它们会穿过固体冰向温度较高的方向移动，同时随着升温而膨胀。这种运动源于未冻结水流经水凝胶网络，由一种称为“低温抽吸”的过程驱动。在此，我们展示了如何利用这一行为，以极高分辨率测量一系列不同的水凝胶输运性质，以及这些性质如何随水凝胶的消胀而变化。这些性质包括渗透率、压缩性和多孔弹性扩散系数：所有这些性质都难以测量，但对于涉及溶胀、脱水、蒸腾和过滤等现象却具有广泛的重要性。我们使用聚（乙二醇）二丙烯酸酯（PEGDA）水凝胶演示了该测量技术。该技术使用皮升级体积的水凝胶，所测得的水凝胶性质与现有文献数据一致。我们测量的高分辨率还使我们能够检验针对水凝胶性质的常用经典预测（这些预测假设水凝胶中存在理想化的均匀聚合物网络）。我们表明，这些经典预测效果不佳，凸显了开发能够准确描述真实水凝胶的新模型的必要性。
英文摘要
Strikingly, when hydrogel particles are embedded in ice in a temperature gradient, they move through the solid ice towards warmer temperatures, while swelling as they warm up. This motion comes from a flow of unfrozen water through the hydrogel mesh, driven by a process known as `cryosuction'. Here, we show how one can use this behavior to measure -- with extremely high resolution -- a range of different hydrogel transport properties, and how these change as a hydrogel deswells. These properties include permeability, compressibility, and poroelastic diffusivity: all of which are challenging to measure, but widely important for phenomena involving swelling, dehydration, transpiration and filtration. We demonstrate the measurement technique using poly(ethylene glycol) diacrylate (PEGDA) hydrogels. The technique uses picoliter-scale hydrogel volumes, and yields measurements of hydrogel properties that are consistent with existing literature data. The high resolution of our measurements also allows us to test commonly-used, classical predictions for hydrogel properties (derived assuming an idealized, homogeneous polymer network in the hydrogel). We show that these classical predictions do not work well, highlighting the need for new models that can accurately describe real hydrogels.
