Tootoonchian Pedram, Bahçeci Levent, Budnyk Andriy, Okur Halil I, Baytekin Bilge
Chemistry Department, Bilkent University, Ankara 06800, Turkey.
UNAM - National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey.
Langmuir. 2025 Jan 14;41(1):162-171. doi: 10.1021/acs.langmuir.4c03291. Epub 2025 Jan 1.
The specific ion effect (SIE), the control of polymer solubility in aqueous solutions by the added ions, has been a phenomenon known for more than a century. The seemingly simple nature of the ion-polymer-water interactions can lead to complex behaviors, which have also been exploited in many applications in biochemistry, electrochemistry, and energy harvesting. Here, we show an emerging diversification of actuation behaviors in "salty" hydrogel and hydrogel-paper actuators. SIE controls not only the dehydration speeds but also the water diffusion and mechanical properties of the gels, leading to composite actuation behavior. Most reported thermally activated hydrogel actuators suffer from expensive precursors or complex fabrication processes. This work addresses these issues by using a physicochemical effect displayed within an inexpensive gel with common salts. SIE-controlled anisotropic actuation in geometrically different systems provides a demonstration of how such physicochemical effects can lead to higher complexity in basic soft material design and hydrogel soft robotics.
特定离子效应（SIE），即通过添加离子来控制聚合物在水溶液中的溶解度，这一现象已为人所知超过一个世纪。离子 - 聚合物 - 水相互作用看似简单的本质却能导致复杂的行为，这些行为也已在生物化学、电化学和能量收集等诸多应用中得到利用。在此，我们展示了“含盐”水凝胶和水凝胶 - 纸致动器中新兴的致动行为多样化。特定离子效应不仅控制脱水速度，还控制凝胶的水扩散和机械性能，从而导致复合致动行为。大多数报道的热激活水凝胶致动器存在前驱体昂贵或制造工艺复杂的问题。这项工作通过利用一种含有普通盐的廉价凝胶中所呈现的物理化学效应来解决这些问题。在几何形状不同的系统中，特定离子效应控制的各向异性致动展示了这种物理化学效应如何能在基本软材料设计和水凝胶软机器人技术中导致更高的复杂性。
