Department of Chemical Engineering, Waterloo Institute for Nanotechnology, Institute for Polymer Research, Centre for Bioengineering and Biotechnology, University of Waterloo, Waterloo, Ontario, Canada.
Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Key Laboratory for the Green Preparation and Application of Functional Materials, Ministry of Education, Hubei Key Laboratory of Polymer Materials, School of Materials Science and Engineering, Hubei University, Wuhan, China.
Nat Mater. 2019 Aug;18(8):874-882. doi: 10.1038/s41563-019-0434-0. Epub 2019 Jul 22.
Most types of solid matter have a single stable solid state for a particular set of conditions. Nonetheless, materials with distinct, interchangeable solid states would be advantageous for several technological applications. Here, we describe a material composed of a polymer impregnated with a supercooled salt solution, termed as sal-gel, that assumes two distinct but stable and reversible solid states under the same conditions for a range of temperatures (-90 to 58 °C) and pressure. On transient stimulation of nucleation, the material switches from a clear and soft solid to a white and hard state, which can be 10 times stiffer than the original (15 kPa versus 385 MPa). This hard solid becomes soft again by transient heating, demonstrating the reversibility of the transition. This concept, exploiting the robust physical metastability of a liquid state, is extended to sugar alcohols, resulting in a stimuli-responsive and non-evaporating sug-gel. These 'two-in-one' solid materials may find potential uses in soft robotics and adhesive applications.
大多数类型的固体物质在特定条件下都只有一种稳定的固态。然而，具有不同、可互换的固态的材料将有利于几种技术应用。在这里，我们描述了一种由聚合物浸渍过冷盐溶液组成的材料，称为 sal-gel，它在相同条件下（-90 至 58°C）和压力下呈现出两种不同但稳定且可重复的固态。在瞬时成核刺激下，该材料从透明柔软的固态转变为白色坚硬的固态，其硬度比原始状态高 10 倍（15kPa 对 385MPa）。通过瞬时加热，这种坚硬的固体再次变软，证明了转变的可逆性。这种利用液体物理亚稳性的概念扩展到糖醇，产生了对刺激有响应且不蒸发的 sug-gel。这些“二合一”的固体材料可能在软机器人和粘合剂应用中具有潜在用途。
