Highly Stretchable and Tough Hydrogels below Water Freezing Temperature. Issue 35 (10th July 2018)

• Record Type: Journal Article
• Authors: Morelle, Xavier P.; Illeperuma, Widusha R.; Tian, Kevin; Bai, Ruobing; Suo, Zhigang; Vlassak, Joost J.
• Is Part Of: Advanced materials. Volume 30:Issue 35(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-07-10
• Subjects: freezing point depression -- ice‐salt solution slurry phase -- nonfreezing ionic devices -- subzero temperatures -- tough hydrogels; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201801541
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Hydrogels consist of hydrophilic polymer networks dispersed in water. Many applications of hydrogels rely on their unique combination of solid‐like mechanical behavior and water‐like transport properties. If the temperature is lowered below 0 °C, however, hydrogels freeze and become rigid, brittle, and non‐conductive. Here, a general class of hydrogels that do not freeze at temperatures far below 0 °C, while retaining high stretchability and fracture toughness, is demonstrated. These hydrogels are synthesized by adding a suitable amount of an ionic compound to the hydrogel. The present study focuses on tough polyacrylamide‐alginate double network hydrogels equilibrated with aqueous solutions of calcium chloride. The resulting hydrogels can be cooled to temperatures as low as −57 °C without freezing. In this temperature range, the hydrogels can still be stretched more than four times their initial length and have a fracture toughness of 5000 J m −2 . It is anticipated that this new class of hydrogels will prove useful in developing new applications operating under a broad range of environmental and atmospheric conditions. Abstract : The present study demonstrates a general class of hydrogels that do not freeze at temperatures far below 0 °C, while retaining high stretchability and fracture toughness. The resulting hydrogels can be cooled to −57 °C without fully freezing, and can still be stretched more than four times their initial length, with a fracture toughness of 5000 J m −2 .