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Highly Stretchable and Tough Hydrogels below Water Freezing Temperature
Author(s) -
Morelle Xavier P.,
Illeperuma Widusha R.,
Tian Kevin,
Bai Ruobing,
Suo Zhigang,
Vlassak Joost J.
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201801541
Subject(s) - materials science , self healing hydrogels , nanotechnology , composite material , chemical engineering , polymer science , polymer chemistry , engineering
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.