Transparent and tough poly(2-hydroxyethyl methacrylate) hydrogels prepared in water/IL mixtures

• Published in: New journal of chemistry Vol. 44; no. 10; pp. 4092 - 4098
• Main Authors: Liu, Yu-wei, Wang, Ping, Wang, Jun, Xu, Bo, Xu, Jin, Yuan, Jiu-gang, Yu, Yuan-yuan, Wang, Qiang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.03.2020
• Subjects: Crosslinking; Elongation; Free radical polymerization; Free radicals; Heat treating; Hydrogels; Hydrogen bonds; Materials fatigue; Mechanical properties; Polyhydroxyethyl methacrylate; Tensile strength
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D0NJ00214C

Poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels with high transparency and excellent mechanical properties are fabricated via in situ free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in mixtures of water and 1-butyl-3-methylimidazolium chloride (BmimCl) followed by the exchange of BmimCl with water. Compared with the PHEMA hydrogels prepared without BmimCl, the obtained hydrogels display a denser and more homogeneous microstructure, which contributes to their highly transparent appearance and outstanding mechanical properties. The hydrogels could achieve elongation at break and tensile strength up to 705% and 173 kPa, respectively, at swollen equilibrium states. Furthermore, the hydrogels also reveal fast recovery in water after circle elongation, showing anti-fatigue properties owing to their quick reformation of hydrogen bonds between polymer chains. More importantly, the hydrogels are able to retain considerable mechanical strength in water over a wide pH range (1 to 13) due to their stable cross-linking structures. It is believed that this novel type of transparent PHEMA hydrogel exhibiting outstanding mechanical properties, superior stability and anti-fatigue properties would find extensive applications in biomedical and industrial fields.