• Pinter, Gerald
• Klein, Andrea
• Philip, G. Whitten
• Resch, Katharina

Abstract

In this study, fracture toughness of nanocomposite<br/>hydrogels is quantified, and active mechanisms for dissipation<br/>of energy of nanocomposite hydrogels are ascertained.<br/>Poly(N,N-dimethylacrylamide) nanocomposite hydrogels are<br/>prepared by in situ free radical polymerization with the incorporation<br/>of Laponite, a hectorite synthetic clay. Transmission<br/>electron microscopy proves exfoliation of clay platelets that<br/>serve as multifunctional crosslinkers in the created physical<br/>network. Extraordinary high fracture energies of up to 6800<br/>J m22 are determined by the pure shear test approach, which<br/>shows that these soft and stretchable hydrogels are insensitive<br/>to notches. In contrast to single- and double-network hydrogels,<br/>dynamic mechanic analysis and stress relaxation experiments<br/>clarify that significant viscoelastic dissipation occurs<br/>during deformation of nanocomposite hydrogels. Similar to<br/>double-network hydrogels, crack tip blunting and plastic deformation<br/>also contribute to the observed massive fracture energies.

Topics

• nanocomposite
• impedance spectroscopy
• polymer
• experiment
• crack
• shear test
• electron microscopy
• fracture toughness