Characterizing Large Strain Elasticity of Brittle Elastomeric Networks by Embedding Them in a Soft Extensible Matrix

TL;DR

This study investigates how embedding brittle elastomeric networks in a soft matrix enhances large strain elasticity and toughness, revealing that the large strain behavior is governed by the initial network properties and entanglement density.

Contribution

It introduces a new approach to design tough, large strain elastic materials by embedding brittle networks in extensible matrices and elucidates the underlying mechanisms.

Findings

Large strain properties are controlled by the initial network elasticity.

Toughness increases with the prestretched network's nonlinear elasticity.

Entanglement density influences small and intermediate strain properties.

Abstract

Here, the general design and properties of new multiple network elastomers with an exceptional combination of stiffness, toughness, and elasticity are reported. In this paper, it is reported in more detail how the increase in strain at break resulting from the toughening can be used to provide great insight in the large strain properties of otherwise brittle acrylic well crosslinked networks. The networks have been prepared by sequences of polymerization and swelling with monomers. The parameters that have been varied are the nature of the base monomers and the degree of crosslinking of the first network. Here, the small strain properties, equilibrium swelling, and large strain properties in uniaxial tension are characterized. It is shown here that the large strain properties of the multiple networks are quantitatively controlled by the large strain properties of the stretched first network which acts as a percolating filler, while the small and intermediate properties are controlled by the entanglement density which can be largely superior to that of homogeneous networks. Different brittle and prestretched elastomer networks are embedded at a low volume fraction in a soft extensible matrix. The increase in toughness of the final material is directly controlled by the nonlinear elastic properties of the prestretched network and its volume fraction, providing a general design rule for tough soft materials