Network Materials with Soft Matrix with Extreme Properties

Most biological materials and many engineering materials, including those used in sports equipment, are network materials with matrix. Their mechanical function is conditioned by the presence of a stochastic network of crosslinked fibers. The embedding matrix is typically a hard thermoset (e.g. epoxy) or a soft hydrogel. The interplay of the two constituents is pronounced when the stiffness of the network tested independently is equal to the stiffness of the matrix. We explore the design principles of this type of composite to determine the parametric space in which special properties can be obtained. Matrices with extreme properties, i.e. incompressible and auxetic, lead to the most pronounced effects. Of special interest is the response to indentation/impact, case in which the interplay of the network and matrix is enhanced. The results are relevant for the design of hybrid materials with exceptional properties and with applications in multiple areas, including in sports equipment design.