Molecular Forces Governing Shear and Tensile Failure in Clay-Dye Hybrid Materials

Hybrid materials based on photoactive molecules confined into nanostructured substrates are very promising for technological applications. However, little is known about the impact of organic dyes on the mechanical properties of the substrate, a key aspect for their practical implementation. In this work, we use atomistic simulation methods to investigate the mechanical properties of two hybrid systems consisting on a clay matrix (laponite) loaded with two different cationic dyes (LDS-722 and pyronin Y). We applied tensile and shear deformations to the layered hybrid materials and characterize the key mechanism triggering their failure. It has been observed that the water and dye molecules located in the interlaminar spaces are those involved in the deformation processes, while the structure of the laponite layers does not change. Furthermore, it has been also found that the incorporation of dye molecules modifies the hydrogen-bonding network of water in the interlaminar space, worsening the mechanical properties of the hybrids with respect to the clay. The information obtained by molecular simulation help us to assess the mechanical behavior of these materials, and to design materials with tailored strength.