Rhodamine‐based force‐sensitive organic polysiloxane for hardness recognition of inorganic particles

The mechanochromic materials can respond to environmental changes by altering the optical properties of the system, which has garnered significant attention in recently. The utilization of these materials for the purpose of sensing tensile and compressive stress has been extensively documented. However, the mechanochromic polymer that can effectively discriminate hardness of inorganic particles is still rarely reported. In this article, a force‐sensitive organic polysiloxane was developed by introducing triethenyl‐substituted rhodamine derivatives crosslinker into the polymethylhydrosiloxane network through hydrosilylation addition reaction. The results demonstrated that the grinding of the crosslinked polysiloxane effectively facilitated the transmission of external force to the polymeric network, leading to an open ring isomerization of rhodamine accompanied by significant alterations in visible and fluorescent color. In addition, we found that the optical properties of the system showed distinct variations when the inorganic particles with different Moh's hardness were co‐ground with the polysiloxane. High Moh's hardness particles, such as Al2O3, could effectively trigger the mechanochromic behavior of the polymer, while Na2SO4 particles with low hardness failed to induce the corresponding change. Therefore, this organic polysiloxane could be used as a potential fluorescent indicator for hardness recognition.