Surfactant-Synthesized PDMS/Silica Nanomaterials Improve Robustness and Stain Resistance of Carbonate Stone

We have developed a simple sol–gel treatment procedure that enhances the properties of pure limestones to make them more suitable for commercial use; in particular, we have improved the mechanical robustness of the stone. When treated, the stone also has enhanced hydrophobic, water-repellent, and stain-resistant properties, which have been evaluated. We have demonstrated that the addition of poly(dimethylsiloxane) (PDMS) to a silica oligomer associated with a neutral catalyst, in the presence of a surfactant, accelerates the gelling process; this reduction of the time needed for the product to gel in carbonate stones helps to achieve effective stone consolidation. The addition of PDMS to the starting sol has been shown to produce a combined effect: it reduces surface energy and creates a dual scale of roughness that is responsible for the improvement of its water-repellent properties. Increasing the PDMS content thus improves the mechanical properties, hydrophobic behavior, and stain-repellent quality of the limestone.