In Situ Polymerization of Acrylic Monomer with Low Molecular Weight Fluorinated Polymers for the Conservation of Stone

Acrylic resins are well known for their properties of surface aggregation and protection of natural and artificial degraded stones. Promising results in term of water repellency and water vapour permeability have been obtained by in situ polymerizing a series of products based on acrylic monomers. It is well known that the introduction of fluorine atoms into polymer structures has the effect of improving their chemical, thermal, photochemical stability and induces higher hydrophobicity. This characteristic had been exploited by the introduction in the polymerizing mixture of a low percentage (2-5 %) of a commercial high molecular weight fluoropolymer (Tecnoflon TN of Solvay-Solexis). This paper reports the evaluation of the effectiveness of in situ polymerization of 1,6-hexanediolediacrylate carried out in presence of higher amounts of fluorinated polymers with lower molecular weight (Tecnoflon N 215 and N 535), chosen in order to increase the penetration depth. The efficiency of the products in situ synthesized at various fluorine content has been comparatively evaluated in terms of hydrophobicity and water vapor permeability on a selected stone substrate.