CoPVDF membranes for protection of cultural heritages

Abstract

The study focuses on the possibility of using polymeric membranes to protect cultural heritages from biological degradation and from corrosive action exhibited by atmospheric agents. These membrane systems may be utilized as intelligent coatings on the porous lithoid material surfaces, which constitute a great part of the heritage and in recent years have suffered from an increase in attack phenomena. In particular vinylidene fluoride copolymer has been used in this study. The hydrophobic character of CoPVDF membranes has been used to avoid direct liquid water contact with Serena stone surfaces. The Pietra Serena is a porous sandstone which has been frequently used to construct balconies, stairs and decorations of Italian monuments. The possibility of modifying the gas and liquid permeability by introducing a mixture of liquid crystals in the CoPVDF polymeric matrix has been also analyzed. In particular, a mixture of liquid crystals has been introduced in the nematic phase in a polymeric matrix. Because of their fluidity and nematic intrinsic anisotropy, those materials are applicable in the electro-optical field, but their gas transport behaviour is also interesting. They can control and facilitate the gas passage through a polymeric film. We have characterized the selectivity of modified CoPVDF membranes for several gases (O 2, N 2, CO 2).