Synthesis of functionalized polyolefins with novel applications as protective coatings for stone Cultural Heritage

Ethylene copolymers were synthetized for application as protective coatings for stone surface monu-ments. An increased compatibility of the apolar polyethylene with inorganic materials was obtained byintroducing some oxydril and ester groups in the polymers. Two different copolymerizations of eth-ylene were followed: with 10-undecen-1-ol (UDO) and 7-methyl-1,6-octadiene (MOD) catalyzed byZiegler–Natta metallocene/methylaluminoxane (MAO) catalyst. In the first case the polar comonomerUDO was reacted with MAO prior to copolymerization to improve its compatibility with the catalyst.Residual double bonds in the copolymerization with MOD were hydroesterificated/hydrogenated. Somesynthesis were performed in the presence of hydrogen as chain transfer agent to reduce molecularweights and increase solubility of the products. The polyolefins were characterized by analytical and spec-troscopic techniques and their photochemical stability in environmental conditions was tested throughan accelerated ageing chamber. Polyolefins were applied on stone specimens showing a slight chromaticchange of the surfaces, not perceptible by naked eye. The protection performances were also evaluatedin terms of water repellency, photo-oxidative stability and colour change of the treated stone surfaces incomparison with Paraloid B-72, an acrylic resin widely applied in the field of conservation. Ethylene/10-undecen-1-ol copolymer kept its protective efficiency after the ageing cycles thanks to its good stabilityto photo-oxidative degradation.