(722ad) Synthesis, Characterization and Surface Properties of Fluorinated Methacrylic Polymers for the Protection and Conservation of Stone

Perfluoroalkyl methacrylic polymers exhibit low surface energy and stability towards degradation with respect to their unfluorinated analogs. Moreover, the introduction of fluorine atoms into methacrylic polymers' structure results in good adhesion and film- forming properties [1]. The above mentioned merits qualify these polymers as promising for stone protection.

The aim of the work presented here was to examine how the fluorine group content in the polymer's chain affects its surface properties. The homopolymers under study were poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA), poly(1,1,1,3,3,3 hexafluoroisopropyl methacrylate) (PHFIMA), poly( 2,2,3,3,3 pentafluoropropyl methacrylate) (PPFPMA) and poly(2,2,3,3,4,4,4 heptafluorobutyl methacrylate) (PHFBMA).The polymers were synthesized by free radical polymerization, using AIBN as initiator in tetrahydrofuran. Supercritical carbon dioxide was also used as an alternative, “green” polymerization medium for the synthesis of all polymers. Fourier Transform Infrared Spectroscopy (FTIR), Size Exclusion Chromatography (SEC), Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA) were employed in the characterization of all the polymer samples.

Polymers' surface energy was studied with Inverse Gas Chromatography (IGC) in conjunction with the Contact Angle Method. The dispersive component of the surface energy, the activity coefficient and the Flory-Huggins interaction parameters were calculated for a pre-defined range of temperatures using IGC. The hydrophobicity of the polymers was investigated with contact angle measurements, while their surface energy (dispersive and polar components) was determined with the use of the Contact Angle Method.

Acknowledgements

This work was supported by the Greek Ministry of Development – GSRT (25%) and the European Union – European Social Fund (75%) through the research grant PENED 2003 with MIS 03EΔ 91

[1] Francesca Signori, Massimo Lazzari, Valter Castelvetro, and Oscar Chiantore :Copolymers of Isopropenyl Alkyl Ethers with Fluorinated Acrylates and Fluoroacrylates: Influence of Fluorine on Their Thermal, Photochemical and Hydrolytic Stability. Macromolecules 2006, 39, 1749-1758.