Re-usable cross-linked poly(ethyl methacrylate) gels for cleaning purposes of artworks

Abstract

Re-usable cross-linked poly(ethyl methacrylate) (PEMA) chemical gels featuring sustainable characteristics besides adjustable flexibility and organic solvent affinity were synthesized and investigated. The gels were prepared through the polymerization of ethyl methacrylate (EMA) using polyethylene glycol (PEG) and polyvinyl acetate (PVAc) as plasticizers. The modulation of the content of the plasticizers, the cross-linker and of the initiator accounted for the final properties of the gels. These properties were demonstrated to be unaltered through several solvent-soaking/drying cycles also by using different solvents, making the gels perfectly re-usable. The covalent gels were fully characterized by rheological measurements, thermogravimetric analysis, scanning electron microscopy (SEM), nitrogen physisorption analysis, and FTIR analysis. Solvent loading and retention capabilities were also determined. The green characteristics of the gels were evaluated in terms of environmental factor (E-Factor), mass intensity (MI) and reaction mass efficiency (RME). In addition, greener alternatives to commonly used solvents in conservation treatments were considered. The cleaning potentialities of the newly developed systems were ascertained through the determination of equilibrium solvent content (ESC), solvent release (SR) and solvent evaporation rates. Finally, the PEMA-based cross-linked gels were successfully used for the cleaning of Édouard Manet's masterpiece “Portrait de M. Arnaud à cheval”.