Innovative hydrogels based on semi-interpenetrating p(HEMA)/PVP networks for the cleaning of water-sensitive cultural heritage artifacts.

Water-based detergent systems offer several advantages, over organic solvents, for the cleaning of cultural heritage artifacts in terms of selectivity and gentle removal of grime materials or aged varnish, which are known to alter the readability of the painting. Unfortunately, easel paintings present specific characteristics that make the usage of water-based systems invasive. The interaction of water with wood or canvas support favors mechanical stresses between the substrate and the paint layers leading to the detachment of the pictorial layer. In order to avoid painting loss and to ensure a fine control (layer by layer) of grime removal, water-based cleaning systems have been confined into innovative chemical hydrogels, specifically designed for cleaning water-sensitive cultural heritage artifacts. The synthesized hydrogels are based on semi-interpenetrating chemical poly(2-hydroxyethyl methacrylate)/poly(vinylpyrrolidone) networks with suitable hydrophilicity, water retention properties, and required mechanical strength to avoid residues after the cleaning treatment. Three different compositions were selected. Water retention and release properties have been studied by quantifying the amount of free and bound water (from differential scanning calorimetry); mesoporosity was obtained from scanning electron microscopy; microstructure from small angle X-ray scattering. To demonstrate both the efficiency and versatility of the selected hydrogels in confining and modulating the properties of cleaning systems, a representative case study is presented.

[1]  Piero Baglioni,et al.  Removal of acrylic coatings from works of art by means of nanofluids: understanding the mechanism at the nanoscale. , 2010, Nanoscale.

[2]  T. C. Huang,et al.  JCPDS—International Centre for Diffraction Data round robin study of silver behenate. A possible low-angle X-ray diffraction calibration standard , 1995, Powder Diffraction.

[3]  Piero Baglioni,et al.  Acrylamide-based magnetic nanosponges: a new smart nanocomposite material. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[4]  R. Wolbers.  The use of a synthetic soiling mixture as a means for evaluating the efficacy of aqueous cleaning materials on painted surfaces , 1992 .

[5]  M. Shibayama,et al.  Inhomogeneity control in polymer gels , 2005 .

[6]  N. Peppas,et al.  Correlation between mesh size and equilibrium degree of swelling of polymeric networks. , 1989, Journal of biomedical materials research.

[7]  Piero Baglioni,et al.  Nanostructured surfactant-based systems for the removal of polymers from wall paintings: a small-angle neutron scattering study. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[8]  A. Mikos,et al.  Preparation of macroporous poly(2-hydroxyethyl methacrylate) hydrogels by enhanced phase separation. , 2000, Biomaterials.

[9]  Richard Wolbers,et al.  Cleaning Painted Surfaces: Aqueous Methods , 2007 .

[10]  Yitzhak Rabin,et al.  Statistical physics of polymer gels , 1996 .

[11]  Fu-qian Sun,et al.  Preparation and antidehydration of interpenetrating polymer network hydrogels based on 2‐hydroxyethyl methacrylate and N‐vinyl‐2‐pyrrolidone , 2010 .

[12]  K. Sutherland,et al.  The cleaning of paintings: effects of organic solvents on oil paint films , 2001 .

[13]  Michael Hess,et al.  DEFINITIONS OF TERMS RELATING TO THE STRUCTURE AND PROCESSING OF SOLS, GELS, NETWORKS, AND INORGANIC-ORGANIC HYBRID MATERIALS , 2009 .

[14]  T. Hatakeyama,et al.  Relationship between hydrogen bonding and bound water in polyhydroxystyrene derivatives , 1983 .

[15]  Gary Bryant,et al.  What is 'unfreezable water', how unfreezable is it, and how much is there? , 2002, Cryo letters.

[16]  Piero Baglioni,et al.  Smart cleaning of cultural heritage: a new challenge for soft nanoscience. , 2012, Nanoscale.

[17]  Piero Baglioni,et al.  Physicochemical characterization of acrylamide/bisacrylamide hydrogels and their application for the conservation of easel paintings. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[18]  R. C. Weast.  CRC Handbook of Chemistry and Physics , 1973 .

[19]  Jianliang Xiao,et al.  Hydrogel–hydrogel composites: The interfacial structure and interaction between water and polymer chains , 2008 .

[20]  A. Concheiro,et al.  Macromolecule release and smoothness of semi-interpenetrating PVP-pHEMA networks for comfortable soft contact lenses. , 2008, European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V.

[21]  O. Okaya,et al.  Macroporous copolymer networks , 2000 .

[22]  Piero Baglioni,et al.  Oil-in-water nanocontainers as low environmental impact cleaning tools for works of art: two case studies. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[23]  Piero Baglioni,et al.  New methodologies for the conservation of cultural heritage: micellar solutions, microemulsions, and hydroxide nanoparticles. , 2010, Accounts of chemical research.

[24]  X. Lou,et al.  Drug release characteristics of phase separation pHEMA sponge materials. , 2004, Biomaterials.

[25]  Piero Baglioni,et al.  Nanomagnetic sponges for the cleaning of works of art. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[26]  Matija Strlič,et al.  IR pulsed laser light interaction with soiled cellulose and paper , 2002 .

[27]  Piero Baglioni,et al.  Poly(vinyl alcohol)-borate hydro/cosolvent gels: viscoelastic properties, solubilizing power, and application to art conservation. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[28]  Piero Baglioni,et al.  Solubilization of Acrylic and Vinyl Polymers in Nanocontainer Solutions. Application of Microemulsions and Micelles to Cultural Heritage Conservation , 2003 .

[29]  N. Stolow.  APPLICATION OF SCIENCE TO CLEANING METHODS: SOLVENT ACTION STUDIES ON PIGMENTED AND UNPIGMENTED LINSEED OIL FILMS , 1961 .

[30]  A. M. Bueche,et al.  Scattering by an Inhomogeneous Solid , 1949 .

[31]  D. Faroongsarng,et al.  Thermal behavior of water in the selected starch- and cellulose-based polymeric hydrogels. , 2008, International journal of pharmaceutics.

[32]  Piero Baglioni,et al.  New frontiers in materials science for art conservation: responsive gels and beyond. , 2010, Accounts of chemical research.

[33]  F. Haaf,et al.  Polymers of N-Vinylpyrrolidone: Synthesis, Characterization and Uses , 1985 .

[34]  Aviva Burnstock,et al.  A study of the clearance of solvent gels used for varnish removal from paintings , 1996 .

[35]  L. Benguigui,et al.  Homogeneous and inhomogenous polyacrylamide gels as observed by small angle neutron scattering: A connection with elastic properties , 1999 .

[36]  Michael R. Landry,et al.  Thermoporometry by differential scanning calorimetry: experimental considerations and applications , 2005 .

[37]  Gunther Wyszecki,et al.  Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd Edition , 2000 .

[38]  S. Kuo,et al.  Properties of PVA-AA cross-linked HEMA-based hydrogels , 1999 .

[39]  A. Khademhosseini,et al.  Hydrogels in Biology and Medicine: From Molecular Principles to Bionanotechnology , 2006 .

[40]  Piero Baglioni,et al.  Nanoscience for art conservation: oil-in-water microemulsions embedded in a polymeric network for the cleaning of works of art. , 2009, Angewandte Chemie.