Hydrogel new uses, as \”the most expensive in the world\” oil cleaning!

Recently \”I repair cultural relics in the Palace\” led to everyone\’s attention for such a popular industry heritage of the hit. From the National Palace Museum to Dunhuang frescoes, paintings from the Renaissance to modern art, both covered with years of dust cream. The first step in the protection of cultural relics, artifacts is to clean up, for those who travel through time in a beautiful brushed the dust. Heritage clean up the need for adequate patient, careful and lightweight craft to be able to avoid possible damage to artifacts caused. The traditional method consumes a large amount of manpower and resources, like conventional solvents and cleaning means to clean the pigment tends to effect destruction of dust or the like when the work surface impurities. Especially for modern high roughness of paintings, the use of traditional means uniform cleaning not only can not completely remove the impurities, and easy to make it swell. The development of modern science and technology, for the protection of cultural relics has injected new strength. Previously, , University of Florence Piero Baglioni component was prepared by wrapping nanoscale hydrogel solvent droplets, such hydrogels can remove the tape from the paper art. However, this hydrogel of modern art such as Vincent van Gogh and Pablo Picasso painting has created a loss of texture. On the basis of previous studies, Piero Baglioni group further by freeze – blending high cycle, low molecular weight polyvinyl alcohol (PVA) prepare a sponge-like porous hydrogel dissolved (FT) (double-stranded polymer network hydrogel -TC-PNs) . Combined high and low molecular weight polymer forms a sponge-like structure, the presence of micron-sized pores in the material are connected to each other. This makes communication pores dirt can be captured through the entire transport gel. The small size of the pores will not ensure a large amount of diffusion of water into the paint, the plasticity and ductility of the material to ensure that it can be molded into any textured surface irregularities. The article to \”Twin-chain polymer hydrogels based onpoly (vinylalcohol) as new advanced tool for the cleaning of modern and contemporary art\” was published in the top journals PNAS on.

Preparation of Principle 1:

during the preparation by freeze cycle, since the High, Low polymer PVA (H-PVA, L-PVA) and a water-generating phases were separated. Since the pressing force of the water generated during the crystallization process, the enriched PVA segments together to form a network connection point. Ice passage hole shape is formed. Due to the expansion of ice during multiple freeze, FT The higher the number of cycles, the larger the pore cross section, the directivity of the growth of the cell walls more obvious. Some pores together, form a sponge-like disordered structure. Since the water-soluble L-PVA stronger than H-PVA, further phase separation does not occur in the freezing phase, thus the freezing process cycle, L-PVA are confined in bladders. Structure is formed as shown in FIG.

水凝胶新用途,为“世界上最昂贵”的油画清灰!
1. The low molecular weight PVA FIG fluorescence (H-PVA / L-PVA) systems confocal microscopy images. H-PVA labeled with green FITC, L-PVA RBITC marked with red.

2. Gel Properties

pHEMA / PVP gel G value of 4-5 × 10 3 Pa, and herein TC -PNs modulus G the gel is 4 to 5 times pHEMA / PVP, and showed good elongation properties and plasticity. Thus, PVA can be adapted to the preparation of the gel rough drawing surface, while the pHEMA / PVP just can not penetrate through the large texture. This feature improves the cleaning efficacy of PVA gel. Compared with pure PVA network, TC-PNs gel having a greater ductility, may adhere better to the painted surfaces, more uniform cleaning effect. Further, since the degree of hydrolysis of L-PVA is less than H-PVA, the PVA-coated in the pores of the surface L of the material can be more effectively adsorbed hydrophobic particles, the particles increase the absorption rate.

水凝胶新用途,为“世界上最昂贵”的油画清灰!
Figure 2. The appearance and rheological measurements PVA gels

3. Efficacy Evaluation

On the TC-PNs condensate rubber and conventional cleaning methods are compared. FIG indicated, when a conventional cleaning material (and solvent cleaning using the same gel), due to repeated friction and mechanical retention is poor, Eventually led to the dissolution and loss of pigment. And when we use TC-PNs gel to clean, it can easily and quickly remove surface dirt without damaging the surface. On further Transform Infrared Spectroscopy (FTIR) Fourier imaging gel further evaluated the cleaning effect. Model spectrum to the original model of the cleaning of the sample (FIG. 3B) consistent, indicating effective stain removal. Further, between the original sample and the samples were cleaned, OH absorbance intensity not significantly different (FIG. 7C), i.e. no significant residual PVA on the surface. while the conventional thickener (e.g., polyacrylic acid, cellulose ether) to leave a residue, the need for further rinsing after cleaning.

水凝胶新用途,为“世界上最昂贵”的油画清灰!
Figure 3. The PVA gel and comparative cleaning efficacy conventional cleaning methods.

In the test duplexes between the polymer gel and a conventional cleaning material, New materials can be removed more dirt art, and better recovery of their original brightness . and tested at the Venice Peggy Guggenheim (Peggy Guggenheim) collection of two paintings.

水凝胶新用途,为“世界上最昂贵”的油画清灰!
Figure 4. Pollock cleaning work.

Thereafter, The hydrogel was used to successfully repair Jackson Pollock (American painter, abstract expressionist painter, has also been recognized as a modern American painting rid of European standards, the first hero to establish leadership in the international art scene, November 3, 2006, Pollock\’s painting \”No. 5, 1948\” the world\’s paintings auction the highest price, up to $ 140 million ( about 109.6 million euros)) of the two masterpieces, , Two and Eyes in the Heat. These two works show the transition from traditional painting to a 3D surface. Pollock draw textured surface by dripping technique. Further, Two paint using only made, but using Eyes in the Heat oil and alkyd paint, which two pigments sensitive to solvents. These combined reasons conventional cleaning tool particularly challenging to remove dirt and risk, the use of such a gel to remove dirt reproduce the original color hue (FIGS. 4 A and D) . According to the team, said ChingSuccessful cleaning work on behalf of cultural heritage protection has taken an important step forward, and is expected for future generations to better protect valuable works of art. The full text link: https: //www.pnas.org/content/early/2020/03/03/1911811117

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