Method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics by using supramolecular polymer

Abstract

The invention discloses a method for dehydrating, shaping and reinforcing a water-saturated wooden cultural relic by using a supramolecular polymer, and belongs to the technical field of a water-saturated wooden cultural relic protection method. The method comprises the following steps: dissolving phenylboronic acid-terminated polydimethylsiloxane in absolute ethyl alcohol to obtain a transparent reinforcing solution, soaking a to-be-treated saturated wood cultural relic in absolute ethyl alcohol for 1-4 weeks, taking out the saturated wood cultural relic, soaking the saturated wood cultural relic in the reinforcing solution for 1-12 weeks, taking out the saturated wood cultural relic, and drying the saturated wood cultural relic in an environment with the temperature of 15-30 DEG C and the relative humidity of 45%-75% for 1-4 weeks to obtain the saturated wood cultural relic. Therefore, dewatering, shaping and reinforcing of the waterlogged wooden cultural relics are achieved. According to the invention, the dimensional stability and environmental stability of the water-saturated wooden cultural relics are obviously improved, and the supramolecular polymer can be completely removed from the cultural relics as required due to the reversible crosslinking characteristic of the supramolecular polymer, so that the technical problem that the stability and reversibility of the traditional reinforcing material are difficult to consider at the same time is effectively solved; therefore, the preservation life of the waterlogged wooden cultural relics is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of water-saturated wooden cultural relics protection methods, and specifically relates to a method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics by using supramolecular polymers. Background Art

[0002] Water-saturated wooden cultural relics are extremely fragile due to long-term degradation. The dimensional stability of such cultural relics is significantly reduced. If they are dried directly without treatment, they will cause serious shrinkage, cracking and other irreversible damage to the wood. Therefore, it is crucial to carry out timely and appropriate protection treatment for water-saturated wooden cultural relics. Traditional protection methods mainly use materials such as polyethylene glycol, various sugars and melamine resin to reinforce water-saturated wooden cultural relics. Although these methods have achieved certain results in protecting important wooden cultural relics, they still face many limitations. For example, polyethylene glycol has the problem of insufficient environmental and chemical stability, prone to moisture absorption and acidification, and has a long treatment cycle and high time cost. The environmental and chemical stability of sucrose is also not ideal. It is not only susceptible to microbial invasion, but also has strong hygroscopicity and is prone to hydrolysis. Although melamine resin has excellent reinforcement strength and chemical stability, it forms a stable covalent bond network structure in wood, which makes the treatment process irreversible and does not conform to the principles of cultural relic protection. In summary, it is difficult for the traditional materials currently used to have excellent permeability, stability and reversibility. Given the inadequacy of traditional reinforcement materials for water-saturated wooden cultural relics, it is particularly important to develop new protective materials and technologies. Summary of the invention

[0003] In order to solve the shortcomings of the above-mentioned traditional methods and technologies, the present invention provides a method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers. The supramolecular polymer can achieve high dimensional stability and environmental stability after reinforcing water-saturated wooden cultural relics, and is also reversible, so that the protective material can be removed as needed later.

[0004] The present invention applies supramolecular polymers to the protection of water-saturated wooden cultural relics, and develops a new method for reinforcing water-saturated wooden cultural relics with supramolecular polymers, in order to develop more effective and environmentally friendly reinforcement materials and methods. Specifically, firstly, a polydimethylsiloxane oligomer terminated with 2-formylphenylboronic acid is used to penetrate into the interior of the cultural relic, and then a hexacyclic borane is formed through a dehydration reaction of phenylboronic acid to achieve three-dimensional cross-linking of the polydimethylsiloxane main chain, and a reversible cross-linked supramolecular polymer network with dynamic covalent bonds is constructed in situ. This new type of reinforcement material not only significantly improves the dimensional stability and environmental stability of water-saturated wooden cultural relics, but also, due to its reversible cross-linking characteristics, it can be completely removed from the cultural relics when needed, effectively solving the technical problem that traditional reinforcement materials are difficult to balance stability and reversibility. Through this new high-performance water-saturated wooden cultural relic reinforcement material, the preservation life of water-saturated wooden cultural relics can be extended.

[0005] The method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers described in the present invention comprises the following steps:

[0006] (1) dissolving phenylboronic acid-terminated polydimethylsiloxane in anhydrous ethanol to prepare a colorless and transparent reinforcement solution with a concentration of 0.1 to 0.8 g / mL;

[0007] (2) Soaking the water-saturated wooden cultural relics to be treated in anhydrous ethanol for 1 to 4 weeks and then taking them out to replace the water in the water-saturated wooden cultural relics, the volume ratio of the water-saturated wooden cultural relics to the anhydrous ethanol being 1:5 to 40;

[0008] (3) soaking the wooden cultural relic taken out from step (2) in the reinforcement solution obtained from step (1) for 1 to 12 weeks and then taking it out, wherein the volume ratio of the saturated wooden cultural relic to the reinforcement solution is 1:5 to 40;

[0009] (4) Drying the wooden cultural relics taken out in step (3) in an environment of 15-30° C. and 45%-75% relative humidity for 1-4 weeks, thereby achieving dehydration, shaping and reinforcement of the saturated wooden cultural relics.

[0010] The preparation steps of phenylboronic acid terminated polydimethylsiloxane are as follows:

[0011] (1) dissolving aminopropyl-terminated polydimethylsiloxane and formylphenylboronic acid in anhydrous ethanol, stirring the mixture evenly at room temperature, placing the resulting even solution in an ice-water bath, and adding NaBH4 in small amounts and multiple times under stirring; the mass ratio of aminopropyl-terminated polydimethylsiloxane, formylphenylboronic acid, and NaBH4 is 2-10:2-4:1-2;

[0012] (2) The reaction mixture obtained in step (1) was concentrated under reduced pressure (concentration ratio 30-50:1), and then dissolved in dichloromethane; and then extracted with saturated NaHCO3 aqueous solution, deionized water and saturated NaCl aqueous solution respectively;

[0013] (3) The dichloromethane solution extracted in step (2) is dried over MgSO4 and concentrated under reduced pressure (concentration ratio 30-50:1) to obtain a phenylboronic acid-terminated polydimethylsiloxane supramolecular polymer with a molecular weight of 1000-5500 g / mol.

[0014] The present invention has the following beneficial effects:

[0015] 1. The technical solution of the present invention can improve the dimensional stability of wooden cultural relics, and the shrinkage rate of wooden cultural relics after reinforcement is greatly reduced, thereby preventing obvious cracking and other damage to the wood;

[0016] 2. The technical solution of the present invention can improve the humidity stability of wooden cultural relics, which helps to improve the safety of the preservation of wooden cultural relics;

[0017] 3. After the wooden cultural relics are protected by the technical solution of the present invention, the protective materials in the wooden cultural relics can be removed by solvent cleaning, which complies with the reversibility principle of cultural relic protection;

[0018] 4. The reinforcement process of the technical solution of the present invention is simple and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The photos are of an untreated water-saturated wooden artifact (left) and one directly dried (right). It can be seen that the wooden artifact has undergone severe shrinkage and deformation.

[0020] Figure 2 Schematic diagram of an untreated water-saturated wooden cultural relic (left picture) and a water-saturated wooden cultural relic treated with the reinforcement solution prepared in Example 2 after drying (right picture); it can be seen that the wooden cultural relic treated with the reinforcement solution has almost no shrinkage and deformation;

[0021] Figure 3 Schematic diagram of contact angles of an untreated water-saturated wooden cultural relic (left picture) and a water-saturated wooden cultural relic treated with the reinforcement solution prepared in Example 2 after drying (right picture);

[0022] Figure 4 This is a photo of a water-saturated wooden cultural relic treated with the reinforcement solution prepared in Example 2 and then reversibly treated by ethanol immersion; it can be seen that due to the removal of the protective material, the water-saturated wooden cultural relic undergoes obvious shrinkage and deformation after ethanol evaporation;

[0023] Figure 5 Aminopropyl-terminated polydimethylsiloxane, phenylboronic acid-terminated polydimethylsiloxane and formylphenylboronic acid at 3600-600cm -1 Infrared spectra within the range;

[0024] Figure 6 The results of the water-saturated wood artifacts reinforced with phenylboronic acid-terminated polydimethylsiloxane, the water-saturated wood artifacts after reversible treatment and the untreated water-saturated wood artifacts at 3600-600cm -1 Infrared spectrum in the range. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific examples. The examples are intended to illustrate but not to limit the present invention.

[0026] Example 1

[0027] The preparation method of phenylboronic acid-terminated polydimethylsiloxane comprises the following steps:

[0028] (1) 10 g of aminopropyl-terminated polydimethylsiloxane and 7.5 g of formylphenylboronic acid were dissolved in anhydrous ethanol (50 mL), and then stirred at room temperature. The resulting uniform solution was placed in an ice-water bath, and 2.5 g of NaBH4 was added in small amounts several times under stirring.

[0029] (2) The reaction mixture obtained in step (1) was concentrated under reduced pressure (concentration ratio was 40:1), and then dissolved in dichloromethane; and then extracted with saturated aqueous NaHCO3 solution, deionized water and saturated aqueous NaCl solution respectively;

[0030] (3) The dichloromethane solution extracted in step (2) was dried over MgSO4 and concentrated under reduced pressure (concentration ratio of 40:1) to obtain a phenylboronic acid-terminated polydimethylsiloxane supramolecular polymer (11.16 g) with a molecular weight of about 1268 g / mol. Figure 5 In the infrared spectrum, formylphenylboronic acid can be seen at 3340 cm -1 The BO-H stretching peak at 749 cm-1 disappears in the polydimethylsiloxane terminated with phenylboronic acid. -1 and 698cm -1 The characteristic absorption peak of the hexacyclic borane appeared at , confirming the synthesis of polydimethylsiloxane terminated with phenylboronic acid.

[0031] Example 2

[0032] A method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers, the steps of which are as follows:

[0033] (1) dissolving phenylboronic acid-terminated polydimethylsiloxane in anhydrous ethanol to prepare a colorless and transparent reinforcement solution with a concentration of 0.4 g / mL;

[0034] (2) Soak the water-saturated wood artifacts to be treated in anhydrous ethanol for 1 week and then take them out (7 cm × 2 cm × 0.3 cm. If the volume of the wood is larger, the soaking time needs to be increased to ensure that the solution penetrates into the wood). Replace the water in the water-saturated wood artifacts. The volume ratio of the water-saturated wood artifacts to anhydrous ethanol is 1:20.

[0035] (3) Soaking the wooden cultural relic taken out from step (2) in the reinforcement solution obtained from step (1) for 1 week and then taking it out, wherein the volume ratio of the saturated wooden cultural relic to the reinforcement solution is 1:20;

[0036] (4) Drying the wooden cultural relics taken out from step (3) in an environment of 25° C. and 58% relative humidity for 1 week, thereby achieving dehydration, shaping and reinforcement of the saturated wooden cultural relics.

[0037] The volume of the water-saturated wooden artifacts before and after treatment was measured using a digital display vernier caliper. The measurement results showed that the shrinkage rate of the untreated water-saturated wooden artifacts was 31.1%, and the shrinkage rate of the water-saturated wooden artifacts treated by the method of the present invention was 2.0%. The calculated shrinkage resistance The result is 93.6%, which proves that the shrinkage rate of the water-saturated wooden cultural relics is significantly improved by the method of the present invention. Figure 3 As shown, the water drop contact angle of the untreated saturated wood artifact is 81.7°, while the water drop contact angle of the saturated wood artifact treated by the method of the present invention is 116.9°, proving that the humidity stability of the saturated wood artifact is also increased.

[0038] In addition, if necessary in the future, the treated water-saturated wooden artifacts can be immersed in ethanol solution again, and the reinforcing materials in the water-saturated wooden artifacts can be removed by taking advantage of the reversibility of the nitrogen-coordinated boron oxide hexacyclic in ethanol. Figure 6 The infrared spectrum shows that the water-saturated wood artifacts after reversible treatment have a peak at 1368 cm -1 、1261cm -1 、1213cm -1 、1100cm -1 、749cm -1 and 698cm -1 The characteristic absorption peak of phenylboronic acid-terminated polydimethylsiloxane is no longer seen at 1508 cm -1 and 3425cm -1 The characteristic absorption peaks of wood also appear nearby.

Claims

1. A method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers, the steps of which are as follows: (1) dissolving phenylboronic acid-terminated polydimethylsiloxane in anhydrous ethanol to prepare a colorless and transparent reinforcement solution with a concentration of 0.1 to 0.8 g / mL; (2) Soak the water-saturated wooden cultural relics to be treated in anhydrous ethanol for 1 to 4 weeks and then take them out; (3) soaking the wooden cultural relic taken out in step (2) in the reinforcement solution obtained in step (1) for 1 to 12 weeks and then taking it out; (4) Drying the wooden cultural relics taken out in step (3) in an environment of 15-30° C. and 45%-75% relative humidity for 1-4 weeks, thereby achieving dehydration, shaping and reinforcement of the saturated wooden cultural relics.

2. The method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers as claimed in claim 1, characterized in that: The polydimethylsiloxane terminated with phenylboronic acid in step (1) is prepared by the following steps: (1) dissolving aminopropyl-terminated polydimethylsiloxane and formylphenylboronic acid in anhydrous ethanol, stirring the mixture evenly at room temperature, placing the resulting even solution in an ice-water bath, and adding NaBH4 in small amounts and multiple times under stirring; the mass ratio of aminopropyl-terminated polydimethylsiloxane, formylphenylboronic acid, and NaBH4 is 2-10:2-4:1-2; (2) The reaction mixture obtained in step (1) was concentrated under reduced pressure, and then dissolved in dichloromethane; and then extracted with a saturated aqueous NaHCO3 solution, deionized water, and a saturated aqueous NaCl solution, respectively; (3) drying the dichloromethane solution extracted in step (2) with MgSO4 and concentrating under reduced pressure to obtain a phenylboronic acid-terminated polydimethylsiloxane supramolecular polymer with a molecular weight of 1000 to 5500 g / mol.

3. The method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers as claimed in claim 2, characterized in that: The ratio of reduced pressure concentration in step (2) and step (3) is 30 to 50:

1.

4. The method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers as claimed in claim 1, characterized in that: In step (2), the volume ratio of the saturated wooden cultural relics to anhydrous ethanol is 1:5-40.

5. The method for dehydrating, shaping and reinforcing water-saturated wooden cultural relics using supramolecular polymers as claimed in claim 1, characterized in that: In step (3), the volume ratio of the saturated wooden cultural relic to the reinforcement solution is 1:5-40.

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