Rigid epoxy resin hydrophobic film and preparation method thereof

Abstract

The invention discloses a rigid epoxy resin hydrophobic film and a preparation method thereof, and belongs to the technical field of hydrophobic materials. When the hydrophobic film is prepared, the sodium tryptophan is firstly prepared, then the sodium tryptophan, the curing agent and the epoxy monomer are jointly dissolved in the solvent, the obtained solution is subjected to curing treatment, and the rigid epoxy resin film is obtained; and putting the prepared rigid epoxy resin film into a liquid culture medium containing escherichia coli, culturing at constant temperature, and etching the film by the escherichia coli, thereby obtaining the film. The hydrophobic material is prepared by adopting a bacterial etching method, and compared with a scheme of etching by adopting a chemical reagent in the prior art, the method is more environment-friendly and efficient. The hydrophobic material prepared by the invention has excellent hydrophobic performance, good chemical stability and thermal stability, and can meet the use requirements of special occasions.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrophobic materials, and in particular relates to a rigid epoxy resin hydrophobic film and a preparation method thereof. Background Art

[0002] As an interfacial phenomenon widely existing in nature, wettability is also one of the basic properties of solid surfaces, playing an important role in solving problems in medicine, transportation, energy and the environment. Hydrophobicity is a common wettability. The hydrophobic surface is characterized by a water contact angle (WCA) greater than 90° in air. Natural biological surfaces such as lotus leaves, rose petals and butterfly wings show excellent hydrophobic properties. Inspired by nature, the preparation of artificial hydrophobic surfaces has become a highly-anticipated research topic. Artificial hydrophobic surfaces are often used in self-cleaning, anti-corrosion, drag reduction, oil-water separation and anti-icing due to their excellent performance.

[0003] To date, researchers have explored a variety of strategies for preparing hydrophobic surfaces, providing a variety of options for the preparation of hydrophobic surfaces. These strategies usually involve the establishment of rough micro-nano structures and low surface energy provided by chemical modification. The design of surface roughness can capture air pockets in the gaps between micro-nano structures, while low surface energy can further enhance liquid repellency. Currently, there are three main ways to prepare artificial hydrophobic surfaces: (1) constructing sufficient roughness on low surface energy materials. This method is to roughen the surface of a specific low surface energy material. This method is limited by the number of low surface energy materials in nature and is still insufficient in achieving diversified and large-scale preparation of hydrophobic materials. (2) Reducing the surface energy of sufficiently rough materials. This method is mostly achieved by molecular layer modification of the material surface, but the low surface energy substances commonly used for modification are fluorine-containing compounds, which are not only expensive but also environmentally unfriendly. (3) Creating a rough micro-nano structure on the material surface and combining it with hydrophobic treatment to reduce the surface energy. This method is a combination of the first two methods and is currently the main method for high-performance hydrophobic materials, but it also has the disadvantages of complex processes and demanding equipment. Summary of the invention

[0004] In view of the above-mentioned prior art, the present invention provides a rigid epoxy resin hydrophobic film and a preparation method thereof, so as to solve the technical problems of the existing hydrophobic film preparation process being complicated and having poor hydrophobic effect.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is to provide a method for preparing a rigid epoxy resin hydrophobic film, comprising the following steps:

[0006] S1: Preparation of sodium tryptophan;

[0007] S2: Sodium tryptophanate, a curing agent and an epoxy monomer are dissolved in a solvent, and then the resulting solution is cast on a substrate and cured at 75 to 85° C. for 10 to 15 hours to obtain a rigid epoxy resin film;

[0008] S3: preparing a liquid culture medium containing Escherichia coli;

[0009] S4: sterilize the rigid epoxy resin film, then put the sterilized rigid epoxy resin film into a liquid culture medium containing Escherichia coli, and culture it at a constant temperature of 35-40° C. for 7-10 days, take out the rigid epoxy resin film, wash it, and dry it.

[0010] Based on the above technical solution, the present invention can also be improved as follows.

[0011] Further, sodium tryptophan is prepared by the following steps:

[0012] Tryptophan is dissolved in N,N-dimethylformamide, and then sodium hydroxide is added, and ultrasonic stirring is performed at room temperature until the sodium hydroxide is completely dissolved to obtain the product; the molar ratio of tryptophan to sodium hydroxide is 1:1.

[0013] Furthermore, the curing agent is p-aminodiphenyl ether; the epoxy monomer is bisphenol A epoxy resin; and the solvent is N,N-dimethylformamide.

[0014] Furthermore, the molar ratio of sodium tryptophanate, the curing agent and the epoxy monomer is 1:1:3.

[0015] Furthermore, in S2, the curing temperature is 80° C. and the curing time is 12 h.

[0016] Further, the liquid culture medium containing Escherichia coli is prepared by the following steps:

[0017] S31: dissolving beef extract, peptone and sodium chloride in water, boiling, and cooling to room temperature to obtain a base solution;

[0018] S32: dissolving soluble starch culture medium and glucose in water, boiling, and cooling to room temperature to obtain a nutrient solution;

[0019] S33: Mix the nutrient solution and the base solution, inoculate Escherichia coli after sterilization, and culture at a constant temperature of 35-40°C.

[0020] Furthermore, the solid-liquid ratio of beef extract, peptone, sodium chloride and water in S31 is 1g:2g:1g:200mL; the solid-liquid ratio of soluble starch culture medium, glucose and water in S32 is 0.85g:0.5g:50mL; and the volume ratio of nutrient solution to base solution in S33 is 1:1.

[0021] Furthermore, the sterilization in S4 is performed by ultraviolet irradiation for half an hour.

[0022] Furthermore, the culture temperature in S4 was 37°C and the culture time was 8 days.

[0023] The invention also discloses a rigid epoxy resin hydrophobic film prepared by the preparation method.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention adopts a bacterial etching method to prepare hydrophobic materials, which is more environmentally friendly and efficient compared to the etching solution using chemical reagents in the prior art.

[0026] 2. The hydrophobic material prepared by the present invention has excellent hydrophobic properties, and also has good chemical stability and thermal stability, and can meet the use requirements of special occasions.

[0027] 3. The present invention provides new ideas and methods for the bacterial etching technology in the hydrophobic modification of epoxy resin surface, laying a foundation for subsequent research. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Tryptophan (Try) and tryptophan sodium (Try-Na + )'s H NMR spectrum;

[0029] Figure 2 The infrared spectra of R-TAEP (DGEBA) films obtained at different curing times;

[0030] Figure 3 This is the infrared spectrum of the R-TAEP (DGEBA) film obtained after curing for 12 hours;

[0031] Figure 4 The infrared spectra of R-TAEP (DGEBA) film before and after etching;

[0032] Figure 5 UV-visible spectra of R-TAEP (DGEBA) films before and after etching in liquid culture medium;

[0033] Figure 6 The results of the indole experiment in liquid culture medium are shown;

[0034] Figure 7 The fluorescence spectra of R-TAEP (DGEBA) film before and after etching;

[0035] Figure 8 This is the EDS spectrum of R-TAEP (DGEBA) film before and after etching;

[0036] Fig. 9 The water contact angles before and after etching of different films;

[0037] Fig.10 Figure 1 shows the ability of R-TAEP (DGEBA) film to capture air underwater.

[0038] Fig.11 SEM images of different films before and after etching;

[0039] Fig.12 The solvent performance diagram for etching R-TAEP (DGEBA) film;

[0040] Fig.13 This is the result of studying the thermal stability of R-TAEP (DGEBA) film before and after etching. DETAILED DESCRIPTION

[0041] The raw materials and reagents used in the present invention are shown in Table 1.

[0042] Table 1 Raw materials and reagents used

[0043] raw material purity source Beef extract BR Beijing Aoboxin Biotechnology Peptone BR Beijing Aoboxin Biotechnology Sodium chloride AR Chengdu Cologne Soluble starch medium BR Qingdao Hibo Biotech glucose AR Tianjin Zhiyuan Chemical Reagent Escherichia coli —— Biological Laboratory L-Tryptophan ≥98.0％ Aladdin Sodium hydroxide AR Chengdu Cologne p-aminodiphenyl ether ≥98.0％ Alpha Chemicals Bisphenol A epoxy resin ≥98.0％ Alpha Chemicals E51 epoxy resin ≥98.0％ Alpha Chemicals N,N-Dimethylformamide AR Chengdu Cologne

[0044] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0045] Example 1: Preparation of Sodium Tryptophan Try-Na +

[0046] The preparation route of sodium tryptophanate is shown in Formula 1-1.

[0047]

[0048] The specific method is as follows: tryptophan is dissolved in N,N-dimethylformamide (DMF) solvent, and then an equimolar amount (the same as the molar amount of tryptophan) of sodium hydroxide is added to the resulting solution, and ultrasonic stirring is performed at room temperature to dissolve it to obtain a DMF solution of sodium tryptophan; the resulting solution is filtered with a microporous filter, and the filtrate is transferred into a crystallization kettle, the temperature is lowered to 5°C, and crystallization is allowed to stand for 5 hours, and the crystals are collected and dried at -0.09MPa and 85°C for 4 hours to obtain sodium tryptophan (Try-Na + ).

[0049] The results of H NMR analysis of tryptophan and sodium tryptophan are as follows: Figure 1 As shown in the figure, it can be seen that the proton hydrogen on the carboxylic acid in tryptophan is a broad peak with a chemical shift of about 13ppm. The hydrogen on the carboxylic acid on sodium tryptophan is deprotonated, so the broad peak at the chemical shift disappears; the number of hydrogens at other positions has not changed, and the chemical environment has basically not changed, so the chemical shift has not changed significantly. By comparing the nuclear magnetic hydrogen spectra of the two, it can be confirmed that tryptophan has been successfully deprotonated and sodium tryptophan has been successfully prepared.

[0050] Example 2: Preparation of Rigid Epoxy Resin Film R-TAEP

[0051] Weigh 0.2mmol Try-Na + , 0.2mmol curing agent aminodiphenyl ether (ODA) and 0.6mmol bisphenol A epoxy resin DGEBA, dissolve them in 1.5mL DMF, mix them evenly, filter the solution with cotton, pour the filtrate on a clean glass sheet (75mm*25mm), and cure it in an oven at 80℃; after curing, slowly cool it to room temperature, carefully remove the film from the glass plate, and obtain the rigid epoxy resin film R-TAEP (DGEBA).

[0052] Weigh 0.2mmol Try-Na + , 0.2mmol curing agent p-aminodiphenyl ether (ODA) and 0.6mmol bisphenol E51 type epoxy resin are dissolved in 1.5mL DMF. After mixing evenly, the solution is filtered with cotton. The filtrate is poured on a clean glass sheet (75mm*25mm) and cured in an oven at 80℃ for 12h. After curing, it is slowly cooled to room temperature and the film is carefully removed from the glass plate to obtain a rigid epoxy resin film R-TAEP (E51).

[0053] The R-TAEP (DGEBA) films cured for 6h, 8h, 10h and 12h were tested by infrared spectroscopy. The results are as follows: Figure 2 As shown in the figure, 870cm -1 The characteristic absorption peak of epoxy is at Figure 2 It can be seen that with the increase of time, the characteristic peak of epoxy gradually decreases and completely disappears at 12h, indicating that the degree of epoxy curing deepens with the extension of time and is completely cured at 12h.

[0054] Take R-TAEP (DGEBA) with a curing time of 12h and perform infrared characterization on it. The characterization results are as follows: Figure 3 As shown. 3411cm -1 The stretching vibration of hydroxyl group OH and imine group NH is at 2930cm -1 and 2865cm -1 The stretching vibration of methylene (-CH2-) is at 1657cm -1 and 1685cm -1 The skeleton of the benzene ring vibrates, and the peak is sharp; the absorption position of the carbonyl group of the carboxylate changes, and the carboxylate ion (-CO2 - -) has symmetric vibration and antisymmetric vibration, which are located at 1396cm -1 and 1455cm -1 At 1120cm-1 The peak at 870cm is the stretching vibration of the ether bond (COC) in p-aminodiphenyl ether. Since the oxygen atom of the ether bond connects two benzene rings, this peak is a strong peak. -1 The characteristic absorption peak of epoxy is basically disappeared, indicating that the curing is complete; because the carboxylate forms a salt with the metal sodium ion, we can -1 The absorption peaks related to metal oxides were observed at 1400 nm, which indicated that the R-TAEP (DGEBA) film was successfully prepared.

[0055] Example 3: Preparation of liquid culture medium containing Escherichia coli

[0056] The present invention uses bacterial etching technology to prepare hydrophobic materials. The bacterial etching technology is based on the decomposition of tryptophan by Escherichia coli. Escherichia coli has a unique metabolic mechanism, that is, through its inherent tryptophanase, it can decompose tryptophan into indole, pyruvic acid and ammonia; among them, when indole reacts chemically with dimethylaminobenzaldehyde in the indole reagent, a rose indole is produced, making the reaction solution red. This significant color change is called the indole positive test.

[0057] The liquid culture medium containing Escherichia coli used in the present invention is prepared by the following steps:

[0058] S1: 0.25 g beef extract, 0.5 g peptone, 0.25 g NaCl and 50 mL distilled water were weighed into a 100 mL beaker, stirred and boiled, and then continued to boil for 10 minutes, and cooled to room temperature to obtain an unsterilized beef extract-peptone culture solution (base solution);

[0059] S2: In a 100 mL beaker, weigh 0.85 g of soluble starch medium, 0.5 g of glucose and 50 mL of distilled water, stir and boil, then continue boiling for 10 minutes, and cool to room temperature to obtain a nutrient solution;

[0060] S3: Put the base liquid and nutrient solution into a 250 mL conical flask, seal the conical flask with cotton gauze, and then place it in a vertical high-pressure steam sterilizer, set the sterilization conditions to 121°C, and continue for 20 minutes to perform high-pressure steam sterilization to obtain a liquid culture medium; after the sterilization process is completed, let the conical flask cool naturally to room temperature, then take it out and move it into the clean bench;

[0061] S4: The clean bench, liquid culture medium and inoculation loop are sterilized under ultraviolet light for half an hour, then the ultraviolet light is turned off, and bacterial inoculation is performed 10 minutes later; before inoculation, both hands are thoroughly disinfected with 75% alcohol by volume, and both hands are kept in the clean bench during the inoculation process. In addition, the entire inoculation operation needs to be performed around the flame of an alcohol lamp; before inoculation, the inoculation loop, the conical bottle mouth and the stopper are sterilized under the flame of an alcohol lamp; after the inoculation loop is cooled, Escherichia coli is taken out and inoculated into the liquid culture medium. After the inoculation is completed, the inoculation loop, the conical bottle mouth and the stopper are sterilized again with the flame of an alcohol lamp; the inoculated liquid culture medium is placed in a 37°C constant temperature incubator for culture until the logarithmic growth phase of Escherichia coli to obtain a liquid culture medium containing Escherichia coli.

[0062] Example 4: Preparation of rigid epoxy resin hydrophobic film

[0063] Take R-TAEP (DGEBA) with a curing time of 12h, cut it into square pieces of 25mm*25mm, put it in a clean bench, first perform ultraviolet sterilization for half an hour, and then put it into the liquid culture medium containing Escherichia coli prepared in Example 3 for bacterial etching; put the liquid culture medium containing R-TAEP (DGEBA) into a 37°C constant temperature incubator and culture it for eight days; after the culture is completed, the etched film is thoroughly cleaned with distilled water and ethanol in turn, and finally, the cleaned film is dried at 50°C for 4h to obtain an etched R-TAEP (DGEBA) film, that is, a rigid epoxy resin hydrophobic film.

[0064] The infrared spectrum analysis of R-TAEP (DGEBA) before and after etching is as follows: Figure 4 As shown in the figure. After bacterial etching, the tryptophan fragments in the film are specifically recognized and decomposed by E. coli, resulting in slight changes in the film structure. Figure 4 As can be seen in the figure, 3411cm -1 The OH stretching vibration peak of the hydroxyl group and the NH stretching vibration peak of the imine group at 1600cm-1 decreased in intensity due to the disappearance of the imine group. -1 The vibration of the nearby benzene ring skeleton also changes due to the disappearance of indole; the decomposition of tryptophan salt leads to the disappearance of carboxylate and sodium ions in the film structure, which is located at 1396cm -1 、1455cm -1 Carboxylate ions (-CO2 - -) symmetrical vibration, antisymmetrical vibration and 740cm -1 The absorption peaks related to metal oxides are significantly reduced or even disappear. Except for the above special structures, the other structures of the film have not changed, so the other characteristic peaks have not changed.

[0065] Take the liquid culture medium before and after etching, centrifuge it to separate the E. coli and the solution, take the supernatant to test the liquid ultraviolet absorption, the test range is 230nm ~ 350nm, the test results are as follows Figure 5 As shown in the figure, it can be seen that the ultraviolet absorption peak of indole appears at 270nm, proving that indole groups in the film are etched by E. coli and dissolved in the liquid culture medium.

[0066] Take 5mL of liquid culture medium etched with R-TAEP (DGEBA) film in a glass bottle, add 1mL of ether for extraction. After standing for a while, the ether layer is observed to gradually float on the surface of the liquid culture medium. At this time, the indole in the liquid culture medium has been effectively extracted into the ether layer. Then, slowly add 5 to 10 drops of indole reagent (Kovacs indole reagent) along the wall of the bottle and observe the phenomenon. At the same time, the indole test was carried out on the indole monomer aqueous solution and the blank liquid culture medium. The results are as follows Figure 6 As shown in the figure, the indole test of indole monomer and the liquid culture medium after etching the film was positive, while the blank liquid culture medium was negative. This result confirmed that the bacterial etching decomposed the tryptophan in the film, causing indole to appear in the liquid culture medium.

[0067] Fluorescence spectroscopy analysis of R-TAEP (DGEBA) films before and after etching was performed. The results are as follows: Figure 7 As shown in the figure, it can be seen that the intensity of the fluorescence spectrum absorption peak of the etched R-TAEP (DGEBA) film is significantly lower than that before etching, and the position of the fluorescence absorption peak has also red-shifted. This is because before etching, the epoxy resin based on sodium tryptophan has a luminescent group indole structure, which has certain fluorescence properties. After etching, most of the sodium tryptophan fragments fall off, and the luminescent group indole group in the epoxy resin no longer exists. Therefore, the fluorescence intensity of the film after etching is significantly reduced.

[0068] EDS energy spectrum analysis was performed on the R-TAEP (DGEBA) film before and after etching, and the distribution of Na element on the film surface was obtained by surface scanning. The results are as follows: Figure 8 As shown, (a) is the EDS spectrum of the R-TAEP (DGEBA) film before etching, (b) is the EDS spectrum of the R-TAEP (DGEBA) film after etching, and the inset is the distribution of the Na element on the film surface. It can be seen from the figure that the R-TAEP (DGEBA) film before etching contains four elements, namely C, N, O, and Na, and the content of Na is 10%; the types of elements in the R-TAEP (DGEBA) film after etching have not changed, but the content of Na has been significantly reduced to only 3%, which further proves the decomposition of sodium tryptophan.

[0069] Experimental example

[0070] 1. Study on the hydrophobicity of rigid epoxy resin hydrophobic film

[0071] The water contact angle is one of the key indicators to measure the wettability of a material surface. The larger the water contact angle, the harder it is for the material surface to be wetted by water, which further indicates that the material surface has good hydrophobicity. Conversely, the smaller the water contact angle, the easier it is for the material surface to be wetted by water, and the poorer the surface hydrophobicity. It is generally believed that a water contact angle below 90° is hydrophilic, above 90° is hydrophobic, and above 150° is super hydrophobic.

[0072] The R-TAEP (E51) film was etched using the same etching process as in Example 4 to obtain an etched R-TAEP (E51) film. The water contact angles of the rigid epoxy resin film R-AEP without tryptophan fragments, the etched R-TAEP (DGEBA) film, and the etched R-TAEP (E51) film were measured respectively. The results are as follows: Fig. 9 As shown, the inset is a photo of the water contact angle. Since the epoxy resin film using amine curing agents contains oxygen atoms and nitrogen atoms with high electronegativity, the polymer usually has a high polarity. Therefore, it can be seen from the figure that the contact angles of the films that have not been treated with bacterial etching are all less than 90°, showing moderate wettability. After bacterial etching, the water contact angle of the film containing sodium tryptophan fragments increased significantly, exceeding 90°, showing hydrophobicity, while the water contact angle of R-AEP in the blank group did not change significantly. In addition, since E51 epoxy resin is more rigid than bisphenol A epoxy resin, the basic hydrophobicity of the formed R-TAEP (E51) film is relatively better, so the etching effect is also more obvious.

[0073] The hydrophobic surface has a microscopic uneven structure, which can form tiny air pockets on the surface, enabling the hydrophobic surface to capture air. The stronger the surface hydrophobicity, the stronger the ability to capture air. Super hydrophobic surfaces can even directly form air films. Fig.10 An image showing an etched R-TAEP(DGEBA) film fully immersed in water, trapping air underwater to form small bubbles.

[0074] 2. Surface morphology of R-TAEP film

[0075] The influence of surface morphology on wettability cannot be ignored. Specifically, a smoother surface tends to facilitate the uniform spreading of the liquid, thereby enhancing the wetting performance. On the contrary, an increase in surface roughness may lead to an increase in the contact angle, thereby weakening the material's wetting ability.

[0076] The surface morphology of the three groups of films before and after etching was observed by SEM. Fig.11As shown. It can be seen from the figure that the surface of the film that has not been etched is very smooth and flat, without the existence of micro-nano structures. The film after etching has formed a micron structure with a certain degree of roughness due to the bacterial etching, and the construction of the micron rough structure has achieved the transformation of the wettability of the film. Since there is no specific site for bacterial etching (sodium tryptophan fragment) in the blank group, bacterial etching has no effect on it, and the wettability and surface morphology of the film have not changed before and after the film treatment.

[0077] 3. Solvent resistance of R-TAEP film

[0078] The etched R-TAEP (DGEBA) film was immersed in DMF, DMSO, DMAc, NMP organic solvents and 5wt% HCl and NaOH solutions respectively and left to stand at room temperature for one week. Fig.12 As shown in the figure, after a week of immersion, the size, color and shape of the etched film did not change significantly, and the solvent remained clear and transparent, indicating that the etched R-TAEP film has excellent chemical stability.

[0079] 4. Thermal stability of R-TAEP film etching

[0080] The thermal decomposition temperature and glass transition temperature of the material are important indicators in practical applications. The thermal stability of the obtained R-TAEP (DGEBA) film before and after etching was studied by TGA and DSC. Fig.13 As shown, (a) is the TGA curve of R-TAEP (DGEBA) film before and after etching, and (b) is the DSC curve of R-TAEP (DGEBA) film before and after etching. Fig.13 As can be seen in (a), the 5% weight loss temperature of the R-TAEP (DGEBA) film before etching is 283°C. After etching, due to the decomposition of tryptophan and the disappearance of the cation-π interaction, the 5% weight loss temperature drops to 228°C. Although the weight loss temperature drops by 55°C, it still has good heat resistance. Fig.13 As can be seen in (b), the glass transition temperature of the R-TAEP (DGEBA) film before etching is 136°C. After etching, due to the reduction of the rigid structure of sodium tryptophan, the glass transition temperature drops slightly to 122°C. From the comprehensive TGA and DSC tests, it can be seen that although bacterial etching will affect the thermal properties of the film, the impact is small. The thermal decomposition temperature and glass transition temperature of the film after etching are maintained at a high level, showing excellent heat resistance.

[0081] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for preparing a rigid epoxy resin hydrophobic film, characterized in that: The following steps are involved: S1: preparing sodium tryptophan; S2: Sodium tryptophanate, a curing agent and an epoxy monomer are dissolved in a solvent, and then the resulting solution is cast on a substrate and cured at 75 to 85° C. for 10 to 15 hours to obtain a rigid epoxy resin film; S3: preparing a liquid culture medium containing Escherichia coli; S4: sterilize the rigid epoxy resin film, then put the sterilized rigid epoxy resin film into a liquid culture medium containing Escherichia coli, and culture it at a constant temperature of 35-40° C. for 7-10 days, take out the rigid epoxy resin film, wash it, and dry it.

2. The preparation method according to claim 1, characterized in that: The sodium tryptophanate is prepared by the following steps: Tryptophan is dissolved in N,N-dimethylformamide, and then sodium hydroxide is added, and ultrasonic stirring is performed at room temperature until the sodium hydroxide is completely dissolved to obtain the product; the molar ratio of the tryptophan to the sodium hydroxide is 1:

1.

3. The preparation method according to claim 1, characterized in that: The curing agent is p-aminodiphenyl ether; the epoxy monomer is bisphenol A epoxy resin or E51 epoxy resin; and the solvent is N,N-dimethylformamide.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the sodium tryptophanate, the curing agent and the epoxy monomer is 1:1:

3.

5. The preparation method according to claim 4, characterized in that: The curing temperature in S2 is 80°C and the curing time is 12h.

6. The preparation method according to claim 1, characterized in that: The liquid culture medium containing Escherichia coli is prepared by the following steps: S31: dissolving beef extract, peptone and sodium chloride in water, boiling, and cooling to room temperature to obtain a base solution; S32: dissolving soluble starch culture medium and glucose in water, boiling, and cooling to room temperature to obtain a nutrient solution; S33: Mix the nutrient solution and the base solution, inoculate Escherichia coli after sterilization, and culture at a constant temperature of 35-40°C.

7. The preparation method according to claim 6, characterized in that: The solid-liquid ratio of beef extract, peptone, sodium chloride and water in S31 is 1g:2g:1g:200mL; the solid-liquid ratio of soluble starch culture medium, glucose and water in S32 is 0.85g:0.5g:50mL; the volume ratio of nutrient solution to base solution in S33 is 1:

1.

8. The preparation method according to claim 7, characterized in that: Sterilization in S4 is performed by irradiating with ultraviolet light for half an hour.

9. The preparation method according to claim 1, characterized in that: The culture temperature in S4 was 37°C and the culture time was 8 days.

10. The rigid epoxy resin hydrophobic film obtained by the preparation method according to any one of claims 1 to 9.

Images