Preparation method for photocatalytic super-hydrophobic bifunctional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane

Abstract

A preparation method for a photocatalytic super-hydrophobic bifunctional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane. The method comprises: first preparing a carbon-phosphorus composite material by means of a hydrothermal process; and then by means of a co-rotation process, preparing the photocatalytic super-hydrophobic bifunctional self-cleaning coating material based on the carbon-phosphorus co-modified polydimethylsiloxane. The coating material based on the carbon-phosphorus co-modified polydimethylsiloxane couples super-hydrophobic and photocatalytic technologies, so that by means of a bifunctional synergistic effect, a novel metal-free fluorine-free environmentally-friendly self-cleaning coating material for hydraulic concrete is prepared. Using the carbon-phosphorus co-modified polydimethylsiloxane material enables the surface contact angle of coating layers to be increased, so as to achieve excellent hydrophobicity and self-cleaning properties. In addition, the preparation method is simple, involves no fluorine-containing substance in the preparation process, is free of carbon emission, and is characterized by high economy, and being green and low-carbon, etc.

Description

Preparation method of photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane Technical Field

[0001] The present invention relates to the technical field of hydraulic concrete, and in particular to a method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane. Background Art

[0002] As a key component of hydraulic structures, hydraulic concrete is frequently and periodically subjected to complex water environmental factors. Over time, the surface of hydraulic concrete, exposed to multiple environmental factors, including physical, chemical, and microbial factors, often becomes blackened and yellowed, stained, and corroded, seriously affecting the aesthetics and operation of hydraulic structures. Existing self-cleaning coating materials still suffer from a single self-cleaning function and a very limited variety of multifunctional self-cleaning coatings; their preparation processes are complex and costly; most contain environmentally hazardous substances such as heavy metals and fluorine; and their coatings have a short service life and poor mechanical properties. Therefore, the development of a new self-cleaning coating technology is essential. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane in order to solve the above problems. The present invention adopts a conical twin-screw micro-mixer to prepare a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating.

[0004] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0005] A method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane comprises the following steps:

[0006] Step 1, preparing a carbon-phosphorus composite material by a hydrothermal method;

[0007] Dissolve red phosphorus in deionized water, place in an ultrasonic stirrer at room temperature, set at 1000-1200 r / min and stir for 70-90 min to obtain solution A with a concentration of 3%-10%;

[0008] Dissolve sucrose in deionized water, place in an ultrasonic stirrer at room temperature, set at 1000-1200 r / min and stir for 50-70 min to obtain a solution B with a concentration of 5%-10%;

[0009] While stirring solution A, slowly add solution B, ultrasonically stir at room temperature, set at 1000-1200 r / min and stir for 130-170 minutes; after the solutions are evenly mixed, put them into a reactor, place them in an oven at 160°C and heat them evenly for 10 hours, and remove the reactor after cooling; remove the materials from the reactor, place them in a 5°C environment and set at 8000-10000 r / min and centrifuge for 10-20 minutes; after centrifugation, wash them alternately with water and alcohol, repeat 5 times, and then dry them in a vacuum drying oven at 50-60°C for more than 36 hours;

[0010] After drying, the modified red phosphorus material is ground and ultrasonically dispersed in anhydrous ethanol for 30 to 50 minutes. The obtained suspension is centrifuged at 5000 to 7000 r / min for 2 to 5 minutes. The supernatant is collected and placed in a vacuum drying oven at 50 to 70° C. and dried for more than 48 hours to obtain a carbon-phosphorus composite material.

[0011] Step 2, preparing a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating material by a co-spinning method;

[0012] At 50°C, a conical twin-screw micro-mixer was started at 80 to 100 r / min for co-rotation processing, and polydimethylsiloxane with a concentration of 97 to 99% was added for rotation. Then, a carbon-phosphorus composite material with a weight ratio of 1.5 to 3% of polydimethylsiloxane was added and co-rotated for 20 to 30 minutes to obtain a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating.

[0013] A further solution is that in step 1, the volume ratio of solution B to solution A is 1:1.2-2.

[0014] A further solution is that in step 1, the volume ratio of solution A to anhydrous ethanol is 1:2.5-4.

[0015] Another aspect of the present invention provides the use of the self-cleaning coating material obtained by the above preparation method.

[0016] The beneficial effects of the present invention are:

[0017] 1. This carbon-phosphorus co-modified polydimethylsiloxane coating material couples superhydrophobicity and photocatalytic technology. Through the synergistic effect of the two functions, it prepares a new metal-free and fluorine-free environmentally friendly self-cleaning coating material for hydraulic concrete. It has high mechanical properties, high catalytic performance, high hydrophobicity, high economic efficiency and environmental friendliness.

[0018] 2. The preparation of carbon-phosphorus composite materials not only improves the separation of red phosphorus photogenerated electron-hole pairs and promotes the photocatalytic activity of the entire coating material, but also significantly improves the mechanical properties of the coating material, such as compression resistance, antifreeze, and anti-scouring;

[0019] 3. Using carbon-phosphorus co-modified polydimethylsiloxane material to increase the contact angle of the coating surface, making it have excellent hydrophobicity and self-cleaning properties;

[0020] 4. The super-hydrophobic photocatalytic dual-function self-cleaning coating prepared by the present invention has a simple preparation process, does not use fluorine-containing substances in the preparation process, has no carbon emissions, and has the characteristics of high economy, green and low carbon;

[0021] 5. The coating stimulates photocatalysis and superhydrophobicity through natural resources such as solar energy and rainfall, and can be widely used for surface protection and aesthetic construction of hydraulic concrete, while reducing the maintenance cost of hydraulic concrete;

[0022] 6. The mechanical properties, photocatalytic self-cleaning efficiency and superhydrophobic self-cleaning efficiency of the coating did not decrease significantly after long-term water erosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the practical drawings required in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 is a SEM image of a carbon-phosphorus composite material;

[0025] FIG2 is a graph showing contact angle and sliding angle measurements on a concrete surface of a spray-coated carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-function self-cleaning coating;

[0026] FIG3 is a comparison of the photocatalytic inactivation effects of a spray-coated carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-function self-cleaning coating and a control group on Escherichia coli;

[0027] FIG4 is a comparison of the photocatalytic self-cleaning effects of the spray-coated carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-function self-cleaning coating and the control group on indigo dye;

[0028] Figure 5 is a comparison of the freeze-thaw cycle effects of the sprayed carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating and the unsprayed coating on concrete. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating based on carbon-phosphorus co-modified polydimethylsiloxane, comprising the following steps:

[0032] Step (1) preparing a carbon-phosphorus composite material by a hydrothermal method;

[0033] A carbon-phosphorus composite material was prepared using a hydrothermal method. 2g of commercial red phosphorus was dissolved in 35ml of deionized water and stirred in an ultrasonic stirrer at 1200 rpm for 90 minutes at room temperature (24°C) to obtain Solution A. 2g of sucrose was dissolved in 25ml of deionized water and stirred at 1200 rpm for 60 minutes to obtain Solution B. While stirring Solution A, Solution B was slowly added to Solution A and stirred at 1200 rpm for 150 minutes at room temperature (24°C). After the solutions were evenly mixed, they were placed in the lining of a 100ml reactor and heated uniformly in an oven at 160°C for 10 hours. After cooling, the reactor was removed from the reactor using a rubber-tipped pipette. The mixture was centrifuged at 9000 rpm for 15 minutes at 5°C. After centrifugation, the mixture was washed five times, alternating between water and alcohol washings, and then dried in a vacuum drying oven at 60°C for 36 hours. After removal, the modified red phosphorus material was mechanically ground and then ultrasonically dispersed in 100 ml of anhydrous ethanol for 40 minutes. The resulting suspension was centrifuged at 6000 rpm for 3 minutes, and the supernatant was collected and dried in a 70°C vacuum oven for 48 hours. This yielded a carbon-phosphorus composite material with optimized photocatalytic performance, as shown in Figure 1.

[0034] Step (2) preparing a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-function self-cleaning coating;

[0035] A carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-function self-cleaning coating was prepared using a conical twin-screw micro-mixer. The preparation process was based on the preferred material obtained in step (1). The conical twin-screw micro-mixer was set at 50°C and rotated at 80 rpm. Polydimethylsiloxane with a concentration of 99% was added and rotated. A carbon-phosphorus composite material with a weight ratio of 2% was then added and co-rotated for 30 minutes. A carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-function self-cleaning coating material was obtained.

[0036] Example 2

[0037] An example of testing the hydrophobicity and self-cleaning properties of the photocatalytic super-hydrophobic dual-functional self-cleaning coating material;

[0038] A carbon-phosphorus co-modified polydimethylsiloxane photocatalytic superhydrophobic dual-functional self-cleaning coating material was sprayed on the surface of an ordinary concrete block using a spray gun. The contact angle and sliding angle of water droplets on the coating sample were measured using a contact angle goniometer. In the sliding angle test, sugarcane bagasse ash was used to represent the dust generated by industrial emissions. The ash was sprinkled on the coating surface, and then water droplets were placed on the dust to determine the self-cleaning ability of the coating.

[0039] The super-hydrophobicity of the surface is characterized by the contact angle. Three sets of data were initially tested by spraying, and the contact angles were 152°, 159°, and 153°, respectively, all meeting the super-hydrophobicity requirements. The sliding angles were 5.2°, 5.3°, and 5.9°, respectively, proving that the coating has good self-cleaning properties. To simulate rain conditions, the water circulation system was set to a water flow rate of 150 mm / h to simulate rainwater erosion and soaking for 72 hours, and then the contact angle and sliding angle were measured. After three cycles (216 hours), the contact angle was measured to be 151° and the sliding angle was 6°, as shown in Figure 2.

[0040] Example 3

[0041] Example of inactivation of Escherichia coli by the photocatalytic super-hydrophobic dual-function self-cleaning coating material:

[0042] Escherichia coli was cultured in nutrient broth at 35°C to 40°C until the logarithmic growth phase. The cells were then centrifuged at high speed, the supernatant filtered, and washed with buffer. After repeated centrifugation and washing three times, the cells were resuspended in 1.8% NaCl solution to obtain an E. coli suspension with a pH of approximately 7 and a concentration of approximately 1 × 108 cfu / mL.

[0043] Get 200mL of Escherichia coli suspension and put it into the water storage tank of photocatalytic reactor, turn on water pump and ultraviolet lamp, flow rate is set slowly, liquid flows out from outlet pipe and is irradiated by ultraviolet light, then flows into circulation through inlet pipe, liquid flows through the spraying carbon-phosphorus co-modified polydimethylsiloxane photocatalysis super-hydrophobic dual-function self-cleaning coating ordinary concrete test block controlled by V-type baffle, water circulation, collects sample at outlet valve at 7min, 14min, 28min respectively. Whole photocatalytic treatment process is repeatedly tested 3 times, to verify the reusability of the polydimethylsiloxane photocatalysis super-hydrophobic dual-function self-cleaning coating modified by the carbon-phosphorus co-modification. Water sample is diluted to suitable concentration, agar plate count method is used to carry out the counting of Escherichia coli, data results such as Figure 3 (the 3rd experimental data). Simultaneously, respectively set not spraying coating concrete, only spraying common photocatalytic coating concrete, only spraying common super-hydrophobic coating concrete and do comparative experiment, find that viable colony reduces quantity and is all less than dual-function self-cleaning coating. Experimental results showed that in samples sprayed with a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic superhydrophobic dual-function self-cleaning coating, bacterial concentrations decreased by 4.8 and 6.9 logarithms in samples collected after 7 and 14 minutes of residence, respectively. No viable colonies were observed in the sample collected after a 28-minute residence time. The photocatalytic degradation effect increased significantly with increasing residence time and photocatalytic activity. In the control group, considering adhesion losses during liquid flow, it is believed that E. coli did not decrease.

[0044] Example 4

[0045] Degradation test example of indigo dye by the photocatalytic super-hydrophobic dual-functional self-cleaning coating:

[0046] The indigo of 50mg is weighed and stirred in 200mL water until solid dye is completely diffused, and concentration is recorded as C0.As water circulation system in Example 3, solution is put into reactor water tank, water pump and uv lamp are opened, flow velocity arranges slowly, and liquid flows out from outlet pipe and is irradiated by ultraviolet light, then flows into circulation through inlet pipe, liquid flows through the polydimethylsiloxane photocatalysis super-hydrophobic dual-function self-cleaning coating common concrete test block of spraying carbon-phosphorus co-modification controlled by V-type baffle, water circulation, respectively at 15min, 30min, 45min, 60min, 75min, 90min in outlet valve place, collect sample.Test sample concentration is measured using spectrophotometer under 610nm wavelength, be recorded as Ct.It is simultaneously arranged that not spraying coating concrete, only spraying common photocatalytic coating concrete, only spraying common super-hydrophobic coating concrete do comparative experiment, repeat experiment 3 times, data such as Fig. 4 (third time experimental data). The experimental results showed that the dye degradation effect of the sample sprayed with carbon-phosphorus co-modified polydimethylsiloxane photocatalytic superhydrophobic dual-functional self-cleaning coating was significantly better than that of the control group.

[0047] Example 5

[0048] The test piece completely sprayed with carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating was immersed in water and tested by adding a certain amount of 3% NaCl solution as deicing salt. The component was subjected to 20 freeze-thaw cycles, each cycle lasting 24 hours, including the temperature dropping from (23±3)℃ to (-23±3)℃ for 16 hours, and then rising from (-23±3)℃ to (23±3)℃ for 8 hours. The freeze-thaw resistance of hardened concrete was determined by recording the weight of material released per unit area (kg / m2). At the same time, an unsprayed test piece was set up as a control group under the same environment. The same experiment was repeated 5 times, and the result data were statistically analyzed, as shown in Figure 5.

[0049] The greatest mass loss caused by freeze-thaw cycles occurred in the uncoated specimens. The results show that the coating material can improve the physical properties of hydraulic concrete and extend its service life.

[0050] The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner unless there is any contradiction. In order to avoid unnecessary repetition, the present invention will no longer describe various possible combinations separately. In addition, the various different embodiments of the present invention can also be arbitrarily combined. As long as they do not violate the ideas of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane, characterized in that: The following steps are involved: Step 1, preparing a carbon-phosphorus composite material by a hydrothermal method; Dissolve red phosphorus in deionized water, put it into an ultrasonic stirrer at room temperature, set the speed to 1000-1200 r / min and stir for 70-90 min to obtain a solution A with a concentration of 3%-10%; Dissolve sucrose in deionized water, put into an ultrasonic stirrer at room temperature, set the speed to 1000-1200 r / min and stir for 50-70 min to obtain a solution B with a concentration of 5%-10%; While stirring solution A, slowly add solution B, ultrasonically stir at room temperature, set 1000-1200 r / min and stir for 130-170 min; after the solutions are evenly mixed, put them into a reactor, place them in an oven at 160° C. and heat them evenly for 10 h, and take out the reactor after cooling; take out the materials in the reactor, place them in a 5° C. environment and set 8000-10000 r / min for centrifugation for 10-20 min; after centrifugation, wash with water and alcohol alternately, repeat 5 times, and then dry them in a vacuum drying oven at 50-60° C. for more than 36 h; After drying, the modified red phosphorus material is ground and ultrasonically dispersed in anhydrous ethanol for 30 to 50 minutes. The obtained suspension is centrifuged at 5000 to 7000 r / min for 2 to 5 minutes, and the supernatant is collected and placed in a vacuum drying oven at 50 to 70° C. for more than 48 hours to obtain a carbon-phosphorus composite material. Step 2, preparing a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating material by a co-spinning method; At 50°C, start a conical twin-screw micro-mixer at 80-100 r / min for co-rotation processing, add polydimethylsiloxane with a concentration of 97-99% for rotation, then add a carbon-phosphorus composite material with a weight ratio of 1.5% to 3% of polydimethylsiloxane and co-rotate for 20-30 minutes to obtain a carbon-phosphorus co-modified polydimethylsiloxane photocatalytic super-hydrophobic dual-functional self-cleaning coating.

2. The method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane as claimed in claim 1, characterized in that: In step 1, the volume ratio of solution B to solution A is 1:1.2-2.

3. The method for preparing a photocatalytic super-hydrophobic dual-functional self-cleaning coating material based on carbon-phosphorus co-modified polydimethylsiloxane as claimed in claim 1, characterized in that: In the step 1, the volume ratio of solution A to anhydrous ethanol is 1:2.5-4.

4. Use of the self-cleaning coating material obtained by the preparation method according to any one of claims 1 to 3.

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