A superhydrophilic phase change latent heat release bifunctional composite coating material, its preparation method, and its application in seawater desalination.

Abstract

This invention belongs to the field of passive seawater desalination technology, specifically relating to a novel organic-inorganic composite micro / nanoparticle self-oriented superhydrophilic phase change latent heat release dual-functional composite coating material, its preparation method, and its application in seawater desalination. The composite coating material is a PDA@SiO2@PS / PDVB@C18 phase change microcapsule, prepared from the following raw materials: 5-20 parts by weight of SiO2@PS / PDVB@C18 phase change microcapsule, 1-10 parts by weight of tris(hydroxymethyl)aminomethane solution, and 1-10 parts by weight of dopamine hydrochloride (PDA). The composite coating prepared by this invention provides greater adhesion and improved mechanical strength. Furthermore, the black outer surface of the PDA, in addition to enhancing the absorption of sunlight by JPs@PCM, can also form covalent crosslinks with the JPs@PCM surface, further improving the mechanical properties of the composite coating. When JPs@PCM is above the melting point of wax, the paraffin wax encased inside melts and absorbs heat, and due to its unique rivet structure, it does not leak. When cooled, it releases heat to heat the coating, which still gives it strong evaporation properties.

Description

Technical Field

[0001] This invention belongs to the field of coating technology for passive seawater desalination, specifically relating to a superhydrophilic phase change latent heat release dual-functional composite coating material, its preparation method, and its application in seawater desalination. Background Technology

[0002] Superhydrophilic phase change latent heat release dual-functional composite coating materials combine the functions of superhydrophilicity and latent heat release during phase change, enabling them to play a role in various application scenarios, such as hydrophilic building materials, material protection, and seawater desalination. In the field of seawater desalination, by coating the surface of evaporative desalination equipment with this superhydrophilic composite coating material, the superhydrophilicity can improve seawater wettability and mass transfer efficiency, while the latent heat release during phase change can help maintain a stable temperature environment during the desalination process, thus optimizing desalination efficiency.

[0003] However, the preparation of this coating material still faces core challenges: how to ensure the independent and stable performance of superhydrophilic properties and latent heat release properties in a single coating system, and avoid performance degradation due to component interactions and structural conflicts during preparation or use; at the same time, it is necessary to take into account the high mechanical properties of the coating (such as adhesion) to meet the durability requirements in practical application scenarios, and achieve synergistic optimization of dual functions and mechanical properties, which are still key technical difficulties that need to be overcome.

[0004] Currently, there are Chinese patents such as CN222846481 U, CN120364785 A, CN223089441 U and CN120364810 A for seawater desalination technologies. However, these patents all involve energy sources such as electricity or wind power and belong to active seawater desalination technologies, which are characterized by high cost, excessive energy consumption and large construction scale.

[0005] Compared to active desalination technology, passive desalination technology, which has no moving mechanical parts, can achieve high-efficiency desalination. Among the currently developed technologies, solar interfacial evaporation technology is considered the most important sustainable technology for passive desalination because it can improve the evaporation efficiency of solar water evaporators by utilizing photothermal materials or efficient water transport and steam escape paths, thus achieving freshwater collection. Chinese patents CN120398170A, CN120367039A, and CN120310536A, among other seawater desalination technologies, all belong to passive desalination technology, achieving good evaporation effects simply by utilizing sunlight.

[0006] Passive seawater desalination technology has made significant progress in recent years, but existing interfacial evaporation systems still have some limitations. Solar illumination is a prerequisite for interfacial evaporation systems, and photothermal materials are quite sensitive to the energy density of sunlight. The evaporation rate of an interfacial evaporation system is affected when irradiance fluctuates with weather and time. For example, on a typical cloudy day, sunlight is easily blocked by clouds, which can cause changes in the evaporation rate of the interfacial evaporator. Although interfacial evaporation systems can achieve high-temperature surfaces to accelerate water evaporation under sufficient sunlight, thermal radiation promotes heat dissipation from the high-temperature surface into the environment, resulting in a waste of absorbed solar thermal energy. Therefore, improving the thermal state management of interfacial evaporation systems under intermittent solar radiation is crucial. Summary of the Invention

[0007] To address the technical problems in the background art, the present invention provides a superhydrophilic phase change latent heat release bifunctional composite coating material, its preparation method, and its application in seawater desalination. This composite coating material has strong hydrophilicity and excellent latent heat release performance.

[0008] To achieve the above objective, the technical solution adopted by the present invention is as follows: A superhydrophilic phase change latent heat release bifunctional composite coating material, wherein the composite coating material is PDA@SiO2@PS / PDVB@C18 phase change microcapsules, which are prepared by the following: by weight, 5-20 parts of SiO2@PS / PDVB@C18 phase change microcapsules, 1-10 parts of tris(hydroxymethyl)aminomethane solution, and 1-10 parts of dopamine hydrochloride PDA.

[0009] Preferably, the PDA@SiO2@PS / PDVB@C18 phase change microcapsules of the present invention are prepared by the following method: SiO2@PS / PDVB@C18 phase change microcapsules are placed in water, and tris(hydroxymethyl)aminomethane solution and dopamine hydrochloride PDA are added and stirred to react. After the oxidative polymerization is completed, the microcapsules are centrifuged, washed and dried to obtain PDA@SiO2@PS / PDVB@C18 phase change microcapsules.

[0010] Preferably, the C18 encapsulation ratio of the SiO2@PS / PDVB@C18 phase change microcapsules of the present invention is 52.9%~93.6%. More preferably, the SiO2@PS / PDVB@C18 phase change microcapsules of the present invention are prepared by the following steps: 1) Preparation of PS / PDVB cross-linked spheres Polystyrene microspheres (PS), divinylbenzene (DVB), azobisisobutyronitrile (AIBN) initiator, sodium dodecyl sulfate (SDS), and deionized water were mixed and emulsified under ultrasonication to form a DVB emulsion. The emulsion was then heated under stirring to initiate a polymerization reaction, resulting in a PS / PDVB copolymer dispersion. After the reaction was completed, the dispersion was rinsed with anhydrous ethanol and deionized water, and then freeze-dried to obtain PS / PDVB crosslinked spheres. 2) Preparation of SiO2@PS / PDVB Janus particles The PS / PDVB crosslinked spheres obtained in step 1), 3(methacryloyloxy)propyltrimethylsilane (MPS), sodium dodecyl sulfate (SDS), and potassium persulfate were subjected to a constant temperature reaction to obtain a SiO2@PS / PDVB Janus particle mixed dispersion. After centrifugation and washing with water and anhydrous ethanol, the SiO2@PS / PDVB Janus particles (JPs) were obtained by freeze drying. 3) Preparation of SiO2@PS / PDVB@C18 phase change microcapsules The SiO2@PS / PDVB Janus particles obtained in step 2) were dispersed in water and heated. Then, molten n-octadecane was added and homogenized under stirring to obtain an oil-in-water emulsion. The emulsion was then cooled. After the reaction was completed, the mixture was washed with anhydrous ethanol and deionized water and freeze-dried to obtain SiO2@PS / PDVB@C18 phase change microcapsules.

[0011] To achieve the other objective mentioned above, the technical solution adopted by the present invention is as follows: A method for preparing a superhydrophilic phase change latent heat release bifunctional composite coating material, the preparation steps of which are as follows: 1) Preparation of PS / PDVB cross-linked spheres Polystyrene microspheres (PS), divinylbenzene (DVB), azobisisobutyronitrile (AIBN) initiator, sodium dodecyl sulfate (SDS), and deionized water were mixed and emulsified under ultrasonication to form a DVB emulsion. The emulsion was then heated under stirring to initiate a polymerization reaction, resulting in a PS / PDVB copolymer dispersion. After the reaction was completed, the dispersion was rinsed with anhydrous ethanol and deionized water, and then freeze-dried to obtain PS / PDVB crosslinked spheres. 2) Preparation of SiO2@PS / PDVB Janus particles The PS / PDVB crosslinked spheres obtained in step 1), 3(methacryloyloxy)propyltrimethylsilane MPS, sodium dodecyl sulfate SDS and potassium persulfate were subjected to a constant temperature reaction to obtain a mixed dispersion of SiO2@PS / PDVB Janus particles. After centrifugation and washing with water and anhydrous ethanol, the SiO2@PS / PDVB Janus particles were obtained by freeze drying. 3) Preparation of SiO2@PS / PDVB@C18 phase change microcapsules The SiO2@PS / PDVB Janus particles obtained in step 2) were dispersed in water and heated. Then, molten n-octadecane was added and homogenized under stirring to obtain an oil-in-water emulsion. The emulsion was then cooled. After the reaction was completed, the mixture was washed with anhydrous ethanol and deionized water and freeze-dried to obtain SiO2@PS / PDVB@C18 phase change microcapsules (JPs@PCM). 4) Preparation of PDA@SiO2@PS / PDVB@C18 phase change microcapsules The PDA@SiO2@PS / PDVB@C18 phase change microcapsules were prepared by the following method: SiO2@PS / PDVB@C18 phase change microcapsules were placed in water, and tris(hydroxymethyl)aminomethane solution and dopamine hydrochloride PDA were added and stirred to react. After the oxidative polymerization was completed, the microcapsules were centrifuged, washed and dried to obtain PDA@SiO2@PS / PDVB@C18 phase change microcapsules.

[0012] Preferably, by weight, the polystyrene (PS) in step 1) of this invention comprises 60-90 parts, divinylbenzene (DVB) 10-40 parts, azobisisobutyronitrile (AIBN) initiator 0.02-0.08 parts, sodium dodecyl sulfate (SDS) 0.02-0.08 parts, and deionized water 160-180 parts; the emulsification time is 5-10 min; the polymerization initiation temperature is 75°C; and the reaction time is 12-16 h.

[0013] Preferably, in step 2) of the present invention, there are 5-20 parts of PS / PDVB crosslinked balls, 5-20 parts of 3(methacryloyloxy)propyltrimethylsilane (MPS), 0.01-0.03 parts of sodium dodecyl sulfate (SDS), and 0.01-0.03 parts of potassium persulfate; the isothermal reaction temperature is 75 °C, and the reaction time is 12-16 h.

[0014] Preferably, by weight, the SiO2@PS / PDVB-1 Janus particles mentioned in step 3) of the present invention are 0.1~0.5 parts, deionized water is 10~50 parts, and n-octadecane is 1~5 parts; the homogenization conditions are: homogenization at 13000 rpm for 5~10 min.

[0015] To achieve the above-mentioned objective, the technical solution adopted by the present invention is as follows: An application of a superhydrophilic phase change latent heat release dual-functional composite coating material is described, which is used in seawater desalination. The specific application method is as follows: Step 1): Place PDA@SiO2@PS / PDVB@C18 phase change microcapsules in deionized water to prepare an aqueous dispersion of phase change microcapsules with PDA deposited on the surface; Step 2): Spin-coating the log substrate with epoxy resin E51 and curing it to obtain a log substrate with an epoxy resin E51 coating on the surface. Step 3): Spin-coat the aqueous dispersion of phase change microcapsules with PDA deposited on the surface of Step 1) onto the wood substrate with an epoxy resin E51 coating. Cure at 90℃ for 12 hours, and after ultrasonic treatment and drying, a hydrophilic phase change latent heat release composite coating evaporator is obtained.

[0016] Preferably, the evaporation rate of the hydrophilic phase change latent heat release composite coating-based evaporator of the present invention is 1.12 kg to 1.93 m³ / h. -2 h -1 The evaporation efficiency is 51.4%~88.5%.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention prepares SiO2@PS / PDVB Janus particles, which are emulsion particles with one hydrophobic end and one oleophilic end. Due to the large volume of its silicon oxide end and the small volume of its polystyrene / polyvinylbenzene end, the outward-facing rivet structure of the large volume silicon oxide end gives the emulsion good stability. Encapsulating n-octadecane with this emulsion can yield stable SiO2@PS / PDVB@C18 phase change microcapsules (JPs@PCM). Polydopamine (PDA) is deposited on the surface of JPs@PCM to improve its hydrophilicity, and finally, a PDA@SiO2@PS / PDVB@C18 phase change microcapsule composite material (PDA@JPs@PCM) is obtained. Then, it is spin-coated onto an epoxy resin (E51) coating to obtain a PDA@JPs@PCM composite coating with epoxy resin (E51) as the adhesive layer. Compared to the multi-layered structure of traditional coatings, the composite coating prepared by this invention provides greater adhesion and improved mechanical strength. Furthermore, the black outer surface of the PDA not only enhances the absorption of sunlight by JPs@PCM but also forms covalent cross-links with the JPs@PCM surface, further improving the mechanical properties of the composite coating. When JPs@PCM is above the melting point of wax, the paraffin wax encased within it melts and absorbs heat, preventing leakage due to its unique rivet structure. Upon cooling, it releases heat to reheat the coating, maintaining its strong evaporation performance and solving the problem of low solar energy utilization under intermittent sunlight exposure in traditional coatings.

[0018] 2) The hydrophilic phase change latent heat release composite coating-based evaporator prepared by this invention can achieve an evaporation rate as high as 1.93 kg m³. -2 h -1 The evaporation efficiency is 88.5%.

[0019] 3) The hydrophilic phase change latent heat release composite coating evaporator prepared by the present invention has high bonding strength and superhydrophilicity. The water contact angle (WCA) of the material surface can be maintained at 0° for a long time, and the contact angle (WCA) does not change significantly after 200 friction cycles.

[0020] 4) The hydrophilic phase change latent heat release composite coating evaporator prepared by the present invention has superhydrophilicity and good thermal stability, and its evaporation performance can be maintained at a high level for a long time. Attached Figure Description

[0021] Figure 1 This is a TEM image of the polystyrene / polydivinylbenzene copolymer (PS / PDVB-3) cross-linked spheres prepared in Example 3 of the present invention.

[0022] Figure 2 This is a TEM image of the snowman-shaped SiO2@PS / PDVB-3 Janus particles prepared in Example 6 of the present invention.

[0023] Figure 3 This is a SEM image of the SiO2@PS / PDVB@C18 phase change microcapsule (JPs@PCM) particles prepared in Example 9 of the present invention.

[0024] Figure 4 The image shows a comparison of the water contact angles of the composite coating constructed from SiO2@PS / PDVB-MPCM nanoparticles without polydopamine deposition in Comparative Example 2 of this invention and the surface of the PDA@SiO2@PS / PDVB@C18-based evaporator with polydopamine deposition in Example 15, from 0.1 s to 10 s.

[0025] Figure 5 Infrared thermal image of the surface temperature evolution of the polydopamine-deposited phase change microcapsules PDA@SiO2@PS / PDVB@C18-based evaporator in Example 15 under conditions of no sunlight.

[0026] Figure 6 The graph shows the temperature changes from 7:00 AM to 5:00 PM on partly cloudy and sunny days, as well as the changes in evaporation rate and water collection volume of evaporators with and without internal phase change materials.

[0027] Figure 7 The graph shows the change in ion concentration before and after the treatment of Bohai Sea water by the PDA@SiO2@PS / PDVB@C18-3 based evaporator prepared in Example 15 of this invention.

[0028] Figure 8The effect of the PDA@SiO2@PS / PDVB@C18-3 based evaporator prepared in Example 15 of this invention on the changes before and after treatment with Rhodamine B to simulate printing industry wastewater.

[0029] Figure 9 A schematic diagram illustrating the operation of the coating abrasion resistance test on the PDA@SiO2@PS / PDVB@C18-3 based evaporator prepared in Example 15 of this invention.

[0030] Figure 10 The graph shows the change in contact angle of the PDA@SiO2@PS / PDVB@C18-3 based evaporator coating prepared in Example 15 of this invention during 0-200 friction cycles. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments and comparative examples.

[0032] Preparation of polystyrene / polyvinylbenzene copolymer (PS / PDVB) in Examples 1-3 Example 1

[0033] 90 parts of polystyrene microspheres (PS), 10 parts of divinylbenzene (DVB), 0.08 parts of azobisisobutyronitrile (AIBN) initiator, 0.08 parts of sodium dodecyl sulfate (SDS), and 200 parts of deionized water were mixed and emulsified under ultrasonication for 10 min to form a DVB emulsion. The DVB emulsion was mechanically stirred at 350 r / min for 12 h at room temperature, and then heated to 75 °C to initiate the polymerization reaction. After 16 h, a PS / PDVB copolymer dispersion was obtained.

[0034] After the reaction was completed, the product was centrifuged and washed three times each with anhydrous ethanol and deionized water to remove unpolymerized DVB monomers. The product was freeze-dried to obtain PS / PDVB copolymer crosslinked spheres. The glass transition temperature was obtained by differential scanning calorimetry (DSC) under air atmosphere. The PDVB crosslinking content was 8 wt%, and it was designated as PS / PDVB-1. Example 2

[0035] 70 parts of polystyrene microspheres (PS), 20 parts of divinylbenzene (DVB), 0.05 parts of azobisisobutyronitrile (AIBN) initiator, 0.05 parts of sodium dodecyl sulfate (SDS), and 180 parts of deionized water were mixed and emulsified under ultrasonication for 8 min to form a DVB emulsion. The DVB emulsion was mechanically stirred at 350 r / min for 10 h at room temperature, and then heated to 75 °C to initiate the polymerization reaction. After 14 h, a PS / PDVB copolymer dispersion was obtained.

[0036] After the reaction was completed, the product was centrifuged and washed three times each with anhydrous ethanol and deionized water to remove unpolymerized DVB monomers. The product was freeze-dried to obtain PS / PDVB copolymer crosslinked spheres. The glass transition temperature was obtained by differential scanning calorimetry (DSC) under air atmosphere. The PDVB crosslinking content was 17wt%, and it was designated as PS / PDVB-2. Example 3

[0037] 50 parts of polystyrene microspheres (PS), 30 parts of divinylbenzene (DVB), 0.03 parts of azobisisobutyronitrile (AIBN) initiator, 0.05 parts of sodium dodecyl sulfate (SDS), and 160 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form a DVB emulsion. The DVB emulsion was mechanically stirred at 350 r / min for 8 h at room temperature, and then heated to 75 °C to initiate the polymerization reaction. After 12 h, a PS / PDVB copolymer dispersion was obtained.

[0038] After the reaction was completed, the product was centrifuged and washed three times each with anhydrous ethanol and deionized water to remove unpolymerized DVB monomers. The product was freeze-dried to obtain PS / PDVB copolymer crosslinked spheres. The glass transition temperature was obtained by differential scanning calorimetry (DSC) under air atmosphere. The PDVB crosslinking content was 30 wt%, and it was designated as PS / PDVB-3. Figure 1 This is a TEM image of the PS / PDVB-3 cross-linked spheres prepared in this embodiment.

[0039] It should be noted that: polystyrene serves as the backbone structure and divinylbenzene serves as the crosslinking agent. If the amount of polystyrene is insufficient, the porosity of the crosslinked spheres will decrease, the pore size will become smaller, and the active sites or exchange groups inside will be difficult to be fully exposed, thus affecting their functional performance. If the amount of divinylbenzene is insufficient, the degree of crosslinking will be greatly reduced.

[0040] Examples 4-6: Preparation of organic-inorganic composite material SiO2@PS / PDVB Janus particles Example 4

[0041] 20 parts of the PS / PDVB-1 copolymer crosslinked spheres prepared in Example 1, 0.03 parts of sodium dodecyl sulfate (SDS), and 100 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form a PS / PDVB-1 seed emulsion. 20 parts of 3(methacryloyloxy)propyltrimethylsilane (MPS), 0.03 parts of potassium persulfate, and 100 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form an MPS monomer emulsion. The MPS monomer emulsion was then added dropwise to the PS / PDVB-1 seed emulsion using a peristaltic pump at a uniform rate (dropping time approximately 20 min). After the addition was complete, the mixture was reacted at 75 °C for 16 h. After the reaction, the mixture was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain the product, snowman-shaped SiO2@PS / PDVB-1 Janus particles. Example 5

[0042] 15 parts of the PS / PDVB-2 copolymer crosslinked spheres prepared in Example 2, 0.03 parts of sodium dodecyl sulfate (SDS), and 100 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form a PS / PDVB-2 seed emulsion. 15 parts of 3(methacryloyloxy)propyltrimethylsilane (MPS), 0.02 parts of potassium persulfate, and 100 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form an MPS monomer emulsion. The MPS monomer emulsion was then added dropwise to the PS / PDVB-2 seed emulsion using a peristaltic pump at a uniform rate (dropping time approximately 15 min). After the addition was complete, the mixture was reacted at 75 °C for 14 h. After the reaction, the mixture was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain the product, snowman-shaped SiO2@PS / PDVB-2 Janus particles. Example 6

[0043] Ten parts of the PS / PDVB-3 copolymer crosslinked spheres prepared in Example 3, 0.02 parts of sodium dodecyl sulfate (SDS), and 100 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form a PS / PDVB-3 seed emulsion. Ten parts of 3(methacryloyloxy)propyltrimethylsilane (MPS), 0.01 parts of potassium persulfate, and 100 parts of deionized water were mixed and emulsified under ultrasonication for 5 min to form an MPS monomer emulsion. The MPS monomer emulsion was added dropwise to the PS / PDVB-3 seed emulsion at a uniform rate using a peristaltic pump (dropping time was approximately 12 min). After the addition was complete, the reaction was carried out at a constant temperature of 75 °C for 12 h. After the reaction was completed, the mixture was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain the product, snowman-shaped SiO2@PS / PDVB-3 Janus particles. Figure 2 This is a TEM image of the snowman-shaped SiO2@PS / PDVB-3 Janus particles.

[0044] Examples 7-9: Preparation of SiO2@PS / PDVB@C18-MPCM phase change microcapsules (JPs@PCM) particles with latent heat of phase change release. Example 7

[0045] 0.5 parts of SiO2@PS / PDVB-1 Janus particles obtained in Example 4 were dispersed in 50 parts of water and heated to 70°C. Five parts of molten n-octadecane were introduced into the aqueous phase, and the mixture was homogenized at 13000 rpm for 10 min to obtain an oil-in-water emulsion. This emulsion was immediately cooled to 20°C. After the reaction was complete, the product was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain SiO2@PS / PDVB@C18-MPCM-1 phase change microcapsules (JPs@PCM-1) particles. The encapsulation ratio was estimated by the mass loss during the heating process using thermogravimetric analysis (TGA) in air atmosphere; the encapsulation ratio of C18 was 52.9%. Example 8

[0046] 0.3 parts of SiO2@PS / PDVB-2 Janus particles obtained in Example 5 were dispersed in 30 parts of deionized water and heated to 70 °C. Three parts of molten n-octadecane were introduced into the aqueous phase, and the mixture was homogenized at 13000 rpm for 7 min to obtain an oil-in-water emulsion. This emulsion was immediately cooled to 20 °C. After the reaction was complete, the product was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain SiO2@PS / PDVB@C18-MPCM-2 phase change microcapsules (JPs@PCM-2) particles. The encapsulation ratio was estimated by the mass loss during the heating process using thermogravimetric analysis (TGA) in air atmosphere; the encapsulation ratio of C18 was 76.8%. Example 9

[0047] 0.1 parts of SiO2@PS / PDVB-3 Janus particles prepared in Example 6 were dispersed in 10 parts of deionized water and heated to 70 °C. One part of molten n-octadecane was introduced into the aqueous phase, and the mixture was homogenized at 13,000 rpm for 5 min to obtain an oil-in-water emulsion. This emulsion was immediately cooled to 20 °C. After the reaction was complete, the product was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain the SiO2@PS / PDVB@C18-MPCM-3 phase change microcapsules (JPs@PCM-3) particles. Figure 3 This is a SEM image of the phase change microcapsule (JPs@PCM) particles. The encapsulation ratio was estimated by mass loss during the heating process using thermogravimetric analysis (TGA) in air atmosphere; the encapsulation ratio of C18 was 93.6%.

[0048] Examples 10-12 Preparation of PDA@SiO2@PS / PDVB@C18 phase change microcapsule composite material (PDA@JPs@PCM) Example 10

[0049] In situ oxidative polymerization of dopamine hydrochloride (DAH) was carried out in tris(hydroxymethyl)aminomethane (Tris solution, purity 99.88%), thereby depositing a polydopamine (PDA) coating layer on the surface of SiO2@PS / PDVB@C18-MPCM-1 prepared in Example 7. Specific preparation method: By weight, 20 parts SiO2@PS / PDVB@C18-MPCM-1, 10 parts DAH, 10 parts Tris solution, and 500 parts deionized water were stirred at room temperature for 18 h. After oxidative polymerization, the mixture was centrifuged, washed three times with deionized water, and dried at room temperature for 18 h to obtain a gray powder, which is the fractionally coated PDA@SiO2@PS / PDVB@C18-MPCM-1 phase change microcapsule composite material (PDA@JPs@PCM-1). Example 11

[0050] DAH was oxidatively polymerized in situ in a Tris solution, thereby depositing a PDA coating layer on the surface of the SiO2@PS / PDVB@C18-MPCM-2 prepared in Example 8. Specific preparation method: 17 parts by weight of SiO2@PS / PDVB@C18-MPCM-2, 7 parts by weight of DAH, 7 parts by weight of Tris solution, and 400 parts by weight of deionized water were stirred at room temperature for 20 h. After oxidative polymerization, the mixture was centrifuged and washed three times with deionized water. After drying at room temperature for 20 h, a gray powder was obtained, which is the PDA@SiO2@PS / PDVB@C18-MPCM-2 phase change microcapsule composite material (PDA@JPs@PCM-2) with graded PDA coating. Example 12

[0051] DAH was oxidatively polymerized in situ in a Tris solution, thereby depositing a PDA coating layer on the surface of the SiO2@PS / PDVB@C18-MPCM-3 prepared in Example 9. 15 parts SiO2@PS / PDVB@C18-MPCM-3, 5 parts DAH, 5 parts Tris, and 300 parts deionized water were stirred at room temperature for 24 h in a three-necked round-bottom flask. After the oxidative polymerization was completed, the mixture was centrifuged, washed three times with deionized water, and dried at room temperature for 24 h to obtain a gray powder, which is the hierarchically coated PDA@SiO2@PS / PDVB@C18-MPCM-3 phase change microcapsule composite material (PDA@JPs@PCM-3).

[0052] Examples 13-15: Fabrication of PDA@SiO2@PS / PDVB@C18-based Evaporators Example 13

[0053] A solution was prepared by dissolving 5 parts of liquid epoxy resin (E51) and 0.5 parts of curing agent diethyltetramethylimidazol in 5 parts of acetone. 0.5 parts of this solution were then spin-coated onto a log substrate (5 mm thick, 5 cm diameter) at 2000 rpm using a spin coater (KW-4A) to form an epoxy resin layer. The layer was then pre-cured in a 70°C oven for 4 hours. Next, 0.3 parts of an aqueous dispersion of PDA@SiO2@PS / PDVB@C18-MPCM-1 was spin-coated onto the pre-cured epoxy resin (E51) layer and rotated at 2000 rpm for 30 seconds to help ensure uniform particle distribution. The sample was then post-cured in an oven at 90°C for 16 hours. Unbonded PDA@SiO2@PS / PDVB@C18-MPCM-1 was removed by ultrasonic cleaning, resulting in a PDA@SiO2@PS / PDVB@C18-MPCM-1 based evaporator.

[0054] Using a contact angle meter, the dynamic water contact angle of the original microcapsule sample was measured with a water droplet volume of 5 μL. The contact angle reached 0° of superhydrophilicity within 0.1 s and did not change within 10 s. After 200 cycles, the contact angle was still below 5°, and the superhydrophilicity did not change significantly. The data obtained are listed in Table 1.

[0055] Using an infrared thermal imager to monitor the temperature distribution and evaporation rate of the beaker Er ) and evaporation efficiency ( η ) Calculate using Equation 1 and Equation 2 respectively.

[0056]

[0057] Where Δ m (kg) represents the mass loss of the brine. S (m) 2 ( ) represents the irradiation area of ​​the evaporator. t (h) represents the irradiation time, Δ H W (J g) −1 ( ) is the enthalpy of vaporization of water. P (kW m) −2 The light intensity is the enthalpy of vaporization of water on the sample surface, which is typically the enthalpy of vaporization of pure water (2440 J / g at 25°C). −1 ).

[0058] Under sunny conditions from 10:00 to 11:00 AM (using a Haier-YY-003 model baking lamp with a rated power of 300 W, an irradiation radius of 13.4 cm, and a light intensity of 532 mW·cm⁻²), the evaporation rate of this PDA@SiO2@PS / PDVB@C18-1 based evaporator was calculated to be 1.12 kg / m³. -2 h -1 (Δm: water collected 0.91 kg), evaporation efficiency is 51.4%. After 200 cycles, the evaporation rate is 1.08 kg m. -2 h -1 (Δm: water collected 0.87 kg), evaporation efficiency was 49.5%, and the data are listed in Table 1. Example 14

[0059] A solution was prepared by dissolving 4 parts of liquid epoxy resin (E51) and 0.3 parts of curing agent diethyltetramethylimidazol in 3 parts of acetone. 0.5 parts of this solution were then spin-coated onto a log substrate (5 mm thick, 5 cm diameter) using a spin coater (KW-4A) at 2000 rpm to form an epoxy resin layer. The layer was then pre-cured in a 70°C oven for 3 hours. Next, 0.2 parts of an aqueous dispersion of PDA@SiO2@PS / PDVB@C18-MPCM-2 was spin-coated onto the pre-cured epoxy resin (E51) layer, and the mixture was rotated at 2000 rpm for 20 seconds to help ensure uniform particle distribution. The sample was then post-cured in an oven at 90°C for 14 hours. Unbonded PDA@SiO2@PS / PDVB@C18-MPCM-2 was removed by ultrasonic cleaning, resulting in a PDA@SiO2@PS / PDVB@C18-MPCM-2-based evaporator.

[0060] From 10:00 AM to 11:00 AM, under simulated sunny conditions (using a Haier-YY-003 model baking lamp with a rated power of 300 W, an illumination radius of 13.4 cm, and a light intensity of 532 mW·cm⁻²), the evaporation rate of this PDA@SiO2@PS / PDVB@C18-1 based evaporator was calculated to be 1.52 kg / m³. -2 h -1 (Δm: water collected 1.23 kg), evaporation efficiency is 62.4%. After 200 cycles, the evaporation rate is 1.49 kg m. -2 h -1 (Δm: water collected 1.21 kg), evaporation efficiency was 68.3%, and the data are listed in Table 1. Example 15

[0061] A solution was prepared by dissolving 3 parts of liquid epoxy resin (E51) and 0.02 parts of curing agent diethyltetramethylimidazol in 1 part of acetone. 0.5 parts of this solution were then spin-coated onto a log substrate (5 mm thick, 5 cm diameter) at 2000 rpm using a spin coater (KW-4A) to form an epoxy resin layer. The layer was then pre-cured in a 70°C oven for 2 hours. Next, 0.1 parts of an aqueous dispersion of PDA@SiO2@PS / PDVB@C18-MPCM-3 was spin-coated onto the pre-cured epoxy resin layer, and the mixture was rotated at 2000 rpm for 10 seconds to help ensure uniform particle distribution. The sample was then post-cured in an oven at 90°C for 12 hours. Unbonded PDA@SiO2@PS / PDVB@C18-MPCM-3 was removed by ultrasonic cleaning, resulting in a PDA@SiO2@PS / PDVB@C18-MPCM-3-based evaporator. Figure 5 Infrared thermal image of the surface temperature evolution of the polydopamine-deposited phase change microcapsules PDA@SiO2@PS / PDVB@C18-based evaporator in this embodiment under both sunlight and non-sunlight conditions.

[0062] Under sunny conditions from 10:00 to 11:00 AM (using a Haier-YY-003 model baking lamp with a rated power of 300 W, an illumination radius of 13.4 cm, and a light intensity of 532 mW·cm⁻²), the evaporation rate of this PDA@SiO2@PS / PDVB@C18-3 based evaporator was calculated to be 1.93 kg / m³. -2 h -1 (Δm: water volume collected 1.56 kg), evaporation efficiency is 88.5%. After 200 cycles, the evaporation rate is 1.91 kg m. -2 h -1 (Δm: water collected 1.55 kg), evaporation efficiency was 87.6%, and the data obtained are listed in Tables 1, 2 and 3.

[0063] Figure 8 The PDA@SiO2@PS / PDVB@C18-3 based evaporator prepared in this embodiment shows the effect on the treatment of simulated printing industry wastewater with Rhodamine B before and after treatment. Figure 8 As can be seen, the Rhodamine B content in the wastewater was almost zero after treatment. Rhodamine B, due to its difficulty in being removed from water, can be used to simulate some difficult-to-remove organic substances in industrial wastewater, demonstrating the effectiveness of this process for treating organic matter in industrial wastewater. Rhodamine B is used to simulate printing industry wastewater primarily because it is easy to detect, and its chemical structure is as stable as most organic substances in printing industry wastewater, not easily destroyed by ordinary water quality conditions. Therefore, it can be used to simulate most organic substances in printing industry wastewater.

[0064] The PDA@SiO2@PS / PDVB@C18-3 based evaporator coating prepared in this embodiment was subjected to a friction cycle experiment. A schematic diagram of the experimental operation is shown below. Figure 9 Record the contact angles after the 30th, 60th, 90th, 120th, 150th, 180th, and 200th degrees respectively. Figure 10 This graph shows the change in contact angle of the PDA@SiO2@PS / PDVB@C18-3 based evaporator coating during 0-200 friction cycles. Figure 10 As can be seen from the results, in the friction test, the water contact angle of the coating did not change significantly after the tape was repeatedly peeled off 200 times, which indicates that the coating has good mechanical properties.

[0065] Comparative Example 1: Composite Coating Constructed from PS / PDVB@C18-MPCM Nanoparticles

[0066] First, 0.1 parts of the PS / PDVB-3 copolymer crosslinked spheres obtained in Example 3 were dispersed in 10 parts of water and heated to 70°C. After introducing 1 part of molten n-octadecane (WAX) into the aqueous phase, the mixture was homogenized at 13000 rpm for 5 min to obtain an oil-in-water emulsion. 3 parts of liquid epoxy resin (E51) and 0.2 parts of curing agent diethyltetramethylimidazol were dissolved in 5 parts of acetone to prepare a solution. 0.5 parts of this solution were taken and spin-coated onto a log substrate (wood thickness 5 mm, diameter 5 cm) at 2000 rpm using a spin coater (KW-4A) to form an epoxy resin layer. The substrate was then placed in a 70°C oven for pre-curing for 2 h to obtain an E51 coated substrate. Finally, the above-mentioned PS / PDVB-3 oil-in-water emulsion was spin-coated onto the surface of the log substrate.

[0067] The dynamic water contact angle of the microcapsule sample was measured using a contact angle meter with a water droplet volume of 5 μL. The contact angle consistently reached 83.6° within 10 s. The data obtained are listed in Table 1.

[0068] The temperature distribution in the beaker was monitored using an infrared thermal imager. The evaporation rate (Er) and evaporation efficiency (η) were calculated using Equations 1 and 2, respectively. The calculated evaporation rate was 0.36 kg m³. -2 h -1 (Δm: water collected 0.29 kg) The evaporation efficiency was 16.5%, and the data obtained are listed in Tables 1, 2, and 3.

[0069] The reason for the poor evaporation performance of Comparative Example 1 is that it only uses PS / PDVB cross-linked balls to wrap n-octadecane, without having the SiO2@PS / PDVB rivet structure (large end facing the water end, small end facing the n-octadecane end), which leads to poor wrapping effect. When the temperature rises, the n-octadecane melts and leaks, resulting in poor evaporation performance.

[0070] Comparative Example: Composite Coating Constructed from 2SiO2@PS / PDVB@C18-MPCM Phase Change Microcapsules First, 0.1 parts of SiO2@PS / PDVB-3 Janus particles obtained in Example 6 were dispersed in 10 parts of water and heated to 70 °C to obtain the desired product. Then, 1 part of molten n-octadecane was introduced into the aqueous phase, and the mixture was homogenized at 13000 rpm for 5 minutes. After min, an oil-in-water emulsion can be obtained, which is the oil-in-water emulsion of SiO2@PS / PDVB@C18-MPCM phase change microcapsule particles. A solution is prepared by dissolving 3 parts of liquid epoxy resin (E51) and 0.2 parts of curing agent diethyltetramethylimidazole in 5 parts of acetone. 0.5 parts of this solution are then spin-coated onto a log substrate (wood thickness 5mm, diameter 5cm) at 2000 rpm using a spin coater (KW-4A) to form an epoxy resin layer. The substrate is then pre-cured in a 70℃ oven for 2 hours to obtain an E51 coated substrate. Finally, the oil-in-water emulsion of SiO2@PS / PDVB@C18-MPCM phase change microcapsule particles is spin-coated onto the surface of the log substrate.

[0071] The dynamic water contact angle of the original microcapsule sample was measured using a contact angle meter with a water droplet volume of 5 μL. The contact angle remained at 134.6° within 10 s. The dynamic water contact angle of the sample after 200 cycles was 132.5 ± 1° within 10 s. The data are listed in Table 1. Figure 4 The image shows a comparison of the water contact angles between the composite coating constructed from SiO2@PS / PDVB-MPCM nanoparticles without polydopamine deposition in this comparative example and the PDA@SiO2@PS / PDVB@C18-based evaporator surface with polydopamine deposition in Example 15, from 0.1 s to 10 s.

[0072] Using an infrared thermal imager to monitor the temperature distribution and evaporation rate of the beaker Er ) and evaporation efficiency ( η The evaporation rate of the original sample was calculated using Equations 1 and 2, respectively. -2 h -1 (Δm: water volume collected 0.46 kg), evaporation efficiency was 26.1%, and the evaporation rate of the sample after 200 cycles was 0.55 kg m. -2 h -1 (Δm: water collected 0.44 kg), evaporation efficiency was 25.2%, and the data obtained are listed in Tables 1, 2 and 3.

[0073] The reason for the poor evaporation performance of Comparative Example 2 is that polydopamine was not deposited on the surface of the phase change microcapsules, resulting in a white and hydrophobic surface. This reduces the absorption of sunlight and prevents the adsorption of liquid water in water, thus leading to poor evaporation performance.

[0074] Table 1 shows the hydrophilic-hydrophobic evaporation performance of Examples 13-15 and Comparative Examples 1-2.

[0075] As can be seen from Table 1, the original contact angles of the samples in Examples 13 to 15 were all 0° (superhydrophilic), and after 200 cycles, they still maintained 1±1° to 2±1°, which is far superior to the 82.5±1° to 132.5±1° (hydrophobic / weakly hydrophilic) of Comparative Examples 1 to 2. The superhydrophilic surface allows seawater to quickly and evenly cover the material surface, avoiding the concentrated precipitation of salt scale caused by local accumulation of seawater (hydrophobic surfaces are prone to forming "seawater droplets", and salt scale is easy to adhere after evaporation). At the same time, it increases the contact area between seawater and air, laying the foundation for a high evaporation rate.

[0076] Examples 13-15 exhibited initial evaporation rates of 1.12-1.93 kg·m⁻²·h⁻¹, which were 1.96-5.36 times that of the comparative examples (0.36-0.57 kg·m⁻²·h⁻¹); their initial evaporation efficiencies ranged from 51.4% to 88.5%, which were 1.97-5.36 times that of the comparative examples (16.5%-26.1%), with Example 15 achieving an efficiency close to 90%. After 200 cycles, Examples 13-15 showed an evaporation rate decrease of ≤3.6%, an efficiency decrease of ≤2.1%, and a contact angle change of ≤2°, indicating virtually no performance loss.

[0077] Table 2 Chemical stability of Example 15 and Comparative Example 1 (original samples were immersed in solutions of different pH for 12 hours).

[0078] Table 3 Abrasion resistance of Example 15 and Comparative Example 1 (the original samples were repeatedly pasted together using Deli 30203 transparent tape).

[0079] Table 4 lists the main pharmaceutical products and manufacturers used in the embodiments and comparative examples of this invention.

Claims

1. An application of a superhydrophilic phase change latent heat release dual-functional composite coating material, characterized in that: The composite coating material is PDA@SiO2@PS / PDVB@C18 phase change microcapsules. This composite coating material is applied in seawater desalination, and the specific application method is as follows: Step 1): Place PDA@SiO2@PS / PDVB@C18 phase change microcapsules in deionized water to prepare an aqueous dispersion of phase change microcapsules with PDA deposited on the surface; Step 2): Spin-coating the log substrate with epoxy resin E51 and curing it to obtain a log substrate with an epoxy resin E51 coating on the surface. Step 3): Spin-coat the aqueous dispersion of phase change microcapsules with PDA deposited on the surface of the obtained step 1) onto the wood substrate with epoxy resin E51 coating on the surface. Curing is carried out at a curing temperature of 90℃ for 12 hours. After ultrasonic treatment and drying, the resulting substrate is obtained as a hydrophilic phase change latent heat release composite coating evaporator. The PDA@SiO2@PS / PDVB@C18 phase change microcapsules are prepared from the following raw materials: by weight, 5-20 parts of SiO2@PS / PDVB@C18 phase change microcapsules, 1-10 parts of tris(hydroxymethyl)aminomethane solution, and 1-10 parts of dopamine hydrochloride. The SiO2@PS / PDVB@C18 phase change microcapsules were prepared by the following steps: a) Preparation of PS / PDVB cross-linked spheres Polystyrene microspheres (PS), divinylbenzene (DVB), azobisisobutyronitrile (AIB), sodium dodecyl sulfate (SO4) and deionized water were mixed and emulsified under ultrasonication to form a DVB emulsion. The emulsion was then heated under stirring to initiate a polymerization reaction, resulting in a PS / PDVB polymer dispersion. After the reaction was completed, the mixture was rinsed with anhydrous ethanol and deionized water and then freeze-dried to obtain PS / PDVB crosslinked spheres. b) Preparation of SiO2@PS / PDVB Janus particles The PS / PDVB crosslinked spheres obtained in step a), 3-(methacryloyloxy)propyltrimethoxysilane, sodium dodecyl sulfate and potassium persulfate were reacted at a constant temperature to obtain a mixed dispersion of SiO2@PS / PDVB Janus particles. After centrifugation and washing with water and anhydrous ethanol, the SiO2@PS / PDVB Janus particles were obtained by freeze drying. c) Preparation of SiO2@PS / PDVB@C18 phase change microcapsules The SiO2@PS / PDVB Janus particles obtained in step b) were dispersed in water and heated. Then, molten n-octadecane was added and homogenized under stirring to obtain an oil-in-water emulsion. The emulsion was then cooled, and after the reaction was completed, it was rinsed with anhydrous ethanol and deionized water. After freeze-drying, SiO2@PS / PDVB@C18 phase change microcapsules were obtained.

2. The application according to claim 1, characterized in that: The PDA@SiO2@PS / PDVB@C18 phase change microcapsules were prepared by the following method: SiO2@PS / PDVB@C18 phase change microcapsules were placed in water, and tris(hydroxymethyl)aminomethane solution and dopamine hydrochloride were added and stirred to react. After the oxidative polymerization was completed, the microcapsules were centrifuged, washed and dried to obtain PDA@SiO2@PS / PDVB@C18 phase change microcapsules.

3. The application according to claim 1, characterized in that: The C18 encapsulation ratio of the SiO2@PS / PDVB@C18 phase change microcapsules is 52.9%~93.6%.

4. The application according to claim 1, characterized in that: By weight, the polystyrene microspheres (PS) in step a) consist of 60-90 parts, divinylbenzene (DVB) 10-40 parts, azobisisobutyronitrile (AIB) initiator 0.02-0.08 parts, sodium dodecyl sulfate 0.02-0.08 parts, and deionized water 160-180 parts; the emulsification time is 5-10 min; the polymerization initiation temperature is 75℃, and the reaction time is 12-16 h.

5. The application according to claim 1, characterized in that: By weight, 5-20 parts of PS / PDVB crosslinked spheres, 5-20 parts of 3-(methacryloyloxy)propyltrimethoxysilane, 0.01-0.03 parts of sodium dodecyl sulfate and 0.01-0.03 parts of potassium persulfate; The constant temperature reaction was 75 ℃, and the reaction time was 12~16 h.

6. The application according to claim 1, characterized in that: By weight, the SiO2@PS / PDVB Janus particles mentioned in step c) are 0.1~0.5 parts, deionized water is 10~50 parts, and n-octadecane is 1~5 parts; the homogenization conditions are: homogenization at 13000 rpm for 5~10 min.

7. The application according to claim 1, characterized in that: The evaporation rate of this hydrophilic phase change latent heat release composite coating-based evaporator is 1.12~1.93 kg·m³. -2 ·h -1 The evaporation efficiency is 51.4%~88.5%.

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