A self-supplementary sustained-release hydrogel and its preparation method

Abstract

The invention discloses a self-replenishing sustained-release hydrogel and a preparation method thereof, belonging to the technical field of underwater drag reduction; the preparation method comprises the following steps: mixing granulated sugar particles, drag-reducing polymer solid particles and granulated sugar concentrated solution, using a molding machine to press into a block structure, and obtaining polymer sugar cubes after drying; coating the organosilicon precursor on the lateral peripheral surface of the polymer sugar cube without immersing its top surface, and curing after vacuum degassing to obtain an organosilicon layer; swelling the organosilicon layer to obtain an organosilicon substrate with improved surface properties; placing a hydrogel prepolymer containing a drag-reducing polymer on the organosilicon substrate so that the top surface of the polymer sugar cube is completely covered by the hydrogel prepolymer, and obtaining a self-replenishing sustained-release hydrogel after curing. The invention improves the durability and environmental protection of the drag reducer, and the preparation method has low cost and can be widely used.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater drag reduction, and particularly relates to a self-supplementary sustained-release hydrogel and a preparation method thereof. Background Art

[0002] Since Toms discovered the drag reduction effect, polymer drag reduction has been attracting much attention from scholars. A large number of studies over the decades have shown that polymer solutions at a certain concentration have excellent drag reduction capabilities. However, currently, polymer drag reduction requires external force injection to take effect in external flows. Therefore, many scholars have added polymers to drag reduction coatings in order to use the released polymers for drag reduction. However, the polymers added in advance often have a serious shortage of polymer content in the coating due to being configured into solutions, and the release time of the polymers is short. At the same time, after long-term use, the surface coating is prone to loss due to water flow scouring, friction, or biological attachment, resulting in a decline in the drag reduction effect.

[0003] Currently, the hydrogel surface prepared using a polymer solution to slowly release polymers has a 10% speed increase effect. However, it has no effect on the duration. The concentration of the polymer solution used in this technology is 1%. Theoretically, without polymer supplementation, after a period of time, the polymers are released completely and the drag reduction effect fails. The polymer coating release technology disclosed in the prior art, but due to the high solubility of polyvinylpyrrolidone in this technology, its duration in water is less than half an hour, and there are serious deficiencies in continuous release. The preparation method of a high-strength antifouling and drag reduction hydrogel soft coating disclosed in the prior art forms a flexible first network hydrogel on the substrate surface and then introduces rigid zwitterionic polymer chains. It can be put into water until it swells to equilibrium. The concentration obtained by swelling in the hydrogel by this chemical bonding method will be lower, and the drag reduction durability in the external flow field is insufficient.

[0004] Therefore, among the related drag reduction technologies that have been disclosed, only the speed increase effect has been improved, and there has been no significant improvement in the duration of the release of the drag reducer. Further improvements need to be made to problems such as durability, environmental protection, and cost. Summary of the Invention

[0005] Technical Problems to be Solved

[0006] In order to avoid the deficiencies of the prior art, the present invention provides a self-supplementary sustained-release hydrogel and a preparation method thereof. The hydrogel is composed of a coupling of a silicone layer and a hydrogel layer. A polymer sugar cube is set in the silicone layer as a storage unit for the drag reduction polymer. The water in the hydrogel induces the release of the drag reduction polymer in the polymer sugar cube, thereby realizing the self-supplementation of the drag reduction polymer, improving the durability and environmental protection of the drag reducer, and the preparation method has a low cost and can be popularized and applied.

[0007] A technical solution of the present invention is: a method for preparing a self-replenishing sustained-release hydrogel, the specific steps are as follows:

[0008] The granulated sugar particles, the drag-reducing polymer solid particles and the granulated sugar concentrated solution are mixed, pressed into a block structure using a molding machine, and dried to obtain a polymer sugar cube;

[0009] The organosilicon precursor is coated on the lateral peripheral surface of the polymer sugar cube without immersing the top surface thereof, and is cured after vacuum degassing to obtain an organosilicon layer;

[0010] Swelling the organic silicon layer to obtain an organic silicon substrate with improved surface properties;

[0011] A hydrogel prepolymer containing a drag-reducing polymer is placed on an organic silicon substrate so that the top surface of the polymer sugar cube is completely covered by the hydrogel prepolymer, and a self-replenishing sustained-release hydrogel is obtained after curing.

[0012] A further technical solution of the present invention is that the particle size of the granulated sugar particles is 0.5 to 2 mm, and the mass ratio of the granulated sugar particles to the drag-reducing polymer solid particles is 1 to 5:1.

[0013] A further technical solution of the present invention is: the concentration of the concentrated sugar solution is 50-65%, and the mass ratio of the concentrated sugar solution to the sugar granules is 1:100-10.

[0014] A further technical solution of the present invention is: the preparation method of the organosilicon precursor is: polydimethylsiloxane, a curing agent, and a diluent are mixed and stirred sufficiently to obtain the organosilicon precursor;

[0015] The mass ratio of the polydimethylsiloxane to the curing agent is 5 to 8:1;

[0016] The diluent is an alkane with a carbon atomic weight between 4 and 10;

[0017] The mass ratio of the diluent to polydimethylsiloxane is 1:1-5.

[0018] A further technical solution of the present invention is: the specific operation of the vacuum degassing is to place the organosilicon precursor containing polymer sugar cubes in a vacuum box, and set the process parameters as: maintaining a pressure of -0.1 MPa for 20 to 30 minutes.

[0019] A further technical solution of the present invention is: the preparation method of the hydrogel prepolymer solution is: acrylic acid, acrylamide, ‌N,N'-methylenebisacrylamide, potassium persulfate, and polymer solution are mixed, and the hydrogel prepolymer solution is obtained after sufficient stirring;

[0020] The mass ratio of acrylic acid to acrylamide is 9:1-21;

[0021] The mass fraction of N,N'-methylenebisacrylamide in the hydrogel prepolymer solution solute is 2% to 5%;

[0022] The mass fraction of potassium persulfate in the hydrogel prepolymer solution solute is 1 to 2‰;

[0023] The mass ratio of the polymer solution to the hydrogel prepolymer solution solute is 4 to 5:1;

[0024] The polymer in the polymer solution is a drag-reducing polymer, and its concentration is 100 to 500 ppm.

[0025] A further technical solution of the present invention is that the drag-reducing polymer is one or a mixture of several of polyethylene oxide, polyacrylamide, biological polysaccharide or the obtained product of dried bionic drag-reducing mucus.

[0026] A further technical solution of the present invention is that the method for swelling the silicone layer is to soak the silicone layer in a methanol solution of benzophenone for swelling, take it out after 12 to 24 h and blow it dry with nitrogen to obtain a silicone substrate.

[0027] One technical solution of the present invention is: a self-supplementary sustained-release hydrogel, which is prepared by the preparation method of the self-supplementary sustained-release hydrogel.

[0028] One technical solution of the present invention is: a drag-reducing surface, including the self-supplementary sustained-release hydrogel, and its silicone substrate is grafted or bonded to the surface to be drag-reduced to form a drag-reducing surface.

[0029] Beneficial effects

[0030] The beneficial effects of the present invention are as follows: The self-supplementary sustained-release hydrogel and its preparation method proposed by the present invention have significant advantages in terms of drag-reducing performance, environmental protection, cost control and long-term stability. The specific advantage analysis is as follows:

[0031] 1. Self-supplementary mechanism to achieve long-term drag reduction:

[0032] Drag-reducing polymer storage unit; in the present invention, the drag-reducing polymer solid particles are combined with sugar particles to form polymer sugar cubes as the storage carrier of the drag-reducing polymer. After the sugar particles are dissolved in water, the drag-reducing polymer is released to form a continuous replenishment mechanism, which solves the problem of insufficient carrying amount of the drag-reducing polymer due to premature dissolution in traditional coatings.

[0033] Silicone layer pore regulation; the silicone layer is usually dense and difficult to permeate water, but the grid pores are artificially enlarged through the sugar template method (such as the sugar particle size of 0.5 to 2 mm in the embodiment), so that water can penetrate to the sugar cube layer and trigger the slow release of the drag-reducing polymer. This design significantly improves the release efficiency of the drag-reducing agent.

[0034] 2. Significantly extend the drag reduction duration: According to Figure 3 the comparative data, the drag reduction effect of ordinary sustained-release hydrogels fails after 12 hours (the surface tension no longer changes), while the drag reduction effect of the self-supplementary sustained-release hydrogel of the present invention can last for more than 40 hours (the surface tension continues to decrease).

[0035] The optimized design of the mass ratio of acrylic acid to acrylamide (9:1 - 21) and the cross-linking agent (the proportion of N,N'-methylenebisacrylamide is 2% - 5%) in the hydrogel prepolymer solution of the present invention forms a stable three-dimensional network structure, controls the slow release of the drag reduction polymer, and avoids exhaustion within a short time.

[0036] 3. Environmental protection and efficient use of materials: The present invention uses hydrogels and silicone materials with good biocompatibility to reduce pollution to the water environment. Traditional technologies need to frequently supplement the polymer solution, while the present invention increases the time for releasing the drag reduction polymer of ordinary sustained-release hydrogels through the sugar cube storage and self-supplementary mechanism, achieving efficient use of resources.

[0037] 4. Low-cost preparation and simplified process: The present invention uses common materials such as granulated sugar, polydimethylsiloxane (PDMS), and acrylic acid, significantly reducing the production cost (for example, the mass ratio of granulated sugar particles to drag reduction polymer solid particles in the examples is 1 - 5:1). At the same time, the preparation process is simple, and steps such as vacuum degassing (-0.1 MPa, 20 - 30 min) and room temperature curing (12 hours) are all easy for industrial operation without complex equipment.

[0038] 5. Enhance mechanical properties and interfacial bonding: After the silicone layer of the present invention is swollen with benzophenone methanol solution (12 - 24 h), the surface is dried with nitrogen to form active sites, and is chemically bonded with the hydrogel prepolymer solution through photoinitiation (such as ultraviolet curing), improving the interfacial bonding strength to obtain a silicone-hydrogel coupling structure and preventing the coating from peeling off. At the same time, the rigidity of the silicone layer (for example, the diluent in the examples is C4 - C 10 alkanes to adjust the hardness) is combined with the flexibility of the hydrogel to enhance the wear resistance and water flow erosion resistance of the coating.

[0039] 6. Wide applicability and multi-functional expansion: The self-supplementary sustained-release hydrogel prepared by the present invention is applicable to the surfaces that require long-term drag reduction such as ships, underwater pipelines, and marine equipment (such as grafting or bonding to the substrate of the surface to be drag-reduced in the examples); and the formula of the drag reduction polymer can be adjusted to various drag reducers such as polyethylene oxide, polyacrylamide, and biological polysaccharides (such as xanthan gum) according to requirements.

[0040] 7. Experimental Verification and Parameter Optimization: In the polymer solution of the present invention, the concentration of the drag-reducing polymer (100 - 500 ppm) matches the release rate, avoiding waste caused by excessive initial concentration or failure due to insufficient concentration in the later stage; the silicone layer swells in the benzophenone methanol solution for 12 - 24 hours to ensure sufficient penetration of active molecules and optimize the subsequent photoinitiated grafting efficiency. Refer to Figure 3 As shown, the drag reduction effect lasts for more than 40 hours, far exceeding the prior art (less than half an hour). BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic structural diagram of a self-supplementary sustained-release hydrogel in Example 1 of the present invention;

[0042] Figure 2 is a physical diagram of a self-supplementary sustained-release hydrogel in Example 1 of the present invention; (a) is the self-supplementary sustained-release hydrogel of the present invention, and (b) is the prior art sustained-release hydrogel;

[0043] Figure 3 is a comparative diagram of the surface tension change data of a self-supplementary sustained-release hydrogel and a common sustained-release hydrogel in water in Example 4 of the present invention.

[0044] Description of the reference numerals: 1 - The sparse oblique cross-grid is a schematic diagram of the three-dimensional grid of the hydrogel; 2 - The curved curve is a schematic diagram of the morphology of the polymer in the drag-reducing polymer solution; 3 - The three-dimensional silicone grid schematic diagram at the place without polymer sugar cube; 4 - The dense oblique cross-grid is a schematic diagram of the three-dimensional silicone grid at the place with polymer sugar cube; 5 - The solid diamond is a schematic diagram of the polymer solid particles in the polymer sugar cube. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0047] Based on the problem that only the speed increase effect has been improved in the currently disclosed related drag reduction technologies, and there has been no significant improvement in the duration of the release of the drag reducer, the present invention provides a preparation method for a self-supplementary sustained-release hydrogel, and the specific steps are as follows:

[0048] Step 1: mix sugar particles, drag-reducing polymer solid particles, and sugar concentrated solution, use a molding machine to press into a block structure, and obtain polymer sugar cubes after drying;

[0049] The particle size of the granulated sugar particles is 0.5 to 2 mm;

[0050] The mass ratio of the granulated sugar particles to the drag-reducing polymer solid particles is 1 to 5:1;

[0051] The concentration of the concentrated sugar solution is 50% to 65%;

[0052] The mass ratio of the concentrated sugar solution to the sugar granules is 1:100-10;

[0053] The drag-reducing polymer is one or a mixture of polyethylene oxide, polyacrylamide, biopolysaccharide or a product obtained by drying biomimetic drag-reducing mucus.

[0054] Step 2: coating the organosilicon precursor on the lateral surface of the polymer sugar cube without immersing the top surface thereof, and curing after vacuum degassing to obtain an organosilicon layer;

[0055] The preparation method of the organosilicon precursor is: polydimethylsiloxane, a curing agent, and a diluent are mixed and stirred sufficiently to obtain the organosilicon precursor;

[0056] The mass ratio of the polydimethylsiloxane to the curing agent is 5 to 8:1;

[0057] The diluent is an alkane with a carbon atomic weight between 4 and 10;

[0058] The mass ratio of the diluent to polydimethylsiloxane is 1:1-5.

[0059] The specific operation of the vacuum degassing is to place the organosilicon precursor containing polymer sugar cubes in a vacuum box, and set the process parameters as follows: maintaining the pressure at -0.1 MPa for 20 to 30 minutes.

[0060] Step 3: Swelling the organic silicon layer to obtain an organic silicon substrate with improved surface properties;

[0061] The method for swelling the organic silicon layer is to immerse the organic silicon layer in a methanol solution of benzophenone to swell, and then take it out after 12 to 24 hours and blow it dry with nitrogen to obtain the organic silicon substrate.

[0062] Step 4: Place a hydrogel prepolymer containing a drag-reducing polymer on a silicone substrate so that the top surface of the polymer sugar cube is completely covered by the hydrogel prepolymer, and obtain a self-replenishing sustained-release hydrogel after curing.

[0063] The preparation method of the hydrogel prepolymer solution is as follows: acrylic acid, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate and polymer solution are mixed and stirred sufficiently to obtain the hydrogel prepolymer solution;

[0064] The mass ratio of acrylic acid to acrylamide is 9:1-21;

[0065] The mass fraction of the N,N'-methylenebisacrylamide in the hydrogel prepolymer solute is 2% to 5%;

[0066] The mass fraction of potassium persulfate in the hydrogel prepolymer solution solute is 1-2‰;

[0067] The mass ratio of the polymer solution to the hydrogel prepolymer solution solute is 4 to 5:1;

[0068] The polymer in the polymer solution is a drag-reducing polymer with a concentration of 100 to 500 ppm.

[0069] The drag-reducing polymer is one or a mixture of polyethylene oxide, polyacrylamide, biopolysaccharide or a product obtained by drying biomimetic drag-reducing mucus.

[0070] The invention provides a self-supplementing sustained-release hydrogel, which is prepared by the preparation method of the self-supplementing sustained-release hydrogel.

[0071] The present invention provides a drag reduction surface, comprising the self-replenishing slow-release hydrogel, wherein the silicone substrate is grafted or bonded to the surface to be drag-reduced to form a drag reduction surface, for example, applied to surfaces requiring long-term drag reduction such as ships, underwater pipelines, and marine equipment.

[0072] The above technical solution is further described below with reference to examples and drawings:

[0073] Embodiment 1:

[0074] Reference Figure 1 and Figure 2 As shown, a self-replenishing sustained-release hydrogel in this embodiment includes an organosilicon layer and a hydrogel layer. The hydrogel layer contains a drag-reducing polymer, and the organosilicon layer is made of a polymer sugar cube containing solid particles of the drag-reducing polymer as a template. The polymer sugar cube directly contacts the water in the hydrogel and dissolves to release the drag-reducing polymer, thereby replenishing the drag-reducing polymer in the hydrogel.

[0075] The organic silicon layer and the hydrogel layer are linked by benzophenone through photoinitiation. The introduction of benzophenone can change the surface energy of the organic silicon substrate, thereby improving its wettability, adhesion or biocompatibility; when combined with the hydrogel layer, the introduction of benzophenone can enhance the interface interaction and improve the bonding strength.

[0076] Embodiment 2:

[0077] The specific steps of a method for preparing a self-replenishing sustained-release hydrogel are as follows:

[0078] Preparation of polymer sugar cubes:

[0079] Mix sugar particles, drag-reducing polymer solid particles and sugar concentrated solution, use a molding machine to press and shape, and obtain polymer sugar cubes after drying;

[0080] The particle size of the granulated sugar is 0.5 mm;

[0081] The drag-reducing polymer solid particles are polyethylene oxide;

[0082] The concentration of the concentrated sugar solution is 50%;

[0083] The mass ratio of the granulated sugar particles to the drag-reducing polymer solid particles is 1:1;

[0084] The mass ratio of the concentrated sugar solution to the sugar granules is 1:100.

[0085] Preparation of silicone layer:

[0086] Put polydimethylsiloxane, curing agent and diluent in a beaker and stir them thoroughly to obtain an organosilicon precursor; put a polymer sugar cube in the organosilicon precursor until the side surface of the polymer sugar cube is just immersed but the top surface of the polymer sugar cube is not immersed; then put it in a vacuum box and keep it at a pressure of -0.1MPa for 20 to 30 minutes before taking it out; finally, put the beaker in an oven for curing to obtain an organosilicon layer;

[0087] The ratio of polydimethylsiloxane to curing agent is 5:1;

[0088] The diluent is n-butane;

[0089] The mass ratio of the diluent to polydimethylsiloxane is 1:1.

[0090] Preparation of hydrogel prepolymer solution:

[0091] Acrylic acid, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate and polymer solution are placed in a beaker and stirred thoroughly to obtain a hydrogel prepolymer solution;

[0092] The mass ratio of acrylic acid to acrylamide is 9:1;

[0093] The mass fraction of the N,N'-methylenebisacrylamide in the hydrogel prepolymer solute is 2%;

[0094] The mass fraction of potassium persulfate in the hydrogel prepolymer solution solute is 1‰;

[0095] The polymer in the polymer solution is polyethylene oxide;

[0096] The concentration of the polymer solution is 100 ppm;

[0097] The mass ratio of the polymer solution to the hydrogel prepolymer solution solute is 4:1.

[0098] Preparation of self-replenishing sustained-release hydrogel:

[0099] The silicone substrate was immersed in a methanol solution of benzophenone to swell, and then taken out and dried with nitrogen after 12 hours. The hydrogel prepolymer solution was placed on the silicone substrate and cured at room temperature for 12 hours to obtain a self-replenishing sustained-release hydrogel.

[0100] Embodiment 3:

[0101] The specific steps of a method for preparing a self-replenishing sustained-release hydrogel are as follows:

[0102] Preparation of polymer sugar cubes:

[0103] Mix sugar particles, drag-reducing polymer solid particles and sugar concentrated solution, use a molding machine to press and shape, and obtain polymer sugar cubes after drying;

[0104] The particle size of the granulated sugar particles is 1.25 mm;

[0105] The polymer is polyacrylamide;

[0106] The concentration of the concentrated sugar solution is 60%;

[0107] The mass ratio of the granulated sugar particles to the drag-reducing polymer solid particles is 3:2;

[0108] The mass ratio of the concentrated sugar solution to the sugar granules is 1:50.

[0109] Preparation of silicone layer:

[0110] Put polydimethylsiloxane, curing agent and diluent in a beaker and stir them thoroughly to obtain an organosilicon precursor; put a polymer sugar cube in the organosilicon precursor until the side surface of the polymer sugar cube is just immersed but the top surface of the polymer sugar cube is not immersed; then put it in a vacuum box and keep it at a pressure of -0.1MPa for 20 to 30 minutes before taking it out. Finally, put the beaker in an oven for curing to obtain an organosilicon layer;

[0111] The ratio of polydimethylsiloxane to curing agent is 6.5:1;

[0112] The diluent is n-heptane;

[0113] The mass ratio of the diluent to polydimethylsiloxane is 1:3;

[0114] Preparation of hydrogel prepolymer solution:

[0115] Put acrylic acid, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and polymer solution into a beaker, and stir well to obtain a hydrogel prepolymer solution;

[0116] The mass ratio of acrylic acid to acrylamide is 9:11;

[0117] The mass fraction of N,N'-methylenebisacrylamide in the hydrogel prepolymer solution solute is 3.5%;

[0118] The mass fraction of potassium persulfate in the hydrogel prepolymer solution solute is 1.5‰;

[0119] The polymer in the polymer solution is polyacrylamide;

[0120] The concentration of the polymer solution is 300 ppm;

[0121] The mass ratio of the polymer solution to the hydrogel prepolymer solution solute is 4.5:1.

[0122] Preparation of self-supplementary sustained-release hydrogel:

[0123] Soak the silicone substrate in a methanol solution of benzophenone for swelling, take it out after 18 h and dry it with nitrogen. Place the hydrogel prepolymer solution on the silicone substrate and cure it at room temperature for 12 h to obtain a self-supplementary sustained-release hydrogel.

[0124] Example 4:

[0125] The specific steps of a preparation method of a self-supplementary sustained-release hydrogel are as follows:

[0126] Preparation of polymer sugar cubes:

[0127] Take granulated sugar particles, drag-reducing polymer solid particles, and concentrated sugar solution, mix them, press them into shape with a molding machine, and obtain polymer sugar cubes after drying;

[0128] The particle size of the granulated sugar particles is 2 mm;

[0129] The polymer is xanthan gum;

[0130] The concentration of the concentrated sugar solution is 65%;

[0131] The mass ratio of the granulated sugar particles to the drag-reducing polymer solid particles is 5:1;

[0132] The mass ratio of the concentrated sugar solution to the granulated sugar particles is 1:10.

[0133] Preparation of silicone layer:

[0134] Put polydimethylsiloxane, curing agent, and diluent in a beaker, and stir well to obtain a silicone precursor; place the polymer sugar cube in the silicone precursor until its lateral circumferential surface is just immersed, without immersing the top surface of the polymer sugar cube; then take it out after maintaining it in a vacuum chamber at a pressure of -0.1 MPa for 20 - 30 minutes, and finally place the beaker in an oven for curing to obtain a silicone layer;

[0135] The ratio of the polydimethylsiloxane to the curing agent is 8:1;

[0136] The diluent is n-decane;

[0137] The mass ratio of the diluent to the polydimethylsiloxane is 1:5;

[0138] Preparation of the hydrogel prepolymer solution:

[0139] Put acrylic acid, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and polymer solution in a beaker, and stir well to obtain a hydrogel prepolymer solution;

[0140] The mass ratio of the acrylic acid to the acrylamide is 9:21;

[0141] The mass fraction of the N,N'-methylenebisacrylamide in the solute of the hydrogel prepolymer solution is 5%;

[0142] The mass fraction of the potassium persulfate in the solute of the hydrogel prepolymer solution is 2‰;

[0143] The polymer in the polymer solution is xanthan gum;

[0144] The concentration of the polymer solution is 500 ppm;

[0145] The mass ratio of the polymer solution to the solute of the hydrogel prepolymer solution is 5:1.

[0146] Preparation of the self-supplementary sustained-release hydrogel:

[0147] Immerse the silicone substrate in a methanol solution of benzophenone for swelling, take it out after 24 hours and dry it with nitrogen. Place the hydrogel prepolymer solution on the silicone substrate and cure it at room temperature for 12 hours to obtain the self-supplementary sustained-release hydrogel.

[0148] Refer to Figure 3 As shown, the curve of the self-supplementary sustained-release hydrogel of the present invention basically coincides with that of the existing sustained-release hydrogel before 12 hours; after 12 hours, the solution tension of the sustained-release hydrogel no longer changes due to the end of the sustained release; for the self-supplementary sustained-release hydrogel, the water dissolved by the polymer sugar cube permeating through the hydrogel is replenished, and further sustained release continues, and the surface tension of the solution continuously decreases until 40 hours.

[0149] Example 5:

[0150] A drag-reducing surface is formed by grafting or bonding the silicone substrate of the self-supplementary slow-release hydrogel to the bottom surface of a ship.

[0151] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Without departing from the principles and spirit of the present invention, those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a self-replenishing sustained-release hydrogel, characterized in that The specific steps are as follows: The granulated sugar particles, the drag-reducing polymer solid particles and the granulated sugar concentrated solution are mixed, pressed into a block structure using a molding machine, and dried to obtain a polymer sugar cube; The organosilicon precursor is coated on the lateral peripheral surface of the polymer sugar cube without immersing the top surface thereof, and is cured after vacuum degassing to obtain an organosilicon layer; The organic silicon layer is swelled to obtain an organic silicon substrate with improved surface properties; the method for swelling the organic silicon layer is to immerse the organic silicon layer in a methanol solution of benzophenone for swelling, and then take it out after 12 to 24 hours and blow dry it with nitrogen to obtain the organic silicon substrate; Placing a hydrogel prepolymer containing a drag-reducing polymer on a silicone substrate so that the top surface of the polymer sugar cube is completely covered by the hydrogel prepolymer, and obtaining a self-replenishing sustained-release hydrogel after curing; The preparation method of the hydrogel prepolymer solution is: acrylic acid, acrylamide, ‌N,N'-methylenebisacrylamide, potassium persulfate and polymer solution are mixed, and the hydrogel prepolymer solution is obtained after sufficient stirring; the polymer in the polymer solution is a drag-reducing polymer.

2. The method for preparing a self-replenishing sustained-release hydrogel according to claim 1, characterized in that: The particle size of the granulated sugar particles is 0.5 to 2 mm, and the mass ratio of the granulated sugar particles to the drag-reducing polymer solid particles is 1 to 5:

1.

3. A method for preparing a self-replenishing sustained-release hydrogel according to claim 2, characterized in that: The concentration of the concentrated sugar solution is 50-65%, and the mass ratio of the concentrated sugar solution to the sugar granules is 1:100-10.

4. The method for preparing a self-replenishing sustained-release hydrogel according to claim 3, characterized in that: The preparation method of the organosilicon precursor is: polydimethylsiloxane, a curing agent, and a diluent are mixed and stirred sufficiently to obtain the organosilicon precursor; The mass ratio of the polydimethylsiloxane to the curing agent is 5 to 8:1; The diluent is an alkane with a carbon atomic weight between 4 and 10; The mass ratio of the diluent to polydimethylsiloxane is 1:1-5.

5. The method for preparing a self-replenishing sustained-release hydrogel according to claim 4, characterized in that: The specific operation of the vacuum degassing is to place the organosilicon precursor containing polymer sugar cubes in a vacuum box, and set the process parameters as follows: maintaining the pressure at -0.1 MPa for 20 to 30 minutes.

6. The method for preparing a self-replenishing sustained-release hydrogel according to claim 4, characterized in that: The mass ratio of acrylic acid to acrylamide is 9:1-21; The mass fraction of the N,N'-methylenebisacrylamide in the hydrogel prepolymer solute is 2% to 5%; The mass fraction of potassium persulfate in the hydrogel prepolymer solution solute is 1-2‰; The mass ratio of the polymer solution to the hydrogel prepolymer solution solute is 4 to 5:1; The drag-reducing polymer concentration is 100 to 500 ppm.

7. A method for preparing a self-replenishing sustained-release hydrogel according to claim 6, characterized in that: The drag-reducing polymer is one or a mixture of polyethylene oxide, polyacrylamide or xanthan gum.

8. A method for preparing the self-replenishing sustained-release hydrogel according to any one of claims 1 to 7 to prepare the self-replenishing sustained-release hydrogel.

9. A drag reducing surface, characterized in that: It comprises the self-replenishing sustained-release hydrogel as described in claim 8, wherein the organic silicon substrate of the self-replenishing sustained-release hydrogel is grafted or bonded to the surface to be drag-reduced to form a drag-reducing surface.

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