A high-strength, tough and hydrophobic polyurethane composite material and its preparation method

Abstract

The present invention discloses a high-strength, tough and hydrophobic polyurethane composite material and a preparation method thereof, which relates to the technical field of multifunctional composite materials. The preparation method comprises the following steps: (1) Dissolve tannic acid in deionized water, add calcium chloride and dissolve and mix evenly, then add disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate and dissolve, and then perform freezing treatment to obtain solution ice cubes; (2) Mix an aqueous polyurethane solution, deionized water and the solution ice cubes obtained in step (1), stir until the solution ice cubes are completely melted, perform vacuum filtration and drying to obtain a high-strength, tough and hydrophobic polyurethane composite material. The composite material has high strength, toughness, high elongation at break and a relatively wide damping temperature range, and at the same time also has hydrophobicity and antibacterial properties, solving the problem that the poor hydrophobicity of traditional polyurethane composite materials leads to reduced resistance and service life.

Description

Technical Field

[0001] The invention relates to the technical field of multifunctional composite materials, and in particular to a high-strength and tough hydrophobic polyurethane composite material and a preparation method thereof. Background Art

[0002] Polyurethane is a polymer containing urea bonds and composed of alternating hard segments and soft segments. Through structural design, the prepared polyurethane composite material can have excellent chemical stability, shock absorption ability, biocompatibility, high elasticity and wear resistance. However, because its molecular chain contains more hydrophilic functional groups, the composite material obtained by structural design often does not have hydrophobicity (the contact angle between the material and water is usually not more than 90°). This greatly affects the water resistance of the composite material, thereby limiting the application of the material. At present, people have explored many effective methods to improve the hydrophobicity of polyurethane composite materials, such as chemical modification and physical blending. Chemical modification is not only complicated to operate, but also changes the original properties of polyurethane, which is not worth the loss; physical blending makes the compatibility between the polyurethane matrix and the filler poor, which leads to the deterioration of its mechanical properties. In order to improve the compatibility between the filler and the polyurethane matrix, the filler is often modified. Such a result will undoubtedly complicate the environment of the polyurethane composite material.

[0003] In addition, with the increasing popularization and deepening of sustainable development and green environmental protection concepts, the demand for the self-healing ability and recyclability of polyurethane composites is becoming increasingly strong. Therefore, under the application requirements of water resistance, self-healing and recyclability, the exploration and research of polyurethane composites that provide dynamic properties and high mechanical properties has become a hot research direction. However, it is difficult for the polyurethane composites currently obtained to have hydrophobic properties, good mechanical properties, and meet the dynamic properties of self-healing and recyclable properties.

[0004] Therefore, there is an urgent need in the art to prepare a high-strength, hydrophobic polyurethane composite material to essentially solve the problems of poor mechanical properties, lack of shock absorption, and non-hydrophobicity of traditional polyurethane composite materials. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a high-toughness hydrophobic polyurethane composite material and a preparation method thereof. The composite material has high toughness, high strength, high elongation at break and a wide damping temperature range, and is also hydrophobic, thereby solving the problems of water resistance and reduced service life caused by poor hydrophobicity of polyurethane composite materials.

[0006] The technical solution of the present invention to solve the above technical problem is as follows: a method for preparing a high-strength and tough hydrophobic polyurethane composite material is provided, comprising the following steps:

[0007] (1) Dissolve tannic acid in deionized water, add calcium chloride and dissolve and mix well, then add disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate and dissolve, and then perform freezing treatment to obtain solution ice cubes;

[0008] (2) Blend the aqueous polyurethane solution, deionized water and the solution ice cubes obtained in step (1), stir until the solution ice cubes are completely melted, perform vacuum filtration and drying to obtain a high-strength and tough hydrophobic polyurethane composite material.

[0009] The beneficial effects of adopting the technical solution of the present invention: In step (1), at room temperature, tannic acid first coordinates with calcium ions to occupy the phenolic hydroxyl sites of tannic acid, and then the added hydrogen phosphate and dihydrogen phosphate ions act on the coordinated calcium ions to generate phosphates, and then the dispersion liquid of the formed tannic acid and phosphate particles is quickly frozen into cold quenched ice; in step (2), the cold quenched ice containing phosphates quickly melts in the polyurethane aqueous solution to obtain supercooled water, so that tannic acid and polyurethane are crosslinked in a limited way in the supercooled water at the interface of the cold quenched ice and the solution. At this time, the tannic acid and phosphates in the system are already connected by coordination bonds, and the coordinated phenolic hydroxyl groups cannot form hydrogen bond interactions anymore. Therefore, the uncoordinated phenolic hydroxyl groups form hydrogen bond interactions with polyurethane in the interfacial supercooled water; this design principle makes the phenolic hydroxyl sites of tannic acid in the composite material fully utilized. Furthermore, when the composite material is exposed to air or water, there are no extra hydrogen bond sites on the surface of the composite material to form interactions with water to support the hydrophilic property of the material, so that the composite material prepared from two hydrophilic raw materials presents hydrophobicity.

[0010] Starting from the perspective of tannic acid-induced phosphate crystallization and the crosslinking of tannic acid and polyurethane in supercooled water, the inventors have found through a large number of studies that: through the above preparation method, a large number of dynamic coordination bonds and hydrogen bond interactions can be introduced into the polyurethane composite material, and at the same time, the hydrophobic effect of the composite material can be improved.

[0011] Furthermore, in step (1), the mass-volume ratio of tannic acid, deionized water, calcium chloride, disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate is 3-7 g: 100 mL: 3-7 g: 1-4 g: 0.5-3 g.

[0012] Furthermore, in step (1), tannic acid, calcium chloride, disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate must be completely dissolved.

[0013] Furthermore, in step (1), disodium hydrogen phosphate dodecahydrate can be replaced by potassium hydrogen phosphate with crystal water, and sodium dihydrogen phosphate can be replaced by potassium dihydrogen phosphate.

[0014] Furthermore, in step (1), freeze in liquid nitrogen. The solution is not pre-frozen.

[0015] Further, in step (2), the solid content of the aqueous polyurethane solution is 20%-70%.

[0016] Further, in step (2), the mass-volume ratio of the aqueous polyurethane solution, deionized water and solution ice cubes is 1-3 g: 35-75 mL: 35-75 mL.

[0017] Further, in step (2), vacuum filtration is carried out using a PP filter membrane with a pore size of 0.22 μm.

[0018] Further, in step (2), drying is carried out at a temperature of 40-80°C.

[0019] The present invention also provides a high-strength, tough and hydrophobic polyurethane composite material prepared by the above method.

[0020] The present invention has the following beneficial effects:

[0021] 1. By the method of tannic acid-induced crystallization and phase interface crosslinking, the high-strength, tough and hydrophobic polyurethane composite material prepared by the present invention has the characteristics of high strength and toughness (381 MJ·m -3 ), high strength (23.1 MPa), high elongation at break (2768%), and a wide damping temperature range (>120°C; the temperature range where tanδ>0.3), and at the same time, the composite material has hydrophobicity. This work provides a new material design concept for high-performance polyurethane composite materials.

[0022] 2. The method of the present invention improves the binding effect between hydroxyapatite and the polyurethane matrix and the density of dynamic bonds in the composite material through in-situ crystallization, and solves the problems that the composite material prepared from tannic acid and polyurethane is not hydrophobic and has poor water resistance, and the poor mechanical properties of the polyurethane composite material.

[0023] 3. The method of the present invention has the advantages of simple process, strong controllability, good stability, mild reaction conditions and low cost, and the overall process is conducive to large-scale industrial treatment. Description of the Drawings

[0024] Figure 1 It is a diagram of the test results of the mechanical properties of the high-strength, tough and hydrophobic polyurethane composite material in Example 1;

[0025] Figure 2 It is a diagram of the test results of the damping properties of the high-strength, tough and hydrophobic polyurethane composite material in Example 1;

[0026] Figure 3 It is a diagram of the XRD test results of the high-strength, tough and hydrophobic polyurethane composite material in Example 1;

[0027] Figure 4 It is a diagram of the test results of the water contact angle of the high-strength, tough and hydrophobic polyurethane composite material in Example 1. Detailed Embodiments

[0028] The principles and features of the present invention will be described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those conditions not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0029] Example 1

[0030] A high-strength, tough and hydrophobic polyurethane composite material, and its preparation method includes the following steps:

[0031] (1) Dissolve 5 g of tannic acid in 100 mL of deionized water, add 5 g of calcium chloride and dissolve and mix well, then add 2 g of disodium hydrogen phosphate dodecahydrate and 2 g of sodium dihydrogen phosphate and dissolve, and then place it in liquid nitrogen for freezing treatment to obtain solution ice cubes;

[0032] (2) Mix 2 g of an aqueous polyurethane solution with a solid content of 60%, 60 mL of deionized water and 60 mL of the solution ice cubes obtained in step (1), stir until the solution ice cubes are completely melted, perform vacuum filtration and dry at a temperature of 70 °C to obtain a high-strength, tough and hydrophobic polyurethane composite material.

[0033] Example 2

[0034] A high-strength, tough and hydrophobic polyurethane composite material, and its preparation method includes the following steps:

[0035] (1) Dissolve 3 g of tannic acid in 100 mL of deionized water, add 3 g of calcium chloride and dissolve and mix well, then add 1 g of potassium hydrogen phosphate trihydrate and 0.5 g of potassium dihydrogen phosphate and dissolve, and then place it in liquid nitrogen for freezing treatment to obtain solution ice cubes;

[0036] (2) Mix 1 g of an aqueous polyurethane solution with a solid content of 20%, 35 mL of deionized water and 35 mL of the solution ice cubes obtained in step (1), stir until the solution ice cubes are completely melted, perform vacuum filtration and dry at a temperature of 40 °C to obtain a high-strength, tough and hydrophobic polyurethane composite material.

[0037] Example 3

[0038] A high-strength, tough and hydrophobic polyurethane composite material, and its preparation method includes the following steps:

[0039] (1) Dissolve 7 g of tannic acid in 100 mL of deionized water, add 7 g of calcium chloride and dissolve and mix well, then add 4 g of disodium hydrogen phosphate dodecahydrate and 3 g of sodium dihydrogen phosphate and dissolve, and then place it in liquid nitrogen for freezing treatment to obtain solution ice cubes;

[0040] (2) Mix 3 g of an aqueous polyurethane solution with a solid content of 70%, 75 mL of deionized water, and 75 mL of ice cubes of the solution obtained in step (1), stir until the ice cubes of the solution completely melt, perform vacuum filtration, and dry at 80 °C to obtain a high-strength, tough, and hydrophobic polyurethane composite material.

[0041] Comparative Example 1

[0042] A composite material with antibacterial properties that can be used for bone transplantation. Refer to Tian et al. for synthesizing by introducing tannic acid-modified hydroxyapatite into polyurethane (Tian Xinggui, Lu Zhihui, Ma Chuying, Wu Min, Zhang Chengfei, Yuan Yuping, Yuan Xiaowei, Xie Denghui, Liu Chao, Guo Jinshan, Antimicrobial hydroxyapatite and its composites for the repair of infected femoral condyle, Materials Science & Engineering C 121 (2021) 111807). Due to the limitations of its method, the obtained composite material has poor mechanical properties, is not hydrophobic, and has no damping properties.

[0043] Test Example 1: Mechanical Properties

[0044] Take the high-strength, tough, and hydrophobic polyurethane composite material prepared in Example 1 for testing, and simultaneously prepare a pure polyurethane comparative sample. Test the mechanical properties of the samples through a tensile testing machine, and the experimental results are as Figure 1 shown.

[0045] It can be seen from Figure 1 that the high-strength, tough, and hydrophobic polyurethane composite material of Example 1 of the present invention exhibits relatively high stress, strain, and toughness; among them, the highest toughness can reach 381 MJ·m -3 , the tensile strength can reach 23.1 MPa, and the elongation at break can reach 2768%, having extremely high mechanical properties. The results show that the lamellar phosphate prepared by the preparation method of tannic acid-induced crystallization and phase interface cross-linking can significantly improve the mechanical properties of the composite material.

[0046] Test Example 2: Damping Properties

[0047] Take the high-strength, tough, and hydrophobic polyurethane composite material prepared in Example 1 for testing, and simultaneously prepare a pure polyurethane comparative sample. Test the curve of the loss factor tanδ of the composite material changing with temperature through a dynamic mechanical analyzer to test the damping properties of the composite material. When tanδ > 0.3, it indicates that the composite material has damping properties, and the experimental results are as Figure 2as shown

[0048] It can be seen from Figure 2 that the high-strength, tough and hydrophobic polyurethane composite material prepared in Example 1 of the present invention exhibits relatively excellent damping performance. The temperature range of the damping performance it possesses is greater than 120 °C, the softening temperature of the composite material is close to 140 °C, and the maximum value of tanδ is also higher than 0.5 but not greater than 0.6. At the same time, it can be seen that the glass transition temperature of the composite material is much higher than that of pure polyurethane.

[0049] Test Example 3: Crystal Characterization

[0050] The high-strength, tough and hydrophobic polyurethane composite material prepared in Example 1 was taken for testing, and the as-prepared composite material in its original state and the sintered powder were subjected to XRD testing and compared with the standard cards of crystals in Jade 6. The experimental results are as Figure 3 shown

[0051] It can be seen from Figure 3 that the high-strength, tough and hydrophobic polyurethane composite material prepared in Example 1 of the present invention has good crystallinity, which contains two kinds of crystals, hydroxyapatite and calcium hydrogen phosphate, while the sintered powder basically only contains one kind of crystal, hydroxyapatite, proving that the preparation method of in-situ crystallization at the phase interface assisted by supercooled water can effectively prepare hydroxyapatite crystals.

[0052] Test Example 4: Wettability Characterization

[0053] The high-strength, tough and hydrophobic polyurethane composite material prepared in Example 1 was taken for testing, and its surface was tested by the sessile drop method. The experimental results are as Figure 4 shown

[0054] It can be seen from Figure 4 that the water contact angle of the high-strength, tough and hydrophobic polyurethane composite material prepared in Example 1 of the present invention is greater than 102°. When the water contact angle is greater than 90°, it has hydrophobic properties. Thus, it can be seen that the prepared composite material has good hydrophobic properties.

[0055] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-strength and tough hydrophobic polyurethane composite material, characterized in that, It includes the following steps: (1) Dissolve tannic acid in deionized water, add calcium chloride and dissolve and mix well, then add disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate and dissolve, and then perform freezing treatment to obtain solution ice cubes; the mass-volume ratio of the tannic acid, deionized water, calcium chloride, disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate is 3-7 g: 100 mL: 3-7 g: 1-4 g: 0.5-3 g; (2) Blend the aqueous polyurethane solution, deionized water and the solution ice cubes obtained in step (1), stir until the solution ice cubes are completely melted, perform vacuum filtration and dry at a temperature of 40-80 °C to obtain a high-strength and tough hydrophobic polyurethane composite material; the mass-volume ratio of the aqueous polyurethane solution, deionized water and the solution ice cubes is 1-3 g: 35-75 mL: 35-75 mL.

2. The preparation method of the high-strength and tough hydrophobic polyurethane composite material according to claim 1, characterized in that In step (1), it is frozen in liquid nitrogen.

3. The preparation method of the high-strength and tough hydrophobic polyurethane composite material according to claim 1, characterized in that, In step (2), the solid content of the aqueous polyurethane solution is 20%-70%.

4. The preparation method of the high-strength and tough hydrophobic polyurethane composite material according to claim 1, characterized in that, In step (2), vacuum filtration is performed using a PP filter membrane with a pore size of 0.22 μm.

5. A high-strength and tough hydrophobic polyurethane composite material prepared by the preparation method of the high-strength and tough hydrophobic polyurethane composite material according to any one of claims 1-4.

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