A hydrophobic elastomer and its preparation method and application

Abstract

The present invention relates to the field of new material technology, and discloses a hydrophobic elastomer, a preparation method thereof, and an application thereof. The hydrophobic elastomer of the present invention is prepared from lauryl methacrylate, tridecafluorooctyl methacrylate, a photoinitiator, and a cross-linking agent. The preparation method comprises the following steps: uniformly mixing lauryl methacrylate, tridecafluorooctyl methacrylate, a photoinitiator, and a cross-linking agent; introducing an inert gas; and obtaining the hydrophobic elastomer after ultraviolet irradiation. The tensile strength of the elastomer of the present invention can reach 740 kPa, and the tensile strain is greater than 1200%; the tensile strain recovers to the original 122.67% after shearing for 24 hours; it exhibits good self-adhesion properties to substrates such as PET film, glass, copper sheet, and pigskin; the water absorption rate is low, and the water contact angle reaches 109.5°. The hydrophobic elastomer of the present invention can meet the needs of various scenarios, such as flexible electronics, medical patches, underwater sensors, and waterproof materials.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and more particularly to a hydrophobic elastomer and a preparation method and application thereof. Background Art

[0002] Elastomers are elastic polymers that can undergo large deformations when subjected to force and quickly return to a state similar to their original size and shape after the force dissipates. Due to their high viscoelasticity, high elongation at break, and low Young's modulus, elastomeric materials are widely used in many fields, including construction, medicine, electronics, and automotive. With the advent of the digital information age, research on high-performance portable flexible sensors has developed rapidly, with potential applications in areas such as human motion and health monitoring, intelligent robotics, and wearable electronic devices. However, traditional metal and semiconductor sensors, due to their inherent rigidity, low deformation, and poor human compatibility, cannot meet the requirements of flexible electronics.

[0003] Elastomer materials are one of the important base materials for flexible strain sensors due to their high elasticity, high resilience, and good skin compatibility. In practical applications, flexible sensors are susceptible to damage caused by mechanical, chemical, thermal, and ultraviolet radiation, which can lead to a decrease in mechanical properties and a shortened service life. Therefore, giving the elastomer as a base material self-healing properties is of great significance to the service life of the device. As a base material for flexible sensors, it has self-adhesive ability, which facilitates effective adhesion to surfaces such as skin, making it convenient to use. In addition, in order to avoid the influence of human sweat on flexible sensors, or to use flexible sensors underwater, the elastomer needs to have good hydrophobicity.

[0004] Chen Ruihu prepared an adhesive and hydrophobic elastomeric material using an emulsion polymerization method to prepare a three-component elastomeric material containing polyacrylate, metal nanoparticles, and polydopamine (Chen Ruihu. Preparation of Superstretchable Polyacrylate Elastomer and Study on Leather Coating Properties [D]. Qilu University of Technology, 2023). This process is complex, and the dispersion stability and long-term performance of the nanoparticles are limited. Wang Hui used polytetrahydrofuran, isophorone diisocyanate, diphenylmethane diisocyanate, and 2-hydroxy-4-amino-6-methylpyrimidine to develop two polyurethane elastomers with adhesive and self-healing properties (Wang Hui. Molecular Design and Performance Research of Highly Adhesive Supramolecular Elastomers [D]. Zhengzhou University, 2022). The preparation process involves temperatures as high as 80°C, takes over 24 hours, consumes a lot of energy, and the raw materials are toxic.

[0005] Prior art CN115651118A proposes an underwater self-adhesive, self-healing transparent ion-conductive elastomer. By designing a hydrophobic deep eutectic solvent and combining soft and hard monomers, it overcomes the drawback of hydrophilic deep eutectic solvents being susceptible to water molecules. However, this solution emphasizes ionic conductivity and optical transparency, but is insufficient for applications that require hydrophobicity and high elasticity without conductive properties (such as flexible non-conductive substrates and hydrophobic adhesive materials).

[0006] Prior art CN118047908A provides a hydrophobic ionic elastomer made from polyurethane acrylate and ionic liquid. This elastomer is primarily targeted at ionic conductivity and 3D printing rapid prototyping. However, its mechanical properties (such as elongation at break and tensile strength) are limited, making it difficult to apply in scenarios requiring high strength and high elasticity. Furthermore, after the ionic liquid is involved in the reaction, the material has poor flexibility and lacks self-healing ability.

[0007] According to current research reports, it is difficult for elastomers to have self-adhesion, self-healing and hydrophobic properties at the same time. Summary of the Invention

[0008] The present invention provides a hydrophobic elastomer to overcome the defects of the above-mentioned prior art elastomers, such as difficulty in achieving self-adhesion, self-repairing and hydrophobic properties, high energy consumption and duplication of the preparation process.

[0009] Another object of the present invention is to provide a method for preparing a hydrophobic elastomer;

[0010] Another object of the present invention is to provide an application of a hydrophobic elastomer.

[0011] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0012] A hydrophobic elastomer is prepared from lauryl methacrylate, tridecafluorooctyl methacrylate, a photoinitiator and a crosslinking agent.

[0013] Furthermore, the molar ratio of lauryl methacrylate to tridecafluorooctyl methacrylate is 3-7:7-3.

[0014] This invention innovatively proposes a proportional blend of lauryl methacrylate (which provides a flexible segment) and tridecafluorooctyl methacrylate (which imparts hydrophobicity and rigidity) to achieve the mechanical and surface properties of the elastomer. The fluorine groups in tridecafluorooctyl methacrylate introduce low surface energy, imparting hydrophobicity to the material. Dynamic intermolecular interactions within the elastomer enhance the self-healing capabilities of the elastomer.

[0015] Furthermore, the photoinitiator is an oil-soluble photoinitiator; the content of the photoinitiator is 0.2% to 1.5% of the total amount of lauryl methacrylate and tridecafluorooctyl methacrylate.

[0016] Preferably, the photoinitiator is 1-hydroxycyclohexyl phenyl ketone and / or benzophenone.

[0017] Furthermore, the cross-linking agent is an acrylate cross-linking agent; the content of the cross-linking agent is 0.2% to 2% of the total amount of lauryl methacrylate and tridecafluorooctyl methacrylate.

[0018] Preferably, the crosslinking agent is 1,6-hexanediol diacrylate and / or ethylene glycol diacrylate.

[0019] Furthermore, the contact angle of water on the surface of the hydrophobic elastomer is greater than 100°.

[0020] Preferably, the contact angle of water on the surface of the hydrophobic elastomer can reach 110°.

[0021] Furthermore, the hydrophobic elastomer is cut and self-repaired for 12 to 24 hours, and the tensile strain of the self-repaired hydrophobic elastomer is 500% to 920%.

[0022] Preferably, after the hydrophobic elastomer is cut and self-repaired, the tensile strain of the self-repairing hydrophobic elastomer can be restored to at least 67% of the original value.

[0023] Preferably, after the hydrophobic elastomer is cut and self-repaired, the tensile strain of the self-repairing hydrophobic elastomer can be restored to at least 123% of the original

[0024] A preparation method of the hydrophobic elastomer comprises the following steps: uniformly mixing lauryl methacrylate, tridecafluorooctyl methacrylate, a photoinitiator and a crosslinking agent; introducing an inert gas; and irradiating the mixture with ultraviolet light to obtain the hydrophobic elastomer.

[0025] Furthermore, the inert gas is introduced for 10 to 30 minutes.

[0026] Preferably, the inert gas is nitrogen.

[0027] Inert gas is introduced to remove oxygen from the reaction system, preventing oxygen from consuming free radicals and ensuring polymerization efficiency. Nitrogen protection enhances the uniformity of free radical reactions and reduces side reactions, which is especially important under UV irradiation.

[0028] Further, the film is irradiated under ultraviolet light for 20 to 30 minutes.

[0029] UV curing is fast and efficient, avoiding the complexity of thermal curing processes. The irradiation time directly affects the degree of cross-linking, thereby affecting the mechanical properties of the elastomer of the present invention.

[0030] Preferably, the wavelength of the ultraviolet light is 200-400 nm.

[0031] Preferably, the ultraviolet light wavelength is 365 nm.

[0032] An application of the hydrophobic elastomer, wherein the hydrophobic elastomer has self-adhesion and can be used for adhering objects; the objects include metal, plastic, glass, and skin.

[0033] Preferably, it can be used for adhering objects in water.

[0034] An application of the hydrophobic elastomer is in the preparation of flexible electronics, medical patches, underwater sensors and waterproof materials.

[0035] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0036] 1. Excellent mechanical properties. Under different ratios, the mechanical properties of the elastomer show good adjustability, with tensile strength reaching 740kPa and tensile strain greater than 1200%, showing high tensile strength and large tensile strain.

[0037] 2. Excellent and extensive adhesion. The elastomer of the present invention exhibits good adhesion to a variety of substrates (such as PET film, glass, copper sheet, pigskin, etc.). In the 90° peel strength test, the maximum peel strength for PET film reached 100.00N / m, copper sheet was 30.74N / m, glass was 18.62N / m, plastic wrap was 19.80N / m, and pigskin was 11.48N / m. This shows that the elastomer of the present invention is suitable for a variety of application scenarios, especially for the bonding of flexible plastic substrates, such as medical patches and flexible electronics.

[0038] 3. Excellent self-healing properties. The elastomer of this invention recovers its tensile strain to 66.67% of its original value after 12 hours of self-recovery after shearing, and to 122.67% of its original value after 24 hours of self-recovery. This self-healing capability effectively extends the material's service life and has important applications in flexible electronics and structural materials requiring long-term durability.

[0039] 4. Significant hydrophobicity. The elastomer of this invention has low water absorption, with only a small amount of water adsorbed on its surface after 10 days of immersion in water. The water contact angle reaches 109.5°, indicating excellent hydrophobicity on the surface. The adhesion and mechanical properties of the elastomer of this invention are largely unaffected in underwater environments, making it ideal for applications such as underwater sensors and waterproof coatings.

[0040] 5. Simple preparation process and adjustable mechanical properties. Rapid preparation via UV-initiated polymerization eliminates the need for complex equipment or high-temperature reactions. By adjusting the ratio of monomer to crosslinker, material properties can be flexibly controlled to meet diverse application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flow chart for the preparation of hydrophobic elastomer;

[0042] Figure 2 The tensile stress-strain curves of the elastomers obtained in Examples 1 to 5 are shown;

[0043] Figure 3 90° peeling curves of the elastomer obtained in Example 3 on various surfaces of adhesion;

[0044] Figure 4 Graph showing the tensile stress-strain curves of the elastomer obtained in Example 3 before and after self-repair;

[0045] Figure 5 This is a graph showing the change in water absorption of the elastomer obtained in Example 4 when immersed in water over time;

[0046] Figure 6 This is a contact angle test photo of the elastomer obtained in Example 5. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0048] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0049] Example 1

[0050] Operation process as follows Figure 1 As shown, lauryl methacrylate and tridecafluorooctyl methacrylate were added to a reaction vessel in a molar ratio of 3:7. A photoinitiator, 1-hydroxycyclohexyl phenyl ketone, was then added in an amount equal to 0.2% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. Finally, a crosslinker, 1,6-hexanediol diacrylate, was added in an amount equal to 0.2% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. After stirring and mixing thoroughly, nitrogen was introduced into the mixture for 10 minutes. The mixture was then transferred to a silicone mold and irradiated under a 365nm UV lamp for 30 minutes to produce an elastomer with self-adhesive, self-healing, and hydrophobic properties.

[0051] Example 2

[0052] Operation process as follows Figure 1 As shown, lauryl methacrylate and tridecafluorooctyl methacrylate were added to a reaction vessel in a molar ratio of 4:6. A photoinitiator, 1-hydroxycyclohexyl phenyl ketone, was then added in an amount equal to 0.5% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. A crosslinker, 1,6-hexanediol diacrylate, was then added in an amount equal to 0.5% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. After stirring and mixing thoroughly, nitrogen was introduced into the mixture for 20 minutes. The mixture was then transferred to a silicone mold and irradiated under a 365nm UV lamp for 20 minutes to produce an elastomer with self-adhesive, self-healing, and hydrophobic properties.

[0053] Example 3

[0054] Operation process as follows Figure 1 As shown, lauryl methacrylate and tridecafluorooctyl methacrylate were added to a reaction vessel in a molar ratio of 5:5. A photoinitiator, 1-hydroxycyclohexyl phenyl ketone, was then added in an amount equal to 1.0% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. Finally, a crosslinker, 1,6-hexanediol diacrylate, was added in an amount equal to 1.0% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. After stirring and mixing, nitrogen was introduced into the mixture for 20 minutes. The mixture was then transferred to a silicone mold and irradiated under a 365nm UV lamp for 25 minutes to produce an elastomer with self-adhesive, self-healing, and hydrophobic properties.

[0055] Example 4

[0056] Operation process as follows Figure 1 As shown, lauryl methacrylate and tridecafluorooctyl methacrylate were added to a reaction vessel in a molar ratio of 6:4. Benzophenone, a photoinitiator, was then added in an amount equal to 1.5% of the total molar amount of lauryl methacrylate and tridecafluorooctyl methacrylate. Ethylene glycol diacrylate, a crosslinker, was then added in an amount equal to 1.0% of the total molar amount of lauryl methacrylate and tridecafluorooctyl methacrylate. After stirring and mixing, nitrogen was introduced into the mixed solution for 30 minutes. The mixed solution was then transferred to a silicone mold and irradiated under a 365nm wavelength ultraviolet lamp for 20 minutes to produce an elastomer with self-adhesive, self-healing, and hydrophobic properties.

[0057] Example 5

[0058] Operation process as follows Figure 1As shown, lauryl methacrylate and tridecafluorooctyl methacrylate were added to a reaction vessel in a molar ratio of 7:3. Benzophenone, a photoinitiator, was then added in an amount equal to 0.5% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. Ethylene glycol diacrylate, a crosslinker, was then added in an amount equal to 2.0% of the total molar ratio of lauryl methacrylate and tridecafluorooctyl methacrylate. After stirring and mixing, nitrogen was bubbled through the mixture for 20 minutes. The mixture was then transferred to a silicone mold and irradiated under a 365nm UV lamp for 25 minutes to produce an elastomer with self-adhesive, self-healing, and hydrophobic properties.

[0059] Comparative Examples 1 to 4

[0060] The technical solutions of Comparative Examples 1 to 4 are similar to that of Example 1, except that the molar ratios of lauryl methacrylate and tridecafluorooctyl methacrylate are 1:9, 2:8, 9:1 and 8:2, respectively.

[0061] Test Method

[0062] 1. Tensile strength

[0063] The dumbbell-shaped sample (5 mm wide and 1 mm thick) was tested for stress-strain curve using a universal mechanical testing machine at a strain rate of 50.00 mm / min.

[0064] 2. 90° peel strength

[0065] The adhesion of the sample (25 mm in length, 5 mm in width, and 1 mm in thickness) on the surface was tested using a universal mechanical testing machine and a 90° adhesion peeling fixture at a peeling rate of 50.00 mm / min.

[0066] 3. Self-repair

[0067] Cut a 3cm long and 5mm wide elastomer sample in half. Place the two small pieces of sample in close contact at the fractured ends, wrap them in plastic wrap, and store them at room temperature for 12 hours to heal. After 12 hours, perform a stress-strain test.

[0068] 4. Water absorption

[0069] The sample was immersed in pure water for 10 days, and the mass of the sample was measured every day. A line graph of the swelling rate over time was calculated using the following formula.

[0070]

[0071] Where R is the swelling ratio, Mn (g) is the sample mass recorded each day, and M0 (g) is the initial mass of the sample.

[0072] 5. Contact angle

[0073] Use a contact angle tester to measure the contact angle of a water drop on the elastomer surface.

[0074] Result Analysis

[0075] The tensile properties of the elastomer come from the three-dimensional cross-linked network. Lauryl methacrylate provides flexible segments, while tridecafluorooctyl methacrylate provides hydrophobicity and rigidity. The flexible segments give the material high ductility, and the cross-linked structure improves tensile strength. Figure 2 As shown, the tensile strength and strain vary significantly at different ratios of lauryl methacrylate to tridecafluorooctyl methacrylate, demonstrating the tunability of the mechanical properties of the resulting elastomers. In Example 1, a tensile strength of 740 kPa and a tensile strain exceeding 1200% were achieved, demonstrating excellent toughness and balanced properties, making it suitable for applications requiring high strength and elasticity. The hydrophobic elastomers obtained in Examples 2-5 achieved tensile strengths of 480 kPa, 360 kPa, 140 kPa, and 50 kPa, respectively.

[0076] The adhesiveness of the elastomer comes from the flexibility of the molecular chain and the dynamic interaction between molecules. The flexible chain segments can closely adhere to the surfaces of different substrates. The hydrophobic groups and van der Waals forces provide strong adhesion. The elastomer prepared by the present invention can adhere to surfaces such as PET film, copper sheet, pigskin, glass, and plastic wrap. The 90° peel strength is as high as 100%. Figure 3 As shown, the elastomer of Example 3 can achieve a maximum peel strength of 100.00 N / m on PET film, 19.80 N / m on plastic wrap, 18.62 N / m on glass, 30.74 N / m on copper sheet, and 11.48 N / m on pigskin. These results demonstrate that the elastomer of the present invention has excellent self-adhesion properties on a variety of substrates, with the highest adhesion strength being achieved on PET film. This indicates that the material is suitable for bonding to flexible plastic substrates, particularly in applications requiring adhesion properties, such as flexible electronics and medical patches.

[0077] The self-repairing function of the elastomer of the present invention relies on the dynamic interaction between molecules. The hydrophobic interaction and van der Waals force promote the rearrangement and bonding of molecules at the fracture interface. The low surface energy characteristics of the fluorine group reduce the friction resistance of the repair interface. Figure 4 As shown, the original tensile strain of the elastomer in Example 3 is 750%. After being sheared and allowed to self-repair for 12 hours, the tensile strain is 500%. After 24 hours of self-repair, the tensile strain of the elastomer is 920%, indicating that the elastomer of the present invention has excellent self-repair performance. Prolonging the self-repair time can significantly improve the mechanical properties, and the tensile strain after repair can exceed the original value.

[0078] The fluorine group in tridecafluorooctyl methacrylate has low surface energy characteristics, and the surface structure formed hinders the penetration of water molecules. Example 4 After the elastomer is immersed in water for 10 days, the water absorption rate is very low ( Figure 5 ), only a small amount of water is adsorbed on the surface, and the contact angle of water droplets on the surface of the elastomer of Example 5 is 109.5° ( Figure 6 ), the low water absorption rate of the elastomer of the present invention reflects its significant hydrophobicity. When used in an underwater environment, the material properties will not be significantly affected by water absorption, and it is very suitable for applications such as underwater sensors.

[0079] In the comparative examples, when the molar ratio of lauryl methacrylate to tridecafluorooctyl methacrylate is 1:9 or 2:8, the ratio of the rigid monomer (tridecafluorooctyl methacrylate) is too high, the flexible chain segments are reduced, resulting in sparse crosslinking points, the tensile strength is reduced to about 30kPa, less than 50kPa in Example 5, and much less than 740kPa in Example 1, and the elongation at break is about 400%. When the molar ratio of lauryl methacrylate to tridecafluorooctyl methacrylate is 9:1 or 8:2, the ratio of the flexible monomer (lauryl methacrylate) is too high, resulting in a weakened dynamic interaction between the molecular chains, a decrease in the crosslinking network density, insufficient rigid support, and thus reduced adhesion. The adhesion of the elastomer material will decrease. Therefore, the protection scope proposed by the present invention is superior. Due to the imbalance of the monomer ratio in Comparative Examples 1 to 4, both the mechanical properties and adhesion are significantly reduced, and the performance is not enough to meet the requirements of high strength and high adhesion. Therefore, the present invention finds the optimal balance between the ratio of flexible and rigid monomers to obtain an elastomer material with excellent mechanical properties and adhesion properties.

[0080] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A hydrophobic elastomer, characterized in that: The invention is prepared from lauryl methacrylate, tridecafluorooctyl methacrylate, a photoinitiator and a crosslinking agent; the molar ratio of lauryl methacrylate to tridecafluorooctyl methacrylate is 3-7:7-3; the crosslinking agent is an acrylate crosslinking agent; and the content of the crosslinking agent is 0.2%-2% of the total amount of lauryl methacrylate and tridecafluorooctyl methacrylate.

2. The hydrophobic elastomer according to claim 1, characterized in that: The photoinitiator is an oil-soluble photoinitiator; the content of the photoinitiator is 0.2% to 1.5% of the total amount of lauryl methacrylate and tridecafluorooctyl methacrylate.

3. The hydrophobic elastomer according to claim 1, characterized in that: The contact angle of water on the surface of the hydrophobic elastomer is greater than 100°.

4. The hydrophobic elastomer according to claim 1, characterized in that: The hydrophobic elastomer is cut and self-repaired for 12 to 24 hours, and the tensile strain of the self-repaired hydrophobic elastomer is 500% to 920%.

5. A method for preparing the hydrophobic elastomer according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: uniformly mixing lauryl methacrylate, tridecafluorooctyl methacrylate, a photoinitiator and a crosslinking agent; introducing an inert gas; and irradiating the mixture with ultraviolet light to obtain the hydrophobic elastomer.

6. The method for preparing a hydrophobic elastomer according to claim 5, characterized in that: Pass inert gas for 10 to 30 minutes; irradiate under ultraviolet light for 20 to 30 minutes.

7. Use of the hydrophobic elastomer according to any one of claims 1 to 4, characterized in that: The hydrophobic elastomer has self-adhesive force and can be used for adhering to objects; the objects include metal, plastic, glass, and skin.

8. Use of the hydrophobic elastomer according to any one of claims 1 to 4, characterized in that: Used in the preparation of flexible electronics, medical patches, underwater sensors and waterproof materials.

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