Silicon-containing polyurethane-modified shear-hardening gels and methods for making the same
By preparing a silicon-containing polyurethane modified shear hardening gel, and utilizing the dynamic BO bonds and Si-O bonds to form a weakly cross-linked network structure, the problem of insufficient creep resistance of shear hardening gel was solved, and superior creep resistance and shear hardening performance were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI XINGXIN MATERIAL TECH CO LTD
- Filing Date
- 2023-07-12
- Publication Date
- 2026-07-28
AI Technical Summary
Existing shear-hardening gels have poor creep resistance and low modulus, which limits their application.
By preparing a silicon-containing polyurethane modified shear-hardening gel, dynamic BO bonds are formed by the reaction of hydroxyl-terminated polydimethylsiloxane with boric acid, which combine with the Si-O bonds in the silicon-containing polyurethane to form a weakly cross-linked network structure, thereby enhancing the creep resistance.
It significantly improves the creep resistance and shear hardening properties of the gel, and enhances the material's flexibility and impact resistance.
Smart Images
Figure CN116855085B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite material preparation technology, specifically to a silicon-containing polyurethane modified shear-hardening gel and its preparation method. Background Technology
[0002] Shear stiffening gel (SG) is a typical example. SG, a novel non-Newtonian fluid material, is a low-crosslinked polyborosiloxane composed of dynamic "BO" bonds. Its mechanical properties can respond reversibly to changes in shear force, exhibiting a "soft-hard" response, thus achieving good impact resistance in flexible materials. It is a physically responsive smart material integrating responsiveness and self-healing capabilities. However, pure SG itself has poor creep resistance and a low modulus, limiting its applications.
[0003] In their paper "Preparation and Impact Resistance Study of Shear Thickening Adhesive / Calcium Carbonate Composites," Zong Hao et al. proposed preparing a shear thickening composite material with excellent buffering and energy absorption properties by using a shear thickening adhesive as the matrix and reinforcing it with nano-CaCO3. The addition of CaCO3 increased the maximum storage modulus of the composite material, allowing it to absorb more impact force with minimal deformation. However, this method is prone to particle accumulation.
[0004] Chinese patent application CN113072810A discloses a cross-linked starch-reinforced composite shear-thickening elastomer. This elastomer combines cross-linked starch with a shear-thickening adhesive to form a polymer network structure, solving the cold flow problem of traditional shear-thickening materials. It also offers better processability, initial elastic modulus, and elastic recovery, which helps maintain overall protective performance over long-term use without degradation. However, this method simply combines starch with a shear-thickening adhesive, resulting in problems of agglomeration and uneven dispersion. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a shear hardening gel with good anti-creep effect and excellent shear hardening performance.
[0006] The present invention solves the above-mentioned technical problems through the following technical means:
[0007] A method for preparing a silicone-containing polyurethane modified shear-hardening gel includes the following steps:
[0008] S1. Hydroxyl-terminated polydimethylsiloxane, hexamethylene diisocyanate and dibutyltin dilaurate are mixed and then nitrogen gas is introduced. After heating, the mixture is dried and extracted to obtain silicone polyurethane.
[0009] S2. Hydroxyl-terminated polydimethylsiloxane is mixed with boric acid and heated to react. After the reaction is completed, it is cooled to room temperature to obtain a shear-hardened gel.
[0010] S3. Dissolve the shear hardening gel and the silicone polyurethane in ethanol, stir evenly, and then remove the solvent to obtain the silicone polyurethane modified shear hardening gel.
[0011] Preferably, in S1, the molar ratio of the hydroxyl-terminated polydimethylsiloxane to hexamethylene diisocyanate is 5-5.5:4.
[0012] Preferably, in S1, the molar amount of dibutyltin dilaurate is 0.1-0.6% of the molar amount of hydroxyl-terminated polydimethylsiloxane.
[0013] Preferably, in S1, the reaction is carried out after heating to 55-65°C for 2-3 hours.
[0014] Preferably, in S1, the drying temperature is 65-75°C and the time is 70-75 hours.
[0015] Preferably, in S1, the extraction time is 20-25 hours, and the solvent used is n-hexane.
[0016] Preferably, in S2, the mass ratio of the hydroxyl-terminated polydimethylsiloxane to boric acid is 15-25:1.
[0017] Preferably, in S2, the mixture is heated to 175-185°C and reacted for 1-3 hours, and during the reaction, it is stirred at 100-150 rpm for 3-8 minutes every half hour.
[0018] Preferably, in S3, the mass ratio of the shear-hardening gel to the silicone-containing polyurethane is 4-5:1.
[0019] Preferably, the weight-average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500-2000.
[0020] The present invention also proposes a silicone polyurethane modified shear hardening gel, which is prepared by the aforementioned method for preparing silicone polyurethane modified shear hardening gel.
[0021] The reaction formula for preparing silicone-containing polyurethane is as follows:
[0022]
[0023] The diagram below illustrates the role of BO bonds in silicone-containing polyurethane modified shear-hardening gel:
[0024]
[0025] The advantages of this invention are:
[0026] (1) Silicon polyurethane contains silicon, which has a similar structure to the silicon in shear hardening gel. According to the principle of like dissolves like, the two have excellent compatibility and will not agglomerate.
[0027] (2) The urethane bonds in the silicone polyurethane can form dynamic BO bonds with the boron element in the shear hardening gel, effectively enhancing the interaction force between molecular chains. Moreover, due to the presence of a large number of Si-O bonds, the silicone polyurethane has excellent molecular chain flexibility and can form a good entanglement structure with the molecular chain of the shear hardening gel. After being impacted and stretched, it has even better cold flow resistance.
[0028] (3) Since the polydimethylsiloxane with hydroxyl end is in excess in the silicone polyurethane system, the end group is hydroxyl. After being compounded with shear hardening gel, the hydroxyl end may undergo dehydration and etherification reaction with B-OH. However, since it is a blend of macromolecular chains, the reactivity is not strong. Therefore, a weak cross-linked network structure is formed, which can enhance the creep resistance. Attached Figure Description
[0029] Figure 1 The creep curves of the shear hardening gel in Example 1 of this invention and a commercially available shear hardening gel are shown.
[0030] Figure 2 The creep curves of the shear hardening gel in Example 2 of this invention and a commercially available shear hardening gel are shown.
[0031] Figure 3 The creep curves of the shear hardening gel in Example 3 of this invention and a commercially available shear hardening gel are shown.
[0032] Figure 4 This is a schematic diagram of the drop hammer impact of the present invention;
[0033] Figure 5 The impact force diagrams for the base under a 30cm drop hammer height in Embodiments 1-3 of the present invention and for commercially available shear hardening gel are shown.
[0034] Figure 6 The images shown are SEM images of Examples 1-3 of the present invention and commercially available shear hardening gels. Detailed Implementation
[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.
[0037] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.
[0038] The hydroxyl-terminated polydimethylsiloxane described in the following examples has a weight-average molecular weight of 1000.
[0039] Example 1
[0040] A method for preparing a silicone-containing polyurethane modified shear-hardening gel includes the following steps:
[0041] (1) Five molar amounts of hydroxyl-terminated polydimethylsiloxane and four molar amounts of hexamethylene diisocyanate were placed in a reactor equipped with a stirrer, a spherical condenser was installed, 0.005 molar amounts of dibutyltin dilaurate were added, nitrogen gas was introduced, and the reactor was heated to 60°C and reacted for 2.5 h to obtain a silicone-containing polyurethane solution. The silicone-containing polyurethane solution was placed in a vacuum drying oven and dried at 70°C for 72 h, then extracted with n-hexane as solvent for 24 h, and dried at 70°C for 72 h to obtain silicone-containing polyurethane.
[0042] (2) Weigh hydroxyl-terminated polydimethylsiloxane and boric acid at a mass ratio of 20:1, pour them into a reactor and stir evenly. Heat to 180°C and react for 2 hours. During the reaction, stir at 100 rpm for 5 minutes every half hour. After the reaction is completed, cool to room temperature and take out the product from the reactor to obtain shear-hardened gel.
[0043] (3) Dissolve the prepared shear hardening gel and the silicone polyurethane in ethanol at a mass ratio of 5:1, stir evenly, and then place the sample in a vacuum oven at 60°C to remove the solvent to obtain the silicone polyurethane modified shear hardening gel.
[0044] Example 2
[0045] A method for preparing a silicone-containing polyurethane modified shear-hardening gel includes the following steps:
[0046] (1) Five molar amounts of hydroxyl-terminated polydimethylsiloxane and four molar amounts of hexamethylene diisocyanate were placed in a reactor equipped with a stirrer, a spherical condenser was installed, 0.005 molar amounts of dibutyltin dilaurate were added, nitrogen gas was introduced, and the reactor was heated to 60°C and reacted for 2.5 h to obtain a silicone-containing polyurethane solution. The silicone-containing polyurethane solution was placed in a vacuum drying oven and dried at 70°C for 72 h, then extracted with n-hexane as solvent for 24 h, and dried at 70°C for 72 h to obtain silicone-containing polyurethane.
[0047] (2) Weigh hydroxyl-terminated polydimethylsiloxane and boric acid at a mass ratio of 20:1, pour them into a reactor and stir evenly. Heat to 180°C and react for 2 hours. During the reaction, stir at 100 rpm for 5 minutes every half hour. After the reaction is completed, cool to room temperature and take out the product from the reactor to obtain shear-hardened gel.
[0048] (3) Dissolve the prepared shear hardening gel and the silicone polyurethane in ethanol at a mass ratio of 4.5:1, stir evenly, and then place the sample in a vacuum oven at 60°C to remove the solvent to obtain the silicone polyurethane modified shear hardening gel.
[0049] Example 3
[0050] A method for preparing a silicone-containing polyurethane modified shear-hardening gel includes the following steps:
[0051] (1) Five molar amounts of hydroxyl-terminated polydimethylsiloxane and four molar amounts of hexamethylene diisocyanate were placed in a reactor equipped with a stirrer, a spherical condenser was installed, 0.005 molar amounts of dibutyltin dilaurate were added, nitrogen gas was introduced, and the reactor was heated to 60°C and reacted for 2.5 h to obtain a silicone-containing polyurethane solution. The silicone-containing polyurethane solution was placed in a vacuum drying oven and dried at 70°C for 72 h, then extracted with n-hexane as solvent for 24 h, and dried at 70°C for 72 h to obtain silicone-containing polyurethane.
[0052] (2) Weigh hydroxyl-terminated polydimethylsiloxane and boric acid at a mass ratio of 20:1, pour them into a reactor and stir evenly. Heat to 180°C and react for 2 hours. During the reaction, stir at 100 rpm for 5 minutes every half hour. After the reaction is completed, cool to room temperature and take out the product from the reactor to obtain shear-hardened gel.
[0053] (3) Dissolve the prepared shear hardening gel and the silicone polyurethane in ethanol at a mass ratio of 4:1, stir evenly, and then place the sample in a vacuum oven at 60°C to remove the solvent to obtain the silicone polyurethane modified shear hardening gel.
[0054] Example 4
[0055] A method for preparing a silicone-containing polyurethane modified shear-hardening gel includes the following steps:
[0056] (1) 5.5 molar parts of hydroxyl-terminated polydimethylsiloxane and 4 molar parts of hexamethylene diisocyanate were placed in a reactor equipped with a stirrer, a spherical condenser was installed, 0.006 molar parts of dibutyltin dilaurate were added, nitrogen gas was introduced, and the reactor was heated to 55°C and reacted for 3 hours to obtain a silicone-containing polyurethane solution. The silicone-containing polyurethane solution was placed in a vacuum drying oven and dried at 75°C for 70 hours, then extracted with n-hexane as solvent for 24 hours, and dried at 75°C for 70 hours to obtain silicone-containing polyurethane.
[0057] (2) Weigh hydroxyl-terminated polydimethylsiloxane and boric acid at a mass ratio of 15:1, pour them into a reactor and stir evenly. Heat to 185°C and react for 1 hour. During the reaction, stir at 150 rpm for 3 minutes every half hour. After the reaction is completed, cool to room temperature and take out the product from the reactor to obtain shear-hardened gel.
[0058] (3) Dissolve the prepared shear hardening gel and the silicone polyurethane in ethanol at a mass ratio of 4:1, stir evenly, and then place the sample in a vacuum oven at 60°C to remove the solvent to obtain the silicone polyurethane modified shear hardening gel.
[0059] Example 5
[0060] A method for preparing a silicone-containing polyurethane modified shear-hardening gel includes the following steps:
[0061] (1) Five molar parts of hydroxyl-terminated polydimethylsiloxane and four molar parts of hexamethylene diisocyanate were placed in a reactor equipped with a stirrer, a spherical condenser was installed, 0.01 molar parts of dibutyltin dilaurate were added, nitrogen gas was introduced, and the reactor was heated to 65°C for 2 hours to obtain a silicone-containing polyurethane solution. The silicone-containing polyurethane solution was placed in a vacuum drying oven and dried at 65°C for 75 hours, then extracted with n-hexane as solvent for 20 hours, and dried at 65°C for 75 hours to obtain silicone-containing polyurethane.
[0062] (2) Weigh hydroxyl-terminated polydimethylsiloxane and boric acid at a mass ratio of 25:1, pour them into a reactor and stir evenly. Heat to 175°C and react for 3 hours. During the reaction, stir at 100 rpm for 8 minutes every half hour. After the reaction is completed, cool to room temperature and take out the product from the reactor to obtain shear-hardened gel.
[0063] (3) Dissolve the prepared shear hardening gel and the silicone polyurethane in ethanol at a mass ratio of 4:1, stir evenly, and then place the sample in a vacuum oven at 60°C to remove the solvent to obtain the silicone polyurethane modified shear hardening gel.
[0064] The performance of the product in the example was tested using the following method:
[0065] Creep curve testing method: A 20mm thick parallel plate fixture was used, the test temperature was 25℃, and the sample thickness was 1mm. The creep properties of the sample were tested under a pressure of 500Pa. The pressure was applied constantly for 300s, and then released and held for 600s. The changes in polymer properties during the process were recorded. The frequency range of the frequency scan test was 0.1~100rad / s, and the strain was 0.5%.
[0066] Drop weight impact test method: The impact resistance of the sample is tested using a drop weight impact testing machine, as shown in the schematic diagram. Figure 4 As shown, the sample was cut into 3×3×0.4cm pieces. 3 The instrument's hammer head has a mass of 0.33 kg. During the test, the hammer was dropped from different heights of 10-30 cm, and the instrument's computer recorded the corresponding force signal data in real time. The smaller the force on the base, the better the material's impact resistance.
[0067] Figure 1 The creep curves of the shear hardening gel in Example 1 of this invention and a commercially available shear hardening gel are shown. Figure 2 The creep curves of the shear hardening gel in Example 2 of this invention and a commercially available shear hardening gel are shown. Figure 3 The creep curves of the shear-hardening gel in Example 3 of this invention and a commercially available shear-hardening gel are shown. Figure 1-3 As can be seen, the creep deformation variables of the embodiments are all smaller than those of commercially available shear-hardening gels, and they have superior anti-creep properties.
[0068] Figure 5 These are impact force diagrams for the base subjected to a 30cm drop hammer height in Embodiments 1-3 of the present invention and for commercially available shear-hardening gel; (from...) Figure 5 It can be seen that the impact resistance of the embodiments is superior to that of commercially available shear-hardening gels.
[0069] Figure 6 The images show SEM images of Examples 1-3 of the present invention and commercially available shear hardening gels, where (a) is a commercially available shear hardening gel; (b) is Example 1; (c) is Example 2; and (d) is Example 3. It can be seen from the images that the two-phase interface in Figure a is obvious and clear, while the two-phase interface in Figures b, c, and d is blurry, indicating that the compatibility of the products in the examples is better than that of commercially available products.
[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a silicone-containing polyurethane modified shear-hardening gel, characterized in that: Includes the following steps: S1. Hydroxyl-terminated polydimethylsiloxane, hexamethylene diisocyanate, and dibutyltin dilaurate are mixed and then purged with nitrogen gas. The mixture is heated to carry out the reaction. After the reaction is completed, the mixture is dried and extracted to obtain a silicone-containing polyurethane. The molar ratio of hydroxyl-terminated polydimethylsiloxane to hexamethylene diisocyanate is 5-5.5:
4. The weight-average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500-2000. S2. After uniformly mixing hydroxyl-terminated polydimethylsiloxane and boric acid, heat to 175-185℃ and react for 1-3 hours. During the reaction, stir at 100-150 rpm for 3-8 minutes every half hour. After the reaction is completed, cool to room temperature to obtain a shear-hardened gel. The mass ratio of hydroxyl-terminated polydimethylsiloxane to boric acid is 15-25:
1. S3. Dissolve the shear hardening gel and the silicone polyurethane in ethanol, stir evenly, and then remove the solvent to obtain the silicone polyurethane-modified shear hardening gel; the mass ratio of the shear hardening gel to the silicone polyurethane is 4-5:
1.
2. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S1, the molar ratio of the hydroxyl-terminated polydimethylsiloxane to hexamethylene diisocyanate is 5:
4.
3. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S1, the molar amount of dibutyltin dilaurate is 0.1-0.6% of the molar amount of hydroxyl-terminated polydimethylsiloxane.
4. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S1, the mixture is heated to 55-65℃ and reacted for 2-3 hours.
5. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S1, the drying temperature is 65-75°C and the time is 70-75 hours.
6. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S1, the extraction time is 20-25 hours, and the solvent used is n-hexane.
7. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S2, the mass ratio of the hydroxyl-terminated polydimethylsiloxane to boric acid is 20:
1.
8. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to claim 1, characterized in that: In S2, the mixture was heated to 180°C and reacted for 2 hours. During the reaction, the mixture was stirred at 100 rpm for 5 minutes every half hour.
9. The method for preparing the silicone-containing polyurethane modified shear-hardening gel according to any one of claims 1-8, characterized in that: In S3, the mass ratio of the shear-hardening gel to the silicone-containing polyurethane is 4:
1.
10. A silicone-containing polyurethane modified shear-hardening gel, characterized in that: It is prepared by the method of any one of the silicone-containing polyurethane modified shear hardening gels as described in any one of claims 1-9.