A method for hydrophilic modification of UHMWPE ultra-thin film
By using an extremely dilute polyvinyl alcohol solution to hydrophilically modify UHMWPE ultrafilms through dip coating, the problem of membrane integrity destruction caused by modification methods in the prior art is solved, and the hydrophilicity of UHMWPE ultrafilms is improved while mechanical stability is maintained.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SICHUAN UNIV
- Filing Date
- 2024-11-12
- Publication Date
- 2026-05-19
AI Technical Summary
In the prior art, surface modification methods for ultra-high molecular weight polyethylene (UHMWPE) ultrafilms are prone to causing damage to the integrity of the film, and existing modification methods are difficult to effectively improve its hydrophilicity.
The UHMWPE ultrafilm was hydrophilically modified by dip coating with an extremely dilute polyvinyl alcohol solution. The specific steps included preparing a 0.0001-10% polyvinyl alcohol solution and immersing the UHMWPE ultrafilm completely in the solution at 40-80℃ for 8-15 hours before drying.
The hydrophilicity of the UHMWPE ultrathin film surface was improved, and the water contact angle was reduced by more than 40°, making the film change from hydrophobic to hydrophilic, while maintaining the integrity and mechanical stability of the film.
Smart Images
Figure CN119463261B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a method for hydrophilic modification of UHMWPE ultrathin films. Background Technology
[0002] In some cases, polyethylene (PE) products require surface modification before use. This modification can be categorized into three main types: chemical, physical, and polymer processing. Physical methods include ultraviolet light, plasma, corona treatment, or flame treatment, which have the advantage of negligible changes to intrinsic properties. However, this physical modification may be superficial and susceptible to environmental degradation, leading to a decline in modification effectiveness. Chemical methods often require chemical reagents or catalysts to oxidize, sulfonate, ammonify, graft, or crosslink the PE surface, introducing various functional groups to improve hydrophilicity, antibacterial properties, and antifouling properties. Polymer processing methods mainly involve modifying the polyethylene surface through polymer blending, co-extrusion, and compounding. This method can achieve a variety of surface modification goals and has scalable production capabilities, but may also be affected by increased costs or operational complexity. In addition to chemical treatment, chemical reactions may also occur during physical and processing modification. Because the C / C bond has a low dissociation energy from the CH bond (80 kcal / mol vs. 100 kcal / mol), carbon skeleton breakage almost inevitably leads to chain breakage. This modification then results in a decrease in the molecular weight and mechanical robustness of the PE product.
[0003] Currently, there is limited research on the polar modification of the surface of ultra-high molecular weight polyethylene (UHMWPE) ultrafilms. Existing techniques for modifying common bulk, rod-shaped, or thin sheet-like polyolefin materials typically involve introducing free radicals: for example, plasma treatment, ultraviolet irradiation, electrochemical ion generation, and grafting reactions. However, for UHMWPE ultrafilms, if any of these modification methods are used to disrupt the surface molecular chains to introduce free radicals and subsequently graft polar functional groups or provide redox sites, based on the applicant's previously prepared UHMWPE ultrafilm (CN 113263747B, A large-area UHMWPE ultrafilm and its preparation method), its thickness of less than 200 nm is equivalent to the characteristic size of several or even a single shish-kebab, which means macroscopic destruction of the entire ultrafilm.
[0004] Therefore, a gentle yet effective modification method is needed to modify UHMWPE ultrathin films to ensure their integrity. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides a method for hydrophilic modification of UHMWPE ultrathin films, which uses an extremely dilute polyvinyl alcohol solution to perform hydrophilic modification on the surface of the UHMWPE ultrathin film via dip coating.
[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:
[0007] A method for hydrophilic modification of UHMWPE ultrathin films, comprising the following steps:
[0008] S1: Prepare an extremely dilute polyvinyl alcohol solution;
[0009] S2: The UHMWPE ultrafilm was surface-modified with hydrophilicity using the polyvinyl alcohol solution prepared in step S1 by dip coating.
[0010] Further, the extremely dilute polyvinyl alcohol solution refers to a polyvinyl alcohol solution with a mass concentration of 0.0001-10%. The mass concentration of 0.0001-10% can include any individual value within this range, such as, but not limited to, 0.0001%, 0.001%, 0.01%, 0.1%, 0.5%, 10%, etc., and any range between the individual values, such as 0.0001-0.1%, 0.0001-0.01%, etc.
[0011] Furthermore, the polyvinyl alcohol solution is prepared as follows: weigh polyvinyl alcohol and deionized water according to the required mass concentration, mix them, and heat to dissolve.
[0012] Furthermore, the heating temperature is 80-90℃.
[0013] Further, the surface hydrophilic modification in step S2 includes the following steps: completely immersing the UHMWPE ultrafilm in the polyvinyl alcohol solution, maintaining it at 40-80°C for 8-15 hours, and then drying it.
[0014] Furthermore, the immersion can be performed on any suitable apparatus. For example, it can be performed on a polytetrafluoroethylene (PTFE) sheet with grooves. In this example, the UHMWPE ultrafilm can be placed in a groove on the PTFE sheet, and a very dilute polyvinyl alcohol solution can be slowly poured into the groove until the UHMWPE ultrafilm is submerged. The entire PTFE sheet is then kept at a constant temperature for 8–15 hours, after which the UHMWPE ultrafilm is dried.
[0015] Furthermore, the molecular weight of the UHMWPE is between 1 million and 10 million.
[0016] Furthermore, the thickness of the UHMWPE ultrathin film is 70-500 nanometers.
[0017] Furthermore, the thickness of the UHMWPE ultrathin film is between 70 and 200 nanometers.
[0018] The UHMWPE ultrathin films described herein are commercially available or can be prepared from UHMWPE itself. Methods for preparing ultrathin films from UHMWPE are known to those skilled in the art. For example, the method disclosed in invention patent CN113263747B can be used to prepare the UHMWPE ultrathin films described herein, or, for example, ultra-high molecular weight polyethylene and a solvent can be stirred and melt-blended to form a suspension, followed by intensive mixing, high-temperature pressing to form a gel film, and then subjected to multi-step stretching, annealing, and extraction to form a film with a thickness of 70-500 nanometers.
[0019] Another object of the present invention is to provide a surface-modified hydrophilic UHMWPE ultrafilm prepared by the hydrophilic modification method described herein.
[0020] Beneficial effects of the invention
[0021] The hydrophilic modification method for UHMWPE ultrathin films of the present invention includes preparing an extremely dilute polyvinyl alcohol solution and performing hydrophilic modification on the surface of the UHMWPE ultrathin film by dip coating. Through a gentle and effective modification method, the integrity of the UHMWPE ultrathin film is guaranteed.
[0022] The hydrophilic modification method for UHMWPE ultrathin films of the present invention benefits from the ultrathin size of UHMWPE ultrathin films. When the surface of UHMWPE ultrathin films is modified, it is almost a modification of the entire UHMWPE ultrathin film.
[0023] The present invention provides a method for hydrophilic modification of UHMWPE ultrathin films, which modifies the surface of UHMWPE ultrathin films by dip coating, so that polyvinyl alcohol can enter the UHMWPE ultrathin films and improve their surface hydrophilicity.
[0024] The hydrophilic modification method for UHMWPE ultrathin films of this invention can reduce the water contact angle by more than 40° when the weight fraction of polyvinyl alcohol in the polyvinyl alcohol solution is only 0.0001%, thereby changing the UHMWPE film from a hydrophobic surface to a hydrophilic surface. As the concentration of the polyvinyl alcohol solution used for dip coating of UHMWPE ultrathin films increases, the water contact angle of the UHMWPE ultrathin film surface gradually decreases, and its hydrophilicity gradually increases.
[0025] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description
[0026] Figure 1These are photographs of the water contact angles of UHMWPE ultrathin films coated with different PVA concentrations according to embodiments of the present invention.
[0027] Figure 2 These are SEM images of UHMWPE ultrathin films coated with different PVA concentrations according to embodiments of the present invention.
[0028] Figure 3 These are AFM images of the surface of UHMWPE ultrathin films coated with different concentrations of PVA according to embodiments of the present invention.
[0029] Figure 4 XRD patterns of UHMWPE ultrathin films modified with PVA at different concentrations.
[0030] Figure 5 SEM images of UHMWPE ultrathin films treated with plasma.
[0031] Figure 6 Energy spectrum of UHMWPE ultrathin films treated with plasma.
[0032] Figure 7 This is a flowchart illustrating the preparation process of PVA-modified UHMWPE ultrathin films.
[0033] Figure 8 SEM images of three membrane materials modified with 0.01% PVA.
[0034] Figure 9 WCA diagrams for three membrane materials modified with 0.01% PVA.
[0035] Figure 10 The images show the SEM and WCA images of the UHMWPE ultrafilm modified with chitosan. Detailed Implementation
[0036] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.
[0037] The UHMWPE ultrathin film is an ultrathin film with a thickness of 200 nanometers made of ultra-high molecular weight polyethylene. It is prepared using conventional methods known in the art. For example, ultra-high molecular weight polyethylene and solvent can be stirred and melted to form a suspension, which is then kneaded and pressed at high temperature to form a gel film. After multiple stretching, annealing and extraction, a film with a thickness of 200 nanometers is formed.
[0038] Example
[0039] A method for hydrophilic modification of UHMWPE ultrathin films includes:
[0040] S1: Prepare an extremely dilute polyvinyl alcohol solution;
[0041] S2: The extremely dilute polyvinyl alcohol solution prepared by S1 was used to perform surface hydrophilic modification on UHMWPE ultrafilm by dip coating.
[0042] In this embodiment, the extremely dilute polyvinyl alcohol solution is prepared as follows:
[0043] A PVA solution was prepared using a dissolution method, wherein the solvent was deionized water and the solute was PVA.
[0044] The preparation process is as follows: PVA raw materials (weighed according to the weight fraction of the solution of 0.1%, 0.01%, 0.001%, 0.1%, 0.5%, and 10%) and deionized water are weighed using an electronic balance;
[0045] Place the weighed raw materials into a three-necked flask, then add deionized water, and heat them thoroughly in an oil bath at 95°C. Stir magnetically during heating to facilitate the complete dissolution of PVA. Once fully dissolved, remove the flask and let it cool for later use.
[0046] In this embodiment, the surface of the UHMWPE ultrafilm is hydrophilically modified using an extremely dilute polyvinyl alcohol solution via dip-coating:
[0047] The UHMWPE ultrathin film is placed in a square polytetrafluoroethylene plate with a groove, and then the prepared PVA extremely dilute solution is slowly poured into the groove containing the UHMWPE film so that the PVA dilute solution can completely immerse the UHMWPE ultrathin film.
[0048] The entire device is placed on a hot plate and kept at 60°C for 12 hours to allow the PVA solution to fully impregnate the UHMWPE. Then, the solvent (water) on the membrane surface is dried in an oven. This method allows PVA to enter the PE membrane and improve its surface hydrophilicity.
[0049] The water contact angle of the hydrophilic modified UHMWPE ultrafilm prepared in this embodiment was tested, and the results are shown in Table 1 and... Figure 1-3 As shown:
[0050] Table 1: Water contact angles of UHMWPE coated with different PVA concentrations
[0051] PVA (%) 10wt 5wt 0.5wt 0.1wt 0.01wt 0.001wt 0.0001wt 0wt WCA(°) 42 53 60 66 70 73 82 125
[0052] The water contact angle of unmodified UHMWPE is 125°, while that of UHMWPE after PVA dipping is reduced to 82° with a concentration of only 0.0001%, a decrease of more than 40°, thus changing the UHMWPE membrane from a hydrophobic surface to a hydrophilic surface. As the concentration of the PVA solution used for dipping the UHMWPE membrane increases, the water contact angle of the UHMWPE membrane surface gradually decreases, and its hydrophilicity gradually increases.
[0053] Figure 1 The images show the water contact angles of UHMWPE ultrafilms coated with different PVA concentrations.
[0054] Figure 2 SEM images of UHMWPE ultrafilms coated with different PVA concentrations are shown.
[0055] Figure 3 AFM images of the surface of UHMWPE ultrafilms after dip coating with different PVA concentrations are shown.
[0056] Figure 4 The XRD patterns of UHMWPE ultrafilms modified with different concentrations of PVA are shown in the figure. Compared with the XRD patterns of pure PE and pure PVA, the XRD patterns of PVA-PE composite films with different loadings show that different loadings of PVA do not change the crystal structure of the PE film itself. The characteristic peaks of PE are shown on both the (110) and (200) planes of PE. The characteristic peaks of PVA are not obvious in the low loading composite film. This is because the PVA loading is too low and the signal is too weak, which is blocked by the PE signal.
[0057] Comparative Example 1
[0058] Plasma-treated UHMWPE ultrathin film samples were prepared using conventional methods known in the art, and significant deformation of the fibers on the sample surface was observed. For example... Figure 5 As shown, Figure 5 -The left image is a scanning electron microscope image of pure PE. Figure 5 - The right image shows a PE membrane after plasma treatment. It can be seen that the untreated membrane surface has smooth, non-adhesive fiber bundles and relatively fine fibers; after plasma treatment, the fiber bundle surface becomes rough, the fibers become thicker, and they adhere together. This is due to the introduction of C=O double bonds, leading to partial oxidation of the polyethylene. Although the hydrophilicity of the polyethylene membrane surface changes significantly after plasma treatment, the structure of the polyethylene is altered, resulting in reduced mechanical properties and increased brittleness and breakage of the ultra-thin polyethylene membrane.
[0059] Comparative Example 2
[0060] As described in the examples, samples of three PE film materials with relatively large thicknesses (including two types of PE films and one type of PTFE film with relatively large thicknesses) were treated with 0.01% PVA using a dip-coating method. The 1.8 μm PE film was a biaxially oriented polyethylene film with a draw ratio of 9x9=81; the 16 μm PE film was a commercial polyethylene battery separator manufactured by Enjie; and the 30 μm PTFE film was manufactured by Taizhou Chenguang Plastics Co., Ltd., model CG003). It was found that the fibers on the sample surface all underwent a certain degree of deformation. Figure 8 As shown, Figure 8 -a is a scanning electron microscope image of a 2.5 μm PE film. Figure 8 -d is a scanning electron microscope image of the modified 2.5μm PE film. Figure 8 -b is a scanning electron microscope image of a 16μm commercial PE battery separator. Figure 8 -e is a scanning electron microscope image of the modified 16μm commercial PE battery separator. Figure 8 -c is a scanning electron microscope image of a 30 μm PTFE film. Figure 8 -f shows a scanning electron microscope (SEM) image of the modified 30 μm PTFE membrane. For the 2.5 μm and 16 μm PE membranes, it can be seen that the surface fiber bundles are smooth, non-adhesive, and relatively thin in the unmodified state. However, after modification, the fiber bundle surface becomes rougher, the fiber bundles become thicker and adhere together, and the 16 μm PE membrane shows a significant reduction in pore blockage. The 30 μm PTFE membrane, being non-porous, shows almost no change in surface morphology before and after modification. Figure 9 As shown, after modification with 0.01% PVA, the water contact angle of all three thick film samples decreased, but the change was not significant, indicating that the hydrophilic modification effect was not obvious. This suggests that PVA's hydrophilic modification effect on thick films is not as good as that on ultrathin films.
[0061] Comparative Example 3
[0062] According to the method described in the examples, the UHMWPE sample was treated with a chitosan solution via dip-coating, such as... Figure 10 As shown, the surface morphology and water contact angle of the treated UHMWPE sample are almost unchanged, indicating a poor hydrophilic modification effect.
[0063] It should be noted that while the preferred embodiments of the present invention are given in the specification and accompanying drawings, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A method for hydrophilic modification of UHMWPE ultrathin films, characterized in that, Includes the following steps: S1: Prepare a polyvinyl alcohol solution with a mass concentration of 0.0001%; S2: The UHMWPE ultrafilm was surface-modified with hydrophilicity using the polyvinyl alcohol solution prepared in step S1 by dip coating. The surface hydrophilic modification in step S2 includes the following steps: completely immersing the UHMWPE ultrafilm in the polyvinyl alcohol solution, maintaining it at 60°C for 8-15 hours, and then drying it; The thickness of the UHMWPE ultrathin film is 70-500 nanometers.
2. The hydrophilic modification method according to claim 1, characterized in that, The polyvinyl alcohol solution is prepared as follows: Weigh polyvinyl alcohol and deionized water according to the required mass concentration, mix them, and heat to dissolve.
3. The hydrophilic modification method according to claim 2, characterized in that, The heating temperature is 80-90℃.
4. The hydrophilic modification method according to claim 1, characterized in that, The immersion is carried out in a grooved polytetrafluoroethylene plate.
5. The hydrophilic modification method according to claim 1, characterized in that, The molecular weight of the UHMWPE is between 1 million and 10 million.
6. A surface-modified hydrophilic UHMWPE ultrathin film, prepared by any one of claims 1-5.