A method of modifying an ethyl cellulose film

Abstract

This invention discloses a method for modifying ethyl cellulose membranes, specifically comprising the following steps: adding ethyl cellulose to a solvent and stirring until homogeneous; the solvent being one or more of ethanol, hexamethyldisiloxane, and isopropanol; adding a wetting agent and stirring until homogeneous; obtaining a mixture; allowing the mixture to stand at -40 to -60°C, followed by evaporation under reduced pressure to obtain a preliminary membrane; immersing the preliminary membrane in a plasticizer at a feed-to-liquid ratio of 1:5 to 1:10; adding an antibacterial agent at 0.1% to 1% of the plasticizer volume and subjecting the membrane to ultrasonic treatment; obtaining a semi-finished membrane; rinsing the semi-finished membrane with deionized water and drying at room temperature to obtain a modified ethyl cellulose membrane. The wetting agent helps to adjust the surface tension imbalance, improving the compatibility between components. During solvent evaporation, the smoothness of the membrane surface is improved.

Description

Technical Field

[0001] This invention relates to the field of biomedical material modification technology, and in particular to a method for modifying ethyl cellulose membranes. Background Technology

[0002] Ethyl cellulose is a common cellulose ether material and one of the most widely used water-insoluble cellulose derivatives. It possesses good biocompatibility and chemical stability, making it suitable as a pharmaceutical excipient for coating materials and release inhibitors. Simultaneously, ethyl cellulose exhibits excellent film-forming properties, thus it can be used to prepare chemical membranes for oxygen-nitrogen separation and medical membranes for wound protection. Notably, due to its low cost, ethyl cellulose has garnered significant attention in the medical membrane field.

[0003] Ethyl cellulose membranes are primarily prepared by casting. First, ethyl cellulose of varying viscosities is dissolved in organic solvents such as dichloromethane, ethyl acetate, or ethanol, and then the solution is cast and spread out. After the solvent evaporates, the ethyl cellulose naturally forms a membrane material. However, this type of ethyl cellulose membrane exhibits poor mechanical properties, including high brittleness and susceptibility to breakage. Furthermore, during membrane preparation, the imbalance of liquid surface tension results in a rough surface structure, further affecting the membrane's mechanical properties. Therefore, improvements to the ethyl cellulose membrane preparation process are needed to enhance its application value.

[0004] To improve the performance of ethyl cellulose membranes, they are typically modified during the preparation process, for example, by adding modifiers. CN 106519044 B discloses a tung oil-modified ethyl cellulose membrane and its preparation method, which introduces the flexible segments of modified tung oil into ethyl cellulose. Although this invention can effectively enhance the toughness and wrinkle resistance of ethyl cellulose membranes, the method involves a long process route and relatively harsh reaction conditions, limiting its industrialization.

[0005] WO2022126628A1 combines the advantages of ethyl cellulose and carboxymethyl chitosan to invent a composite membrane with adhesive properties. However, the excessive addition of water-soluble components to this composite membrane weakens its water resistance, thus affecting its service life. CN114763675A discloses a biomass composite material, its preparation method, and its application. It utilizes ionic liquids to adsorb polysaccharide nanofibers onto the surface of biomass microfibers, designing a fully biodegradable filter material. However, this method requires mixing biomass with ionic liquids or solvents containing ionic liquids before air-jet spinning. This increases production costs and time, affecting production efficiency.

[0006] To address the aforementioned technical challenges, it is crucial to develop a gentler modification method that is more suitable for ethyl cellulose membranes. Summary of the Invention

[0007] The purpose of this invention is to provide a method for modifying ethyl cellulose membranes to overcome the shortcomings of the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This application discloses a method for modifying ethyl cellulose membranes, specifically including the following steps: S1. Add ethyl cellulose to the solvent at a material-to-liquid ratio of 1:10 to 1:15 and stir until homogeneous; the solvent is one or more of ethanol, hexamethyldisiloxane, and isopropanol. S2. Add a wetting agent at 10-40% of the mass of ethyl cellulose and stir until homogeneous to obtain a mixture; S3. The mixture obtained in step S2 is allowed to stand at -40~-60℃, and then evaporated under reduced pressure to obtain a preliminary membrane. S4. Immerse the preliminary film obtained in step S3 in plasticizer at a material-to-liquid ratio of 1:5 to 1:10; add antibacterial agent at 0.1% to 1% of the plasticizer volume, and perform ultrasonic treatment to obtain a semi-finished film. S5. Rinse the semi-finished membrane obtained in step S4 with deionized water, and after drying at room temperature, obtain the modified ethyl cellulose membrane.

[0009] Preferably, the viscosity of ethyl cellulose in step S1 is 6~8 mPa·s.

[0010] Preferably, the wetting agent in step S2 is one or more of isopropyl palmitate, triethyl glycerol, polyvinylpyrrolidone, triethanolamine, and polyethylene glycol.

[0011] Preferably, the settling time in step S3 is 0.5~2h.

[0012] Preferably, the pressure of the decompression condition in step S3 is 0.1~10 Pa.

[0013] Preferably, the ultrasonic treatment conditions in step S4 are 80W, 40kHz, and the treatment time is 30~300min.

[0014] Preferably, the plasticizer in step S4 is one or more of ethyl oleate, tributyl citrate, and triethyl citrate.

[0015] Preferably, the antibacterial agent in step S4 is one or more of povidone-iodine, sodium benzoate, methylparaben, and benzalkonium chloride.

[0016] The beneficial effects of this invention are: (1) The surface tension imbalance was adjusted by using the wetting agent, which improved the compatibility between components. During the solvent evaporation process, the smoothness of the film surface was improved.

[0017] (2) Modified ethyl cellulose membrane is a typical resistance-type composite membrane. It couples a highly permeable plasticizer with a porous membrane structure after vacuum evaporation, thereby improving the mechanical properties of the membrane. In particular, the plasticizer can improve the hydrophilicity of the membrane and enhance its adhesion.

[0018] (3) Modified ethyl cellulose membrane has good antibacterial properties, which improves its clinical application value.

[0019] (4) Ultrasonic treatment accelerates the mass transfer of plasticizers and antibacterial agents in the porous membrane structure and improves the mixing efficiency.

[0020] (5) The process of this invention is simple, easy to control, and suitable for industrial production.

[0021] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0022] Figure 1 The images show the morphological appearance of the modified ethyl cellulose membrane obtained after S3 and S5 in Example 1, as well as the morphological appearance of the ethyl cellulose membranes in Comparative Examples 1, 2, and 3.

[0023] Figure 2 This refers to the bacterial contamination status of the membranes in Example 1 and Comparative Example 1. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0025] Example 1: This embodiment provides a method for modifying ethyl cellulose membranes, including the following steps: S1: Add ethyl cellulose (7 mPa·s) to ethanol at a material-to-liquid ratio of 1:10 (w / v) and stir continuously for 30 min at a stirring speed of 600 rpm.

[0026] S2: Add isopropyl palmitate at 20% (w / w) of the mass of ethyl cellulose and stir continuously for 5 min.

[0027] S3: The liquid obtained in S2 was placed at -60°C for 1 h, and then evaporated under reduced pressure (0.1 Pa).

[0028] S4: Immerse the membrane obtained in S3 in triethyl citrate at a feed-to-liquid ratio of 1:10 (w / v). Add povidone-iodine at 0.3% (w / v) of the volume of triethyl citrate and sonicate for 300 min.

[0029] S5: Rinse the membrane obtained in S4 with deionized water and dry it at room temperature to obtain a modified ethyl cellulose membrane.

[0030] Example 2: This embodiment provides a method for modifying ethyl cellulose membranes, including the following steps: S1: Add ethyl cellulose (7 mPa·s) to hexamethyl disiloxane at a feed-to-liquid ratio of 1:12.5 (w / v) and stir continuously for 20 min at a stirring speed of 600 rpm.

[0031] S2: Add triethyl glycerol at 30% (w / w) of the mass of ethyl cellulose and stir continuously for 5 min.

[0032] S3: The liquid obtained in S2 was placed at -40°C for 0.5 h, and then evaporated under reduced pressure (0.1 Pa).

[0033] S4: Immerse the membrane obtained in S3 in triethyl citrate at a feed-to-liquid ratio of 1:10 (w / v). Add sodium benzoate at 0.3% (w / v) of the volume of ethyl oleate and sonicate for 300 min.

[0034] S5: Rinse the membrane obtained in S4 with deionized water and dry it at room temperature to obtain a modified ethyl cellulose membrane.

[0035] Example 3: This embodiment provides a method for modifying ethyl cellulose membranes, including the following steps: S1: Add ethyl cellulose (7 mPa·s) to isopropanol at a feed-to-liquid ratio of 1:15 (w / v) and stir continuously for 60 min at a stirring speed of 600 rpm.

[0036] S2: Add polyvinylpyrrolidone at 40% (w / w) of the mass of ethyl cellulose and stir continuously for 5 min.

[0037] S3: The liquid obtained in S2 was placed at -60°C for 2 hours, and then evaporated under reduced pressure (0.1 Pa).

[0038] S4: Immerse the membrane obtained in S3 in triethyl citrate at a feed-to-liquid ratio of 1:5 (w / v). Add methylparaben at 0.1% (w / v) of the volume of tributyl citrate and sonicate for 150 min.

[0039] S5: Rinse the membrane obtained in S4 with deionized water and dry it at room temperature to obtain a modified ethyl cellulose membrane.

[0040] Example 4 This embodiment provides a method for modifying ethyl cellulose membranes, including the following steps: S1: Add ethyl cellulose (7 mPa·s) to ethanol at a material-to-liquid ratio of 1:10 (w / v) and stir continuously for 30 min at a stirring speed of 600 rpm.

[0041] S2: Add triethanolamine at 10% (w / w) of the mass of ethyl cellulose and stir continuously for 5 min.

[0042] S3: The liquid obtained in S2 was placed at -40°C for 2 h, and then evaporated under reduced pressure (0.1 Pa).

[0043] S4: Immerse the membrane obtained in S3 in ethyl oleate at a feed-to-liquid ratio of 1:5 (w / v). Add benzalkonium chloride at 1% (w / v) of the volume of ethyl oleate and sonicate for 30 min.

[0044] S5: Rinse the membrane obtained in S4 with deionized water and dry it at room temperature to obtain a modified ethyl cellulose membrane.

[0045] Comparative Example 1: Ethyl cellulose (7 mPa·s) was added to ethanol at a feed-to-liquid ratio of 1:10, and the mixture was stirred continuously for 30 min at a stirring speed of 600 rpm. The resulting liquid was placed at -60°C for 1 h, and then evaporated under reduced pressure (0.1 Pa).

[0046] Comparative Example 2: The difference between this comparative example and Example 1 is that povidone-iodine is not added in step S4, while the rest is the same as in Example 1.

[0047] Comparative Example 3: The difference between this comparative example and Example 1 is that triethyl citrate is not added in step S4, while the rest is the same as in Example 1.

[0048] See Figure 1From left to right, the images show the morphological appearance of the ethyl cellulose membranes from Examples 1, 1, 2, and 3 (Comparative Examples 1, 2, and 3). Observing the morphological appearance of the membranes from Examples 1 and 1 (Comparative Example 1), it can be found that the ethyl cellulose membrane in Comparative Example 1 has a rough and irregular surface with pores and hollow network structures; while the membrane in Example 1 has a smooth and continuous surface. This indicates that by adding a wetting agent and following steps S2-S5 of Example 1, the surface tension imbalance was adjusted, improving the compatibility between components. During solvent evaporation, the smoothness of the membrane surface was improved.

[0049] The microbial contamination was analyzed using Example 1 and Comparative Example 1. The membrane material was first exposed to air for 3 hours, and then tested according to the membrane filtration method in Chapter 1105 of the 2020 edition of the Pharmacopoeia of the People's Republic of China (General Chapter IV, Non-sterile Products Microbial Limit Test). The culture medium was tryptic soy peptone agar. The results are shown in […]. Figure 2 The left image shows the bacterial contamination status of the membrane in Example 1, and the right image shows the bacterial contamination status of the membrane in Comparative Example 1. It can be seen that the addition of the antibacterial agent gives Example 1 a certain degree of antibacterial activity.

[0050] Water resistance tests were conducted on the examples and comparative examples. The membranes were placed in deionized water and left to stand at room temperature for 120 hours. The presence of wrinkles, blistering, or cracking on the membrane surface was observed. The test results are shown in Table 1. It can be seen that the membranes of each example exhibit better water resistance compared to the comparative example; therefore, the addition of plasticizers can improve the hydrophilicity of the membrane, resulting in better water resistance for the membranes of each example. Table 1 The elongation at break tests were conducted on the examples and comparative examples, and the results are shown in Table 2. It can be seen that Comparative Examples 1 and 2 have uneven thicknesses and relatively small mechanical results; Comparative Example 3's mechanical properties were too poor to be tested. The membranes of each example exhibit superior mechanical properties and higher elongation at break, indicating better flexibility. This demonstrates that coupling a highly permeable plasticizer with the porous membrane structure after vacuum evaporation improves the membrane's mechanical properties. Table 2 Table 2 Water vapor transmission rate tests were conducted on the examples and comparative examples, and the results are shown in Table 3. It can be seen that, except for Example 3 where a well-formed membrane could not be obtained due to poor mechanical properties, the differences in water vapor transmission rate among the other examples and comparative examples are not significant. However, the water vapor transmission rate of each example is lower, indicating that the membranes of each example are denser than those of Comparative Example 1.

[0051] Table 3 Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for modifying an ethyl cellulose membrane, characterized in that, Specifically, the steps include the following: S1. Add ethyl cellulose to the solvent at a material-to-liquid ratio of 1:10 to 1:15 and stir until homogeneous; the solvent is one or more of ethanol, hexamethyldisiloxane, and isopropanol. S2. Add a wetting agent at 10-40% of the mass of ethyl cellulose and stir until homogeneous to obtain a mixture; S3. The mixture obtained in step S2 is allowed to stand at -40~-60℃, and then evaporated under reduced pressure to obtain a preliminary membrane. S4. Immerse the preliminary film obtained in step S3 in plasticizer at a material-to-liquid ratio of 1:5 to 1:10; add antibacterial agent at 0.1% to 1% of the plasticizer volume, and perform ultrasonic treatment. A semi-finished film is obtained; the plasticizer in step S4 is one or more of ethyl oleate, tri-n-butyl citrate, and triethyl citrate; S5. Rinse the semi-finished membrane obtained in step S4 with deionized water, and after drying at room temperature, obtain the modified ethyl cellulose membrane.

2. The method for modifying an ethyl cellulose membrane as described in claim 1, characterized in that: The viscosity of ethyl cellulose in step S1 is 6~8 mPa·s.

3. The method for modifying an ethyl cellulose membrane as described in claim 1, characterized in that: In step S2, the wetting agent is one or more of isopropyl palmitate, triethyl glycerol, polyvinylpyrrolidone, triethanolamine, and polyethylene glycol.

4. The method for modifying an ethyl cellulose membrane as described in claim 1, characterized in that: The settling time in step S3 is 0.5~2 hours.

5. The method for modifying an ethyl cellulose membrane as described in claim 1, characterized in that: The pressure under the decompression condition in step S3 is 0.1~10 Pa.

6. The method for modifying an ethyl cellulose membrane as described in claim 1, characterized in that: The ultrasonic treatment conditions in step S4 are 80W, 40kHz; the treatment time is 30~300min.

7. The method for modifying an ethyl cellulose membrane as described in claim 1, characterized in that: The antibacterial agent mentioned in step S4 is one or more of povidone-iodine, sodium benzoate, methylparaben, and benzalkonium chloride.

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