CN1844175A - The method of polyethersulfone graft modification - Google Patents

Abstract

This invention is the method of polyethersulfone grafting to modify properties. Its characteristic is exposing polyethersulfone powder and andacroleic acid monomer directly to gamma-ray for grafting. The polyethersulfone obtain in this invention has hydrophilicity. The following product polyethersulfone film has hydrophilicity to reduce the jamming possibility in film grafting. So the better permeability and filteration is gained.

Description

The method of polyethersulfone graft modification

technical field

The invention relates to a method for grafting and modifying polyethersulfone.

Background technique

At present, the annual sales of membrane separation technology products in the world are about 5 billion US dollars, with an annual growth rate of 8%-15%. It is estimated that by 2005, the world's market sales of separation membranes will reach 8-10 billion US dollars. By 2010, the total sales of the world film market will reach 11.0-13.5 billion US dollars. The annual sales of domestic membrane technology products are about 1 billion to 1.5 billion yuan, with an annual growth rate of about 15%, far exceeding the growth rates of world GDP and domestic GDP respectively, and its development potential and space are huge.

At present, the main obstacle restricting the industrialization of membrane technology is membrane fouling. Selecting the appropriate membrane material or modifying the membrane material is an effective way to prevent membrane fouling. In general, the modified membrane can greatly increase the service life of the membrane, relatively improve the continuous service life of the membrane, reduce the cost of the membrane, and meet the requirements of the membrane in water purification, sewage treatment, hemodialysis, and food industry. Severe requirements for continuous processing of large batches.

Polyethersulfone (Polyethersulfone abbreviated as PES) is a kind of engineering plastic with excellent performance developed in recent years. The molecular structural formula is:

Polyethersulfone has been widely used in the following aspects due to its advantages of high strength, high temperature resistance (up to 120°C), corrosion resistance, oxidation resistance, and wide pH range:

1) Coil bobbins, printed circuit boards, timing switches, etc. in the electrical and electronic industries;

2) Manufacturing of bearing cages, gears, precision instrument parts, etc. in the machinery industry;

3) Materials and structural materials in the cabin of the aviation industry;

4) Various parts resistant to gasoline and engine oil in the automobile industry;

5) Pipeline pumps for various medical machinery and food production equipment in the medical food industry;

6) Anti-corrosion materials, ultrafiltration membranes, etc.

The emergence of polyethersulfone membranes has greatly promoted the development of membrane filtration technology. However, like all modern membranes, polyethersulfone membranes are prone to contamination during actual use, resulting in a rapid and significant decrease in flux, shortened service life, and production costs. Add a series of questions. Membrane fouling is an obstacle to the further popularization and application of ultrafiltration membrane technology, and is a key problem to be solved urgently in current and future applications.

From the point of view of solution thermodynamics, non-polar interfaces are easy to adsorb non-polar solutes from polar solvents. Due to the lack of hydrophilic groups such as hydroxyl, carboxyl, amino, and mercapto groups in the chemical structure of polyethersulfone, it shows strong hydrophobicity, which leads to strong hydrophobicity on the surface of the membrane prepared from it. . Therefore, polyethersulfone membrane fouling is closely related to its hydrophobicity. Obviously, modifying polyethersulfone, that is, introducing hydrophilic groups into the chemical structure of polyethersulfone, is expected to effectively solve the problem of polyethersulfone membrane fouling.

At present, the modification of polyethersulfone is basically to use polyethersulfone as the base material to perform surface treatment on the formed film to improve the hydrophilic property of the film surface. Common means include the use of surfactants, chemical modification, plasma modification, photochemical modification, radiation modification, and the like. Chemical methods generally use sulfonation to graft sulfonic acid groups on the surface of the membrane to change the hydrophilicity of the membrane surface and improve the anti-fouling ability of the membrane to proteins. However, due to the excellent chemical stability of polyethersulfone itself, strong acids and strong bases must be used as reagents in chemical modification, but strong acids and strong bases will lead to degradation of polyethersulfone, thereby greatly reducing the mechanical properties of polyethersulfone itself ; The effective wavelength of ultraviolet light-induced graft polymerization is around 254nm, but the radiation degradation of polyethersulfone itself is more obvious at this wavelength; plasma-induced graft polymerization usually occurs at the outermost surface of the polyethersulfone molecular chain At one end, after a period of use, due to the movement of the chain segment, the modified end will be covered by other chain segments, thereby reducing its anti-pollution performance.

Compared with the above methods, the use of radiation technology, especially γ-ray irradiation, to graft polyethersulfone has significant advantages: (1) Due to the presence of aromatic groups in the chemical structure, polyethersulfone has certain radiation resistance Therefore, the use of radiation polarity technology to introduce polar functional groups into the polyethersulfone molecular chain can endow polyethersulfone with new properties on the basis of maintaining the original mechanical properties of polyethersulfone; (2) radiation grafting reaction It can be directly initiated by radiation without an initiator, so a pure graft copolymer can be obtained; (3) radiation graft polymerization can be carried out at room temperature or even low temperature; (4) radiation graft reaction can be carried out in solid state, liquid state, Carrying out in a solid-liquid state can alleviate the problem of using a large amount of solvents often encountered in chemical grafting reactions; (5) The radiation grafting reaction has better uniformity and controllability. The above advantages make it possible to realize the industrialization of polyethersulfone radiation grafting.

At present, gamma ray irradiation is mainly used to graft and modify the finished polyethersulfone membrane, but it is found that when the grafting rate is increased to improve the hydrophilicity of the membrane, there will be problems due to the blockage of the membrane pores by the grafted monomer segments. Defects that lead to a decrease in the working efficiency of the membrane and affect the actual use of the membrane. This problem can be effectively avoided by directly modifying the polyethersulfone material before film formation, but there is no such product or report yet.

Contents of the invention

The inventors of the present invention have made the above attempts in order to solve the above problems and provide a method for grafting modification of polyethersulfone different from the conventional ones.

The object of the present invention is achieved through the following technical solutions: a polyethersulfone graft modification method, which is characterized in that polyethersulfone powder and acrylic monomers are subjected to γ-ray irradiation grafting reaction.

Wherein, the weight ratio of the polyethersulfone powder and the acrylic monomer is preferably 1:0.1-5, more preferably 1:0.16-4.21; the volume concentration of the acrylic monomer is 2-50%, which is relatively Preferably it is 10-45%.

The graft-modified monomers can be graft-modified various monomers of existing polyethersulfone membranes, such as acrylic acid, methacrylic acid, hydroxyacrylate and other acrylic monomers containing hydrophilic groups such as hydroxyl groups or amino groups. body, or polyethylene glycol, etc.

Like the existing polyethersulfone membrane grafting reaction, in order to suppress the homopolymerization reaction between acrylic monomers, it is preferable to add a polymerization inhibitor in the reaction system. The polymerization inhibitor can be Cu ²⁺ or Fe ²⁺ salt (Mohamed Mahmoud Nasef.Preparation and applications of ion exchangemembranes by radiation-induced graft copolymerization of polar monomers ontonon-polar films.Prog.Polym.Sci.29(2004)499 -561), in the present invention, its concentration in the reaction system is preferably 0.001-0.04mol/L.

The reaction of the present invention is preferably carried out at a pH of 0.5-6.0.

In the present invention, gamma ray irradiation is preferably carried out by cobalt sources with a total dose of 1.88-30 kGy and an average dose rate of 0.100-0.347, preferably 0.1-0.324 kGy/h.

For better film formation in the future, the method of the present invention also includes further processing steps to remove impurities such as homopolymers, such as extracting the product obtained by the above method with three times distilled water for at least 72 hours; and drying to remove moisture as much as possible, preferably Vacuum dry.

The present invention uses commercial polyethersulfone powder with an average particle size of 0.01mm. Of course, it is well known that the smaller the particle size of the reactants, the larger the reaction surface area, which is more favorable for the reaction. Therefore, the average particle size of the preferred polyethersulfone powder in the present invention is ≤0.01mm.

The present invention uses powder directly as the modified material, which has the following advantages:

1) The specific surface area is large, and the material flow characteristics such as solid solubility are also improved, so that some bounded participation processes can be fully carried out, providing a large enough surface area for chemical reactions;

2) After the polymer material is powdered by means of external force, the adjacent coexistence state of the crystal region and the amorphous region in the original structure is reduced, so that the contact surface of the amorphous region increases, which is conducive to improving the reactivity;

3) Most of the particles of polymer powder materials do not always exist as solid cores, and there are slits and pores in the particles, so they have an adsorption effect on liquids.

Therefore, the polyethersulfone powder obtained by the method of the present invention has better hydrophilicity, and compared with ungrafted polyethersulfone powder, the hydrophilicity is significantly improved, and graft modification is no longer required after film formation. , so as to avoid the decrease of the working efficiency of the membrane due to the clogging of the membrane pores by the monomer segment of the membrane grafting, which affects the actual use effect of the membrane, thereby improving the service life of the membrane.

Description of drawings

Fig. 1 is the infrared spectrum of the product that the inventive method makes.

Detailed ways

The operation process of the present invention and the effect of the product are further described below with examples, but the present invention is not limited thereto.

Wherein, the present invention takes the acrylic monomer as an example to test, and the following examples further select the acrylic monomer wherein as an example, the polyethersulfone powder is a commercially available (Indian, Garda) product, and the average particle diameter is 0.01mm . Infrared spectrometer (Nicolet, Avater360 type) was used to detect the grafting effect; the modified powder was compressed with an infrared tablet press, and then the surface of the modified PES powder was measured by a contact angle meter (dataphysis, OCA20). Contact angle; weigh the mass of polyethersulfone powder before and after grafting, and calculate the grafting rate according to the following formula.

Grafting rate = (WW _o )/W _o × 100%

Where W _o and W are the mass of the sample before and after grafting, respectively.

In addition, for the needs of infrared spectroscopy after the test, the above commercial polyethersulfone powder is pretreated, such as extracted with triple distilled water for more than 24 hours to remove the additives contained in polyethersulfone.

Examples 1-7

Put 5g of pretreated polyethersulfone powder into the irradiation tube, add 40ml, 50% (v/v) acrylic acid aqueous solution (PES:acrylic acid monomer is 5:21.04), and then add CuSO ₄ as a polymerization inhibitor , and make its concentration in the reaction system 0.004mol/L, adjust the pH value of the system to 1.0 with 1mol/L HCl aqueous solution. Then the irradiation tube was placed under the cobalt source for irradiation, and the experiments with different cobalt source irradiation total doses were set for irradiation modification (as shown in Table 1), and the average dose rate was 0.324kGy/h. The sample was taken out, extracted with triple distilled water for more than 72 hours, and vacuum-dried in a vacuum oven at 100 degrees Celsius to constant weight.

The contact angle of water on the surface of the modified PES powder was measured with a contact angle meter; and the grafting rate of the PEI powder was calculated. The test results are shown in Table 1.

Table 1 Examples of different total radiation doses Example 1 2 3 4 5 6 7 Radiation dose (kGy) 1.88 7.24 9.36 14.72 16.81 22.17 24.23 Grafting rate (%) 33.5 36.4 38.3 41.3 47.7 49.1 67.8 Contact angle 64.5 59.8 56.4 50.1 45.1 42.1 32.0 blank sample contact angle 72.6

Embodiment 8～10

The total cobalt source irradiation dose was set to 5kGy, and different average dose rates were set for irradiation modification (as shown in Table 2). The rest are the same as in Example 1, and the test results are shown in Table 2.

Table 2 Examples of different average dose rates Example 8 9 10 Average dose rate (kGy/h) 0.100 0.220 0.324 Grafting rate (%) 7.4 10.8 37.8 Contact angle 71.2 68.2 63.1 blank sample contact angle 72.6

Examples 11-15

Put 5g of pretreated polyethersulfone powder into the irradiation tube, add 40ml of acrylic acid aqueous solution with different proportions (w/w) and volume concentration (as shown in Table 3), put the irradiation tube under the cobalt source for irradiation Irradiation dose is 15kGy, and the average dose rate is 0.324kGy/h, the remainder is the same as in Example 1, and the results are shown in Table 3.

Table 3 Examples of different ratios and concentrations of monomers Example 11 12 13 14 15 Monomer Concentration (v/v) PES: Monomer (w/w) 2%5:0.8416 13%5:5.4704 26%5:10.941 39.4%5:16.580 45.6%5:19.189 Grafting rate (%) 4 30 60.1 52.7 46.9 Contact angle 71.8 64.0 37 40.4 43.7 blank sample contact angle 72.6

Examples 16-18

Put 5g of pretreated polyethersulfone powder into the irradiation tube, add 40ml of 50% (v/v) acrylic acid aqueous solution, and add other different polymerization inhibitors so that the concentration in the reaction system is 0.004mol/L (As shown in Table 4), the HCL adjustment system pH value is 1.0 with the HCL of 1mol/L. Then put the irradiation tube into the cobalt source for irradiation, the irradiation dose is 5kGy, and the average dose rate is 0.324kGy/h, the remainder is the same as in Example 1, and the test results are shown in Table 4.

The embodiment of table 4 different polymerization inhibitors Example 16 17 18 Polymerization inhibitor CuCl _{2 FeCl2} FeSO ₄ ·(NH ₄ ) ₂ SO ₄ ·6H ₂ O Grafting rate (%) 32.3 28.7 22.3 Contact angle 65.1 66.1 68.6 blank sample contact angle 72.6

Examples 19-22

Put 5 g of pretreated polyethersulfone powder into the irradiation tube, add 40 ml of 50% (v/v) acrylic acid aqueous solution, and add CuSO ₄ to make it have different molar concentrations in the reaction system (as shown in Table 5). Shown), the pH value of the system was adjusted to 1.0 with 1 mol/L HCl aqueous solution. The remainder is the same as in Example 10, and the test results are as shown in Table 5.

The embodiment of table 5 different polymerization inhibitor concentrations Example 19 20 twenty one twenty two CuSO ₄ (mol/L) 0.001 0.016 0.026 0.038 Grafting rate (%) 26.4 24.7 21.7 19 Contact angle 69.2 68.0 63.1 69.4 blank sample contact angle 72.6

Examples 23-26

Use acid (such as 1mol/L HCl or H ₂ SO ₄ ) or alkali (such as 1mol/L NaOH) to adjust the pH value of the system (as shown in Table 6), the cobalt source irradiation dose is 5kGy, and the average dose rate is 0.324kGy/h, more than the same as embodiment 1, the results are shown in table 6.

Table 6 Examples of pH values of different reaction systems Example twenty three twenty four 25 26 pH value 0.52 1.0 3.05 5.58 Grafting rate (%) 44.43 39 41.9 8.73 Contact angle 40.1 56 39.6 69.2 blank sample contact angle 72.6

Example 27

Put 5 g of polyethersulfone powder into the irradiation tube after pretreatment, add 40 ml of 50% (v/v) acrylic acid aqueous solution, and then add CuSO ₄ to make the concentration in the reaction system 0.004 mol/L. Then put the irradiation tube into the cobalt source for irradiation, the irradiation dose is 15kGy, and the average dose rate is 0.324kGy/h. Yu Tong

Example 1.

Its graft rate is 41.3%, and its contact angle is 49.7.

The powder extracted from the above examples was dried in a vacuum oven at 100 degrees Celsius to constant weight, and its infrared spectrum was tested (as shown in Figure 1). It was found that the grafted polyethersulfone powder was at 1720 ^cm The C=O peak that does not appear in the unmodified polyethersulfone powder shows that acrylic acid has been successfully grafted to the surface of the polyethersulfone powder.

The contact angle of water on the surface of the modified PES powder was measured with a contact angle meter, and the hydrophilicity was significantly improved compared with the ungrafted PES powder (the smaller the surface contact angle, the better the hydrophilicity).

The acrylic acid monomer in the above examples is the product of China Pharmaceutical Group Shanghai Reagent Co., Ltd., chemically pure; the cobalt source is ⁶⁰ Co, and Canada provides the source rod.

Claims (10)

1, a kind of method of graft modification of polyethersulfone is characterized in that polyethersulfone powder and acrylic monomer are carried out the gamma-ray irradiation graft reaction.

2, method according to claim 1, the weight ratio that it is characterized in that this polyethersulfone powder and acrylic monomer is 1: 0.1-5, the volumetric concentration of this acrylic monomer is 2-50%.

3, method according to claim 2, the volumetric concentration that it is characterized in that this acrylic monomer is 10-45%.

4, method according to claim 1 is characterized in that this acrylic monomer is an Acrylic Acid Monomer.

5, method according to claim 1 is characterized in that being added with stopper in this reaction system.

6, method according to claim 5 is characterized in that this stopper is Cu ²⁺Or Fe ²⁺Salt, its concentration in reaction system is 0.001-0.04mol/L.

7, method according to claim 1, it is characterized in that this is reflected under the condition that pH is 0.5-6.0 carries out.

8, method according to claim 1 is characterized in that it adopts total dose is 1.88-30kGy, and gamma-ray irradiation is carried out in the cobalt source of mean dose rate 0.100-0.347kGy/h.

9, method according to claim 1 is characterized in that it also comprises further treatment step: the continuous extracting of product that claim 1 is made with three distilled water at least 72 hours, and dry.

10,, it is characterized in that the median size≤0.01mm of this polyethersulfone powder according to each described method of claim 1～9.