CN116850799A - Ultrafiltration membrane with pH response switchable pore diameter and preparation method thereof - Google Patents

Ultrafiltration membrane with pH response switchable pore diameter and preparation method thereof Download PDF

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CN116850799A
CN116850799A CN202310352337.8A CN202310352337A CN116850799A CN 116850799 A CN116850799 A CN 116850799A CN 202310352337 A CN202310352337 A CN 202310352337A CN 116850799 A CN116850799 A CN 116850799A
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ultrafiltration membrane
response
switchable
membrane
polymer
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钟奇伟
郑振华
陈天涯
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Sepp Hangzhou Filtration Technology Co ltd
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Sepp Hangzhou Filtration Technology Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/34—Polyvinylidene fluoride
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/145—Ultrafiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
    • B01D71/68—Polysulfones; Polyethersulfones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/36—Hydrophilic membranes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
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  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention relates to the technical field of membrane separation, and discloses an ultrafiltration membrane with a pH response switchable pore diameter and a preparation method thereof. The method comprises the following steps: 1) Preparing a pH responsive polymer; 2) Adding a pH response polymer, a polymer resin and a pore-forming agent into a binary solvent mixture, heating and stirring, and then defoaming to prepare a casting solution; 3) And (3) scraping the membrane, pre-evaporating and solidifying the membrane casting solution to obtain the ultrafiltration membrane. According to the invention, the pH response polymer is dispersed in the polymer resin by a blending method, the pH response sensitivity of the obtained ultrafiltration membrane is high, the pH response influences the movement of a side chain to change the size of the membrane aperture, and the efficient fractional filtration or recovery of substances with different sizes is realized.

Description

Ultrafiltration membrane with pH response switchable pore diameter and preparation method thereof
Technical Field
The invention belongs to the technical field of membrane separation, and particularly relates to a preparation method of an ultrafiltration membrane with a switchable pH response aperture.
Background
The ultrafiltration membrane is used as a multifunctional separation tool and is widely used for water purification, biopharmaceutical purification and molecular separation. The ultrafiltration membrane with responsiveness is considered as intelligent, and the separation purpose can be achieved by adjusting the surrounding magnetic field, the temperature and the pH value and switching the fields of solute, permeability and self-cleaning characteristics, so that the purification precision is improved, the unit operation times are reduced, and the steps in complex purification can be reduced. Among these, the pH responsive membrane is of greater interest than other stimulus responsive membranes and can be easily deployed in conventional membrane filtration systems. In general, pH-responsive ultrafiltration membranes can be prepared by mixing an amphiphilic pH-responsive polymer with other polymers, followed by a phase inversion process; or post-treatment means such as grafting 00 pH-responsive brushes and coating the pH-responsive material on the support membrane.
In general, a key factor in the pH response of polymer films is that the backbone typically contains a large number of pH sensitive groups (weak electrolyte groups), such as carboxyl groups, amino groups, pyridine, imidazole, and the like. When the pH or hydrogen ion concentration in the external environment changes, the groups can accept or release protons to respond to the change of the pH in the external environment, and the movement of the polymer chain segment is affected. For example, at low pH, the free pyridine groups are protonated, resulting in polymer segment movement. The pH response membrane is expected to provide smart separation of biomolecules in double-scale filtration, and remove larger or smaller impurities under different pH conditions. For example, common membrane materials such as polyvinylidene fluoride (PVDF), polysulfone (PS), polyether sulfone (PES) and the like are all hydrophobic materials, the water flux and the pollution resistance can be greatly improved after hydrophilization modification is carried out by adding a pH response polymer, and the pore diameter of the porous membrane can be adjusted by controlling the pH response environment so as to achieve more efficient and rapid separation capability. Chinese patent (CN 114768548A) "blending modified ultrafiltration membrane with pH response and preparation method thereof" the composite membrane is prepared by blending polyacrylonitrile powder in polysulfone solution, and then the composite membrane is placed in alkaline solution for further modification, so that the membrane has pH responsiveness, but the anti-pollution capability is not strong, and the service life is limited. Chinese patent (CN 112957932B) "preparation and application of an amphiphilic graft copolymer uniform pore ultrafiltration membrane with high permeability" preparation of amphiphilic graft copolymer with pH response by grafting hydrophilic monomers to hydrophobic polymers through atom transfer radical polymerization, preparation of an amphiphilic graft copolymer uniform Kong Chaolv membrane with pH response by a phase inversion method, effective pore size regulation and control between pH=3-11 can be carried out to realize fractional interception of pollutants, but the process is complicated, and the corresponding performance of pH regulation and control is general.
Disclosure of Invention
In order to solve the problems, the invention provides the ultrafiltration membrane with the pH response switchable pore diameter, which solves the problems of poor pollution resistance and low selectivity of the traditional ultrafiltration membrane, improves the purification precision and reduces the unit operation times. The pH response sensitivity is high, and the size of the pore diameter of the membrane can be rapidly changed only by regulating and controlling the pH response environment, so that the method is suitable for separation of substances with different molecular weights. The polymer membrane with the pH response switchable pore diameter is prepared by taking a monomer with a pH sensitive group as an additive, carrying out Atom Transfer Radical Polymerization (ATRP) reaction under the catalysis, synthesizing a pH response copolymer, then blending the pH response copolymer with a polymer resin, and carrying out a non-solvent induced phase inversion method.
The invention also provides a preparation method of the ultrafiltration membrane with the pH response switchable aperture.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
1) Selecting at least two compounds containing-COOH, -CNH 2 、-C 2 NH or-C 3 The method comprises the steps of taking N-group monomers as raw materials, dissolving the raw materials in a solvent, heating for reaction under the action of a catalyst, sequentially removing the catalyst and the solvent, and obtaining a pH response polymer through precipitation, filtration, concentration and drying;
2) Adding a pH response polymer, a polymer resin and a pore-forming agent into a binary solvent mixture, heating and stirring, and then defoaming to prepare a casting solution;
3) And (3) scraping the membrane, pre-evaporating and solidifying the membrane casting solution to obtain the ultrafiltration membrane.
In the prior art, a general preparation method of the pH responsive ultrafiltration membrane is to graft a polymer corresponding to the pH on a polymer resin in a polymer resin synthesis process (see background for details, which is not described in detail), but the problems are that: 1) The synthesis process is complex and the cost is high; 2) The pH response sensitivity is low because the polymer on the side wall of the ultrafiltration membrane pore canal has a smaller corresponding group amount in the grafting process. According to the invention, the pH responsive polymer is blended with the polymer resin, and the membrane is prepared by a phase inversion method, so that on one hand, the hydrophilic side chains with pH response are arranged in the pore canal and on the surface of the membrane, the hydrophilicity of the membrane is improved, and the anti-pollution performance of the ultrafiltration membrane is greatly improved; on the other hand, the pH response environment can be regulated and controlled, the pH response sensitivity is high, the pH response influences the movement of the side chain to change the size of the membrane aperture, the efficient fractional filtration or the recovery of substances with different sizes is realized, and the method has wide prospects in the fields of protein separation, drug controlled release and water treatment.
Preferably, the monomer in the step 1) is acrylic acid, methacrylic acid ester, hydroxyethyl methacrylate, 4-vinyl pyridine, N-isopropyl acrylamide or dimethylaminoethyl methacrylate.
Preferably, the mass ratio of the raw materials, the solvent and the catalyst in the step 1) is (1-3): 10-25): 0.1-0.2; the reaction temperature is controlled between 60 and 80 ℃; the reaction time is controlled between 4 and 8 hours.
Preferably, the polymer resin in the step 2) is any one of polyvinylidene fluoride, polysulfone and polyethersulfone.
Preferably, the pore-forming agent in the step 2) is at least one of PEG200, PEG400, PEG600, triglycol and glycerol.
Preferably, the content ratio of the polymer resin, the pH responsive polymer, the porogen and the binary solvent mixture in the step 2) is (14-25): (5-10): (5-20): (45-60);
the heating and stirring temperature in the step 2) is 50-100 ℃; heating and stirring for 12-24h.
Preferably, the binary solvent mixture in the step 2) is a mixture of dimethylformamide and tetrahydrofuran, and the mass ratio of the dimethylformamide to the tetrahydrofuran is 1-5:1.
Preferably, the pre-evaporation in the step 3) is performed under an air medium, the relative humidity of the air medium is 50% -80%, the temperature of the air medium is 20 ℃ -25 ℃, and the pre-evaporation time is 10s-60s.
Preferably, the solidification in the step 3) is performed in a solidification bath, and the solidification bath is a mixed solution of dimethylformamide and water; the concentration of the dimethylformamide is 5-15wt percent, and the coagulating bath temperature is 20-45 ℃.
The beneficial effects are that:
according to the invention, the pH responsive polymer is blended with the polymer resin, and the membrane is prepared by a phase inversion method, so that on one hand, the hydrophilic side chains with pH response are arranged in the pore canal and on the surface of the membrane, the hydrophilicity of the membrane is improved, and the anti-pollution performance of the ultrafiltration membrane is greatly improved; on the other hand, the pH response environment can be regulated and controlled, the pH response sensitivity is high, the pH response influences the movement of the side chain to change the size of the membrane aperture, the efficient fractional filtration or the recovery of substances with different sizes is realized, and the method has wide prospects in the fields of protein separation, drug controlled release and water treatment.
Drawings
FIG. 1 is a scanning electron microscope image of pH-responsive polymer particles prepared from example 1;
fig. 2 is a scanning electron microscope image of the membrane surface of the pH-responsive ultrafiltration membrane (a) prepared in example 1 after immersion in an aqueous solution of HC l (ph=3);
fig. 3 is a scanning electron microscope image of the membrane surface of the pH-responsive ultrafiltration membrane (a) prepared in example 1 after immersion in an aqueous NaOH (ph=11) solution;
FIG. 4 is a scanning electron microscope image of the upper surface of the cross section at 10000 times magnification of the pH responsive ultrafiltration membrane (a) prepared in example 1.
Detailed Description
The invention will be further illustrated with reference to specific examples.
Example 1:
1) The mass ratio of methacrylic acid, 4-vinyl pyridine, solvent methylene dichloride and catalyst N-bromosuccinimide is 1:1:10: transferring the materials into an anhydrous anaerobic reaction bottle together, reacting for 8 hours in a water bath kettle at 60 ℃, removing a catalyst from the solution obtained after the reaction through a neutral alumina chromatographic column, removing a solvent through reduced pressure rotary evaporation, slowly dripping an organic phase into cold n-hexane for precipitation, filtering, concentrating, and finally vacuum drying for 24 hours at 45 ℃ to prepare a pH response polymer PMAA-g-P4VP;
2) Blending and dissolving PMAA-g-P4VP, polyethersulfone and PEG200 prepared in the step 1) into a binary solvent mixture of dimethylformamide and tetrahydrofuran, increasing the temperature to 60 ℃, stirring and reacting for 12 hours to prepare a homogeneous casting solution, and standing and defoaming, wherein the mass ratio of the polyethersulfone, PMAA-g-P4VP, PEG200, dimethylformamide (DMF) and Tetrahydrofuran (THF) mixture is 18:5:18:45:14;
3) And (3) the defoamed casting film liquid obtained in the step (2) is subjected to film scraping, is exposed for 20s under an air medium with the relative humidity of 70% and the air temperature of 20 ℃, and is transferred to a 10wt% DMF solution with the temperature of 35 ℃ to prepare the ultrafiltration film (a) with the pH response switchable pore diameter.
Example 2:
1) Selecting hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, solvent dichloromethane and catalyst stannous octoate according to the mass ratio of 1:1:10: transferring the mixture to an anhydrous anaerobic reaction bottle together for reaction for 6 hours in a water bath kettle at 70 ℃, removing catalyst from the solution obtained after the reaction through a neutral alumina chromatographic column, removing solvent through reduced pressure rotary evaporation, slowly dripping an organic phase into cold n-hexane for precipitation, filtering, concentrating, and finally vacuum drying at 45 ℃ for 24 hours to prepare a pH response polymer PHEMA-g-PDMAEMA;
2) Blending and dissolving PHEMA-g-PDMAEMA, polyvinylidene fluoride and triethylene glycol prepared in the step 1) into a binary solvent mixture of dimethylformamide and tetrahydrofuran, raising the temperature to 50 ℃, stirring and reacting for 24 hours to prepare a homogeneous casting solution, and standing and defoaming, wherein the content ratio of the mixture of polyvinylidene fluoride, PHEMA-g-PDMAEMA, triethylene glycol, DMF and THF is 14:8:20:48:10;
3) And (3) the defoamed casting film liquid obtained in the step (2) is subjected to film scraping, is exposed for 60 seconds in an air medium with the relative humidity of 80% and the air temperature of 25 ℃, and is transferred to a 5wt% DMF solution with the air temperature of 25 ℃ to prepare the ultrafiltration film (c) with the pH response switchable pore diameter.
Example 3:
1) The mass ratio of the acrylic acid, the methacrylic acid ester, the N-isopropyl acrylic acid ester, the solvent methylene dichloride and the catalyst N-bromosuccinimide is selected as 1:1:1:20: transferring the mixture into an anhydrous anaerobic reaction bottle together, reacting for 4 hours in a water bath kettle at 80 ℃, removing catalyst from the solution obtained after the reaction through a neutral alumina chromatographic column, removing solvent through reduced pressure rotary evaporation, slowly dripping an organic phase into cold n-hexane for precipitation, filtering, concentrating, and finally vacuum drying at 45 ℃ for 24 hours to prepare a pH response polymer PAA-g-PMP-g-PNIPAM;
2) Blending and dissolving PAA-g-PMP-g-PNIPAM, polyether sulfone and PEG400 prepared in the step 1) into a binary solvent mixture of dimethylformamide and tetrahydrofuran, raising the temperature to 80 ℃, stirring and reacting for 12 hours to prepare a homogeneous casting solution, and standing and defoaming, wherein the content ratio of the polyether sulfone, PAA-g-PMP-g-PNIPAM, PEG400, DMF and THF mixture is 20:5:20:50:5, a step of;
3) And (3) the defoamed casting film liquid obtained in the step (2) is subjected to film scraping, is exposed for 10s under an air medium with the relative humidity of 70% and the air temperature of 20 ℃, and is transferred to a 5wt% DMF solution with the temperature of 45 ℃ to prepare the ultrafiltration film (d) with the pH response switchable pore diameter.
Example 4:
1) Selecting methacrylic acid, dimethylaminoethyl methacrylate, solvent tetrahydrofuran and catalyst N-bromosuccinimide according to the mass ratio of 1:1:20: transferring the mixture into an anhydrous anaerobic reaction bottle together, reacting for 4 hours in a water bath kettle at 80 ℃, removing catalyst from the solution obtained after the reaction through a neutral alumina chromatographic column, removing solvent through reduced pressure rotary evaporation, slowly dripping an organic phase into cold n-hexane for precipitation, filtering, concentrating, and finally vacuum drying at 45 ℃ for 24 hours to prepare a pH response polymer PMAA-g-PDMAEMA;
2) The PMAA-g-PDMAEMA, polysulfone and glycerol prepared in the step 1) are mixed and dissolved in a binary solvent mixture of dimethylformamide and tetrahydrofuran, the temperature is increased to 80 ℃, stirring reaction is carried out for 12 hours, a homogeneous casting solution is prepared, standing and defoaming are carried out, wherein the content ratio of the mixture of polysulfone, PMAA-g-PDMAEMA, glycerol, DMF and THF is 14:10:10:41:25, a step of selecting a specific type of material;
3) And (3) the defoamed casting film liquid obtained in the step (2) is subjected to film scraping, is exposed for 30 seconds in an air medium with the relative humidity of 50% and the air temperature of 20 ℃, and is transferred to a 15wt% DMF solution with the temperature of 25 ℃ to prepare the ultrafiltration film (e) with the pH response switchable pore diameter.
Example 5:
1) The mass ratio of the acrylic acid, the methacrylic acid ester, the 4-vinyl pyridine, the solvent methylene dichloride and the catalyst stannous octoate is 1:1:1:25: transferring the materials into an anhydrous anaerobic reaction bottle together, reacting for 6 hours in a water bath kettle at 80 ℃, removing catalyst from the solution obtained after the reaction through a neutral alumina chromatographic column, removing solvent through reduced pressure rotary evaporation, slowly dripping an organic phase into cold n-hexane for precipitation, filtering, concentrating, and finally vacuum drying for 24 hours at 45 ℃ to prepare a pH response polymer PMAA-g-PMP-g-P4VP;
2) Blending and dissolving PMAA-g-PMP-g-P4VP, polyether sulfone and PEG600 prepared in the step 1) into a binary solvent mixture of dimethylformamide and tetrahydrofuran, raising the temperature to 60 ℃, stirring and reacting for 24 hours to prepare a homogeneous casting solution, and standing and defoaming, wherein the mass ratio of the polyether sulfone to the PMAA-g-PMP-g-P4VP to the PEG600 to the DMF to the THF mixture is 25:5:25:40:5, a step of;
3) And (3) the defoamed casting film liquid obtained in the step (2) is subjected to film scraping, is exposed for 10s under an air medium with the relative humidity of 70% and the air temperature of 25 ℃, and is transferred to a 5wt% DMF solution with the temperature of 35 ℃ to prepare the ultrafiltration film (f) with the pH response switchable pore diameter.
Comparative example 1:
1) Blending and dissolving methacrylic acid, 4-vinyl pyridine, polyether sulfone and PEG200 in a binary solvent mixture of dimethylformamide and tetrahydrofuran, wherein the blending mass ratio of the methacrylic acid to the 4-vinyl pyridine to the polyether sulfone to the PEG200 to the dimethylformamide to the tetrahydrofuran is 2.5:2.5:18:18:45:14, raising the temperature to 60 ℃, stirring and reacting for 12 hours to prepare a homogeneous casting solution, and standing and defoaming to obtain a defoamed casting solution;
2) And (3) the defoamed casting film liquid obtained in the step (1) is subjected to film scraping, is exposed for 20s under an air medium with the relative humidity of 70% and the air temperature of 20 ℃, and is transferred to a 10wt% DMF solution with the temperature of 35 ℃ to prepare the ultrafiltration film (b) with the pH response switchable pore diameter.
The 6 ultrafiltration membranes prepared from examples and comparative examples were measured for water contact angle, studied for water flux at different pH (3-11) and further characterized for pH effect on pore size. Table 1 shows the measurement results of the ultrafiltration membranes a to f. As can be seen from the data in Table 1, the instantaneous water contact angles of different ultrafiltration membranes a-f obtained by the preparation method of the invention are J at 13.6-60.8 DEG and different pH values pH＝3 /J pH＝11 The water flux ratio is 1.0-5.5, D pH＝3 /D pH＝11 The pore diameter ratio is 1-3.2, it is fully verified that the introduction of the pH response polymer can enable the ultrafiltration membrane to switch pore diameters in different pH response environments, when the pH is reduced, sensitive groups on the ultrafiltration membrane can be protonated to form hydrogen bonds, molecular chain shrinkage enables the pore diameters to be large, and when the pH is increased, the sensitive groups enable the chains to repel in the form of anions, and the pores on the membrane are small.
Fig. 1 is a scanning electron microscope image of the dried pH-responsive polymer PMAA-g-P4VP, and it can be seen that the particles are uniformly distributed, and fig. 2 and 3 are scanning electron microscope images of the pH-responsive switchable pore size ultrafiltration membrane prepared in example 1 after soaking in HC l (ph=3) aqueous solution and NaOH (ph=11) aqueous solution for 30mi, and the average pore size of the membrane reaches 22.8nm at ph=3 and decreases to 9.2nm at ph=11. FIG. 4 is a scanning electron microscope image of a cross section of an ultrafiltration membrane in example 1, in which a significant distribution of pH responsive polymer in the membrane can be observed, thereby accommodating different pH environments. The pH response switchable pore ultrafiltration membrane prepared by the invention effectively solves the problems that the high molecular filter membrane has poor anti-fouling capability and wide pore size distribution, and cannot adapt to some problems requiring high selectivity. The pH response copolymer is prepared by an ATRP method, and then a film is formed by a phase inversion method, so that the hydrophilic modification and uniform pore diameter of the film are realized.
The PES ultrafiltration membrane with the highly regionalized sponge pore structure obtained in each of the above examples was subjected to performance test evaluation by the following test methods.
1. Contact angle of water
The static contact angle of the PES ultrafiltration membrane surface was measured by the sitting-drop method. During the test, ultra-pure water drops are placed on the surface of a film, a camera is used for rapidly shooting the curved surface of the lower liquid drop, and an optical method based on liquid level (liquid meniscus) shape analysis is adopted to obtain the static contact angle of a sample.
2. Flux of water
The test was performed using an ultrafiltration cup. At the time of the test, the air pressure was adjusted to 1bar, 50ml of an aqueous HCl (ph=3) solution or an aqueous NaOH (ph=11) solution was poured into the ultrafilter cup, and the water flux was calculated according to the following formula:
wherein J is pure water flux, V (L) is permeate water capacity, A (m) 2 ) Δt (h) is the permeation time, which is the effective membrane area.
3. Surface pore size analysis
The test was performed using a nitrogen adsorption pore size analyzer. In a liquid nitrogen environment, the adsorption quantity and adsorption and desorption isotherms of each partial pressure point are measured by feeding gas and extracting air into a sample tube, and the aperture is obtained by applying theoretical calculation of BET, BJH and the like.
TABLE 1
The foregoing list is only illustrative of specific embodiments of the invention. The invention is not limited to the above embodiments, but many variations are possible. All modifications directly derivable or conceivable by a person skilled in the art from the disclosure of the present invention should be considered as the scope of the present invention.

Claims (10)

1. The preparation method of the ultrafiltration membrane with the pH response switchable pore diameter is characterized by comprising the following steps of:
1) Selecting at least two kinds of componentsHas the structure of-COOH and-CNH 2 、-C 2 NH or-C 3 The method comprises the steps of taking N-group monomers as raw materials, dissolving the raw materials in a solvent, heating for reaction under the action of a catalyst, sequentially removing the catalyst and the solvent, and performing precipitation, filtration, concentration and drying to obtain a pH response polymer;
2) Adding the pH response polymer, the polymer resin and the pore-forming agent into a binary solvent mixture, heating and stirring, and then defoaming to prepare a casting solution;
3) And (3) scraping, pre-evaporating and solidifying the casting film liquid to obtain the ultrafiltration film.
2. The method for preparing an ultrafiltration membrane with switchable pore diameters according to claim 1, wherein the monomer in the step 1) is acrylic acid, methacrylic acid ester, hydroxyethyl methacrylate, 4-vinylpyridine, N-isopropylacrylamide or dimethylaminoethyl methacrylate.
3. The method for preparing the ultrafiltration membrane with the switchable pH response pore diameter according to claim 1, wherein the mass ratio of raw materials, solvent and catalyst in the step 1) is (1-3): 10-25): 0.1-0.2;
the reaction temperature is controlled between 60 ℃ and 80 ℃; the reaction time is controlled between 4h and 8h.
4. The method for preparing an ultrafiltration membrane with switchable pore diameters according to claim 1, wherein the polymer resin in the step 2) is any one of polyvinylidene fluoride, polysulfone and polyethersulfone.
5. The method for preparing a pH-responsive switchable pore size ultrafiltration membrane according to claim 1, wherein the pore-forming agent in step 2) comprises at least one of PEG200, PEG400, PEG600, triglycol, and glycerol.
6. The method for preparing an ultrafiltration membrane with switchable pore size according to claim 1, wherein the content ratio of the polymer resin, the pH-responsive polymer, the porogen and the binary solvent mixture in the step 2) is (14-25): (5-10): (5-20): (45-60);
the heating and stirring temperature in the step 2) is 50-100 ℃; the reaction time is 12-24h.
7. The method for preparing an ultrafiltration membrane with switchable pore diameters according to claim 1, wherein the binary solvent mixture in the step 2) is a mixture of dimethylformamide and tetrahydrofuran, and the mass ratio of dimethylformamide to tetrahydrofuran is 1-5:1.
8. The method for preparing an ultrafiltration membrane with switchable pore size according to claim 1, wherein the pre-evaporation in the step 3) is performed under an air medium, the relative humidity of the air medium is 50% -80%, the temperature of the air medium is 20 ℃ -25 ℃, and the pre-evaporation time is 10-60s.
9. The method for preparing an ultrafiltration membrane with a switchable pore size according to claim 1, wherein the coagulation in the step 3) is performed in a coagulation bath, and the coagulation bath is a mixed solution of dimethylformamide and water; the concentration of the dimethylformamide is 5-15wt%, and the coagulation bath temperature is 20-45 ℃.
10. A pH responsive switchable pore size ultrafiltration membrane prepared by the method of any one of claims 1 to 9.
CN202310352337.8A 2023-04-04 2023-04-04 Ultrafiltration membrane with pH response switchable pore diameter and preparation method thereof Pending CN116850799A (en)

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