CN113171692A - Preparation method of polytetrafluoroethylene hydrophilic membrane - Google Patents
Preparation method of polytetrafluoroethylene hydrophilic membrane Download PDFInfo
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- CN113171692A CN113171692A CN202110386542.7A CN202110386542A CN113171692A CN 113171692 A CN113171692 A CN 113171692A CN 202110386542 A CN202110386542 A CN 202110386542A CN 113171692 A CN113171692 A CN 113171692A
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- 239000012528 membrane Substances 0.000 title claims abstract description 147
- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims abstract description 96
- -1 polytetrafluoroethylene Polymers 0.000 title claims abstract description 93
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims abstract description 93
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000012982 microporous membrane Substances 0.000 claims abstract description 35
- 239000000178 monomer Substances 0.000 claims abstract description 33
- 239000001257 hydrogen Substances 0.000 claims abstract description 32
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 32
- 230000004048 modification Effects 0.000 claims abstract description 26
- 238000012986 modification Methods 0.000 claims abstract description 26
- 238000005516 engineering process Methods 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 19
- 239000002131 composite material Substances 0.000 claims abstract description 18
- 238000004140 cleaning Methods 0.000 claims abstract description 17
- 239000012535 impurity Substances 0.000 claims abstract description 12
- 238000012719 thermal polymerization Methods 0.000 claims abstract description 9
- 230000008569 process Effects 0.000 claims abstract description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 42
- 239000007789 gas Substances 0.000 claims description 36
- 229910052786 argon Inorganic materials 0.000 claims description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 19
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 12
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 9
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 claims description 6
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 claims description 6
- MNCGMVDMOKPCSQ-UHFFFAOYSA-M sodium;2-phenylethenesulfonate Chemical compound [Na+].[O-]S(=O)(=O)C=CC1=CC=CC=C1 MNCGMVDMOKPCSQ-UHFFFAOYSA-M 0.000 claims description 6
- 238000006116 polymerization reaction Methods 0.000 claims description 5
- 230000010355 oscillation Effects 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 2
- 238000010559 graft polymerization reaction Methods 0.000 abstract description 7
- 238000009776 industrial production Methods 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 3
- 125000000524 functional group Chemical group 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract description 3
- 238000003860 storage Methods 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 66
- 230000004907 flux Effects 0.000 description 26
- 238000012360 testing method Methods 0.000 description 24
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 20
- 239000000243 solution Substances 0.000 description 16
- 230000003068 static effect Effects 0.000 description 16
- 238000002791 soaking Methods 0.000 description 11
- 238000001035 drying Methods 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 10
- 239000007864 aqueous solution Substances 0.000 description 9
- 239000008367 deionised water Substances 0.000 description 9
- 229910021641 deionized water Inorganic materials 0.000 description 9
- 239000000428 dust Substances 0.000 description 9
- 230000006872 improvement Effects 0.000 description 9
- 230000035484 reaction time Effects 0.000 description 9
- 238000000926 separation method Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000009832 plasma treatment Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 1
- XUCNUKMRBVNAPB-UHFFFAOYSA-N fluoroethene Chemical group FC=C XUCNUKMRBVNAPB-UHFFFAOYSA-N 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Classifications
-
- 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
- B01D71/36—Polytetrafluoroethene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
-
- 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
- B01D69/12—Composite membranes; Ultra-thin membranes
-
- 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
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
-
- 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
Abstract
The invention provides a preparation method of a polytetrafluoroethylene hydrophilic membrane, which comprises the following steps: cleaning a polytetrafluoroethylene microporous membrane, removing impurities, airing, and treating the cleaned polytetrafluoroethylene microporous membrane by using a normal-pressure argon-hydrogen mixed plasma technology; putting the treated polytetrafluoroethylene microporous membrane into a hydrophilic monomer solution, carrying out hydrophilic modification in a thermal polymerization mode, and cleaning the modified polytetrafluoroethylene microporous membrane. The invention introduces active functional groups on the surface of the membrane by utilizing the normal pressure plasma technology, has simple production process, is easy to operate continuously and is suitable for industrial production. The hydrophilic monomer adopted in the graft polymerization process has low cost and easy storage of raw materials, and meets the requirement of industrial production. The composite monomers adopted by the invention are subjected to graft polymerization, the complementation of performances among the composite monomers can be realized, the modification effect is better, and the hydrophilic performance after modification is greatly improved.
Description
Technical Field
The invention relates to the technical field of membrane surface modification, in particular to a preparation method of a polytetrafluoroethylene hydrophilic membrane.
Background
Membrane separation is a novel separation technology at present, and has been widely used in many fields such as environmental management, petrochemical industry, and biological medicine due to its high-efficiency separation performance and advantages. With the development of membrane separation technology, more and more membrane materials are used in the fields of environmental protection, water treatment and the like. The polytetrafluoroethylene membrane has excellent performances of acid and alkali resistance, chemical corrosion resistance, high porosity, high flux and the like, can adapt to relatively harsh filtering conditions, and is an ideal filtering material in the field of water treatment at present. However, due to the chemical inertness and low surface energy of polytetrafluoroethylene, the surface of a polytetrafluoroethylene film has strong hydrophobicity, poor surface wettability and other properties, which limits the application of the polytetrafluoroethylene film in the field of water treatment. Therefore, it is necessary to provide a further solution to the above problems.
Disclosure of Invention
The invention aims to provide a preparation method of a polytetrafluoroethylene hydrophilic membrane, which overcomes the defects in the prior art.
In order to achieve the above object, the present invention provides a method for preparing a polytetrafluoroethylene hydrophilic membrane, comprising the following steps:
cleaning a polytetrafluoroethylene microporous membrane, removing impurities, airing, and treating the cleaned polytetrafluoroethylene microporous membrane by using a normal-pressure argon-hydrogen mixed plasma technology;
putting the treated polytetrafluoroethylene microporous membrane into a hydrophilic monomer solution, carrying out hydrophilic modification in a thermal polymerization mode, and cleaning the modified polytetrafluoroethylene microporous membrane.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the device corresponding to the normal-pressure argon-hydrogen mixed plasma technology comprises the following steps: the device comprises an argon gas source, a hydrogen gas source, a gas mixing chamber, a reaction cavity, an upper polar plate, a lower polar plate and a plasma power supply;
argon gas source, hydrogen source respectively with the gas mixing chamber is connected, the gas mixing chamber with the reaction chamber is connected, upper polar plate, bottom plate are located in the reaction chamber, upper polar plate and bottom plate set up relatively, upper polar plate and outside the plasma power is connected.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the device corresponding to the normal-pressure argon-hydrogen mixed plasma technology further comprises: and the voltage regulator is electrically connected with the plasma power supply.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the corresponding process conditions of the normal-pressure argon-hydrogen mixed plasma technology are as follows:
the distance between the upper polar plate and the lower polar plate is 0.1-3cm, the volume ratio of argon to hydrogen is 1: 99-99: 1, the air inlet speed of the argon and the hydrogen is 0.2-5L/min, the discharge power of the plasma power supply is 10-1000W, and the processing time is 10-800 s.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the hydrophilic monomer solution is a single hydrophilic monomer solution or a composite hydrophilic monomer solution.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the composite hydrophilic monomer solution comprises: two or three of acrylic acid, sodium styrene sulfonate and itaconic acid.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the mass concentration of the hydrophilic monomer solution is 10-20%.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the temperature of thermal polymerization is between room temperature and 100 ℃, and the polymerization time is 0.1 to 10 hours.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the polytetrafluoroethylene microporous membrane is a polytetrafluoroethylene bubble point membrane or a polytetrafluoroethylene composite membrane.
As an improvement of the preparation method of the polytetrafluoroethylene hydrophilic membrane, the polytetrafluoroethylene microporous membrane modified by thermal polymerization is cleaned in an ultrasonic oscillation mode.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention introduces active functional groups on the surface of the membrane by utilizing the normal pressure plasma technology, has simple production process, is easy to operate continuously and is suitable for industrial production.
(2) The hydrophilic monomer adopted in the graft polymerization process has low cost and easy storage of raw materials, and meets the requirement of industrial production.
(3) Compared with a single hydrophilic monomer, the composite monomer adopted by the invention is used for graft polymerization, so that the defect of single hydrophilic modification is overcome, the complementation of the realizable performances among the composite monomers is realized, the modification effect is better, the modified hydrophilic performance is greatly improved, and the method has important significance for the application of the membrane technology in water treatment.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an apparatus corresponding to a normal pressure argon-hydrogen mixed plasma technology in a preparation method of a polytetrafluoroethylene hydrophilic membrane according to the invention;
FIG. 2 is a molecular formula of a composite hydrophilic monomer solution;
FIG. 3 is a surface SEM photograph of a polytetrafluoroethylene membrane before modification;
fig. 4 is a surface SEM photograph of the modified polytetrafluoroethylene membrane.
Detailed Description
The present invention is described in detail below with reference to various embodiments, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should be able to make modifications and substitutions on the functions, methods, or structures of these embodiments without departing from the scope of the present invention.
The invention is based on the normal pressure argon-hydrogen mixed plasma technology, single or composite hydrophilic monomers are introduced on the surface of the polytetrafluoroethylene microporous membrane for in-situ polymerization, so that the permanent hydrophilic modification of the membrane is realized, and the problem that the application of the polytetrafluoroethylene membrane in the field of water treatment is limited is further solved.
The preparation method of the polytetrafluoroethylene hydrophilic membrane comprises the following steps:
s1: soaking a polytetrafluoroethylene microporous membrane in absolute ethyl alcohol, cleaning and airing, placing between two polar plates of a normal-pressure plasma, introducing a mixed gas of discharge gas argon and hydrogen, and performing pretreatment;
s2: placing the pretreated polytetrafluoroethylene microporous membrane in absolute ethyl alcohol for soaking for 5-15 min, then placing the polytetrafluoroethylene microporous membrane in a hydrophilic monomer solution, and performing graft polymerization reaction on the surface of the membrane in a thermal polymerization mode;
s3: and (3) cleaning the grafted membrane by using an ethanol water solution, and drying the membrane in an oven to obtain the hydrophilic polytetrafluoroethylene microporous filtering membrane for water treatment.
In step S1, the ptfe microporous membrane may be a ptfe bubble point membrane or a composite membrane thereof, but is not limited thereto.
As shown in fig. 1, the apparatus corresponding to the atmospheric pressure argon-hydrogen mixed plasma technology comprises: argon source, hydrogen source, gas mixing chamber, reaction chamber, upper polar plate, lower polar plate, plasma power supply and voltage regulator.
Wherein, the argon source and the hydrogen source are respectively connected with the gas mixing chamber. The reaction cavity is provided with an air inlet hole and an air outlet hole which are communicated with the outside, and the air mixing chamber is connected with the air inlet hole of the reaction cavity. The upper polar plate and the lower polar plate are positioned in the reaction cavity, the upper polar plate and the lower polar plate are arranged oppositely, and a space for placing a polytetrafluoroethylene microporous membrane to be treated is formed between the upper polar plate and the lower polar plate. The upper polar plate is connected with a plasma power supply outside the reaction chamber. The voltage regulator is electrically connected with the plasma power supply so that the plasma power supply has the required discharge air filter. The voltage regulator can adopt the voltage regulator of the prior model.
Based on the normal-pressure argon-hydrogen mixed plasma device, the plasma treatment conditions are as follows: the distance between the two discharge electrode plates is 0.1-3cm, the discharge gas introduced into the chamber is a mixed gas of argon and hydrogen, the volume ratio of the discharge gas to the mixed gas is 1: 99-99: 1, the gas inlet speed is 0.2-5L/min, the discharge power is 10-100W, and the treatment time is 10-800 s.
In step S2, the hydrophilic monomer solution is a single hydrophilic monomer solution or a composite hydrophilic monomer solution, in one embodiment, the composite hydrophilic monomer solution includes acrylic acid, sodium styrene sulfonate, and itaconic acid, which are two-by-two or three-by-three composite, and the corresponding molecular formula is shown in fig. 2. The mass concentration of the hydrophilic monomer solution is 10-20%. The polymerization temperature of the thermal polymerization (heating or illumination) is between room temperature and 100 ℃, and the polymerization time is 0.1 to 10 hours.
In step S3, the modified ptfe microporous membrane is cleaned by ultrasonic oscillation in order to remove homopolymers or unreacted monomers adsorbed on the membrane surface.
The following will illustrate the technical scheme of the preparation method of the polytetrafluoroethylene hydrophilic membrane of the invention by combining with specific examples.
Example 1
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for fully cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and carrying out a normal pressure plasma treatment process on a polytetrafluoroethylene microporous membrane by combining a graph 1 as follows: putting the polytetrafluoroethylene microporous membrane 6 to be treated between an upper polar plate 5 and a lower polar plate 7 of a plasma device. The distance between the two polar plates is 0.1cm, 95:5 mixed gas of argon and hydrogen is introduced into the chamber through the air inlet 3, the air inlet speed is 0.2L/min, the power supply 9 is switched on, the discharge power is adjusted to 100W through the transformer 10, and the treatment time is 10 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid aqueous solution with the mass fraction of 15% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 60 ℃, and the reaction time is 4 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 1 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 41 degrees, and the water flux is 673L/m2 h.
Further, as shown in fig. 3 and 4, the polytetrafluoroethylene membrane before modification was used as a comparative example. And characterizing the surface morphology of the membrane before and after modification by using a KYKY-EM6900 scanning electron microscope to obtain SEM pictures of the surface of the polytetrafluoroethylene hydrophilic membrane before and after modification. From surface SEM pictures of the two, the modified polytetrafluoroethylene membrane introduces hydrophilic groups, so that the hydrophobicity of the membrane is improved, and the hydrophilization modification of the membrane is realized.
Example 2
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for fully cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and carrying out a normal pressure plasma treatment process on a polytetrafluoroethylene microporous membrane by combining a graph 1 as follows: putting the polytetrafluoroethylene microporous membrane 6 to be treated between an upper polar plate 5 and a lower polar plate 7 of a plasma device. The distance between the two plates is 1cm, the mixed gas of argon and hydrogen is introduced into the chamber at the ratio of 90:10, the gas inlet speed is 0.5L/min, the discharge power is 50W, and the treatment time is 30 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid aqueous solution with the mass fraction of 20% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 70 ℃, and the reaction time is 2.5 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 2 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 38 degrees, and the water flux is 773L/m2h。
Example 3
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 1.5cm, the mixed gas of argon and hydrogen with the ratio of 99.5:0.5 is introduced into the chamber, the gas inlet speed is 1L/min, the discharge power is 10W, and the treatment time is 120 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid aqueous solution with the mass fraction of 10% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 80 ℃, and the reaction time is 1.5 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 3 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 43 degrees, and the water flux is 577L/m2h。
Example 4
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 1cm, 95:5 mixed gas of argon and hydrogen is introduced into the chamber, the gas inlet speed is 0.5L/min, the discharge power is 100W, and the treatment time is 10 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid and sodium styrene sulfonate aqueous solution with the mass fraction of 15% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 70 ℃, and the reaction time is 2.5 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 4 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the obtained hydrophilic poly-tetra-ethylThe contact angle of the fluoroethylene hydrophilic membrane porous membrane is 32 degrees, and the water flux is 836L/m2h。
Example 5
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 3cm, 95:5 mixed gas of argon and hydrogen is introduced into the chamber, the gas inlet speed is 1L/min, the discharge power is 50W, and the treatment time is 30 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid and sodium styrene sulfonate aqueous solution with the mass fraction of 20% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 60 ℃, and the reaction time is 4 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 5 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 28 degrees, and the water flux is 943L/m2h。
Example 6
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 2cm, 95:5 mixed gas of argon and hydrogen is introduced into the chamber, the gas inlet speed is 0.7L/min, the discharge power is 60W, and the treatment time is 20 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid and sodium styrene sulfonate aqueous solution with the mass fraction of 15% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 80 ℃, and the reaction time is 1.5 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 6 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 34 degrees, and the water flux is 798L/m2h。
Example 7
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 0.1cm, the mixed gas of argon and hydrogen is introduced into the chamber at a ratio of 90:10, the gas inlet speed is 0.4L/min, the discharge power is 50W, and the treatment time is 30 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid and itaconic acid aqueous solution with the mass fraction of 20% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 60 ℃, and the reaction time is 4 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 7 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 25 degrees, and the water flux is 1085L/m2h。
Example 8
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 1.5cm, 95:5 mixed gas of argon and hydrogen is introduced into the chamber, the gas inlet speed is 0.5L/min, the discharge power is 60W, and the treatment time is 20 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid and itaconic acid aqueous solution with the mass fraction of 15% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 70 ℃, and the reaction time is 2 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use.
The polytetrafluoroethylene microporous membrane obtained in example 8 was tested for static water contact angle and water flux. Wherein, for static water contact angle: using a JC2000D3 contact angle measuring instrument to measure 5 points on a membrane sample and taking an average value to characterize the surface hydrophilicity of the modified membrane; for water flux: the test was carried out using the relevant equipment at a test pressure of 0.1 MPa. The test results are: the contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 27 degrees, and the water flux is 956L/m2h。
Example 9
Placing a polytetrafluoroethylene hydrophilic membrane with a certain area in absolute ethyl alcohol for full cleaning, removing dust and impurities on the surface of the membrane, placing the membrane between two polar plates of a normal pressure plasma after drying, and pre-treating conditions are as follows: the distance between the two plates is 1cm, 95:5 mixed gas of argon and hydrogen is introduced into the chamber, the gas inlet speed is 0.2L/min, the discharge power is 100W, and the treatment time is 10 s. Then soaking the treated membrane in absolute ethyl alcohol for 15min, taking out and placing the membrane in an acrylic acid and itaconic acid aqueous solution with the mass fraction of 10% for graft modification treatment, wherein the treatment conditions are as follows: the water bath heating temperature is 80 ℃, and the reaction time is 1.5 hours. And after the treatment is finished, the membrane is placed in deionized water, ultrasonically cleaned for 30min, and dried for later use. The contact angle of the prepared hydrophilic polytetrafluoroethylene hydrophilic membrane porous membrane is 31 degrees, and the water flux is 852L/m2h。
In conclusion, the invention introduces active functional groups on the surface of the membrane by utilizing the normal pressure plasma technology, has simple production process, is easy to operate continuously and is suitable for industrial production. The hydrophilic monomer adopted in the graft polymerization process has low cost and easy storage of raw materials, and meets the requirement of industrial production. Compared with a single hydrophilic monomer, the composite monomer adopted by the invention is used for graft polymerization, so that the defect of single hydrophilic modification is overcome, the complementation of the realizable performances among the composite monomers is realized, the modification effect is better, the modified hydrophilic performance is greatly improved, and the method has important significance for the application of the membrane technology in water treatment.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (10)
1. The preparation method of the polytetrafluoroethylene hydrophilic membrane is characterized by comprising the following steps of:
cleaning a polytetrafluoroethylene microporous membrane, removing impurities, airing, and treating the cleaned polytetrafluoroethylene microporous membrane by using a normal-pressure argon-hydrogen mixed plasma technology;
putting the treated polytetrafluoroethylene microporous membrane into a hydrophilic monomer solution, carrying out hydrophilic modification in a thermal polymerization mode, and cleaning the modified polytetrafluoroethylene microporous membrane.
2. The method for preparing a polytetrafluoroethylene hydrophilic membrane according to claim 1, wherein the device corresponding to the normal-pressure argon-hydrogen mixed plasma technology comprises: the device comprises an argon gas source, a hydrogen gas source, a gas mixing chamber, a reaction cavity, an upper polar plate, a lower polar plate and a plasma power supply;
argon gas source, hydrogen source respectively with the gas mixing chamber is connected, the gas mixing chamber with the reaction chamber is connected, upper polar plate, bottom plate are located in the reaction chamber, upper polar plate and bottom plate set up relatively, upper polar plate and outside the plasma power is connected.
3. The method for preparing a polytetrafluoroethylene hydrophilic membrane according to claim 2, wherein the device corresponding to the normal-pressure argon-hydrogen mixed plasma technology further comprises: and the voltage regulator is electrically connected with the plasma power supply.
4. The preparation method of the polytetrafluoroethylene hydrophilic membrane according to claim 2 or 3, wherein the normal-pressure argon-hydrogen mixed plasma technology corresponds to the following process conditions:
the distance between the upper polar plate and the lower polar plate is 0.1-3cm, the volume ratio of argon to hydrogen is 1: 99-99: 1, the air inlet speed of the argon and the hydrogen is 0.2-5L/min, the discharge power of the plasma power supply is 10-1000W, and the processing time is 10-800 s.
5. A method for preparing a hydrophilic membrane of polytetrafluoroethylene according to claim 2, wherein said hydrophilic monomer solution is a single hydrophilic monomer solution or a composite hydrophilic monomer solution.
6. A method for preparing a hydrophilic membrane of polytetrafluoroethylene according to claim 5, wherein said composite hydrophilic monomer solution comprises: two or three of acrylic acid, sodium styrene sulfonate and itaconic acid.
7. A method for preparing a hydrophilic membrane of polytetrafluoroethylene according to any one of claims 1, 5 or 6, wherein the mass concentration of the hydrophilic monomer solution is 10-20%.
8. The method for preparing a polytetrafluoroethylene hydrophilic membrane according to claim 1, wherein the temperature of the thermal polymerization is room temperature to 100 ℃, and the polymerization time is 0.1 to 10 hours.
9. The method for preparing a polytetrafluoroethylene hydrophilic membrane according to claim 1, wherein the polytetrafluoroethylene microporous membrane is a polytetrafluoroethylene bubble point membrane or a polytetrafluoroethylene composite membrane.
10. The method for preparing a polytetrafluoroethylene hydrophilic membrane according to claim 1, wherein the polytetrafluoroethylene microporous membrane modified by thermal polymerization is cleaned by ultrasonic oscillation.
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