CN103272493A - Method for hydrophilic modification of polyvinylidene fluoride membrane - Google Patents
Method for hydrophilic modification of polyvinylidene fluoride membrane Download PDFInfo
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- CN103272493A CN103272493A CN 201310151115 CN201310151115A CN103272493A CN 103272493 A CN103272493 A CN 103272493A CN 201310151115 CN201310151115 CN 201310151115 CN 201310151115 A CN201310151115 A CN 201310151115A CN 103272493 A CN103272493 A CN 103272493A
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Abstract
The invention relates to a method for hydrophilic modification of a polyvinylidene fluoride membrane under the supercritical carbon dioxide condition. The method is characterized in that a polyvinylidene fluoride membrane is used as a base membrane; acrylic acid and N-hydroxymethyl acrylamide are used as functional monomers; benzoyl peroxide is used as a radical initiator; and in supercritical carbon dioxide, through adjustment of reaction pressure, reaction time and amounts of the two monomers, a grafting-modification polymerization reaction is carried out. The polyvinylidene fluoride membrane obtained by the method has high hydrophilicity, produces response according to an environmental pH change thereby causing a membrane aperture size change, and can be used for intelligent selective separation of materials needing to be separated. The method has simple processes, does not produce pollution, can be controlled easily, and is a simple and green preparation method.
Description
Technical field
The invention belongs to supercritical carbon dioxide (SC CO
2) prepare the technical field of pH response type film for solvent, being specially and adopting pH sensitiveness and hydrophilic monomer is grafted monomers, and being initator with the benzoyl peroxide carries out the preparation method that hydrophilic modifying obtains the polyvinylidene fluoride film that fenestra can regulate with pH to polyvinylidene fluoride film.
Background technology
Kynoar (PVDF) is a kind of polymer of easy crystal type, because C-F bond distance is shorter, bond energy is higher, therefore have good chemical stability and mechanical strength, its ageing-resistant and anti-ultraviolet property excellence, strong oxidizer corrosive powers such as antiacid under the room temperature, alkali are strong, have good temperature resistance, weatherability, anti-x radiation x performance, having properties such as piezoelectricity, dielectricity, pyroelectricity in addition, is the good separation membrane material of a kind of combination property.At present, pvdf membrane has been widely used in industrial circles such as chemical industry, biochemistry, food, weaving.But the pvdf membrane surface can be lower, has extremely strong hydrophobicity, makes that its pick up is low, resistance to mass tranfer is high, and separative efficiency is low, separation function is single, and its application is very limited.Main cause is: the strong-hydrophobicity of pvdf membrane makes strong absorption between the materials such as itself and organic matter, colloid, microorganism/stick effect, it is contaminated to cause pvdf membrane to be easy in water treatment procedure, and membrane flux reduces, in use need frequent clean, cause cost of water treatment to increase, efficient reduces.In addition, the strong-hydrophobicity of pvdf membrane all is not easy by water-wet its film surface and fenestra wall, needs bigger driving force in water treatment procedure, has therefore increased the energy consumption cost of its water treatment.Graft modification is carried out on the film surface can be changed the film surface nature, improve its resistance tocrocking, little to the influence of membrane material body simultaneously, expanded its range of application.
Existing method to the PVDF hydrophilic modifying mainly contains two kinds, and a kind of is by material modification, and the blend hydrophilic component realizes the modification of film simultaneously in the film preparation process; Another kind is to prepare hydrophobic pvdf membrane earlier, introduce the hydroaropic substance layer by the surface graft modification technology on pvdf membrane surface and hole inwall again, realize the modification of film, this method can realize the permanent hydrophilic modification of film, effectively reduces the loss of surface hydrophilic material and to the migration of film inside.
The employed grafted monomers acrylic acid of this law and N hydroxymethyl acrylamide all have good hydrophily, and belong to the pH sensitive monomer.PH sensitiveness and hydrophilic monomer are introduced in the pvdf membrane, utilized the configuration of pH sensitive monomer and micro-structural to change the reversible variation of generation with extraneous pH condition, give pvdf membrane pH response characteristic, and increased its hydrophilicity greatly.This membrane material is with the premium properties of PVDF and pH sensitive polymer, thereby all has huge potential at aspects such as many applications such as selectively penetrating, controlled delivery of pharmaceutical agents releases.
Because the high stability of PVDF, percent grafting is often on the low side, and performance does not reach ideal standard, has radiation method grafting, BPO to cause copolymerization method, atom transferred free radical method, plasma grafting modification method etc. to its main method of carrying out graft modification.The present invention adopts radical initiator benzoyl peroxide (BPO) to cause the PVDF grafting, and equipment is simple, earlier PVDF is carried out modification and handle before grafting, makes film produce more more complicated grafting active sites, has improved grafting efficiency.
The general monomer that is used for surface modification is hydrophilic function monomer and the difficult surface that is diffused into pvdf membrane of initator particularly, makes difficulty of face grafting, and grafting can not be deep into the profound part of film.The present invention is with SC CO
2Be reaction dissolvent, carry out the graft polymerization reaction of acrylic acid and N hydroxymethyl acrylamide on PVDF microporous barrier surface, grafting does not occur over just the outer surface of film, and gos deep into the inner surface of fenestra, improve the hydrophily of film, improved the antifouling property of grafting efficiency and film.And SC CO
2Have advantages such as nontoxic, pollution-free, easy recovery, the easy purifying noresidue of product, make the course of reaction green non-pollution.
Summary of the invention
The objective of the invention is for solve existing polyvinylidene fluoride film (PVDF) in application low pick up and the problem of high resistance to mass tranfer, and improve fenestra functionalization degree and separating property.The invention provides a kind of PVDF graft copolymer membrane and preparation method to the pH sensitivity.The fenestra of this film is inner all to contain pH sensitive high molecular weight copolymer with the surface, and this pH sensitive high molecular weight copolymer is regulated the fenestra size by the variation of environment pH, has realized the pH response of film.
The preparation of PVDF graft copolymer membrane provided by the present invention is at supercritical carbon dioxide (SC CO
2) implement under the condition.Supercritical carbon dioxide has good flowability and scattering and permeating performance as reaction medium, and polymer is had good wetting and plasticity, can promote initator and glycerol polymerization monomer to outer surface and the inner surface diffusion of PVDF microporous barrier.And can change SC CO by adjusting temperature and pressure
2Solubility property, thereby adjust monomer at polymer mutually and SC CO
2Distribution mutually is with the grafting degree of control PVDF microporous barrier.
The present invention is reaction dissolvent with the supercritical carbon dioxide, adopts two kinds of functional monomers to assist grafting, and a kind of new method of the pH of preparation responsive type polyvinylidene fluoride film is provided, and the technical scheme of employing is as follows:
A) preliminary treatment of film: the diameter that will have certain mass is that 55mm, aperture are that the polyvinylidene fluoride film of 0.22um is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
B) glycerol polymerization of film: in autoclave, add a certain amount of acrylic acid and N hydroxymethyl acrylamide as grafted monomers, benzoyl peroxide is initator, with a kind of bracing frame the resulting polyvinylidene fluoride film of step (a) is supported on the middle part of reactor, reaction monomers adopts electromagnetic agitation at the bottom of the still.In autoclave, charge into a certain amount of carbon dioxide, make its sealing then, and preheating in water-bath at a certain temperature, raw material is fully mixed in precritical carbon dioxide.Slowly be warming up to reaction temperature then, reach predetermined pressure, carry out glycerol polymerization.Reaction makes reactor naturally cool to room temperature after finishing, and emits carbon dioxide in the still, opens reactor and can obtain dry graft copolymer membrane.
The pH responsive type graft copolymerization film that the present invention is prepared, the surface of film and inside all are grafted with pH sensitiveness graft copolymer, can realize the adjusting to the fenestra size in different pH environment by the variation of self structure.Advantage of the present invention is that the high-molecular copolymer with pH sensitiveness is fixed on film surface and inner, thereby make pH response function and the perfect adaptation of isolated by filtration function of film, by regulating the size of the pH sensitive copolymers strand conformational change fenestra in the fenestra, thereby regulate the filtering property of film, having improved simultaneously the hydrophilicity of pvdf membrane again largely, is a kind of new membrane parting material with big application prospect.
PH response type PVDF copolymer membrane preparation method of the present invention is simple, efficient, and agents useful for same is conventional reagent, and course of reaction controls easy to be nontoxicly, pollution-free, and the easy purifying noresidue of product is a kind of eco-friendly " green " new synthetic method.
Description of drawings
Fig. 1 is the infrared spectrum of different percent grafting films;
Fig. 2 for the differential responses pressure that obtains by case study on implementation 1,2,3,4,5 grafting method to the influence of film at different pH value water fluxes
The specific embodiment
In order to make technological means of the present invention, creation characteristic, to reach purpose and effect and be easy to understand and understand, introduce specific embodiments of the invention below.
Embodiment 1
1. the polyvinylidene fluoride film with certain mass is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
2. take by weighing acrylic acid 0.8g, N hydroxymethyl acrylamide 0.8g, benzoyl peroxide 0.02g;
3. put into ice-water bath after the autoclave sealing, the air with in the carbon dioxide eliminating reactor charges into the 95g carbon dioxide then;
4. reactor is put into water-bath, 35 ℃ of preheating 3 h slowly are warming up to 65 ℃ then, reach predetermined pressure 26MPa, react 6 h;
5. after reaction finishes, make reactor naturally cool to room temperature, open reactor after the venting and can obtain dry graft copolymer membrane.
1. the polyvinylidene fluoride film with certain mass is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
2. take by weighing acrylic acid 0.8g, N hydroxymethyl acrylamide 0.8g, benzoyl peroxide 0.02g;
3. put into ice-water bath after the autoclave sealing, the air with in the carbon dioxide eliminating reactor charges into the 90g carbon dioxide then;
4. reactor is put into water-bath, 35 ℃ of preheating 3 h slowly are warming up to 65 ℃ then, reach predetermined pressure 22MPa, react 6 h;
5. after reaction finishes, make reactor naturally cool to room temperature, open reactor after the venting and can obtain dry graft copolymer membrane.
Embodiment 3
1. the polyvinylidene fluoride film with certain mass is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
2. take by weighing acrylic acid 0.8g, N hydroxymethyl acrylamide 0.8g, benzoyl peroxide 0.02g;
3. put into ice-water bath after the autoclave sealing, the air with in the carbon dioxide eliminating reactor charges into the 85g carbon dioxide then;
4. reactor is put into water-bath, 35 ℃ of preheating 3 h slowly are warming up to 65 ℃ then, reach predetermined pressure 20MPa, react 6 h;
5. after reaction finishes, make reactor naturally cool to room temperature, open reactor after the venting and can obtain dry graft copolymer membrane.
1. the polyvinylidene fluoride film with certain mass is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
2. take by weighing acrylic acid 0.8g, N hydroxymethyl acrylamide 0.8g, benzoyl peroxide 0.02g;
3. put into ice-water bath after the autoclave sealing, the air with in the carbon dioxide eliminating reactor charges into the 80g carbon dioxide then;
4. reactor is put into water-bath, 35 ℃ of preheating 3 h slowly are warming up to 65 ℃ then, reach predetermined pressure 18MPa, react 6 h;
5. after reaction finishes, make reactor naturally cool to room temperature, open reactor after the venting and can obtain dry graft copolymer membrane.
Embodiment 5
1. the polyvinylidene fluoride film with certain mass is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
2. take by weighing acrylic acid 0.8g, N hydroxymethyl acrylamide 0.8g, benzoyl peroxide 0.02g;
3. put into ice-water bath after the autoclave sealing, the air with in the carbon dioxide eliminating reactor charges into the 75g carbon dioxide then;
4. reactor is put into water-bath, 35 ℃ of preheating 3 h slowly are warming up to 65 ℃ then, reach predetermined pressure 16MPa, react 6 h;
5. after reaction finishes, make reactor naturally cool to room temperature, open reactor after the venting and can obtain dry graft copolymer membrane.
The present invention has prepared a kind of Kynoar graft copolymerization film of pH response, and its preparation method is convenient, efficient and course of reaction is controlled easy to be nontoxicly, pollution-free, and the easy purifying noresidue of product is a kind of eco-friendly " green " new synthetic method.
Claims (8)
1. in the supercritical carbon dioxide grafting functional monomer is carried out on the polyvinylidene fluoride film surface, preparation pH response type Kynoar graft copolymerization film.
2. pH response type Kynoar graft copolymerization film according to claim 1 is characterized in that the grafted monomers that adopts is acrylic acid and N hydroxymethyl acrylamide.
3. pH response type Kynoar graft copolymerization film according to claim 1 is characterized in that fenestra inner surface and outer surface form by pH sensitiveness high-molecular copolymer.
4. pH response type Kynoar graft copolymerization film according to claim 1 is characterized in that referring to that in use the through performance of fenestra size and film can change according to environment pH change.
5. according to claim 1 described pH response type Kynoar graft copolymerization film, preparation method's step is as follows:
A) preliminary treatment of film: the diameter that will have certain mass is that 55mm, aperture are that the polyvinylidene fluoride film of 0.22um is immersed in 2 h in the ethanolic solution under room temperature, dries to constant weight;
B) glycerol polymerization of film: in autoclave, add a certain amount of hydrophily grafted monomers, benzoyl peroxide is initator, with a kind of bracing frame the resulting polyvinylidene fluoride film of step (a) is supported on the middle part of reactor, reaction monomers adopts electromagnetic agitation at the bottom of the still.In autoclave, charge into a certain amount of inorganic solvent, make its sealing then, under the certain reaction temperature, in water-bath, carry out glycerol polymerization.
6. pH response type Kynoar graft copolymerization film according to claim 5 is characterized in that described reaction temperature is 60-80 ℃.
7. pH response type Kynoar graft copolymerization film according to claim 5 is characterized in that the inorganic solvent that adopts is supercritical carbon dioxide.
8. according to claim 5, it is characterized in that employed hydrophilic monomer also comprises hydroxy-ethyl acrylate and N-isopropylacrylamide.
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| CN103657429A (en) * | 2013-11-08 | 2014-03-26 | 江南大学 | Cationic surface cationic method of support-free porous high-polymer separation membrane by thermosetting |
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| CN107115795A (en) * | 2017-03-24 | 2017-09-01 | 浙江师范大学 | A kind of flux in acid condition has seperation film of pH dependences and preparation method thereof |
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| CN103657429A (en) * | 2013-11-08 | 2014-03-26 | 江南大学 | Cationic surface cationic method of support-free porous high-polymer separation membrane by thermosetting |
| CN103657429B (en) * | 2013-11-08 | 2016-05-04 | 江南大学 | A kind of method without the cationic finishing of supporter porous polymeric membrane for separation of heat cure |
| CN104667767A (en) * | 2015-03-19 | 2015-06-03 | 新疆大学 | Preparation method for chitosan/polycaprolactone antibacterial composite porous membrane |
| CN107921370B (en) * | 2015-07-01 | 2022-03-29 | 3M创新有限公司 | Polymeric ionomer separation membranes and methods of use thereof |
| CN107921370A (en) * | 2015-07-01 | 2018-04-17 | 3M创新有限公司 | Polymeric ionomer seperation film and its application method |
| CN105642132B (en) * | 2016-04-15 | 2017-12-12 | 北京碧水源膜科技有限公司 | A kind of polyvinylidene fluoride film being modified through targetting synergy nano-functional material and preparation method thereof |
| CN105642132A (en) * | 2016-04-15 | 2016-06-08 | 北京碧水源膜科技有限公司 | Targeted synergized and nanometer functional material modified polyvinylidene fluoride membrane and preparation method thereof |
| CN107115795A (en) * | 2017-03-24 | 2017-09-01 | 浙江师范大学 | A kind of flux in acid condition has seperation film of pH dependences and preparation method thereof |
| CN107115795B (en) * | 2017-03-24 | 2021-01-19 | 浙江师范大学 | Separation membrane with pH-dependent flux under acidic condition and preparation method thereof |
| CN111481993A (en) * | 2019-01-28 | 2020-08-04 | 笙特科技股份有限公司 | Filter material and method for producing same |
| US11224686B2 (en) | 2019-01-28 | 2022-01-18 | Sangtech Lab Inc. | Filter material and manufacturing method thereof |
| CN112029057A (en) * | 2020-07-14 | 2020-12-04 | 乳源东阳光氟树脂有限公司 | Hydrophilic modified polyvinylidene fluoride block copolymer, water treatment membrane, preparation method and application thereof |
| CN113083030A (en) * | 2021-03-30 | 2021-07-09 | 浙江师范大学 | Anti-pollution high-flux modified polymer separation membrane and preparation method thereof |
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Application publication date: 20130904 |