CN116288931A - Single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane and preparation method thereof - Google Patents
Single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane and preparation method thereof Download PDFInfo
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- D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
- D06M13/322—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing nitrogen
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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Abstract
The invention relates to a preparation method of a single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane, which comprises the following steps: (1) Centrifugal spinning process of preparing nanometer polytetrafluoroethylene/PVA/silica (PTFE/PVA/SiO) 2 ) A fibrous membrane; (2) PTFE/PVA/SiO prepared in the step (1) is mixed with 2 The fiber membrane is fully sintered in a tubular furnace with uniform temperature rise to remove PVA components, and is taken out, ultrasonically cleaned and dried to obtain the hydrophobic micro-nano PTFE/SiO 2 A fibrous membrane; (3) PTFE/SiO prepared in the step (2) is treated 2 The fiber membrane is subjected to single-sided modification in PDA buffer solution to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane. The three-dimensional fiber membrane prepared by the method can be used for unidirectional water transfer of liquid, and has better separation rate and excellent reusability for dispersing various oil/water mixtures.
Description
Technical Field
The invention relates to an oil-water separation film, in particular to a single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber film and a preparation method thereof, and belongs to the technical field of new materials.
Background
In recent years, water resources have become limited, and due to this problem, reuse of water has become unavoidable. Thus, treating the reuse water in an efficient manner may reduce the impact on human health and the environment. One major environmental problem is the direct discharge of oily water and oily wastewater into the environment. Today, direct emission of oil-in-water contaminants generated by petroleum, automobiles, and refineries into an aqueous environment can affect human health and the aqueous environment. Used engine oil from automotive service stations contains high contaminants. Thus, the wastewater needs to be effectively treated before entering the ground, water body or sewer. The industrial oil-water separation methods mainly comprise air flotation, gravity separation, adsorption separation, condensation, flocculation and the like, but the methods can not effectively separate oil-water mixtures, are easy to cause energy consumption and secondary pollution, and are gradually replaced by some emerging separation technologies.
In order to maintain good ecological environment and human health and protect limited water resources, it is important to effectively separate oily sewage, and the traditional oil-water separation method has the disadvantages of long separation time, complex operation, incapability of continuous separation and incomplete separation. Although various special wettability materials with good oil-water separation function are currently available, most of the materials are mainly nondegradable or nondegradable high polymer materials, and the materials are easy to be polluted in the process of treating oily sewage due to the oleophilic property, so that a large amount of polluted garbage and waste materials which are difficult to treat are often generated after the materials are used, secondary pollution is easy to cause to the environment, and the comprehensive cost of post-treatment is high, so that the materials become one of important factors restricting the practical application of the oil-water separation materials. The membrane separation technology is an advanced novel separation technology, has the advantages of low energy consumption, low cost, high efficiency, no phase change, simple operation and the like, and in recent years, the strategic position in the fields of industry, municipal water treatment and the like is gradually highlighted, and is considered as a new generation of water treatment technology. However, with the continuous development of separation membrane technology, the requirements on the membrane materials in the aspects of intelligent response and accurate control are higher and higher, so that the development of novel separation membranes with special functions is of great significance.
Janus membranes, a separation membrane with liquid passage properties, are often characterized by differences in the chemical wetting properties of the two sides of the membrane. In recent years, materials having a Janus structure have been receiving increasing attention from researchers in the field of structural and functional design, and Janus membranes can remove certain liquids from specific areas and can effectively prevent liquid accumulation and contamination during related liquid transportation. With the technological progress, there is an increasing demand for composite materials, and the Janus structure can bring about dual-function effect or function synergistic effect compared with other single homogeneous materials, so that the composite materials are applied to a plurality of fields. However, the preparation method of the Janus material is complex, single in function and high in cost so far, so that the practical application of the material is hindered, the preparation process of the Jaun material is simplified, the cost is reduced, and more applications are still important in the research of the field.
Disclosure of Invention
The invention aims to provide a preparation method of a three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic, which is simple and easy to control, is suitable for composite finishing of various polymer fiber membranes, has the characteristic of single-sided superhydrophobic and single-sided superhydrophilic double-sided anisotropy, and has good oil-water separation performance.
The technical scheme adopted for solving the technical problems is as follows:
a preparation method of a single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane comprises the following steps:
(1) Centrifugal spinning process of preparing nanometer polytetrafluoroethylene/PVA/silica (PTFE/PVA/SiO) 2 ) A fibrous membrane;
the spinning solution is prepared from SiO containing nanometer 2 The PVA aqueous solution of the particles and the PTFE emulsion are mixed to prepare the spinning solution, wherein the mass fraction of PVA in the spinning solution is 5-9wt% and the mass fraction of PVA in the spinning solution is nano SiO 2 0.5 to 1.5 weight percent of particles and 27 to 33 weight percent of PTFE;
(2) PTFE/PVA/SiO prepared in the step (1) is mixed with 2 The fiber membrane is fully sintered in a tubular furnace with uniform temperature rise to remove PVA components, and is taken out, ultrasonically cleaned and dried to obtain the hydrophobic micro-nano PTFE/SiO 2 A fibrous membrane;
when the sintering temperature reaches 384+/-10 ℃, preserving the heat for 20 to 60 minutes;
(3) PTFE/SiO prepared in the step (2) is treated 2 Performing single-sided modification on the fiber membrane in PDA buffer solution to prepare a single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane;
the PDA buffer is an aqueous solution containing dopamine hydrochloride (HCL-PDA) and tris (hydroxymethyl) aminomethane, and the pH is adjusted to 7-8 by hydrochloric acid.
The three-dimensional fiber membrane prepared by the method can be used for unidirectional water transfer of liquid, and has better separation rate and excellent reusability for dispersing various oil/water mixtures.
The invention is different from the single-sided super-hydrophobic or hydrophilic finishing of the fiber membrane, and is characterized in that the hydrophilic fiber membrane is sintered to obtain super-hydrophobic, and then is subjected to hydrophilic modification, so that the fiber membrane has higher oil-water separation effect.
The invention takes economic and environment-friendly polyvinyl alcohol (PVA) and Polytetrafluoroethylene (PTFE) emulsion as raw materials, and adds a small amount of nano-particles SiO 2 The PVA particles can be uniformly dispersed in water, and the problems of insufficient swelling and wall hanging of the PVA particles in the dissolving process can be solved. Hydrophilic PTFE/PVA/SiO prepared by centrifugal spinning 2 The fiber membrane is prepared into a Janus micro-nano fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic through sintering and PDA modification, and the Janus micro-nano fiber membrane is applied to oil-water separation, so that the oil-water separation efficiency can be improved to 98.7%, and the problem of oil-water pollution in the environment can be effectively solved.
The invention prepares the asymmetric wettability micro-nano composite fiber membrane by using a hot pressing method and an adhesive method, and prepares hydrophilic PTFE/PVA/SiO by using a centrifugal spinning technology 2 The fiber membrane is sintered at 384 ℃ in a tubular furnace to become a super-hydrophobic membrane, and is subjected to PDA single-sided modification (pH is 7.5) to obtain PTFE/SiO 2 The fiber membrane has single-sided hydrophilicity, and the single-sided superhydrophobic single-sided superhydrophilic Janus micro-nano fiber membrane is prepared. The three-dimensional fiber membrane prepared by the method can be used for industrial oil-water separation and has the characteristics of simple raw materials, good operability, simple process, high efficiency, environmental protection, high oil-water separation efficiency and the like.
Preferably, in step (1), the PTFE emulsion has a PTFE solids content of 50 to 60%.
Preferably, in step (1), nano SiO 2 The mass fraction of the particles was 1wt%.
During centrifugal spinning, the mass fraction of PVA in the spinning solution is 6-9wt%;
preferably, in the step (2), the constant temperature rising method of sintering is: in the air environment, when the temperature is between 0 and 370 ℃, the temperature rising rate is 5 ℃/min; the temperature is 370-384 ℃, and the heating rate is 1 ℃/min; the temperature is 384 ℃, and the heat preservation time is 30min; at 384-27 ℃, the cooling rate is 25 ℃/min.
Preferably, in the PDA buffer solution in the step (3), the mass concentration of the dopamine hydrochloride solution is 5-20g/L, and the mass concentration of the tris (hydroxymethyl) aminomethane is 10-30%. More preferably, the mass concentration of the dopamine hydrochloride solution is 13-17g/L, and the mass concentration of the tris (hydroxymethyl) aminomethane is 20%.
Preferably, the spinning conditions of the centrifugal spinning are: the diameter of the spinning hole is 0.2-0.6mm, and the spinning rotating speed is 2000-10000rpm/min.
Preferably, the control of the receiving rod is 12 cm.+ -.2 cm from the spinneret during centrifugal spinning.
Preferably, the PVA particles and the nano SiO are mixed in the formula amount 2 Placing the particles and water on a magnetic stirrer, stirring for 1h at room temperature, heating to 90 ℃, preserving heat for 1h, cooling to room temperature, then placing into ultrasonic treatment for 20min, adding PTFE emulsion, and uniformly mixing to obtain spinning solution for centrifugal spinning.
The single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane obtained by the preparation method disclosed by the invention.
The single-sided superhydrophobic single-sided superhydrophilic three-dimensional PTFE/SiO prepared by the invention 2 The micro-nano composite fiber membrane is prepared by sintering and single-sided modification, so that stable super-hydrophobic characteristics of a fibril membrane are maintained, a composite fiber membrane with hydrophilic and hydrophobic double-sided anisotropy is prepared, and the single-sided super-hydrophobic single-sided super-hydrophilic Jaun composite fiber membrane prepared by the method has good separation effect when being used for oil-water separation, and has the following characteristics:
(1) The preparation method is simple in preparation process, efficient, environment-friendly, simple and convenient to operate and good in controllability;
(2) The invention is realized by adding a small amount of nano-particle SiO 2 The PVA particles can be uniformly dispersed in water, the phenomenon of insufficient swelling and wall hanging of the PVA particles is improved, the dissolution of the PVA particles in water can be accelerated, and the performance of the prepared fiber film is enhanced. But SiO 2 When the content exceeds 1wt%, an agglomeration effect is generated, and uniformity of the spinning solution is affected. Specific different SiO 2 Effect of content on PVA dissolution timeAs shown in fig. 7;
(3) The invention utilizes the high-temperature sintering and PDA single-sided modification method to lead the PTFE/PVA/SiO with hydrophilicity to be prepared 2 Removing hydrophilic component PVA in the fiber membrane to obtain superhydrophobicity, modifying the fiber membrane by using PDA buffer solution to make one side of the fiber membrane hydrophilic, and obtaining the composite fiber membrane with excellent asymmetric wettability;
(4) The Jauns type micro-nano composite fiber membrane prepared by the invention has good stability and large porosity, and the highest oil-water separation efficiency can reach 98.7%.
Drawings
FIG. 1 is a photograph of the hydrophobic side (a) and the hydrophilic side (b) of a Janus micro-nanofiber membrane prepared in 1;
FIG. 2 is a droplet contact angle of a hydrophobic surface of Janus composite fiber membranes prepared in various examples;
FIG. 3 shows the oil-water separation rate of the Janus composite fiber membrane prepared in each example for oil-water separation application test;
FIG. 4 is an Atomic Force Microscope (AFM) image of Janus micro-nanofiber membranes prepared in example 4;
FIG. 5 is a Transmission Electron Microscope (TEM) image obtained by the various embodiments;
FIG. 6 is a graph showing the stress-strain curves of three fiber films during the preparation of example 6.
FIG. 7 shows the different SiO's during the spin fluid in the single factor test 2 Effect of the content on PVA dissolution time.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
The invention will now be further illustrated with reference to specific examples, which are given solely for the purpose of illustration and are not to be construed as limiting the invention. The test specimens and test procedures used in the following examples include those (if the specific conditions of the experiment are not specified in the examples, generally according to conventional conditions or according to the recommended conditions of the reagent company; the reagents, consumables, etc. used in the examples described below are commercially available unless otherwise specified).
In the following examples, the molecular weight of PVA is 10000g/mol, and the solid content of PTFE in PTFE emulsion is 60%;
tube furnace, OTF-1200X, hefei Ke Jing materials technology Co.
The PDA buffer solution comprises dopamine hydrochloride, tris and deionized water. The preparation method comprises the following steps: taking a 150ml beaker, adding 120ml deionized water into the beaker, adding dopamine chloride and trimethylol methane, wherein the mass concentration of the dopamine chloride is 5-20g/L, the mass concentration of the trimethylol aminomethane is 10-30%, the reaction temperature is 25 ℃, and simultaneously, dropwise adding the solution into the solution by using 37% concentrated hydrochloric acid, stirring and adjusting the pH to 7.5.
The single-sided modification reaction time of the fiber membrane in PDA buffer is 6-12 hours.
Example 1
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) 13wt% of PVA and SiO are prepared 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25 ℃ for 1h, slowly heating to 95 ℃ until PVA is completely dissolved, cooling to room temperature, adding a PTFE emulsion with solid content of 60% to ensure that the PTFE accounts for 30% of the spinning solution, stirring on the heating magnetic stirrer at 25 ℃ for 12h, stirring the spinning solution obtained after the stirring is completed, stirring on the heating magnetic stirrer at 55 ℃ for 1h, performing centrifugal spinning, wherein the diameter of a spinning head is 0.4mm, and the spinning rotating speed is 8000rpm/min。
(2) Spin PTFE/PVA/SiO 2 Placing the fibrous membrane into a tubular furnace with constant temperature rise for full sintering,
the constant-speed temperature rising method for sintering comprises the following steps: setting the temperature at 0-370 deg.C, and setting the heating rate at 5 deg.C/min. Setting the temperature at 370-381 deg.C, and setting the heating rate at 1 deg.C/min.
Setting the temperature at 381 deg.C, and setting the heat preservation time at 30min.
Setting the temperature at 381-27 deg.C, setting the cooling rate at 25 deg.C/min.
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 16g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
Example 2
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) Preparation of PVA with mass fraction of 15wt% and SiO 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25deg.C for 0.5h, slowly heating to 98deg.C until PVA is completely dissolved, cooling to room temperature, adding PTFE emulsion with solid content of 60% to make PTFE content be 30% in the spinning solution, stirring on a heating magnetic stirrer at 25deg.C for 12h, stirring completely to obtain spinning solution, and placing on a heating magnetic stirrerStirring at 55deg.C for 1 hr, and centrifuging to obtain spinning powder with spinning head diameter of 0.4mm and spinning rotation speed of 8000rpm/min;
(2) Spin PTFE/PVA/SiO 2 The fiber membrane is put into a tube furnace to be fully sintered at 0-384 ℃, and the heating rate is set to be 5 ℃/min when the set temperature is 0-370 ℃. Setting the temperature at 370-384 deg.C, and setting the heating rate at 1 deg.C/min. Setting the temperature at 384 ℃ and setting the heat preservation time to be 30min. Setting the temperature at 384-27 ℃ and setting the cooling rate at 25 ℃/min.
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 16g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
Example 3
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) Preparation of PVA with a mass fraction of 14wt% and SiO 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25 ℃ for 1h, slowly heating to 95 ℃ until PVA is completely dissolved, cooling to room temperature, adding a PTFE emulsion with solid content of 60% to make the PTFE accounts for 30% of the spinning solution, stirring on the heating magnetic stirrer at 25 ℃ for 12h, stirring the spinning solution completely to obtain a spinning solution, stirring on the heating magnetic stirrer at 55 ℃ for 1h, and performing centrifugal spinning to obtain a spinning head with a diameter of 0.4mm, the spinning rotating speed is 8000rpm/min;
(2) Spin PTFE/PVA/SiO 2 The fibrous membrane is put into a tube furnace to be fully sintered at 0-381 ℃, and the heating rate is set to be 5 ℃/min when the set temperature is 0-370 ℃. Setting the temperature at 370-381 deg.C, and setting the heating rate at 1 deg.C/min. Setting the temperature at 381 deg.C, and setting the heat preservation time at 30min. Setting the temperature at 381-27 deg.C, setting the cooling rate at 25 deg.C/min. The method comprises the steps of carrying out a first treatment on the surface of the
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 17g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
Example 4
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) Preparation of PVA with mass fraction of 15wt% and SiO 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25 ℃ for 1h, slowly heating to 95 ℃ until PVA is completely dissolved, cooling to room temperature, adding a PTFE emulsion with solid content of 60% to ensure that the PTFE accounts for 30% of the spinning solution, stirring on the heating magnetic stirrer at 25 ℃ for 12h, stirring the spinning solution completely to obtain the spinning solution, stirring on the heating magnetic stirrer at 55 ℃ for 1h, and carrying out centrifugal spinning, wherein the diameter of a spinning head is 0.4mm, and the spinning rotating speed is 8000rpm/min;
(2) Spin PTFE/PVA/SiO 2 The fibrous membrane is put into a tube furnace to be fully sintered at 0-381 ℃, and the heating rate is set to be 5 ℃/min when the set temperature is 0-370 ℃. Setting the temperature at 370-381 deg.C, and setting the heating rate at 1 deg.C/min. Setting the temperature at 381 deg.C, and setting the heat preservation time at 30min. Setting the temperature at 381-27 deg.C, setting the cooling rate at 25 deg.C/min. The method comprises the steps of carrying out a first treatment on the surface of the
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 18g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
To examine the surface wettability of the fiber films of the examples at different contents. And detecting the water contact angle of the prepared nano composite fiber membrane, testing the surface contact angle of the nano composite fiber membrane by using a video contact angle tester, designing 3 mu L of deionized water to drop on the surface of the fiber membrane, randomly selecting five points for testing each sample, and calculating the average value of test data.
The results of the experiment in FIG. 2 show that the water contact angle is 155℃at the highest, and that the hydrophobicity is optimal at 15wt% PVA addition.
The wettability of porous surfaces is described by the Cassie-Baxter equation:
cosθ c ＝R f f s1 cosθ+f sl -1
wherein: r is R f Represents a wet sectionA divided roughness factor f s1 Is the percentage of the actual contact area to the composite area. The larger the proportion of air in the groove, the larger the contact angle. The model shows that when the contact angle on the same smooth solid is greater than 90 °, the contact angle increases by decreasing the contact area between the solid and the liquid (i.e., increasing the contact area of the liquid with air). Using a micropillar array, nanoparticles are added to increase the roughness on the nanometer scale. This results in an increase in roughness and an increase in superhydrophobic property.
In the above test, in the preparation of the spinning film, high-temperature calcination was performed to remove PVA components and reduce surface energy, thereby improving hydrophobicity. Unexpectedly, after the high temperature calcination is carried out, the roughness of the composite fiber film is also improved, and the water contact angle is also increased. From an atomic force microscope AFM image, it was found that the fiber roughness changed from the original film roughness ra=88.9 (nm) to the sintered film ra=302 (nm) and finally the modified film ra=172 (nm), and the roughness was increased as a whole compared with the original film.
Example 5
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) Preparation of PVA with mass fraction of 16wt% and SiO 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25 ℃ for 0.5h, slowly heating to 98 ℃ until PVA is completely dissolved, cooling to room temperature, adding a PTFE emulsion with a solid content of 60% to ensure that the PTFE accounts for 30% of the spinning solution, stirring on the heating magnetic stirrer at 25 ℃ for 12h, stirring the spinning solution after complete stirring, stirring on the heating magnetic stirrer at 55 ℃ for 1h, and carrying out centrifugal spinning, wherein the diameter of a spinning head is 0.5mm, and the spinning rotating speed is 9000rpm/min; the method comprises the steps of carrying out a first treatment on the surface of the (2) Spin PTFE/PVA/SiO 2 The fiber membrane is put into a tube furnace to be fully sintered at 0-384 ℃, and the heating rate is set to be 5 ℃/min when the set temperature is 0-370 ℃. Setting the temperature at 370-384 deg.C, and setting the heating rate at 1 deg.C/min. Setting the temperature at 384 ℃ and setting the heat preservation time to be 30min. Setting the temperature at 384-27 ℃ and setting the cooling rate at 25 ℃/min.
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 19g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
Example 6
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) Preparation of PVA with mass fraction of 17wt% and SiO 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25 ℃ for 0.5h, slowly heating to 98 ℃ until PVA is completely dissolved, cooling to room temperature, adding a PTFE emulsion with solid content of 60% to ensure that the PTFE accounts for 30% of the spinning solution, stirring on the heating magnetic stirrer at 25 ℃ for 12h, stirring the spinning solution after complete stirring, stirring on the heating magnetic stirrer at 55 ℃ for 1h, and carrying out centrifugal spinning, wherein the diameter of a spinning head is 0.4mm, and the spinning rotating speed is 8000rpm/min; the method comprises the steps of carrying out a first treatment on the surface of the (2) Spin PTFE/PVA/SiO 2 The fiber membrane is put into a tube furnace to be fully sintered at 0-384 ℃, and the heating rate is set to be 5 ℃/min when the set temperature is 0-370 ℃. Setting the temperature at 370-384 deg.C, and setting the heating rate at 1 deg.C/min. Setting the temperature at 384 ℃ and setting the heat preservation time to be 30min. Setting the temperature at 384-27 ℃ and setting the cooling rate at 25 ℃/min.
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 20g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
It can also be seen that the maximum stress that the fibrous membrane can withstand during the preparation process is increasing. The mechanical strength increased from 1.95MPa to 2.49MPa.
Example 7
The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic comprises the following specific steps:
(1) Preparation of PVA with mass fraction of 17wt% and SiO 2 PVA/SiO with mass fraction of nano particles of 1wt% 2 Stirring the solution on a heating magnetic stirrer at 25 ℃ for 0.5h, slowly heating to 98 ℃ until PVA is completely dissolved, cooling to room temperature, adding a PTFE emulsion with solid content of 60% to ensure that the PTFE accounts for 30% of the spinning solution, stirring on the heating magnetic stirrer at 25 ℃ for 12h, stirring the spinning solution after complete stirring, stirring on the heating magnetic stirrer at 55 ℃ for 1h, and carrying out centrifugal spinning, wherein the diameter of a spinning head is 0.6mm, and the spinning rotating speed is 8600rpm/min; the method comprises the steps of carrying out a first treatment on the surface of the (2) Spin PTFE/PVA/SiO 2 The fiber membrane is put into a tube furnace to be fully sintered at 0-384 ℃, and the heating rate is set to be 5 ℃/min when the set temperature is 0-370 ℃. Setting the temperature at 370-384 deg.C, and setting the heating rate at 1 deg.C/min. Setting the temperature at 384 ℃ and setting the heat preservation time to be 30min. Setting the temperature at 384-27 ℃ and setting the cooling rate at 25 ℃/min.
(3) Preparing a PDA buffer solution: a150 ml beaker was taken, 120ml deionized water was added thereto, and dopamine chloride and trimethylol methane were added thereto, wherein the mass concentration of dopamine chloride was 20g/L, the mass concentration of trimethylol amino methane was 20wt%, the reaction temperature was 25 ℃, and the pH was adjusted to 7.5 with hydrochloric acid, and the solution preparation reaction time was 6 hours.
The hydrophobic micro-nano PTFE/SiO obtained by sintering the step (2) 2 The fiber membrane is subjected to single-sided modification in the PDA buffer solution for 12 hours, namely one side of the fiber membrane floats on the surface of the buffer solution, PDA molecules are oxidized and self-gathered on the surface of the fiber, and the modified surface has good hydrophilicity after modification.
(4) And (3) carrying out ultrasonic cleaning on the three-dimensional micro-nano composite fiber membrane obtained through single-sided modification of the PDA solution to remove superfluous polydopamine on the surface, and drying the membrane in an oven at 60 ℃ to prepare the single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane.
To examine different SiO in the preparation process of spinning solution 2 Influence of the content on PVA dissolution time the following single-factor test was performed:
as in the preparation of the dope in step (1) of example 1, siO was examined under the condition that the PVA and PTFE components content in the dope were unchanged 2 The effect of the content of 0%, 0.25%, 0.50%, 0.75%, 1.00%, 1.25% on the complete dissolution time of PVA particles in the spinning solution. As shown in FIG. 7, it can be seen from FIG. 7 that SiO is contained in the range of 0% -1.00% 2 The content is increased and the complete dissolution time of PVA grains is reduced. But SiO 2 When the content reaches 1.25wt%, the spinning solution is stirred to obtain nano SiO 2 The particles can generate obvious agglomeration phenomenon, and the components of the spinning solution are unevenly dispersed.
The invention is realized by adding a small amount of nano-particle SiO 2 The PVA particles can be uniformly dispersed in water, the phenomenon of insufficient swelling and wall hanging of the PVA particles is improved, the dissolution of the PVA particles in water can be accelerated, and the performance of the prepared fiber film is enhanced. But SiO 2 When the content exceeds 1wt%, an agglomeration effect is generated, and uniformity of the spinning solution is affected.
The performance test result of the Janus micro-nano fiber film prepared by the invention is as follows:
1. as can be seen from fig. 1, when water droplets and oil droplets (1, 2-dibromoethane) were dropped on the hydrophobic surface of the Janus micro-nanofiber membrane prepared in example 1, it was observed that the fiber membrane had good hydrophobicity and lipophilicity. In order to more intuitively observe the states of the water phase and the oil phase on the Janus composite fiber membrane, the Janus fiber membranes prepared in examples 1-6 are tested for water-oil contact angle under a liquid drop morphological analyzer, the liquid drops are contacted with fabrics for 60 seconds, the test data are tested, the average value is obtained after the liquid drops are tested for 5 times at different positions of the same sample, and the liquid drop contact angle of the water repellent surface of the Janus composite fiber membrane is measured as shown in figure 2.
As can be seen from fig. 2, the water contact angle of the hydrophobic surface of the prepared three-dimensional micro-nano composite fiber membrane is up to 150 degrees or more, wherein the water contact angle of the hydrophobic surface of the three-dimensional micro-nano composite fiber membrane prepared in example 4 is up to 155 degrees, and the water contact angle of the oil phase of the three-dimensional micro-nano composite fiber membrane prepared in each example is 0 degree, which indicates that the three-dimensional micro-nano composite fiber membrane prepared by the method has higher hydrophobicity and good lipophilicity.
2. The three-dimensional micro-nano composite fiber membrane prepared in the embodiment is used for carrying out an oil-water separation application test on an oil-water mixed solution of 1, 2-dibromoethane and deionized water (water/1, 2-dibromoethane mixed solution: 1, 2-dibromoethane is dyed by disperse red FB, deionized water is dyed by methylene blue, the two are mixed to be used as oil-water mixed solution), water separation equipment is a sand core suction filtration device, a filter bowl is arranged above the water separation equipment, the oil-water mixed solution is added from above, a sand core filtration head is arranged in the middle of the water separation equipment, the prepared Janus fiber membrane is placed between the filter bowl and the filtration head, the water/1, 2-dibromoethane mixed solution is fixed by a fixing clamp, and separation liquid is collected after separation is completed. The oil-water separation rate is shown in figure 3, and the separation efficiency of the composite fiber membrane prepared by the method is above 98%, wherein the highest oil-water separation rate of examples 1 and 2 is 98.7%, which shows that the composite fiber membrane has good oil-water separation effect.
3. As can be seen from fig. 4, a Scanning Electron Microscope (SEM) image shows that the three-dimensional micro-nano composite fiber film prepared in example 3 has a fiber morphology with a uniform diameter. As can be seen from FIG. 5, the three-dimensional micro-nano complex prepared in example 1Transmission Electron Microscopy (TEM) of the synthetic fiber film reveals the nano SiO supported on the individual fibers 2 The particles are more uniformly arranged in the fiber and on the surface.
Example 6 the stress-strain curves of three fibrous membranes during the preparation process are shown in fig. 6, and it can be seen from fig. 6 that the maximum stress that the fibrous membranes can withstand during the preparation process is larger and larger. The mechanical strength of the original fiber film is increased from 2.09MPa to 2.74MPa after calcination. The mechanical property is further improved after PDA modification, and the mechanical strength is increased from 2.74MPa to 3.22MPa.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane and the preparation method thereof provided by the invention are described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (10)
1. The preparation method of the three-dimensional micro-nano composite fiber membrane with single-sided superhydrophobic and single-sided superhydrophilic is characterized by comprising the following steps:
(1) Centrifugal spinning process of preparing nanometer polytetrafluoroethylene/PVA/silica (PTFE/PVA/SiO) 2 ) A fibrous membrane;
the spinning solution is prepared from SiO containing nanometer 2 The PVA aqueous solution of the particles and the PTFE emulsion are mixed to prepare the spinning solution, wherein the mass fraction of PVA in the spinning solution is 5-9wt% and the mass fraction of PVA in the spinning solution is nano SiO 2 0.5 to 1.5 weight percent of particles and 27 to 33 weight percent of PTFE;
(2) PTFE/PVA/SiO prepared in the step (1) is mixed with 2 The fiber membrane is fully sintered in a tubular furnace with uniform temperature rise to remove PVA components, and is taken out, ultrasonically cleaned and dried to obtain the hydrophobic micro-nano PTFE/SiO 2 A fibrous membrane;
when the sintering temperature reaches 384+/-10 ℃, preserving the heat for 20 to 60 minutes;
(3) PTFE/SiO prepared in the step (2) is treated 2 Performing single-sided modification on the fiber membrane in PDA buffer solution to prepare a single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane;
the PDA buffer is an aqueous solution containing dopamine hydrochloride (HCL-PDA) and tris (hydroxymethyl) aminomethane, and the pH is adjusted to 7-8 by hydrochloric acid.
2. The method of manufacturing according to claim 1, characterized in that: in the step (1), the solid content of PTFE in the PTFE emulsion is 50-60%.
3. The method of manufacturing according to claim 1, characterized in that: in the step (1), the step of (a),
during centrifugal spinning, nano SiO in spinning solution 2 The mass fraction of the particles was 1wt%.
4. The method of manufacturing according to claim 1, characterized in that: in the step (2), the constant-speed temperature rising method for sintering is as follows: in the air environment, when the temperature is between 0 and 370 ℃, the temperature rising rate is 5 ℃/min; the temperature is 370-384 ℃, and the heating rate is 1 ℃/min; the temperature is 384 ℃, and the heat preservation time is 30min; at 384-27 ℃, the cooling rate is 25 ℃/min.
5. The method of manufacturing according to claim 1, characterized in that: in the PDA buffer solution in the step (3), the mass concentration of the dopamine hydrochloride solution is 5-20g/L, and the mass concentration of the tris (hydroxymethyl) aminomethane is 10-30%.
6. The method of manufacturing according to claim 1, characterized in that: the mass concentration of the dopamine hydrochloride solution is 13-17g/L, and the mass concentration of the tris (hydroxymethyl) aminomethane is 20%.
7. The method of manufacturing according to claim 1, characterized in that: the spinning conditions of centrifugal spinning are: the diameter of the spinning hole is 0.2-0.6mm, and the spinning rotating speed is 2000-10000rpm/min.
8. The method of manufacturing according to claim 1, characterized in that: the distance between the receiving rod and the spinning head is controlled to be 12cm plus or minus 2cm during centrifugal spinning.
9. The method of manufacturing according to claim 1, characterized in that: PVA particles and nano SiO with the formula amount 2 Placing the particles and water on a magnetic stirrer, stirring for 1h at room temperature, heating to 90 ℃, preserving heat for 1h, cooling to room temperature, then placing into ultrasonic treatment for 20min, adding PTFE emulsion, and uniformly mixing to obtain spinning solution for centrifugal spinning.
10. A single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane obtained by the preparation method of claim 1.
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| CN202310277458.0A CN116288931A (en) | 2023-03-21 | 2023-03-21 | Single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane and preparation method thereof |
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| CN202310277458.0A CN116288931A (en) | 2023-03-21 | 2023-03-21 | Single-sided superhydrophobic single-sided superhydrophilic three-dimensional micro-nano composite fiber membrane and preparation method thereof |
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