CN114642970B - POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane and preparation method - Google Patents
POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane and preparation method Download PDFInfo
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Abstract
The invention discloses a nanofiber membrane attached by a POSS-PMMA-b-PDMS super-hydrophobic compound and a preparation method thereof, wherein the nanofiber membrane comprises a PI membrane or a PI/PANI composite membrane and a copolymer attached to the surface of the membrane, and the copolymer is the POSS-PMMA-b-PDMS super-hydrophobic compound. The invention also discloses a preparation method of the nanofiber membrane, which specifically comprises the following steps: s1) preparing a PI film or a PI/PANI composite film; s2) preparing a POSS-PMMA-b-PDMS super-hydrophobic compound; s3) immersing the activated PI film or PI/PANI composite film into POSS-PMMA-b-PDMS super-hydrophobic compound suspension, and then heating and attaching to obtain the product. The super-hydrophobic composite membrane has the advantages of good hydrophobic property, low surface energy and the like.
Description
Technical Field
The invention relates to the technical field of super-hydrophobic membrane materials, in particular to a nanofiber membrane attached by a POSS-PMMA-b-PDMS super-hydrophobic compound and a preparation method.
Background
Membrane separation is the most effective method for treating oily boiling water, and is considered by the public as the current optimal oil-water mixture separation technology because of high separation efficiency, environmental friendliness and simple and reliable operation. Thus, more and more research is focused on polymer-based membrane separation technology.
The introduction of cage-type silsesquioxane (POSS) into polymers by grafting or end capping can improve the thermal stability, mechanical stability and hydrophobic and dielectric properties of materials, and has become a research hot spot for current hydrophobic materials or oleophobic materials. However, the introduction of POSS into hydrophobic and oleophobic materials is still concentrated on the modification of diblock polymers at present, and the problems that the hydrophobic effect is difficult to improve and the thermal stability is difficult to improve exist.
Disclosure of Invention
In order to solve the problems existing in the prior art. The invention provides a POSS-PMMA-b-PDMS super-hydrophobic compound which is formed by copolymerizing methyl methacrylate monomer, cage polysilsesquioxane and polydimethylsiloxane.
A nanofiber membrane attached by POSS-PMMA-b-PDMS super-hydrophobic compound adopts a PI membrane as a base material, and a POSS-PMMA-b-PDMS super-hydrophobic compound containing POSS is attached to the PI membrane to obtain a copolymer attached super-hydrophobic nanofiber membrane with good hydrophobic performance and low surface energy.
The invention also discloses a nano-fiber membrane attached by the POSS-PMMA-b-PDMS super-hydrophobic compound, which adopts the PI membrane as a base material, and sequentially attaches PANI and the POSS-PMMA-b-PDMS super-hydrophobic compound containing POSS on the PI membrane to obtain the copolymer attached super-hydrophobic nano-fiber membrane with good hydrophobic performance and low surface energy.
The invention also discloses a preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane.
The technical scheme of the invention is as follows:
the nanofiber membrane attached by the POSS-PMMA-b-PDMS super-hydrophobic compound comprises a PI membrane and a copolymer attached to the surface of the PI membrane, wherein the copolymer is the POSS-PMMA-b-PDMS super-hydrophobic compound.
The nanofiber membrane attached by the POSS-PMMA-b-PDMS super-hydrophobic compound comprises a PI membrane, PANI and a copolymer which are sequentially attached to the surface of the PI membrane, wherein the copolymer is the POSS-PMMA-b-PDMS super-hydrophobic compound.
Wherein, the mass percentage of the block POSS-PMMA-b-PDMS of the PDMS is 25-45%; the mass percentage of the PMMA block in the POSS-PMMA-b-PDMS is 15-40%.
The invention also discloses a preparation method of the copolymer-attached super-hydrophobic nanofiber membrane, which specifically comprises the following steps:
s1) PI film preparation;
s2) PI film activation: immersing the prepared PI film into a sodium dodecyl benzene sulfonate solution with the mass fraction of 2-5% for ultrasonic activation to obtain an activated PI film.
S3) immersing the activated PI film into POSS-PMMA-b-PDMS super-hydrophobic compound suspension, and then heating and attaching to obtain the product.
Further, in the step S1), the PI film may be prepared using a commercially available PI film or using the following method:
s11) preparing a polyamic acid solution:
adding biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid into N, N-dimethylformamide, stirring and dissolving, and then reacting for 8-20 hours at the temperature of-10-0 ℃ under the protection of nitrogen to obtain polyamic acid solution;
s12) preparation of PI film:
spinning the prepared polyamic acid solution in a high-voltage electrostatic field to obtain a PAA fiber film, and carrying out heating imidization on the obtained PAA fiber film under the protection of nitrogen to obtain the PI film.
Further, in the step S11), the molar ratio of the biphenyl tetracarboxylic dianhydride to the p-phenylenediamine is 0.8-1.2:1; the concentration of the biphenyl tetracarboxylic dianhydride after being dissolved in N, N-dimethylformamide is 0.2-0.4 mol/L.
Further, the spinning process parameters are as follows: the voltage is 15-40 kV, the rotating speed of the grounded flywheel is 1200-1800 rpm, and the electrospinning speed is 0.08-2 mL/h.
Further, the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
Further, the step S3) specifically includes the following steps:
s31) preparing a POSS-PMMA-b-PDMS super-hydrophobic compound solution;
s32) soaking the PI film activated in the step S2) in POSS-PMMA-b-PDMS super-hydrophobic compound suspension, standing for 15-24 h, and performing heat treatment under vacuum conditions to obtain the super-hydrophobic composite film.
Further, in the step S31), the POSS-PMMA-b-PDMS super-hydrophobic compound suspension is prepared by using deionized water, and the preparation method is that the POSS-PMMA-b-PDMS super-hydrophobic compound is added into deionized water, and after being stirred and mixed, the suspension is obtained by ultrasonic dispersion.
Further, in the step S32), the heat treatment temperature is 290-350 ℃; the heat treatment temperature rise curve is as follows: preserving heat for 30min to 250 ℃ at room temperature to 150 ℃ for 30min to 290 to 350 ℃ for 8 to 12h; the temperature rising rate is 3-5 ℃/min.
The invention also discloses a preparation method of the super-hydrophobic nanofiber membrane, which specifically comprises the following steps:
s1) PI (polyimide) film preparation;
s2) immersing the prepared PI film into inorganic acid, adding aniline monomer and ammonium persulfate, and reacting under the protection of nitrogen to obtain a PI/PANI (polyaniline) composite film;
s3) immersing the prepared PI/PANI composite film into POSS-PMMA-b-PDMS super-hydrophobic compound solution, and then heating and attaching to obtain the product.
Further, in the step S1), the PI film may be prepared using a commercially available PI film or using the following method:
s11) preparing a polyamic acid solution:
adding biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid into N, N-dimethylformamide, stirring for dissolving, and then
Reacting for 8-20 h at-10-0 ℃ under the protection of nitrogen to obtain polyamic acid solution;
s12) preparation of PI film:
spinning the prepared polyamic acid solution in a high-voltage electrostatic field to obtain a PAA fiber film, and carrying out heating imidization on the obtained PAA fiber film under the protection of nitrogen to obtain the PI film.
Further, in the step S11), the molar ratio of the biphenyl tetracarboxylic dianhydride to the p-phenylenediamine is 0.8-1.2:1; the concentration of the biphenyl tetracarboxylic dianhydride after being dissolved in N, N-dimethylformamide is 0.2-0.4 mol/L.
Further, the spinning process parameters are as follows: the voltage is 15-40 kV, the rotating speed of the grounded flywheel is 1200-1800 rpm, and the electrospinning speed is 0.08-2 mL/h.
Further, the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
Further, in the step S2), the inorganic acid is any one of sulfuric acid, nitric acid, and hydrofluoric acid; the concentration of the inorganic acid is 0.5-1 mol/L.
Further, in the step S2), the concentration of the aniline monomer in the inorganic acid is 0.01-0.05 mol/L; the addition amount of the ammonium persulfate is 0.0025-0.01 mol/L; the reaction temperature is-10 ℃ to 5 ℃.
Further, in the step S2), the prepared PI/PANI composite film is soaked in ammonia water to remove impurities, and then vacuum-dried.
Further, the step S3) specifically includes the following steps:
s31) preparing a POSS-PMMA-b-PDMS super-hydrophobic compound solution;
s32) soaking the PI/PANI composite film prepared in the step S2) in POSS-PMMA-b-PDMS super-hydrophobic compound suspension, standing for 15-24 h, and performing heat treatment under vacuum condition to obtain the super-hydrophobic composite film.
Further, in the step S31), the POSS-PMMA-b-PDMS super-hydrophobic compound suspension is prepared by using deionized water, and the preparation method is that the POSS-PMMA-b-PDMS super-hydrophobic compound is added into deionized water, and after being stirred and mixed, the suspension is obtained by ultrasonic dispersion.
Further, in the step S32), the heat treatment temperature is 300 to 350 ℃; the heat treatment temperature rise curve is as follows: preserving heat for 45min to 275 ℃ at room temperature to 300 to 350 ℃ for 6 to 12 hours at 180 ℃; the temperature rising rate is 3-5 ℃/min.
The beneficial technical effects of the invention are as follows:
the invention provides a preparation method of a POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane, which adopts a PI membrane or a PI/PANI composite membrane as a base material, and attaches a POSS-PMMA-b-PDMS super-hydrophobic compound containing POSS on the PI membrane or the PI/PANI composite membrane to obtain a copolymer attached super-hydrophobic nanofiber membrane with good hydrophobic performance and low surface energy. Compared with a diblock copolymer, the triblock POSS-PMMA-b-PDMS super-hydrophobic compound forms an interpenetrating three-dimensional structure, so that more raised nanometer microstructures are formed on the surface of the polymer, the surface is rougher, and the hydrophobic property is obviously improved.
The water contact angle measured by the nanofiber membrane attached by the POSS-PMMA-b-PDMS super-hydrophobic compound prepared by the invention can reach more than 163 degrees, and the nanofiber membrane has strong hydrophobic property and low surface energy.
Detailed Description
The invention is further illustrated below with reference to examples.
The POSS-PMMA-b-PDMS super-hydrophobic compound adopted in the invention is prepared by the following method:
s1) preparing polydimethylsiloxane (PDMS for short);
s2) end capping of polydimethylsiloxane;
s3) preparing an initiator by adopting the end-capped polydimethylsiloxane in the step S2;
s4) adding POSS into polymethyl methacrylate (PMMA for short), adding azodiisobutyronitrile and tetrahydrofuran, heating to 55-65 ℃ for copolymerization reaction to obtain POSS-PMMA copolymer;
s5) adding an initiator into the POSS-PMMA copolymer, and heating to 75-85 ℃ to perform copolymerization reaction to obtain the POSS-PMMA-b-PDMS super-hydrophobic compound.
The specific preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound used in the following examples is as follows:
s1) adopting an alkoxy silane monomer to carry out hydrolytic condensation reaction under an acidic condition to prepare polydimethylsiloxane;
s2) drying the polydimethylsiloxane prepared in the step S1) in a nitrogen environment, then adding a silane coupling agent, and adopting the silane coupling agent and hydroxide for end capping to generate amino double-end capped polydimethylsiloxane;
s3) preparing an initiator;
s31) adding azo initiator and DPTS into the amino double-end-capped polydimethylsiloxane, then adding dichloromethane and DMF, and stirring and mixing uniformly to obtain a mixed solution;
s32) dissolving DCC in dichloromethane to obtain a DCC solution with the mass fraction of 20%;
s33) adding the DCC solution into the mixed solution, and stirring and reacting for 6 hours at 50 ℃ to obtain a macromolecular initiator of the polydimethylsiloxane;
s4) adding POSS into PMMA, adding azodiisobutyronitrile and tetrahydrofuran, heating to 60 ℃ under the protection of nitrogen to carry out copolymerization reaction for 5 hours, and carrying out precipitation separation to obtain a POSS-PMMA copolymer;
s5) preparing a solution with the mass concentration of 20% of the macromolecular initiator of the prepared polydimethylsiloxane by using benzene, adding the POSS-PMMA copolymer into the solution according to the mass ratio of the macromolecular initiator of the polydimethylsiloxane to the POSS-PMMA copolymer of 1:2.5, heating to 80 ℃ under the protection of nitrogen, reacting for 8 hours, and carrying out precipitation separation to obtain the POSS-PMMA-b-PDMS super-hydrophobic compound.
Example 1
The preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane comprises the following steps of:
s1) PI film preparation;
s11) preparing a polyamic acid solution:
adding biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid into N, N-dimethylformamide according to the molar ratio of 0.8:1, stirring and dissolving to prepare a mixed solution with the concentration of 0.2mol/L of biphenyl tetracarboxylic dianhydride, and then reacting for 20 hours at the temperature of minus 10 ℃ under the protection of nitrogen to obtain a polyamic acid solution;
s12) preparation of PI film
Spinning the prepared polyamic acid solution in a high-voltage electrostatic field to obtain the PAA fiber film, wherein the spinning process parameters are as follows: the voltage is 15kV, the rotating speed of the grounded flywheel is 1200rpm, and the electrospinning speed is 0.08mL/h; heating and imidizing the PAA fiber membrane under the protection of nitrogen to obtain a PI membrane;
the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
S2) PI film activation: immersing the prepared PI film into a sodium dodecyl benzene sulfonate solution with the mass fraction of 2% for ultrasonic activation to obtain an activated PI film.
S3) immersing the activated PI film into POSS-PMMA-b-PDMS super-hydrophobic compound suspension, and then heating and attaching to obtain a product;
s31) stirring and ultrasonically dispersing a POSS-PMMA-b-PDMS super-hydrophobic compound into a suspension with the mass fraction of 1% by using deionized water;
s32) soaking the activated PI film prepared in the step S2) in POSS-PMMA-b-PDMS super-hydrophobic compound suspension, standing for 10 hours, and performing heat treatment under vacuum conditions to obtain a super-hydrophobic composite film A; the heat treatment temperature is 290 ℃; the heat treatment temperature rise curve is as follows: preserving heat at room temperature to 150 ℃ for 30min to 250 ℃ for 30min to 290 ℃ for 20h; the temperature rise rate is 3 ℃/min.
Example 2
The preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane comprises the following steps of:
s1) PI film preparation;
s11) preparing a polyamic acid solution:
adding biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid into N, N-dimethylformamide according to the molar ratio of 1.2:1, stirring and dissolving to prepare a mixed solution with the concentration of 0.4mol/L of biphenyl tetracarboxylic dianhydride, and then reacting for 8 hours at the temperature of 0 ℃ under the protection of nitrogen to obtain a polyamic acid solution;
s12) preparation of PI film
Spinning the prepared polyamic acid solution in a high-voltage electrostatic field to obtain the PAA fiber film, wherein the spinning process parameters are as follows: the voltage is 40kV, the rotating speed of the grounded flywheel is 1800rpm, and the electrospinning speed is 2mL/h; heating and imidizing the PAA fiber membrane under the protection of nitrogen to obtain a PI membrane;
the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
S2) PI film activation: immersing the prepared PI film into a sodium dodecyl benzene sulfonate solution with the mass fraction of 2-5% for ultrasonic activation to obtain an activated PI film.
S3) immersing the activated PI film into POSS-PMMA-b-PDMS super-hydrophobic compound suspension, and then heating and attaching to obtain a product;
s31) stirring and ultrasonically dispersing a POSS-PMMA-b-PDMS super-hydrophobic compound into a suspension with the mass fraction of 1% by using deionized water;
s32) soaking the activated PI film prepared in the step S2) in POSS-PMMA-B-PDMS super-hydrophobic compound suspension, standing for 10 hours, and performing heat treatment under vacuum conditions to obtain a super-hydrophobic composite film B; the heat treatment temperature is 290 ℃; the heat treatment temperature rise curve is as follows: preserving heat at room temperature to 150 ℃ for 30min to 250 ℃ for 30min to 350 ℃ for 8h; the temperature rise rate is 3 ℃/min.
Example 3
The preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane comprises the following steps of:
s1) PI film preparation;
s11) preparing a polyamic acid solution:
taking biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid according to a molar ratio of 0.8:1, adding N, N-dimethylformamide into the biphenyl tetracarboxylic dianhydride and the p-phenylenediamine polyamic acid, stirring and dissolving to obtain a mixed solution with the concentration of 0.2mol/L of biphenyl tetracarboxylic dianhydride, and then reacting for 20 hours at-10 ℃ under the protection of nitrogen to obtain a polyamic acid solution;
s12) preparation of PI film:
spinning the prepared polyamic acid solution in a high-voltage electrostatic field of 15kV, wherein the rotating speed of a grounded flywheel is 1200rpmrpm, the electrospinning speed is 0.08mL/h, so as to obtain a PAA fiber membrane, and carrying out heating imidization on the obtained PAA fiber membrane under the protection of nitrogen so as to obtain a PI membrane;
the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
S2) preparing a PI/PANI composite film:
immersing the prepared PI film into sulfuric acid with the concentration of 1mol/L, adding an aniline monomer solution into the sulfuric acid, wherein the addition amount of the aniline monomer is 0.01mol/L, adding ammonium persulfate, and the addition amount of the ammonium persulfate is 0.0025mol/L, and reacting for 12 hours at the temperature of minus 8 ℃ under the protection of nitrogen to obtain a PI/PANI composite film; the prepared PI/PANI composite membrane is soaked in ammonia water with the concentration of 1mol/L for impurity removal, and then vacuum drying is carried out.
S3) immersing the prepared PI/PANI composite film into a POSS-PMMA-b-PDMS super-hydrophobic compound solution.
S31) stirring and ultrasonically dispersing a POSS-PMMA-b-PDMS super-hydrophobic compound into a suspension with the mass fraction of 1% by using deionized water;
s32) soaking the PI/PANI composite film prepared in the step S2) in POSS-PMMA-b-PDMS super-hydrophobic compound suspension, standing for 10h, and performing heat treatment under vacuum condition to obtain a super-hydrophobic composite film C; the heat treatment temperature is 300 ℃; the heat treatment temperature rise curve is as follows: preserving heat for 45min to 275 ℃ at room temperature to 180 ℃ for 20min to 300 ℃ for 12h; the temperature rise rate is 3 ℃/min.
Example 4
The preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane comprises the following steps of:
s1) PI film preparation;
s11) preparing a polyamic acid solution:
taking biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid according to a molar ratio of 1.2:1, adding N, N-dimethylformamide into the biphenyl tetracarboxylic dianhydride and the p-phenylenediamine polyamic acid, stirring and dissolving to obtain a mixed solution with the concentration of 0.4mol/L of biphenyl tetracarboxylic dianhydride, and then reacting for 8 hours at 0 ℃ under the protection of nitrogen to obtain a polyamic acid solution;
s12) preparation of PI film:
spinning the prepared polyamic acid solution in a high-voltage electrostatic field of 40kV, wherein the rotating speed of a grounded flywheel is 1800rpm, the electrospinning speed is 0.2mL/h, so as to obtain a PAA fiber membrane, and carrying out heating imidization on the obtained PAA fiber membrane under the protection of nitrogen so as to obtain a PI membrane;
the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
S2) preparing a PI/PANI composite film:
immersing a PI film in sulfuric acid with the concentration of 1mol/L, adding an aniline monomer solution into the sulfuric acid, wherein the addition amount of the aniline monomer is 0.05mol/L, adding ammonium persulfate, and reacting for 6 hours at the temperature of 10 ℃ under the protection of nitrogen to obtain a PI/PANI composite film, wherein the addition amount of the ammonium persulfate is 0.01mol/L; the prepared PI/PANI composite membrane is soaked in ammonia water with the concentration of 1mol/L for impurity removal, and then vacuum drying is carried out.
S3) immersing the prepared PI/PANI composite film into a POSS-PMMA-b-PDMS super-hydrophobic compound solution.
S31) stirring and ultrasonically dispersing a POSS-PMMA-b-PDMS super-hydrophobic compound into a suspension with the mass fraction of 5% by using deionized water;
s32) soaking the PI/PANI composite film prepared in the step S2) in POSS-PMMA-b-PDMS super-hydrophobic compound suspension, standing for 10h, and performing heat treatment under vacuum condition to obtain a super-hydrophobic composite film D; the heat treatment temperature is 300 ℃; the heat treatment temperature rise curve is as follows: preserving heat for 45min to 275 ℃ at room temperature to 180 ℃ for 20min to 350 ℃ for 6h; the temperature rise rate is 5 ℃/min.
Hydrophobic property detection
The water contact angles of the super-hydrophobic composite film A, the super-hydrophobic composite film B, the super-hydrophobic composite film C and the super-hydrophobic composite film D are respectively detected, and the measurement results are as follows: the water contact angle of the super-hydrophobic composite film A can reach 164.7 degrees+/-0.5 degrees; the water contact angle of the super-hydrophobic composite film B can reach 163.2 degrees plus or minus 0.5 degrees; the water contact angle of the super-hydrophobic composite film C can reach 166.5 degrees+/-0.5 degrees; the water contact angle of the super-hydrophobic composite film D can reach 167.1 degrees+/-0.5 degrees, the hydrophobic performance is strong, and the surface energy is low.
The foregoing has outlined and described the basic principles, features, and advantages of the present invention in order that the description that follows is merely an example of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, but rather that the foregoing embodiments and description illustrate only the principles of the invention, and that the invention is susceptible to various equivalent changes and modifications without departing from the spirit and scope of the invention, all of which are intended to be within the scope of the invention as hereinafter claimed. The scope of the invention is defined by the appended claims and their equivalents.
Claims (12)
1. The nanofiber membrane attached by the POSS-PMMA-b-PDMS super-hydrophobic compound is characterized by comprising a PI membrane or a PI/PANI composite membrane and a copolymer attached to the surface of the membrane, wherein the copolymer is the POSS-PMMA-b-PDMS super-hydrophobic compound and is a triblock copolymer formed by copolymerizing cage-type polysilsesquioxane, polymethyl methacrylate and polydimethylsiloxane, and the percentage by mass of PMMA blocks in the POSS-PMMA-b-PDMS is 15-40%; the mass percentage of the PDMS block in the POSS-PMMA-b-PDMS is 25-45%; the preparation process of the POSS-PMMA-b-PDMS super-hydrophobic compound comprises the following steps:
1) Preparing a macromolecular initiator of polydimethylsiloxane as an initiator;
11 Preparing polydimethylsiloxane;
12 Polydimethylsiloxane end caps;
13 Adding azo initiator and DPTS into the end-capped polydimethylsiloxane, then adding dichloromethane and DMF, and stirring and mixing uniformly to obtain a mixed solution;
14 Dissolving DCC in dichloromethane to obtain 15-25% DCC solution;
15 Adding the DCC solution into the mixed solution, and stirring and reacting for 4-8 hours at the temperature of 40-60 ℃ to obtain a macromolecular initiator of the polydimethylsiloxane;
2) Adding POSS into polymethyl methacrylate, adding azodiisobutyronitrile and tetrahydrofuran, and heating to 55-65 ℃ to perform copolymerization reaction to obtain POSS-PMMA copolymer;
3) And adding the macromolecular initiator of the polydimethylsiloxane into the POSS-PMMA copolymer, and heating to 75-85 ℃ to perform copolymerization reaction to obtain the POSS-PMMA-b-PDMS superhydrophobic compound.
2. The preparation method of the POSS-PMMA-b-PDMS super-hydrophobic compound attached nanofiber membrane is characterized by comprising the following steps of:
s1) preparing an activated PI film or a PI/PANI composite film;
s2) preparing a POSS-PMMA-b-PDMS super-hydrophobic compound:
s21) preparing a macromolecular initiator of polydimethylsiloxane as an initiator;
s22) adding POSS into polymethyl methacrylate, adding azodiisobutyronitrile and tetrahydrofuran, heating to 55-65 ℃ to perform copolymerization reaction, and obtaining a POSS-PMMA copolymer;
s23) adding a macromolecular initiator of the polydimethylsiloxane into the POSS-PMMA copolymer, and heating to 75-85 ℃ to perform copolymerization reaction to obtain a POSS-PMMA-b-PDMS superhydrophobic compound;
s3) immersing the activated PI film or PI/PANI composite film into POSS-PMMA-b-PDMS super-hydrophobic compound suspension, then heating and attaching to obtain the product,
said step S21) comprises the steps of:
s211) preparing polydimethylsiloxane;
s212) polydimethylsiloxane end capping;
s213) adding azo initiator and DPTS into the end-capped polydimethylsiloxane, then adding dichloromethane and DMF, and stirring and mixing uniformly to obtain a mixed solution;
s214) dissolving DCC in dichloromethane to obtain 15-25% DCC solution;
s215) adding the DCC solution into the mixed solution, and stirring and reacting for 4-8 hours at the temperature of 40-60 ℃ to obtain the macromolecular initiator of the polydimethylsiloxane.
3. The method according to claim 2, characterized in that the preparation of the activated PI film comprises the steps of:
s11) preparing a PI film;
s12) PI membrane activation: immersing the prepared PI film into a sodium dodecyl benzene sulfonate solution with the mass fraction of 2-5% for ultrasonic activation to obtain an activated PI film.
4. The method according to claim 2, characterized in that the preparation of the PI/PANI composite film comprises the steps of:
s11) preparing a PI film;
s12) preparing a PI/PANI composite film: immersing the prepared PI film into inorganic acid, adding aniline monomer and ammonium persulfate, and reacting under the protection of nitrogen to obtain the PI/PANI composite film.
5. The method according to claim 3 or 4, characterized in that the preparation of PI film comprises the steps of:
s111) preparing a polyamic acid solution:
adding biphenyl tetracarboxylic dianhydride and p-phenylenediamine polyamic acid into N, N-dimethylformamide, stirring and dissolving, and then reacting for 8-20 hours at-10-0 ℃ under the protection of nitrogen to obtain polyamic acid solution;
s112) preparation of PI film:
spinning the prepared polyamic acid solution in a high-voltage electrostatic field to obtain a PAA fiber film, and carrying out heating imidization on the obtained PAA fiber film under the protection of nitrogen to obtain a PI film;
the spinning process parameters are as follows: the voltage is 15-40 kV, the rotating speed of the grounded flywheel is 1200-1800 rpm, and the electrospinning speed is 0.08-2 mL/h;
the heating curve of the PAA fiber membrane for heating imidization is as follows: room temperature to 150 ℃, heat preservation for 1h to 200 ℃, heat preservation for 1h to 250 ℃, heat preservation for 1h to 300 ℃, heat preservation for 1h to 350 ℃ and heat preservation for 0.5h; the temperature rise rate is 1 ℃/min.
6. The method according to claim 5, wherein in the step S111), the molar ratio of biphenyl tetracarboxylic dianhydride to p-phenylenediamine is 0.8-1.2:1; the concentration of the biphenyl tetracarboxylic dianhydride after being dissolved in N, N-dimethylformamide is 0.2-0.4 mol/L.
7. The method according to claim 4, wherein in the step S12), the inorganic acid is any one of sulfuric acid, nitric acid, and hydrofluoric acid; the concentration of the inorganic acid is 0.5-1 mol/L.
8. The method according to claim 4, wherein in the step S12), the concentration of the aniline monomer in the mineral acid is 0.01 to 0.05mol/L; the addition amount of the ammonium persulfate is 0.0025-0.01 mol/L; the reaction temperature is-10 ℃ to 5 ℃.
9. The method according to claim 4, wherein in the step S12), the prepared PI/PANI composite film is soaked in ammonia water to remove impurities, and then vacuum-dried.
10. The method according to claim 2, characterized in that said step S3) comprises in particular the steps of:
s31) preparing a POSS-PMMA-b-PDMS super-hydrophobic compound suspension: adding a POSS-PMMA-b-PDMS super-hydrophobic compound into deionized water, stirring and mixing, and performing ultrasonic dispersion to obtain a suspension;
s32) soaking the PI film or the PI/PANI composite film activated in the step S1) in POSS-PMMA-b-PDMS super-hydrophobic compound suspension, standing for 15-24 h, and performing heat treatment under vacuum conditions to obtain the super-hydrophobic composite film.
11. The method according to claim 10, characterized in that the activated PI film is immersed in a POSS-PMMA-b-PDMS superhydrophobic compound suspension, the heat treatment temperature of step S32) is 290-350 ℃; the heat treatment temperature rise curve is as follows: preserving heat at room temperature to 150 ℃ for 30min to 250 ℃ for 30min to 290-350 ℃ for 8-12 h; the temperature rising rate is 3-5 ℃/min.
12. The method of claim 10, wherein the PI/PANI composite film is immersed in a POSS-PMMA-b-PDMS superhydrophobic compound suspension, and the heat treatment temperature of step S32) is 300-350 ℃; the heat treatment temperature rise curve is as follows: preserving heat at room temperature-180 ℃ for 45 min-275 ℃ for 20 min-300-350 ℃ for 6-12 h; the temperature rising rate is 3-5 ℃/min.
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