CN110777559A - Polyimide composite paper with catalytic performance and SERS performance and preparation thereof - Google Patents

Polyimide composite paper with catalytic performance and SERS performance and preparation thereof Download PDF

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Publication number
CN110777559A
CN110777559A CN201910955378.XA CN201910955378A CN110777559A CN 110777559 A CN110777559 A CN 110777559A CN 201910955378 A CN201910955378 A CN 201910955378A CN 110777559 A CN110777559 A CN 110777559A
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polyimide
composite paper
fibrid
preparation
metal
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CN110777559B (en
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赵昕
秦秀芝
张清华
董杰
甘锋
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Donghua University
National Dong Hwa University
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Donghua University
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/10—Organic non-cellulose fibres
    • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H13/26—Polyamides; Polyimides
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/94—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of other polycondensation products
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/36—Polyalkenyalcohols; Polyalkenylethers; Polyalkenylesters

Abstract

The invention relates to polyimide composite paper with catalytic performance and SERS performance and a preparation method thereof, wherein the preparation method comprises the following steps: directly papermaking the precipitation fiber loaded with the metal nano particles; or mixing the metal nanoparticle-loaded fibrids and the polyimide chopped fibers and papermaking to obtain the polyimide composite paper. The polyimide fiber composite paper prepared by mixing the polyimide fiber composite paper with the chopped fibers has high catalytic efficiency, can be used as an SERS substrate, and has better enhancement effect and higher detection sensitivity.

Description

Polyimide composite paper with catalytic performance and SERS performance and preparation thereof
Technical Field
The invention belongs to the field of functional polyimide composite paper and preparation thereof, and particularly relates to polyimide composite paper with catalytic performance and SERS performance and preparation thereof.
Background
Polyimide (PI) fiber is a high-technology fiber, the main molecular chain of the fiber contains aromatic imide and other groups, and the high conjugation and aromaticity of the main chain structure endow the polyimide fiber with good mechanical properties, outstanding heat resistance, excellent low-temperature resistance and the like. The polyimide fibrid has excellent processing property and reinforcing property, good dispersibility in water, large specific surface area and high strength. The polyimide fiber paper prepared by the polyimide fiber and the polyimide fibrid at present has the advantages of high porosity of the traditional paper and high-performance fiber, and the high-temperature resistance and the electrical insulation performance of the polyimide fiber paper are superior to those of aramid fiber composite paper and PBO fiber composite paper.
The research finds that: in many catalytic systems, metal nanoparticles are used as catalytically active sites. Metal nanoparticles are widely used in the field of catalysis due to their strong adsorption and desorption capacity for reactants and products. When the size of the metal ions is in the nanometer level, the specific surface area is large, and abundant dangling bonds are provided, so that the transition metal nanoparticle catalyst has high activity and high selectivity. However, the metal nanoparticles have high surface energy and are easy to agglomerate, the catalytic performance of the agglomerated metal nanoparticles is obviously reduced, and in order to prevent the agglomerated metal nanoparticles from obtaining high catalytic performance, the metal nanoparticles are usually loaded into a carrier.
The SERS effect can overcome the disadvantage of low sensitivity of raman spectroscopy, provides structural information of molecules adsorbed or close to metal surfaces, can enhance raman signals by several orders of magnitude, and is an important technique for analyzing nano-sized metal particles. The enhancement of the signal in SERS is mainly due to the electromagnetic interaction between light and metal. At present, most of metal nanoparticles used for SERS analysis are in a solution or sol state, metal in the solution or sol can directly grow on a substrate, and the metal nanoparticles with the substrate can conveniently provide reliable data. In addition, nanoparticles of metals such as Au, Pt and the like are loaded on the carrier, so that the SERS sensitivity is improved, and the composite substrate has good catalytic performance. The polyimide paper-based composite material has good flexibility, mechanical property, high temperature resistance and the like, and also shows stability and recyclability in the using process, so the polyimide paper-based composite material is an ideal SERS substrate material.
The polyimide composite paper is made from polyimide chopped fibers and polyimide fibrids, metal ion salt solution is used as a precipitation solution, the metal ion-loaded fibrids are obtained in the forming process, and the functional composite paper can be obtained through a simple paper making process. Patent No. CN103776812A discloses a method for preparing a Surface Enhanced Raman Scattering (SERS) substrate, in which a base layer is soaked in an adhesive and then nano silver particles are attached to the surface of the base layer to form a surface enhanced raman scattering substrate, and the base layer and the nano silver particles are connected by a chemical adhesive, which introduces impurities and further causes the degradation of thermal properties, mechanical properties, and the like. Patent No. CN106865537B discloses a method for preparing high-strength graphene-based composite paper, in which a graphene oxide/silver/carbon fiber composite suspension is applied to a dried slide glass after hydrophilization treatment, which may result in uneven thickness of the obtained composite paper. Patent No. CN108543547A discloses a catalytic test paper prepared by compounding bacterial cellulose-loaded metal ions and plant fibers and a method thereof, wherein functionalized bacterial cellulose is directly soaked in a metal ion inorganic salt aqueous solution and stirred to load metal ions on the surface of cellulose, so that the obtained metal ions loaded on cellulose are easily distributed unevenly, and further the catalytic performance of composite paper is affected, and the mechanical properties of the obtained product are lower than that of polyimide composite paper.
Disclosure of Invention
The invention aims to solve the technical problem of providing polyimide composite paper with catalytic performance and SERS performance and preparation thereof, and overcomes the defects of uneven distribution, poor catalytic performance, poor mechanical performance and the like of cellulose-loaded metal ions in the prior art.
The polyimide composite paper comprises polyimide precipitation fibers loaded with metal nanoparticles.
The metal nano particles are one or more of gold, silver, platinum, copper and chromium; the length of the polyimide chopped fiber is 3-12 mm.
The preparation method of the polyimide composite paper comprises the following steps:
(1) injecting the post-treated polyimide PI stock solution into a metal inorganic salt aqueous solution under the stirring condition to obtain polyimide PI fibrid suspension, washing, filtering, vacuum drying to obtain PI fibrid, carrying out in-situ reduction,
washing, filtering and vacuum drying to obtain the fibrid loaded with the metal nano particles;
(2) directly papermaking the fibrid loaded with the metal nano particles to obtain polyimide composite paper;
or mixing the metal nanoparticle-loaded fibrids and the polyimide chopped fibers in a mass ratio of 9: 1-1: 9, adding a dispersant to obtain uniform slurry, papermaking, hot pressing, and vacuum drying to obtain the polyimide composite paper.
The preferred mode of the above preparation method is as follows:
the post-treatment in the step (1) comprises filtering, defoaming and diluting; the injection is specifically as follows: the stirring speed is 2000-10000 r/min, the injection speed is 0.5-1 mL/min, and after the solution is completely injected, the stirring is continued for 1-2 min.
The polyimide PI stock solution in the step (1) is prepared by the following method: adding a diamine monomer into an aprotic polar organic solvent at 0-25 ℃ under the protection of nitrogen, adding a dianhydride monomer after completely dissolving, stirring, and then adding a catalyst for heating cyclization or adding a chemical cyclization agent for chemical cyclization to obtain a polyimide stock solution; the concentration of the metal inorganic salt aqueous solution is 2-50 mg/mL; wherein the metal ions are one or more of gold, silver, platinum, copper and chromium.
Further, the aprotic polar organic solvent is dimethylacetamide or N-methylpyrrolidone; the diamine monomer is one or more of p-phenylenediamine, m-phenylenediamine, hexafluoro-diamine, bisphenol A diether diamine, 4 '-diaminodiphenylmethane and 4, 4' -methylene diphenylamine; the dianhydride is one or a mixture of more than two of pyromellitic dianhydride, benzophenone dianhydride, biphenyl dianhydride, diphenyl ether dianhydride and hydroquinone diether dianhydride; diamine (b): the molar ratio of dianhydride is: 1: 0.9-1: 1.1.
Further, preferably, the aprotic polar organic solvent is N-methylpyrrolidone; the diamine is a mixture of 2, 4-diaminotoluene (TDA) and 4, 4' -diaminodiphenylmethane (MDA); the dianhydride is 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride (BTDA).
Further, the reaction time is 3-7 h after the dianhydride is added, and the stirring speed is 200-300 r/min.
Further, the catalyst is one or more of isoquinoline, acetic anhydride, triethylamine and the like, and the dropping speed is 1 mL/min; the reaction parameters of the heating cyclization are as follows: polymerizing for 1-3 h at 100 ℃, heating to 120 ℃, polymerizing for 1-3 h, and heating to 180 ℃ for polymerizing for 5-15 h; the chemical cyclizing agent is one or more of triethylamine, acetic anhydride and pyridine, and the molar ratio of the cyclizing agent to the diamine is 0: 1-1: 1; the reaction temperature of the chemical cyclization is 60-80 ℃.
The in-situ reduction in the step (1) is specifically as follows: soaking the fibrid in an aqueous solution of a reducing agent, wherein the molar ratio of metal ions to the reducing agent is 1: 1-1.5.
The reducing agent is one or more of hydrazine hydrate, sodium borohydride, sodium hypophosphite and hydrogen peroxide.
The length of the polyimide chopped fiber in the step (2) is 3-12 mm; the dispersant is polyethylene glycol.
The hot pressing process parameters in the step (2) are as follows: the hot pressing temperature is 200-; the technological parameters of vacuum drying are as follows: the vacuum drying temperature is 40-80 ℃, and the time is 1-10 h.
The invention provides polyimide composite paper prepared by the method.
The invention provides application of the polyimide composite paper.
Advantageous effects
(1) In the invention, the soluble polyimide stock solution is synthesized by a one-step method, and the metal ions are added into the precipitation solution, so that the polyimide stock solution can directly load the metal ions in the precipitation process, and the precipitation fiber loaded with the metal nanoparticles can be obtained by simple in-situ reduction, and the process is simple, low in cost and high in production efficiency;
(2) the polyimide fibrid obtained by the invention has small shrinkage rate, high specific surface area, good mechanical property, heat resistance, electric insulation property and the like, and can be directly used for preparing high-performance composite paper;
(3) according to the invention, a metal ion salt solution is used as a precipitation solution to obtain a precipitation fiber in a high-speed stirring process, and the precipitation fiber loaded with metal nanoparticles is obtained by in-situ reduction, so that the dispersibility of metal ions on the surface of the precipitation fiber is enhanced, and the catalytic efficiency and SERS performance are improved;
(4) the invention mixes the fibrid loaded with metal nano particles and the polyimide chopped fiber to make paper, not only retains the excellent mechanical property, the electric insulation property with excellent heat resistance and the like of the polyimide fiber, but also endows the composite paper with
Good catalytic performance and SERS performance.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
First, experimental medicine
TABLE 1 Experimental drugs
Second, testing method
1. Intrinsic viscosity
And measuring by using a Ubbelohde viscometer and a stopwatch, and obtaining the intrinsic viscosity of the product by using the relation between the solution viscosity and the solution concentration and an extrapolation method.
2. Tensile index
According to GB/T12914-2008 constant-rate loading method, a tensile strength tester is used to stretch a specimen of a prescribed size to break under constant-rate loading, measure the tensile strength thereof, and calculate the tensile index from the obtained result and the quantitative amount of the specimen.
3. Compressive strength
The breakdown voltage of the fibrous base paper was measured according to the ASTM-149 standard, using a cylindrical copper electrode, 50mm in diameter, 25mm in thickness and 6.4mm in chamfer radius. And (3) adopting a common-frequency rapid boosting method, namely controlling the boosting rate to ensure that the breakdown time of the fiber paper is between 15s and 20 s.
4. Test for catalytic Performance
The catalytic performance of the composite paper is investigated by using sodium borohydride to reduce p-nitrophenol as a model reaction, and the specific method comprises the following experiments: 3mL of water, 10. mu.L of p-nitrophenol aqueous solution (concentration: 0.03mol/L), 10. mu.L of sodium borohydride aqueous solution (concentration: 45mg/mL), and 1.5mg of composite paper were sequentially added to a quartz cuvette, and the change in the UV-visible absorption spectrum of the obtained solution was examined with a UV-visible spectrophotometer. And (3) timing from the addition of the composite paper, recording the spectrum every 5min, and recording the spectrum of the sample before the catalyst is added as 0 min. The whole reaction conforms to a first-order reaction kinetic equation:
dC t/d t＝-kC tor ln (C) t/C 0)＝ln(A t/A 0)＝-kt，
In the formula C tAnd A tConcentration of p-nitrophenol in the solution at time t and absorbance at 400nm, C 0And A 0The concentration of p-nitrophenol at the beginning of the reaction and the absorbance at 400nm, respectively, k is the rate constant for the catalyzed reaction. With ln (A) t/A 0) And (3) plotting the reaction time t to obtain a linear relation, wherein the slope of a fitted line is the reaction rate constant.
5. Raman spectroscopy
A rhodamine 6G solution is selected as a probe molecule for detecting the Raman enhancement effect of the SERS substrate of the composite paper, the composite paper is laid on a glass slide, 15 mu L of the rhodamine 6G solution is dropped on the composite paper by a micro sample injector (50 mu L), and a Raman spectrometer is used for measuring a Raman spectrum.
Example 1
(1) 171mL of N-methylpyrrolidone was added to a 250mL three-necked flask under nitrogen, and 3.0364g of 2, 4-diaminotoluene and 4.9354g of diphenylmethanediamine were added at room temperature with stirring. After stirring to dissolve, 16.0282g of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride was added and stirring was continued for 3 hours. Then 2.5556g of isoquinoline was added, the temperature was raised to 100 ℃ for reaction for 1 hour, the temperature was raised to 120 ℃ for reaction for 1 hour, and the temperature was raised to 180 ℃ for reaction for 12 hours. To obtain polyimide stock solution with solid content of 15 percent.
(2) And (2) carrying out post-treatment on the polyimide stock solution in the step (1), including filtration, defoaming and dilution to 5 wt%. Then, 10mL of the stock solution was injected into 100mL of 10mg/mL silver nitrate solution at a rate of 1mL/min with a syringe having a diameter of 2.1cm and a stirring rate of 5000r/min to obtain a polyimide fibrid suspension, which was washed, filtered and dried to obtain polyimide fibrids.
(3) And (3) soaking the fibrid obtained in the step (2) in 100mL of 2mg/mL sodium borohydride solution, washing, filtering and drying to obtain the fibrid loaded with the metal nanoparticles.
(4) Mixing the fibrid in the step (3) with polyimide chopped fiber according to the mass ratio of 3: and 7, mixing, placing in water, adding a dispersant to obtain uniform slurry, and carrying out papermaking, hot pressing and vacuum drying to obtain the polyimide composite paper.
The intrinsic viscosity of the polyimide stock solution obtained in this example was 3.2 dl/g; the fibrids had an average length of 2.0mm and a specific surface area of 55m 2(ii)/g; the glass transition temperature of the prepared fibrid is 300 ℃, and the thermal weight loss average temperature when the mass loss is 5 percent is 480 ℃; when the polyimide composite paper is hot-pressed at the temperature of 210 ℃ and the pressure of 10MPa, the size of the obtained polyimide composite paper is not obviously shrunk, the tensile index of the composite paper is 23 N.m/g, and the compressive strength is 11.7 kV/mm. The composite paper is used as an SERS linerThe rhodamine 6G (R6G) is used as a Raman probe molecule, and the rhodamine molecular weight can be measured at 1360cm -1Has a detection limit of about 1X 10 -8mol/L. The catalytic rate constant of the composite paper for catalytic reduction of p-nitrophenol is about 0.14min -1。
Example 2
(1) 171mL of N-methylpyrrolidone was added to a 250mL three-necked flask under nitrogen, and 3.0364g of 2, 4-diaminotoluene and 4.9354g of diphenylmethanediamine were added at room temperature with stirring. After stirring to dissolve, 16.0282g of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride was added and stirring was continued for 3 hours. Then 2.5556g of isoquinoline was added, the temperature was raised to 100 ℃ for reaction for 1 hour, the temperature was raised to 120 ℃ for reaction for 1 hour, and the temperature was raised to 180 ℃ for reaction for 12 hours. To obtain polyimide stock solution with solid content of 15 percent.
(2) And (2) carrying out post-treatment on the polyimide stock solution in the step (1), including filtration, defoaming and dilution to 5 wt%. Then, 10mL of the stock solution was injected into 100mL of 10mg/mL silver nitrate solution at a rate of 1mL/min with a syringe having a diameter of 2.1cm and a stirring rate of 5000r/min to obtain a polyimide fibrid suspension, which was washed, filtered and dried to obtain polyimide fibrids.
(3) And (3) soaking the fibrid obtained in the step (2) in 100mL of 2mg/mL sodium borohydride solution, washing, filtering and drying to obtain the fibrid loaded with the metal nanoparticles.
(4) Mixing the fibrid in the step (3) with polyimide chopped fiber according to the mass ratio of 5: 5, mixing and placing in water, adding a dispersant to obtain uniform slurry, and carrying out papermaking, hot pressing and vacuum drying to obtain the polyimide composite paper.
The intrinsic viscosity of the polyimide stock solution obtained in this example was 3.2 dl/g; the fibrids had an average length of 2.0mm and a specific surface area of 55m 2(ii)/g; the glass transition temperature of the prepared fibrid is 300 ℃, and the thermal weight loss average temperature when the mass loss is 5 percent is 480 ℃; when the polyimide composite paper is hot-pressed at the temperature of 210 ℃ and the pressure of 10MPa, the size of the obtained polyimide composite paper is not obviously shrunk, the tensile index of the composite paper is 25 N.m/g, and the compressive strength is 12.1 kV/mm. The composite material is used as a SERS substrate, and rhodamine 6G (B) (R6G) as Raman probe molecule, it can be measured at 1360cm -1Has a detection limit of about 1X 10 -9mol/L. The catalytic rate constant of the composite paper for catalytic reduction of p-nitrophenol is about 0.25min -1。
Example 3
(1) 171mL of N-methylpyrrolidone was added to a 250mL three-necked flask under nitrogen, and 3.0364g of 2, 4-diaminotoluene and 4.9354g of diphenylmethanediamine were added at room temperature with stirring. After stirring to dissolve, 16.0282g of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride was added and stirring was continued for 3 hours. Then 2.5556g of isoquinoline was added, the temperature was raised to 100 ℃ for reaction for 1 hour, the temperature was raised to 120 ℃ for reaction for 1 hour, and the temperature was raised to 180 ℃ for reaction for 12 hours. To obtain polyimide stock solution with solid content of 15 percent.
(2) And (2) carrying out post-treatment on the polyimide stock solution in the step (1), including filtration, defoaming and dilution to 5 wt%. Then, 10mL of the stock solution was injected into 100mL of 10mg/mL silver nitrate solution at a rate of 1mL/min with a syringe having a diameter of 2.1cm and a stirring rate of 5000r/min to obtain a polyimide fibrid suspension, which was washed, filtered and dried to obtain polyimide fibrids.
(3) And (3) soaking the fibrid obtained in the step (2) in 100mL of sodium borohydride solution with the concentration of 2mg/mL, washing, filtering and drying to obtain the fibrid loaded with the metal nano particles.
(4) And (3) mixing the fibrid in the step (3) with the polyimide chopped fiber according to the mass ratio of 7: 3, mixing and placing in water, adding a dispersant to obtain uniform slurry, and carrying out papermaking, hot pressing and vacuum drying to obtain the polyimide composite paper.
The intrinsic viscosity of the polyimide stock solution obtained in this example was 3.2 dl/g; the fibrids had an average length of 2.0mm and a specific surface area of 55m 2(ii)/g; the glass transition temperature of the prepared fibrid is 300 ℃, and the thermal weight loss average temperature when the mass loss is 5 percent is 480 ℃; when the polyimide composite paper is hot-pressed at the temperature of 210 ℃ and the pressure of 10MPa, the size of the obtained polyimide composite paper is not obviously shrunk, the tensile index of the composite paper is 23 N.m/g, and the compressive strength is 11.5 kV/mm. The composite material is used as an SERS substrate, and rhodamine 6G (R6G) is used as a Raman probeCan be measured at 1360cm -1Has a detection limit of about 1X 10 -12mol/L. The catalytic rate constant of the composite paper for catalytic reduction of p-nitrophenol is about 0.32min -1。
Example 4
(1) 171mL of N-methylpyrrolidone was added to a 250mL three-necked flask under nitrogen, and 3.0364g of 2, 4-diaminotoluene and 4.9354g of diphenylmethanediamine were added at room temperature with stirring. After stirring to dissolve, 16.0282g of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride was added and stirring was continued for 3 hours. Then 2.5556g of isoquinoline was added, the temperature was raised to 100 ℃ for reaction for 1 hour, the temperature was raised to 120 ℃ for reaction for 1 hour, and the temperature was raised to 180 ℃ for reaction for 12 hours. To obtain polyimide stock solution with solid content of 15 percent.
(2) And (2) carrying out post-treatment on the polyimide stock solution in the step (1), including filtration, defoaming and dilution to 3 wt%. Then, 10mL of the stock solution was injected into 100mL of 10mg/mL silver nitrate solution at a rate of 1mL/min with a 20mL syringe having a diameter of 2.1cm at a stirring rate of 2000r/min to obtain a polyimide fibrid suspension, which was washed, filtered and dried to obtain polyimide fibrids.
(3) And (3) soaking the fibrid obtained in the step (2) in 100mL of sodium borohydride solution with the concentration of 2mg/mL, washing, filtering and drying to obtain the fibrid loaded with the metal nano particles.
(4) Mixing the fibrid in the step (3) with polyimide chopped fiber according to the mass ratio of 5: 5, mixing and placing in water, adding a dispersant to obtain uniform slurry, and carrying out papermaking, hot pressing and vacuum drying to obtain the polyimide composite paper.
The intrinsic viscosity of the polyimide stock solution obtained in this example was 3.2 dl/g; the fibrids had an average length of 2.0mm and a specific surface area of 55m 2(ii)/g; the glass transition temperature of the prepared fibrid is 300 ℃, and the thermal weight loss average temperature when the mass loss is 5 percent is 480 ℃; when the polyimide composite paper is hot-pressed at the temperature of 210 ℃ and the pressure of 10MPa, the size of the obtained polyimide composite paper is not obviously shrunk, the tensile index of the composite paper is 25 N.m/g, and the compressive strength is 12.5 kV/mm. The composite material is used as a SERS substrate, rhodamine 6G (R6G) is used as a Raman probe molecule, and the Raman probe molecule can be measured at 13 DEG60cm -1Has a detection limit of about 1X 10 --10mol/L. The catalytic rate constant of the composite paper for catalytic reduction of p-nitrophenol is about 0.27min -1。
Example 5
(1) 171mL of N-methylpyrrolidone was added to a 250mL three-necked flask under nitrogen, and 3.0364g of 2, 4-diaminotoluene and 4.9354g of diphenylmethanediamine were added at room temperature with stirring. After stirring to dissolve, 16.0282g of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride was added and stirring was continued for 3 hours. Then 2.5556g of isoquinoline was added, the temperature was raised to 100 ℃ for reaction for 1 hour, the temperature was raised to 120 ℃ for reaction for 1 hour, and the temperature was raised to 180 ℃ for reaction for 12 hours. To obtain polyimide stock solution with solid content of 15 percent.
(2) And (2) carrying out post-treatment on the polyimide stock solution in the step (1), including filtration, defoaming and dilution to 3 wt%. Then, 10mL of the stock solution was injected into 100mL of 10mg/mL silver nitrate solution at a rate of 1mL/min with a 20mL syringe having a diameter of 2.1cm at a stirring rate of 2000r/min to obtain a polyimide fibrid suspension, which was washed, filtered and dried to obtain polyimide fibrids.
(3) And (3) soaking the fibrid obtained in the step (2) in 100mL of sodium borohydride solution with the concentration of 2mg/mL, washing, filtering and drying to obtain the fibrid loaded with the metal nano particles.
(4) And (3) mixing the fibrid in the step (3) with the polyimide chopped fiber according to the mass ratio of 7: 3, mixing and placing in water, adding a dispersant to obtain uniform slurry, and carrying out papermaking, hot pressing and vacuum drying to obtain the polyimide composite paper.
The intrinsic viscosity of the polyimide stock solution obtained in this example was 3.2 dl/g; the fibrids had an average length of 2.0mm and a specific surface area of 55m 2(ii)/g; the glass transition temperature of the prepared fibrid is 300 ℃, and the thermal weight loss average temperature when the mass loss is 5 percent is 480 ℃; when the polyimide composite paper is hot-pressed at the temperature of 210 ℃ and the pressure of 10MPa, the size of the obtained polyimide composite paper is not obviously shrunk, the tensile index of the composite paper is 22 N.m/g, and the compressive strength is 11.8 kV/mm. The composite material is used as a SERS substrate, rhodamine 6G (R6G) is used as a Raman probe molecule, and the Raman probe molecule can be measured at 1360cm -1Is pulled byThe detection limit of the Raman intensity is about 1 × 10 -11mol/L. The catalytic rate constant of the composite paper for catalytic reduction of p-nitrophenol is about 0.29min -1。
Example 6
(1) 171mL of N-methylpyrrolidone was added to a 250mL three-necked flask under nitrogen, and 3.0364g of 2, 4-diaminotoluene and 4.9354g of diphenylmethanediamine were added at room temperature with stirring. After stirring to dissolve, 16.0282g of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride was added and stirring was continued for 3 hours. 3.5732g of acetic anhydride and 3.5417g of triethylamine were then added and the reaction was carried out at 70 ℃ for 12 h. To obtain polyimide stock solution with solid content of 15 percent.
(2) And (2) carrying out post-treatment on the incompletely cyclized polyimide stock solution in the step (1), wherein the post-treatment comprises filtering, defoaming and diluting to 3 wt%. Then, 10mL of the stock solution was injected into 100mL of 10mg/mL silver nitrate solution at a rate of 1mL/min with a 20mL syringe having a diameter of 2.1cm at a stirring rate of 2000r/min to obtain a polyimide fibrid suspension, which was washed, filtered and dried to obtain polyimide fibrids.
(3) And (3) soaking the fibrid obtained in the step (2) in 100mL of 2mg/mL sodium borohydride solution, washing, filtering and drying to obtain the fibrid loaded with the metal nanoparticles.
(4) Mixing the fibrid in the step (3) with polyimide chopped fiber according to the mass ratio of 5: 5, mixing and placing in water, adding a dispersant to obtain uniform slurry, and carrying out papermaking, hot pressing and vacuum drying to obtain the polyimide composite paper.
The intrinsic viscosity of the polyimide stock solution obtained in this example was 3.0 dl/g; the fibrids had an average length of 2.0mm and a specific surface area of 60m 2(ii)/g; the glass transition temperature of the prepared fibrid is 320 ℃, and the average temperature of thermal weight loss when the mass loss is 5 percent is 510 ℃; when the polyimide composite paper is hot-pressed at the temperature of 210 ℃ and the pressure of 10MPa, the size of the obtained polyimide composite paper is not obviously shrunk, the tensile index of the composite paper is 21 N.m/g, and the compressive strength is 11.2 kV/mm. The composite material is used as a SERS substrate, rhodamine 6G (R6G) is used as a Raman probe molecule, and the Raman probe molecule can be measured at 1360cm -1Raman intensity of (2), detectionLimit of about 1 × 10 -10mol/L. The catalytic rate constant of the composite paper for catalytic reduction of p-nitrophenol is about 0.27min -1。

Claims (11)

1. The polyimide composite paper is characterized by comprising polyimide fibrids loaded with metal nano particles.
2. The composite paper as claimed in claim 1, wherein the metal nanoparticles are one or more of gold, silver, platinum, copper and chromium; the length of the polyimide chopped fiber is 3-12 mm.
3. A preparation method of polyimide composite paper comprises the following steps:
(1) injecting the post-treated polyimide PI stock solution into a metal inorganic salt aqueous solution under the stirring condition to obtain polyimide PI fibrid suspension, washing, filtering and vacuum drying to obtain PI fibrid, carrying out in-situ reduction, washing, filtering and vacuum drying to obtain fibrid loaded with metal nanoparticles;
(2) directly papermaking the fibrid loaded with the metal nano particles to obtain polyimide composite paper;
or mixing the metal nanoparticle-loaded fibrids and the polyimide chopped fibers in a mass ratio of 9: 1-1: 9, adding a dispersant to obtain uniform slurry, papermaking, hot pressing, and vacuum drying to obtain the polyimide composite paper.
4. The preparation method according to claim 3, wherein the step (1) post-treatment comprises filtration, deaeration, dilution; the injection is specifically as follows: the stirring speed is 2000-10000 r/min, the injection speed is 0.5-1 mL/min, and after the solution is completely injected, the stirring is continued for 1-2 min.
5. The preparation method according to claim 3, wherein the polyimide PI stock solution in the step (1) is prepared by the following method: adding a diamine monomer into an aprotic polar organic solvent at 0-25 ℃ under the protection of nitrogen, adding a dianhydride monomer after completely dissolving, stirring, and then adding a catalyst for heating cyclization or adding a chemical cyclization agent for chemical cyclization to obtain a polyimide stock solution; the concentration of the metal inorganic salt aqueous solution in the step (1) is 2-50 mg/mL; wherein the metal ions are one or more of gold, silver, platinum, copper and chromium.
6. The preparation method according to claim 5, wherein the reaction time after the dianhydride is added is 3-7 h, and the stirring speed is 200-300 r/min; the catalyst is one or more of isoquinoline, acetic anhydride, triethylamine and the like, and the dropping speed is 1 mL/min; the reaction parameters of the heating cyclization are as follows: polymerizing for 1-3 h at 100 ℃, heating to 120 ℃, polymerizing for 1-3 h, and heating to 180 ℃ for polymerizing for 5-15 h; the chemical cyclizing agent is one or more of triethylamine, acetic anhydride and pyridine, and the molar ratio of the cyclizing agent to the diamine is 0: 1-1: 1; the reaction temperature of the chemical cyclization is 60-80 ℃.
7. The preparation method according to claim 3, wherein the in-situ reduction in the step (1) is specifically: soaking the fibrid in an aqueous solution of a reducing agent, wherein the molar ratio of metal ions to the reducing agent is 1: 1-1.5; wherein the reducing agent is one or more of hydrazine hydrate, sodium borohydride, sodium hypophosphite and hydrogen peroxide.
8. The preparation method according to claim 3, wherein the length of the polyimide chopped fiber in the step (2) is 3-12 mm; the dispersant is polyethylene glycol.
9. The preparation method according to claim 3, wherein the hot pressing process parameters in the step (2) are as follows: the hot pressing temperature is 200-; the technological parameters of vacuum drying are as follows: the vacuum drying temperature is 40-80 ℃, and the time is 1-10 h.
10. A polyimide composite paper prepared by the method of claim 3.
11. Use of the polyimide composite paper of claim 1 as a catalyst or SERS.
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CN107354808A (en) * 2017-06-28 2017-11-17 徐昌霞 Aramid fiber/polyimide fiber composite-insulating paper of excellent performance and preparation method thereof is worn in a kind of resistance
CN109487630A (en) * 2018-11-15 2019-03-19 东华大学 A kind of polyimides extrusion coating paper of nano silicon nitride boron modification and its preparation and application
CN110079884A (en) * 2019-05-08 2019-08-02 东华大学 A kind of preparation method of high-specific surface area polyimides fibrid

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CN105672025A (en) * 2016-01-07 2016-06-15 江苏先诺新材料科技有限公司 Polyimide paper with controllable electrical property and preparation method thereof
CN107354808A (en) * 2017-06-28 2017-11-17 徐昌霞 Aramid fiber/polyimide fiber composite-insulating paper of excellent performance and preparation method thereof is worn in a kind of resistance
CN109487630A (en) * 2018-11-15 2019-03-19 东华大学 A kind of polyimides extrusion coating paper of nano silicon nitride boron modification and its preparation and application
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