Synergistic polyimide photocatalytic powder and preparation method thereof

Abstract

The invention relates to synergistic polyimide photocatalytic powder and a preparation method thereof, which are characterized in that amino groups are grafted on the surface of optical synergist powder, then polyimide precursor polyamide acid is electrostatically adsorbed, and after heat treatment, the synergistic polyimide photocatalytic powder taking an optical synergist as an inner core and polyimide as a shell is obtained. The preparation method mainly comprises the following steps: 1) putting light synergist powder into an amino-containing silane coupling agent solution, stirring, filtering and airing to obtain a modified light synergist; and 2) completely dissolving a diamine monomer with a conjugated structure in a solvent, adding a dianhydride monomer with a conjugated structure, stirring until the viscosity of the solution is not changed, and diluting to obtain a polyamide acid solution. And (3) preparing the modified optical synergist into dispersion liquid. And (4) dropwise adding the polyamide acid solution into the modified optical synergist dispersion liquid, continuously stirring during the period, and filtering, cleaning, drying and grinding after dropwise adding to obtain the synergistic polyamide acid powder. 5, the synergistic polyamide acid powder is subjected to heat treatment, and the synergistic polyimide photocatalytic powder.The preparation method has the advantage that after the optical synergist is introduced, the catalytic effect of the polyimide photocatalyst is improved.

Description

Technical Field

[0001] A synergistic polyimide photocatalytic powder and a preparation method thereof. Background Art

[0002] Some polyimide materials with π-π conjugated structures have certain photoelectric properties, but the spectral response range of polyimide is relatively narrow. For example, PMDA / PDA type polyimide photocatalysts can only absorb light with a wavelength of less than 800 nm and cannot effectively utilize light in the long wavelength range. In addition, due to the influence of the light-dark transition of the environment, such as the day-night transition caused by the rotation of the earth, the actual action time of the photocatalytic material is greatly reduced. These problems have greatly reduced the efficiency of polyimide photocatalytic materials in practical applications.

[0003] Long afterglow luminescent materials are a type of photoluminescent material that emits visible light when excited by a light source and stores part of the light energy obtained. After the excitation stops, the energy is slowly released in the form of light. For example, the long afterglow luminescent material SrAl2O4:Eu 2+ ,Dy 3+ After being irradiated by sunlight, it can emit a yellow-green afterglow with a wavelength of about 514 nm. Upconversion luminescent materials refer to materials that are excited by low-energy light and emit high-energy light, that is, after being excited by long-wavelength, low-frequency light, the material emits short-wavelength, high-frequency light. For example, the upconversion luminescent material NaYF4:Yb 3+ ,Er 3+ It can absorb light in the near-infrared spectrum of sunlight and emit green light in the band of about 542 nm. If the above-mentioned long afterglow luminescent material or upconversion luminescent material is added to the polyimide photocatalyst, the photocatalytic time or light utilization rate can be effectively increased. Both methods can significantly increase the catalytic efficiency of the photocatalyst. Therefore, long afterglow luminescent materials and upconversion luminescent materials can be used as photosynthesizers for polyimide photocatalysts. However, photosynthesizers are mostly inorganic metal compound powder particles, which are difficult to dissolve and melt, and organic polyimide photocatalyst materials also have the problem of being difficult to dissolve and melt. The physical and chemical properties of the two are very different, and it is difficult to disperse them evenly by simple mixing, or to combine them together by sintering or the like. Summary of the invention

[0004] A synergistic polyimide photocatalytic powder and a preparation method thereof are invented, wherein amino groups are grafted onto the surface of the photosynergist powder, and then the polyimide precursor polyamic acid is electrostatically adsorbed, thereby achieving the effect of coating the photosynergist. After heat treatment, the synergistic polyimide photocatalytic powder is obtained.

[0005] The present invention is achieved through the following specific technical solutions: Step 1: Place a certain mass of photosynthesizer powder in a certain concentration of aminosilane coupling agent solution, stir overnight, filter out the powder, dry it, and obtain a modified photosynthesizer. The photosynthesizer powder is a long afterglow luminescent powder or an up-conversion luminescent powder; the aminosilane coupling agent includes but is not limited to KH-550, KH-602, and KH-792; the mass of the photosynthesizer powder is 10 to 50 times the mass of the aminosilane coupling agent, preferably 20 times; the concentration of the aminosilane coupling agent solution is 2 to 10%, preferably 3%. The solvent used in the aminosilane coupling agent solution includes but is not limited to ethanol, methanol, isopropanol, dioxane, and tetrahydrofuran.

[0006] Step 2: Weigh the diamine and dianhydride monomers with a conjugated structure in a mass ratio of 1:1, completely dissolve the diamine monomer in a solvent with a mass of 10 times that of the diamine monomer, add the dianhydride monomer after it is completely dissolved, stir until the solution viscosity remains unchanged, and dilute to a certain concentration to obtain a polyamic acid solution. The diamine with a conjugated structure includes but is not limited to phenylenediamine, naphthalenediamine, biphenylenediamine, dinaphthylenediamine, diaminofluorene, diaminophenanthrene, diaminoanthraquinone, diaminopyridine, and methylguanamine; the dianhydride monomer with a conjugated structure includes but is not limited to pyrophthalic anhydride, biphenyl dianhydride, naphthalenetetracarboxylic anhydride, and perylenetetracarboxylic anhydride; the solvent includes but is not limited to DMF, NMP, DMAc, and DMSO; the concentration of the polyamic acid solution is 1 to 10%, preferably 3%.

[0007] Step 3: Disperse the modified light synergist in step 1 in the solvent in step 2 to prepare a modified light synergist dispersion liquid with a certain concentration. The concentration of the modified light synergist dispersion liquid is 3-10%, preferably 6%.

[0008] Step 4: Add an equal volume of the polyamic acid solution in step 2 dropwise to the modified light synergist dispersion in step 3, stirring continuously during the process, filtering after the dropwise addition is completed, washing the filter cake, drying it, and grinding it to obtain the synergistic polyamic acid powder. The filter cake washing condition is to immerse the filter cake in a low boiling point solvent and then filter it. The low boiling point solvent includes but is not limited to ethanol, methanol, isopropanol, ether, chloroform, preferably ethanol.

[0009] Step 5: heat-treating the enhanced polyamic acid powder in step 4 to obtain enhanced polyimide photocatalytic powder. The heat treatment conditions are 250°C to 350°C for 1 to 5 hours, preferably 300°C for 2 hours.

[0010] The present invention has the following beneficial effects: 1. By introducing long afterglow luminescent powder, the action time of polyimide photocatalyst in a lightless and weak light environment is increased, thereby improving the catalytic effect. 2. By introducing up-conversion luminescent powder, the utilization efficiency of polyimide photocatalyst for long-wavelength light in sunlight is enhanced, thereby improving the catalytic effect. 3. With the structure of a photosynthesizer as the core and polyimide as the shell, the polyimide photocatalyst shell can protect the photosynthesizer core from being quenched by external factors such as oxygen, heteroatoms, and molecules, thereby improving the service life of the photosynthesizer. Specific embodiment: The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present invention, several variations and improvements can also be made, which all belong to the protection scope of the present invention. Example 1

[0012] 20g SrAl2O4:Eu 2+ ,Dy 3+ The long afterglow material powder is placed in 33ml of 3% silane coupling agent KH-550 ethanol solution, stirred overnight, filtered out the powder, dried, and a modified photosynergist is obtained. The modified photosynergist is dispersed in DMAc to obtain a 6% modified photosynergist dispersion. After 0.03mol 3.24g of phenylenediamine is completely dissolved in 33g DMAc, 0.03mol 6.54g of phthalic anhydride is added, stirred until the solution viscosity remains unchanged, and diluted to 3% to obtain a polyamic acid solution. The modified photosynergist dispersion is added dropwise to the polyamic acid solution, stirred continuously during the period, and the filter cake is filtered out after the dropwise addition is completed. After the filter cake is immersed in ethanol and filtered, it is dried and ground to obtain a synergistic polyamic acid powder. The above powder is heated to 300℃ and kept warm for 2h to obtain a synergistic polyimide photocatalytic powder. Example 2

[0013] 60g CaAl2O4:Eu 2+ ,Nd 3+The long afterglow luminescent material powder is placed in 60ml of 10% silane coupling agent KH-602 methanol solution, stirred overnight, filtered out the powder, dried, and a modified photosynergist is obtained. The modified photosynergist is dispersed in DMF to obtain a 3% modified photosynergist dispersion. After 0.044mol 6.95g naphthalene diamine is completely dissolved in 70g DMF, 0.044mol 12.94g biphenyl dianhydride is added, stirred until the solution viscosity remains unchanged, and diluted to 1% to obtain a polyamic acid solution. The modified photosynergist dispersion is added dropwise to the polyamic acid solution, stirred continuously during the period, and the filter cake is filtered out after the dropwise addition is completed. After the filter cake is immersed in ether and filtered, it is dried and ground to obtain a synergistic polyamic acid powder. The above powder is heated to 250°C and kept warm for 5h to obtain a synergistic polyimide photocatalytic powder. Example 3

[0014] 5g NaYF4:Yb 3+ ,Er 3+ The upconversion luminescent material powder is placed in 5ml of 2% silane coupling agent KH-792 tetrahydrofuran solution, stirred overnight, filtered out the powder, dried, and a modified photosynergist is obtained. The modified photosynergist is dispersed in NMP to obtain a 10% modified photosynergist dispersion. After 0.011mol 2.02g of benzyl diamine is completely dissolved in 20ml NMP, 0.011mol 2.95g of naphthalenetetracarboxylic dianhydride is added, stirred until the viscosity of the solution remains unchanged, and diluted to 10% to obtain a polyamic acid solution. The modified photosynergist dispersion is added dropwise to the polyamic acid solution, stirred continuously during the period, and the filter cake is filtered out after the dropwise addition is completed. The filter cake is immersed in methanol and filtered, dried, and ground to obtain a synergistic polyamic acid powder. The above powder is heated to 350°C and kept warm for 1h to obtain a synergistic polyimide photocatalytic powder.

[0015] In order to compare and show the catalytic effect of the enhanced polyimide photocatalytic powder, the photosynergist was replaced with silicon dioxide of the same particle size, and the same preparation method as that described in Examples 1, 2, and 3 was used to prepare polyimide photocatalytic powder control examples 1, 2, and 3, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a TEM image of the morphology of the synergistic polyimide photocatalytic powder in Example 1.

[0017] Explanation of the attached table The photocatalytic effect of the synergistic polyimide photocatalytic powder can be more clearly demonstrated through photocatalytic experiments. The specific method is as follows: Weigh 50 mg of the enhanced polyimide photocatalytic powder in the embodiment and the control polyimide photocatalytic powder, disperse them into 100 mL, 4 mg / L rhodamine B (RhB) solution, stir them in a dark environment for 1 hour to allow RhB to reach adsorption equilibrium, place them under a 300W xenon lamp for 0.5 hour, and then place them in a dark environment for 0.5 hour as one cycle, and continue for 2 cycles to perform photocatalytic degradation of RhB. Take the supernatant every 0.5 hour, use a UV-visible spectrophotometer to measure the absorbance at a wavelength of 554 nm, calculate the residual rate of RhB, and then investigate the visible light catalytic activity of the sample. The results are shown in Table 1 for the photodegradation effect of the enhanced polyimide photocatalytic powder on RhB.

[0018] Schedule 1

Claims

1. This patent invents a synergistic polyimide photocatalytic powder and its preparation method, the main steps of which are: 1) Place a certain mass of photosynergist powder in a certain concentration of aminosilane coupling agent solution, stir overnight, filter out the powder, dry it, and obtain the modified photosynergist. 2) Weigh the diamine and dianhydride monomers with a conjugated structure at a mass ratio of 1:1, completely dissolve the diamine monomer in a solvent with a mass of 10 times that of the diamine monomer, add the dianhydride monomer after it is completely dissolved, stir until the viscosity of the solution remains unchanged, and dilute to obtain a polyamic acid solution. 3) Disperse the modified photosynergist described in step 1 in the solvent described in step 2 to prepare a modified photosynergist dispersion. 4) Add an equal volume of the polyamic acid solution described in step 2 dropwise to the modified photosynergist dispersion described in step 3, stirring continuously during the process, filter after the dropwise addition is completed, wash the filter cake, dry it, and grind it to obtain a synergistic polyamic acid powder. 5) The enhanced polyamic acid powder in step 4 is heat-treated to obtain enhanced polyimide photocatalytic powder.

2. The synergistic polyimide photocatalytic powder and preparation method thereof according to claim 1, characterized in that The light synergist powder in step 1 is a long afterglow luminescent powder or an up-conversion luminescent powder; the amino-containing silane coupling agent includes but is not limited to KH-550, KH-602, and KH-792; the mass of the light synergist powder is 10 to 50 times the mass of the amino-containing silane coupling agent, preferably 20 times; the concentration of the amino-containing silane coupling agent solution is 2 to 10%, preferably 3%. The solvent used in the amino-containing silane coupling agent solution includes but is not limited to ethanol, methanol, isopropanol, dioxane, and tetrahydrofuran.

3. The synergistic polyimide photocatalytic powder and preparation method thereof according to claim 1, characterized in that The diamines having a conjugated structure in step 2 include but are not limited to phenylenediamine, naphthalenediamine, biphenylenediamine, binaphthylenediamine, diaminofluorene, diaminophenanthrene, diaminoanthraquinone, diaminopyridine, and methylguanamine; the dianhydride monomers having a conjugated structure include but are not limited to pyrophthalic anhydride, biphenyl dianhydride, naphthalenetetracarboxylic anhydride, and perylenetetracarboxylic anhydride; the solvents include but are not limited to DMF, NMP, DMAc, and DMSO; and the concentration of the polyamic acid solution is 1 to 10%, preferably 3%.

4. The synergistic polyimide photocatalytic powder and preparation method thereof according to claim 1, characterized in that The concentration of the modified photosynthesizer dispersion in step 3 is 3-10%, preferably 6%.

5. The synergistic polyimide photocatalytic powder and preparation method thereof according to claim 1, characterized in that The filter cake cleaning condition in step 4 is to immerse the filter cake in a low boiling point solvent and then filter it. The low boiling point solvent includes but is not limited to ethanol, methanol, isopropanol, ether, chloroform, preferably ethanol.

6. The synergistic polyimide photocatalytic powder and preparation method thereof according to claim 1, characterized in that The heat treatment conditions in step 5 are 250° C. to 350° C., and insulation for 1 to 5 hours, preferably 300° C., and insulation for 2 hours.

7. A synergistic polyimide photocatalytic powder and a preparation method thereof, characterized in that The preparation method is described in claim 1 to 6.

8. A synergistic polyimide photocatalytic powder and a preparation method thereof according to claims 1 to 6, characterized in that: The synergistic polyimide photocatalytic powder has a structure with a photosynergist as the core and polyimide as the shell.

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