CN115028863A

CN115028863A - Fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film and preparation method and application thereof

Info

Publication number: CN115028863A
Application number: CN202210649962.4A
Authority: CN
Inventors: 欧阳朝柳; 李庆; 刘胜; 郭宇娟; 彭华玲; 冯洁盈; 陆建宾; 黄照华; 邓菲
Original assignee: Guangxi University for Nationalities
Current assignee: Guangxi University for Nationalities
Priority date: 2022-06-10
Filing date: 2022-06-10
Publication date: 2022-09-09
Anticipated expiration: 2042-06-10
Also published as: CN115028863B

Abstract

The invention relates to a fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film and a preparation method and application thereof, wherein the preparation method comprises the following steps: 1) putting PSZN and dopamine hydrochloride into a container according to a certain mass ratio, then adding an alkaline buffer solution, fully stirring at normal temperature for reaction, and then centrifuging and washing to obtain PSZN @ polydopamine particles; 2) and (2) completely dissolving FPI in DMF under a heating condition to obtain a solution, then adding a certain amount of PSZN @ polydopamine particles into the solution, uniformly mixing to obtain a mixed solution, forming a liquid film on a substrate by using the mixed solution, then drying, naturally cooling and separating to obtain the FPI. The preparation method has the advantages that after the surface of PSZN is coated with a layer of polydopamine, the compatibility of the polydopamine and FPI is enhanced to ensure uniform dispersion, and the mechanical property of an FPI film is enhanced to a certain extent; polydopamine and PSZN cooperate in the aspect of ultraviolet shielding, and the ultraviolet resistance of the composite membrane can be effectively improved.

Description

Fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film and preparation method and application thereof

Technical Field

The invention relates to the field of material science, in particular to a fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film and a preparation method and application thereof.

Background

The improvement of the civilian level and the guarantee of stable and sufficient supply of electric power are important, but the transmission cable is susceptible to aging caused by ultraviolet rays, high temperature and the like, and in addition, the corrosion of wind and rain causes a plurality of problems of insulator breakage, conductor exposure, electric shock short circuit and the like. The common cable coating material is an organic polymer composite film, and the service life of the cable coating material under outdoor conditions is short. Therefore, it is of great practical significance to use Polyimide (PI) having excellent heat resistance, chemical stability, mechanical properties, electrical properties and durability as such an electrical insulating material. However, PI does not absorb ultraviolet light strongly, but blocks the transmission of visible light. Fluorine atoms are introduced into PI to prepare fluorine-containing polyimide (FPI), and the introduction of F atoms increases the molecular chain spacing, so that the original electron cloud conjugation of a PI molecular structure is changed, and the final result is that the color of the FPI is much lighter than that of the PI, so that the working section with faults can be effectively checked by directly observing the working condition of a lead, the dielectric constant of the PI is reduced, and the thermal stability is enhanced.

In addition, porous Pure Silicalite (PSZN) is a class of nanomaterials with controllable particle size and excellent stability and low dielectric constant. Chinese patent CN202010791303.5 discloses a pure silicon BETA molecular sieve with ultraviolet resistance and its preparation method, wherein PSZN is described as plastic anti-aging auxiliary agent, and the ultraviolet resistance aging life of the added plastic is improved by more than 3 times than that of the common anti-aging auxiliary agent. However, although PSZN is a fine particle having a particle size of only about 140nm, direct dispersion in the FPI film greatly reduces the mechanical properties of the base film, and thus cannot meet the use requirements.

Disclosure of Invention

The invention aims to solve the technical problem of providing a fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film, a preparation method and application thereof, and aims to overcome the defects in the prior art.

The technical scheme for solving the technical problems is as follows: a preparation method of a fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film comprises the following steps:

1) synthesis of PSZN @ polydopamine particles: pure silicalite powder PSZN and dopamine hydrochloride were mixed as 1: 4-5, adding the Tris-HCl buffer solution with the pH value maintained above 8.0, fully stirring at normal temperature for reaction, and centrifuging and washing to obtain PSZN @ polydopamine particles for later use;

2) preparing an FPI/PSZN @ polydopamine nano composite film: taking fluorine-containing polyimide FPI, completely dissolving the fluorine-containing polyimide FPI in DMF under a heating condition to obtain a solution, wherein the dosage ratio of the fluorine-containing polyimide to the DMF is 0.5g:8-10mL, then adding PSZN @ polydopamine particles into the solution, the mass of the PSZN @ polydopamine particles is 0.05-1.00% of that of the fluorine-containing polyimide in the solution, fully and uniformly mixing to obtain a mixed solution, forming a liquid film on a substrate by using the mixed solution, then placing the substrate in an oven for drying treatment, and then naturally cooling and separating to obtain the FPI/PSZN @ polydopamine nano composite film.

On the basis of the technical scheme, the invention can be further specifically selected as follows.

Specifically, the dosage ratio of the pure silicalite to the Tris-HCl buffer solution in the step 1) is 100mg:200-300 mL.

Preferably, the pH of the Tris-HCl buffer in the step 1) is 8.5.

Specifically, the pure silicalite powder in the step 1) is prepared by taking TBAOH and TEOS as raw materials.

Specifically, the fluorine-containing polyimide in the step 2) is prepared by taking TFDB and 6FDA as raw materials.

Specifically, the mass of the PSZN @ polydopamine particles in the step 2) is 0.05-0.5% of that of the fluorine-containing polyimide in the solution.

Specifically, the substrate in the step 2) is a glass plate with a silica gel template.

Specifically, the drying treatment in the step 2) is to dry the mixture for 30 to 40 hours at 80 ℃, then heat the mixture to 100 ℃, and continue drying for 2 to 3 hours.

The invention also provides a fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film which is prepared by the method.

The invention also provides an application of the fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film, and particularly relates to the fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano composite film serving as an ultraviolet shielding material for packaging a power transmission cable.

Compared with the prior art, the invention has the beneficial effects that:

after the surface of PSZN is coated with a layer of polydopamine, the compatibility of the polydopamine and FPI is enhanced to ensure uniform dispersion, and the mechanical property of an FPI film is enhanced to a certain extent; particularly, polydopamine and PSZN both have excellent ultraviolet absorption and shielding performance, and are cooperatively matched in an FPI film, so that the ultraviolet light aging resistance of the FPI/PSZN @ polydopamine composite film can be effectively improved, and the mechanical performance of the FPI film is also improved.

Drawings

FIG. 1 is a transmission electron microscope image of PSZN (a) and PSZN @ polydopamine (b) prepared and used in accordance with the present invention;

FIG. 2 is a graph showing the effect of the addition of PSZN @ polydopamine particles on the tensile strength and elongation at break of the prepared composite film;

FIG. 3 is a graph of the dielectric constant of composite films with different PSZN @ polydopamine particle loadings;

FIG. 4 is a graph of dielectric loss for composite films with different PSZN @ polydopamine particle loadings;

FIG. 5 is a graph showing UV shielding performance curves of composite films and pure fluorine-containing polyimide films with different PSZN @ polydopamine particle addition amounts;

FIG. 6 is a repeated experimental curve of the ultraviolet shielding performance of the composite film containing 0.5% of PSZN @ polydopamine particles and the pure fluorine-containing polyimide film.

Detailed Description

The technical solutions provided by the present invention are further described in detail with reference to the following specific embodiments, which are only used for explaining the present invention and are not used for limiting the scope of the present invention.

For the sake of brevity, the methods used in the following examples are all conventional in the art unless otherwise specified, and the pharmaceutical products used are all commercially available products unless otherwise specified.

The pure silicalite powder used in the following examples is prepared from TBAOH and TEOS as raw materials, and the specific preparation method comprises the following steps: 10.38g of TBAOH was mixed with 4.21g of deionized water and the mixture was then added dropwise slowly with stirring by a large magnetic force into a polypropylene cup containing 7.04g TEOS. Stirring at room temperature for 24 hr after the dropwise addition, transferring the obtained solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating in an oven at 110 deg.C for 24 hr. After the crystallization reaction is finished, separating out PSZN crystals by high-speed centrifugation, washing the PSZN crystals with deionized water for multiple times, then freezing and drying the PSZN crystals to obtain powder, and calcining the powder in a muffle furnace at 450 ℃ for 6 hours to obtain pure PSZN for later use. A transmission electron micrograph of the prepared PSZN is shown in fig. 1 a.

The fluorine-containing polyimide (FPI) used in the following examples is prepared from TFDB and 6FDA as raw materials, and the specific preparation method comprises the following steps: 3.843g of TFDB mixed with 60mL of DMF was put into a 100mL two-necked flask, magnetically stirred (600rad/min), 5.437g of 6FDA was added to the flask, nitrogen was introduced, and the reaction was continued at room temperature for 22 hours and then 0.2667g of 6FDA was added. The reaction was stirred for two hours, and 14.4mL of acetic anhydride and 7.2mL of pyridine were mixed and added to the flask, and after stirring at room temperature for 18 hours, the mixture was heated and stirred at 60 ℃ for 6 hours. The temperature was then raised to 80 ℃ for an additional 2 hours of stirring, after which the temperature was increased further to 100 ℃ and stirring was continued for an additional 2 hours. And finally, cooling the obtained mixed solution to room temperature, and pouring the cooled mixed solution into excessive absolute ethyl alcohol to obtain flocculent FPI precipitate. After filtration, it was washed with absolute ethanol several times, and the resulting solid was dried in an oven at 100 ℃ for 24 hours to give a dried FPI solid, which was stored in a drying tower for later use.

Example 1

A preparation method of a fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film comprises the following steps:

1) synthesis of PSZN @ polydopamine particles: putting 100mg of pure silicalite Powder (PSZN) and 400mg of dopamine hydrochloride into a 250mL flask, then adding 200mL of Tris-HCl buffer solution, keeping the pH value of the buffer solution at about 8.5, stirring for 24h (300rad/min) at normal temperature, then centrifuging and washing the solid matter with clear water to obtain pure silicalite coated with Polydopamine (PDA) (PSZN @ polydopamine particles, namely PSZN is a core and polydopamine is an outer coating or shell) for later use, wherein the transmission electron microscope picture of the pure silicalite Powder (PSZN) and the dopamine hydrochloride powder is shown in figure 1 b;

2) preparing an FPI/PSZN @ polydopamine nano composite film: taking 0.5g of fluorine-containing polyimide (FPI), completely dissolving the fluorine-containing polyimide (FPI) in 8mL of DMF under the heating condition of 80 ℃ to obtain a solution, then adding 0.25mg of PSZN @ polydopamine particles (which is 0.05 wt% of the solid content of the FPI in the solution), fully and uniformly mixing (stirring for 1h first, then repeatedly carrying out ultrasonic dispersion to uniformly mix) to obtain a mixed solution, dripping the mixed solution onto a glass plate with a silica gel template to form a liquid film, then placing the liquid film in an oven at 80 ℃ for drying for about 36h, then heating to 100 ℃ to continue drying for 2h, and then naturally cooling and separating the obtained nano polymeric film to obtain the FPI/PSZN @ polydopamine nano composite film, which is marked as FPI/PSZN PDA-0.05 @.

Example 2

The content of the composite film is basically the same as that in the example 1, only the mass of the PSZN @ polydopamine particles added in the step 2) is different, specifically, 0.5mg of PSZN @ polydopamine particles (namely 0.1 wt.% of the solid content of FPI in the solution) is added into the solution, and the finally obtained FPI/PSZN @ polydopamine nano composite film is recorded as FPI/PSZN @ PDA-0.1%.

Example 3

The content is basically the same as that in the example 1, only the mass of the PSZN @ polydopamine particles added in the step 2) is different, specifically, 2.5mg of PSZN @ polydopamine particles (which is 0.5 wt.% of the solid content of FPI in the solution) are added into the solution, and the finally obtained FPI/PSZN @ polydopamine nano composite film is marked as FPI/PSZN @ PDA-0.5%.

Example 4

The content is basically the same as that in the example 1, only the mass of the PSZN @ polydopamine particles added in the step 2) is different, specifically, 5mg of PSZN @ polydopamine particles (which is 1 wt% of the solid content of FPI in the solution) are added into the solution, and the finally obtained FPI/PSZN @ polydopamine nano composite film is marked as FPI/PSZN @ PDA-1%.

Comparative example 1

Basically the same as the content in example 1, only the PSZN @ polydopamine particles added in step 2) have different mass, specifically, 0mg of PSZN @ polydopamine particles are added to the solution (i.e., 0 wt.% of the solid content of FPI in the solution, that is, PSZN @ polydopamine particles are not added to FPI), and the finally obtained FPI/PSZN @ polydopamine nanocomposite film is denoted as pure FPI.

Performance characterization and testing

The PSZN prepared and used in the invention and the PSZN @ polydopamine particles prepared in example 1 are respectively used as samples for transmission electron microscopy characterization, a transmission electron microscopy image of the PSZN is shown in figure 1a, and a transmission electron microscopy image of the PSZN @ polydopamine particles is shown in figure 1 b. As can be seen from FIG. 1a, the prepared PSZN is spindle-shaped nanoparticles with the major diameter of 140nm and the minor diameter of 80nm, and has porous rough outer surfaces, which is favorable for air to enter and reduce the dielectric constant of the composite film. In fig. 1b, it is obvious that a layer of poly-dopamine coated on the surface of PSZN is beneficial to the dispersion of PSZN in FPI and improves the mechanical and ultraviolet shielding performance of the substrate film.

The present inventors conducted tests on the tensile strength and elongation at break of the composite film using the films obtained in examples 1 to 4 and comparative example 1, respectively, to examine the influence of the different PSZN @ polydopamine particle addition amounts on the tensile strength and elongation at break of the composite film, and the results are shown in fig. 2. As can be seen from fig. 2, when PSZN @ polydopamine particles are added in the ranges of 0%, 0.05% and 0.1%, the maximum tensile strength and elongation at break of the composite film are increased along with the increase of the PSZN @ polydopamine particles, and the maximum tensile strength and elongation at break are 118.17Mpa and 6.47% (0.1% of the added amount). The sections of 0.1%, 0.5% and 1% decreased conversely the tensile strength and elongation at break of the composite film as the amount added increased. The main possible reason is that when the addition amount of PSZN @ PDA is less than or equal to 0.1 wt.%, the PSZN @ PDA has a large specific surface area and can be uniformly dispersed in FPI, the prepared composite film has uniform properties, the specific surface area of the composite film is reduced along with the increase of the content of PSZN @ PDA, and the PSZN @ PDA is not easily dispersed in FPI along with the increase of the content, so that the properties of the subsequently prepared composite film are not uniform as a whole, and the property of the high-content PSZN @ PDA is reduced in a cliff-off manner during testing. In summary, both tensile strength and elongation at break are increased for FPI incorporating an amount of PSZN @ PDA, preferably from 0.05 to 0.5 wt.%, most preferably 0.1%.

The films obtained in examples 1 to 4 and comparative example 1 were also tested for their insulating properties according to the present invention, and a dielectric constant map and a dielectric loss map were obtained as shown in fig. 3 and 4, respectively. It can be seen from FIG. 3 that the dielectric constants at 1MHz of the 0%, 0.05%, 0.1%, 0.5% and 1% concentrations decrease and increase as the data from the figure is available, and the dielectric constant of the composite film with PSZN @ PDA added is lower than that of pure low dielectric FPI at 1MHz, indicating that the addition of PSZN @ PDA is helpful for FPI to lower the dielectric constant, but is limited to the addition of low concentrations of PSZN @ PDA. When the filler concentration is too high, a large dispersed phase is formed due to agglomeration of the filler or collapse of the filler structure, which in turn causes an increase in the dielectric constant of the material. The principle of dielectric loss is that under the condition of alternating electric field, the material consumes part of electric energy to make the dielectric body generate heat. It can be seen from FIG. 4 that the dielectric loss of both the pure FPI and the PSZN @ PDA composite film at 1MHz is less than 0.01, which indicates that the pure FPI and the composite film have excellent dielectric loss performance.

In order to further evaluate the ultraviolet shielding performance of the film prepared by each embodiment of the invention, the invention designs an experiment for degrading curcumin through photocatalysis, and the ultraviolet shielding performance of the material is evaluated by monitoring the absorbance of the curcumin solution at 425 nm. Because curcumin has the characteristic of degrading in the presence of ultraviolet light, the degradation degree of the curcumin solution is used in the experiment to quantify the ultraviolet shielding performance of the film, and the test result is shown in fig. 5. From the attenuation curve of fig. 5, it can be seen visually that the curve of the curcumin solution of the blank control group is sharply decreased and tends to 0 under the unprotected condition, while when the curcumin solution is covered by the pure FPI film, the rate of decrease of the curve is slow and tends to be gentle, and a higher ultraviolet shielding rate is still maintained during the last irradiation, which proves that the pure FPI film has good ultraviolet shielding performance. With the addition of the PSZN @ PDA particles, the curve of the composite film with higher content is more slowly and smoothly reduced, and the curve with 1% of PSZN @ PDA content is almost not reduced, which shows that the ultraviolet shielding performance of the composite film after the PSZN @ PDA is added is greatly improved.

In addition, for the ultraviolet shielding material, whether the ultraviolet shielding material can be reused or not is an important performance index. Therefore, a composite film with better comprehensive performance and 0.5% PSZN @ polydopamine content and a pure FPI film are selected to be tested in a repeatability experiment, the reusability of the composite film and the pure FPI film is compared, and the result is shown in figure 6. As can be seen from fig. 6, both of the films exhibit excellent ultraviolet shielding efficiency, the composite film added with PSZN @ polydopamine particles exhibits a more gradual drop curve of the ultraviolet shielding efficiency in a repeatability test, and the ultraviolet shielding effect is significantly better than that of a pure FPI film. After ten times of repeatability tests, the FPI/PSZN @ polydopamine nano composite film can still keep higher ultraviolet shielding efficiency, which indicates that the prepared FPI/PSZN @ polydopamine nano composite film is a reusable ultraviolet shielding material with excellent performance.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.

Claims

1. A preparation method of a fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film is characterized by comprising the following steps:

1) synthesis of PSZN @ polydopamine particles: pure silicalite powder PSZN and dopamine hydrochloride were mixed as 1: 4-5, adding into a container, adding Tris-HCl buffer solution with the pH value maintained above 8.0, fully stirring at normal temperature for reaction, and centrifuging and washing to obtain PSZN @ polydopamine particles for later use;

2. The method for preparing fluorine-containing polyimide/pure silicalite @ polydopamine nanocomposite film as claimed in claim 1, wherein the dosage ratio of pure silicalite to Tris-Hcl buffer solution in step 1) is 100mg:200-300 mL.

3. The method for preparing the fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano-composite film according to claim 1, wherein the pH of the Tris-HCl buffer solution in the step 1) is 8.5.

4. The method for preparing fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film according to claim 1, wherein the pure silicalite powder in step 1) is prepared by taking TBAOH and TEOS as raw materials.

5. The method for preparing the fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film according to claim 1, wherein the fluorine-containing polyimide obtained in the step 2) is prepared by taking TFDB and 6FDA as raw materials.

6. The method for preparing the fluorine-containing polyimide/pure silicalite @ polydopamine nano composite film as claimed in claim 1, wherein the mass of the PSZN @ polydopamine particles in the step 2) is 0.05-0.5% of the mass of the fluorine-containing polyimide in the solution.

7. The method for preparing the fluorine-containing polyimide/pure silicon zeolite @ polydopamine nano-composite film according to claim 1, wherein the substrate in the step 2) is a glass plate with a silica gel template.

8. The preparation method of the fluorine-containing polyimide/pure silicalite @ polydopamine nanocomposite film according to claim 1, wherein the drying treatment in the step 2) is to dry the film for 30-40h at 80 ℃, then to heat the film to 100 ℃, and to continue drying for 2-3 h.

9. A fluorine-containing polyimide/pure silicalite @ polydopamine nanocomposite film characterized by being prepared by the method of any one of claims 1 to 8.

10. The use of the fluorine-containing polyimide/pure silicalite @ polydopamine nanocomposite film as claimed in claim 9, as an ultraviolet shielding material for packaging of power transmission cables.