CN115028863B

CN115028863B - Fluorine-containing polyimide/pure silicon zeolite@polydopamine nano composite film and preparation method and application thereof

Info

Publication number: CN115028863B
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: 2023-10-13
Anticipated expiration: 2042-06-10
Also published as: CN115028863A

Abstract

The invention relates to a fluorine-containing polyimide/pure silicalite@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 centrifugally washing to obtain PSZN@polydopamine particles; 2) And taking FPI, completely dissolving the FPI in DMF under the 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, drying, naturally cooling and separating to obtain the transparent conductive film. The preparation method has the advantages that after the surface of the PSZN is coated with a layer of polydopamine, the compatibility of the polydopamine and the FPI is enhanced to ensure uniform dispersion, and the mechanical property of the FPI film is enhanced to a certain extent; the polydopamine and the PSZN are cooperatively matched in the aspect of ultraviolet shielding, so that 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 silicalite@polydopamine nano composite film and a preparation method and application thereof.

Background

The improvement of the civilian level is an important one in ensuring stable and sufficient supply of electric power, but the transmission cable is easy to age under the influence of ultraviolet rays, high temperature and the like, and the problems of insulator fracture, exposed conductor, electric shock type short circuit and the like are caused by wind and rain erosion. The common cable coating material is an organic polymer composite film, and the service life of the cable coating material under outdoor parts is short. Therefore, polyimide (PI) having excellent heat resistance, chemical stability, mechanical properties and electrical properties and durability is used as such an electrical insulating material, and has great practical significance. However, PI has not strong absorption capacity for ultraviolet light, but can block transmission of visible light. The fluorine-containing polyimide (FPI) is prepared after fluorine atoms are introduced into PI, because the F atoms are introduced to increase the molecular chain distance, the original electron cloud conjugation of the PI molecular structure is changed, and the final result is that the color of the FPI is more shallow than that of the PI, so that the working condition of a lead can be conveniently and directly observed, the working section with faults can be effectively eliminated, 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 No. 202010791303.5 discloses a pure silicon BETA molecular sieve with ultraviolet resistance and its preparation method, wherein PSZN can be used as anti-aging additive for plastics, and the ultraviolet aging resistance life of plastics is improved by more than 3 times than that of common anti-aging additive. However, PSZN is a fine particle having a particle diameter of only about 140nm, but the direct dispersion in the FPI film greatly reduces the mechanical properties of the matrix film, and 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 and 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: the preparation method of the fluorine-containing polyimide/pure silicalite@polydopamine nanocomposite film comprises the following steps:

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

2) Preparation of FPI/PSZN@polydopamine nanocomposite film: taking fluorine-containing polyimide FPI and fully 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, wherein 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 liquid film on an oven for drying treatment, and then naturally cooling and separating to obtain the FPI/PSZN@polydopamine nano composite film.

Based on the technical scheme, the invention can also make the following further specific selection.

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

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

Specifically, the pure silicalite powder in step 1) is prepared from 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 PSZN@polydopamine particles in the step 2) is 0.05-0.5% of the mass of 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 for 30-40 hours at 80 ℃, then raise the temperature to 100 ℃ and continue to dry for 2-3 hours.

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

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

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

according to the invention, after the surface of the PSZN is coated with a layer of polydopamine, the compatibility of the polydopamine with the FPI is enhanced to ensure uniform dispersion, and the mechanical property of the FPI film is enhanced to a certain extent; in particular, polydopamine and PSZN have excellent ultraviolet absorption and shielding performance, and the polydopamine and the PSZN are matched in the FPI film in a synergistic manner, so that the ultraviolet aging resistance of the FPI/PSZN@polydopamine composite film can be effectively improved, and meanwhile, 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 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 dielectric constants of composite films with different PSZN@polydopamine particle loadings;

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

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

FIG. 6 is a graph showing the ultraviolet shielding performance repeatability of a composite film with 0.5% PSZN@polydopamine particles and a pure fluorine-containing polyimide film.

Detailed Description

The technical scheme provided by the invention is further described in detail below with reference to specific embodiments, and the examples are only for explaining the invention and are not used for limiting the scope of the invention.

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

The pure silicalite powder used in the following examples was prepared from TBAOH and TEOS as raw materials, and the specific preparation method was: after mixing 10.38g of TBAOH with 4.21g of deionized water, the solution was slowly dropped into a polypropylene cup containing 7.04g of TEOS with extensive magnetic stirring. After the completion of the dropwise addition, stirring was continued at room temperature for 24 hours, and the resulting solution was transferred to a high-pressure reaction vessel with a polytetrafluoroethylene liner and heated in an oven at 110℃for 24 hours. And after the crystallization reaction is finished, separating PSZN crystals through high-speed centrifugation, washing the PSZN crystals with deionized water for multiple times, freeze-drying the PSZN crystals to obtain powder, and placing the powder in a muffle furnace at 450 ℃ for calcination for 6 hours, thereby obtaining pure PSZN for later use. The transmission electron microscope image of the prepared PSZN is shown in FIG. 1 a.

The fluorine-containing polyimide (FPI) used in the following examples was prepared from TFDB and 6FDA as raw materials, and the specific preparation method was: into a 100mL two-necked flask, 3.843g of TFDB mixed with 60mL of DMF was added, and the mixture was magnetically stirred (600 rad/min), 5.437g of 6FDA was added to the flask, and after continuing the reaction at room temperature for 22 hours, 0.2667g of 6FDA was added. The reaction was continued for two hours with stirring, and 14.4mL of acetic anhydride and 7.2mL of pyridine were mixed and then added to the flask, followed by stirring at room temperature for 18 hours and then heating and stirring at 60℃for 6 hours. Then, the temperature was further raised to 80℃and stirred for 2 hours, after which the temperature was further raised to 100℃and stirred for 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. Subsequently, the mixture was filtered, 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 use.

Example 1

The preparation method of the fluorine-containing polyimide/pure silicalite@polydopamine nanocomposite film comprises the following steps:

1) Synthesis of pszn@polydopamine particles: adding 100mg of pure silicalite Powder (PSZN) and 400mg of dopamine hydrochloride into a 250mL flask, then adding 200mL of Tris-HCl buffer solution, maintaining the pH of the buffer solution at about 8.5, stirring for 24 hours (300 rad/min) at normal temperature, centrifuging and washing solid substances with clear water to obtain Polydopamine (PDA) -coated pure silicalite (PSZN@polydopamine particles, namely PSZN is a core and polydopamine is an outer envelope or shell), and reserving the particles, wherein a transmission electron microscopic image of the particles is shown in figure 1 b;

2) Preparation of FPI/PSZN@polydopamine nanocomposite film: taking 0.5g of fluorine-containing polyimide (FPI), completely dissolving the fluorine-containing polyimide (FPI) in 8mL of DMF at 80 ℃ to obtain a solution, adding 0.25mg of PSZN@polydopamine particles (namely 0.05wt.% of the solid content of the FPI in the solution) into the solution, fully and uniformly mixing (stirring for 1h, then repeatedly and ultrasonically dispersing and uniformly mixing) to obtain a mixed solution, dripping the mixed solution on a glass plate with a silica gel template to form a liquid film, then placing the liquid film in an oven at 80 ℃, drying for about 36h, heating to 100 ℃, continuously drying for 2h, and naturally cooling and separating the obtained nano-polymerized film to obtain the FPI/PSZN@polydopamine nano-composite film, which is denoted as FPI/[email protected]%.

Example 2

Substantially the same as in example 1, only the mass of the pszn@polydopamine particles added in step 2) was different, specifically, 0.5mg of pszn@polydopamine particles (i.e. 0.1wt.% of FPI solid content in the solution) was added to the solution, and finally the obtained FPI/pszn@polydopamine nanocomposite film was designated as FPI/[email protected]%.

Example 3

Substantially the same as in example 1, only the mass of the pszn@polydopamine particles added in step 2) was different, specifically, 2.5mg of pszn@polydopamine particles (i.e. 0.5wt.% of FPI solid content in the solution) was added to the solution, and finally the obtained FPI/pszn@polydopamine nanocomposite film was designated as FPI/[email protected]%.

Example 4

Substantially the same as in example 1, only the mass of the pszn@polydopamine particles added in step 2) was different, specifically, 5mg of pszn@polydopamine particles (i.e. 1wt.% of FPI solid content in the solution) was added to the solution, and the finally obtained FPI/pszn@polydopamine nanocomposite film was designated as FPI/pszn@pda-1%.

Comparative example 1

Substantially the same as in example 1, only the mass of the pszn@polydopamine particles added in step 2) was different, specifically, 0mg of pszn@polydopamine particles was added to the solution (i.e. 0wt.% of the solid content of FPI in the solution, i.e. no pszn@polydopamine particles were added to the FPI), and the finally obtained FPI/pszn@polydopamine nanocomposite film was denoted as pure FPI.

Performance characterization and testing

The PSZN prepared and used by the invention and the PSZN@polydopamine particles prepared in the embodiment 1 are respectively used as samples for transmission electron microscope characterization, a transmission electron microscope image of the PSZN is shown in fig. 1a, and a transmission sub-microscope image of the PSZN@polydopamine particles is shown in fig. 1 b. From FIG. 1a, it can be seen that the prepared PSZN is spindle-shaped nanoparticle with a long diameter of 140nm and a short diameter of 80nm, and the rough outer surface has multiple pores, so that air can enter into the particle to reduce the dielectric constant of the composite membrane. In fig. 1b, it is obviously found that a layer of material, namely polydopamine, is coated on the surface of the PSZN, which is favorable for dispersing the PSZN in the FPI, and improves the mechanical and ultraviolet shielding properties of the matrix film.

The films prepared in examples 1 to 4 and comparative example 1 are used as test objects respectively, and the tensile strength and the elongation at break of the composite film are tested to examine the influence of the addition amounts of different PSZN@polydopamine particles on the tensile strength and the elongation at break of the composite film, and the results are shown in figure 2. As can be seen from fig. 2, when the addition amount of pszn@polydopamine particles is 0%, 0.05%, and 0.1% in the interval, the tensile strength and elongation at break of the composite film are improved with the increase of the addition amount, and the maximum tensile strength and elongation at break are 118.17Mpa and 6.47% (0.1% of the addition amount). The intervals of 0.1%, 0.5% and 1% are decreased as the addition amount thereof increases the tensile strength and elongation at break of the composite film. The possible main reasons are that when the addition amount of PSZN@PDA is less than or equal to 0.1wt.%, the specific surface area of PSZN@PDA is larger at this time, and the PSZN@PDA can be uniformly dispersed in the FPI, the property of the prepared composite film is uniform, and as the content of PSZN@PDA is increased, the specific surface area becomes smaller, and as the content is increased, the PSZN@PDA is not easy to disperse in the FPI, so that the property of the subsequently prepared composite film is not uniform in overall performance, and the property of the high-content PSZN@PDA is reduced during testing. In combination, the tensile strength and elongation at break are increased for FPI incorporating an amount of PSZN@PDA, preferably in the range of 0.05 to 0.5wt.%, most preferably 0.1%.

The films prepared in examples 1 to 4 and comparative example 1 were also tested for insulating properties, and dielectric constant and dielectric loss patterns were measured as shown in fig. 3 and 4, respectively. From fig. 3 it can be seen that the dielectric constants at 1MHz, 0%, 0.05%, 0.1%, 0.5% and 1% decrease and then increase as the data from the graph become available, whereas the composite film with pszn@pda added has a lower dielectric constant than pure low dielectric FPI at a frequency of 1MHz, indicating that the addition of pszn@pda is helpful for the FPI to lower the dielectric constant, but is limited to the addition of a low concentration of pszn@pda. When the filler concentration is too high, the dielectric constant of the material is raised instead due to the aggregation of the filler or the collapse of the filler structure to form a large dispersed phase. The principle of dielectric loss is the situation where a material consumes a portion of the electrical energy under an alternating electric field, causing the dielectric to heat. It can be seen from FIG. 4 that the dielectric loss of both the pure FPI and the PSZN@PDA composite film added at 1MHz is less than 0.01, indicating excellent dielectric loss performance of both the pure FPI and the composite film itself.

In order to further evaluate the ultraviolet shielding performance of the film prepared by the embodiments of the invention, the invention designs an experiment for degrading curcumin by photocatalysis, and the ultraviolet shielding performance of the material is evaluated by monitoring the absorbance of the curcumin solution at 425 nm. Because of the property that curcumin can degrade when exposed to ultraviolet light, the degradation degree of 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 decay curve of fig. 5, it can be seen that under the unprotected condition, the curve of the curcumin solution of the blank group drops sharply and tends to 0, while when the pure FPI film is used for covering the curcumin solution, the curve drop rate is slow and tends to be gentle, and the higher ultraviolet shielding rate is still remained at the last irradiation, which proves that the pure FPI film has good ultraviolet shielding performance. And along with the addition of PSZN@PDA particles, the curve of the composite film with higher content is gradually and gently reduced, and the curve of the composite film with the PSZN@PDA content of 1% is almost free from reduced change, so that the ultraviolet shielding performance of the composite film is greatly improved after the PSZN@PDA is added.

In addition, the ability to reuse the ultraviolet shielding material is an important performance index. For this purpose, a composite film with better comprehensive performance and PSZN@polydopamine content of 0.5% and a pure FPI film are selected for repeated experimental test, and the repeated use performance of the composite film and the pure FPI film is compared, wherein the result is shown in FIG. 6. As can be seen from fig. 6, both of the films showed excellent uv shielding efficiency, and the composite film added with the pszn@polydopamine particles showed a more gradual decrease in uv shielding efficiency in the repeatability test, and the uv shielding effect was significantly better than that of the pure FPI film. After ten repeatability tests, the FPI/PSZN@polydopamine nano composite film can still keep higher ultraviolet shielding efficiency, which shows that the prepared FPI/PSZN@polydopamine nano composite film is a reusable ultraviolet shielding material with excellent performance.

The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

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

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

3. The method for preparing a fluorine-containing polyimide/pure silicalite @ polydopamine nanocomposite film according to claim 1, wherein the pH of the Tris-Hcl buffer in step 1) is 8.5.

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

5. The preparation method of the fluorine-containing polyimide/pure silicalite@polydopamine nanocomposite film according to claim 1, wherein the fluorine-containing polyimide is prepared from TFDB and 6FDA serving as raw materials in the step 2).

6. The preparation method of the fluorine-containing polyimide/pure silicalite@polydopamine nanocomposite film according to claim 1, wherein the mass of PSZN@polydopamine particles in the step 2) is 0.05-0.5% of the mass of fluorine-containing polyimide in the solution.

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

8. The method for preparing a fluorine-containing polyimide/pure silicalite@polydopamine nanocomposite film according to claim 1, wherein the drying treatment in the step 2) is that the temperature is raised to 100 ℃ and the drying is continued for 2-3 hours before the drying treatment at 80 ℃ for 30-40 hours.

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

10. Use of a fluorine-containing polyimide/pure silicalite @ polydopamine nanocomposite film according to claim 9 as uv shielding material for packaging of power transmission cables.