CN111229049B

CN111229049B - Size-controllable micro-nano pore membrane and preparation method and application thereof

Info

Publication number: CN111229049B
Application number: CN202010038134.8A
Authority: CN
Inventors: 谢彦博; 吉振铭; 张书颂
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2020-01-14
Filing date: 2020-01-14
Publication date: 2021-09-14
Anticipated expiration: 2040-01-14
Also published as: CN111229049A

Abstract

The invention discloses a size-controllable micro-nano pore membrane and a preparation method and application thereof, wherein the preparation method comprises the following steps: 1) preparing a pore structure on the polymer film; 2) carrying out heat treatment on the prepared porous polymer film, wherein the heat treatment is to put the porous polymer film into water with different temperatures for water bath heating treatment; 3) and cleaning and airing the film after the heat treatment. The method has simple process, and can prepare the micro-nano pore channel so as to solve the problems of fixed pore diameter and single shape of the micro-nano pore channel.

Description

Size-controllable micro-nano pore membrane and preparation method and application thereof

Technical Field

The invention belongs to the field of micro-nano processing, relates to a processing method of a pore channel, and particularly relates to a micro-nano pore channel diaphragm with controllable size and a preparation method and application thereof.

Background

Both water and common chemical agents contain more or less invisible solid particles, which often pose a hazard to industrial production and human health. At present, the solid particles are usually removed by using a microporous membrane filtration technology. However, such a microporous membrane is not a nuclear pore membrane having a single pore size.

The nuclear pore membrane is a microporous membrane obtained by irradiating a high molecular material film by using heavy ion beams or reactor fission fragments and then etching by using a proper chemical reagent, wherein the pore density and the pore diameter of the nuclear pore membrane are respectively controlled by irradiation conditions and etching conditions; the nuclear pore membrane has uniform aperture and regular shape, is an extremely ideal precise filter material, and is widely applied in many fields due to the excellent filtering performance; the aperture and the shape of the nuclear pore membrane are realized by controlling etching conditions, but the method still has some defects, such as inaccurate etching condition control and single shape.

The filtering membrane is a thin membrane which can intercept impurities in water without chemical change and filter the water by membrane pores, the filtering membrane is classified by the size of intercepting raw water particles, and the membrane pores are divided into a micro-filtering membrane, an ultra-filtering membrane, a nanofiltration membrane and a reverse osmosis membrane from coarse to fine. Wherein the micro-filtration membrane is mainly used for removing ultra-fine particles larger than about 0.05um in the solution, and the ultra-filtration membrane technology is widely applied to removing particles, including removing bacteria, viruses and other foreign matters.

In the construction of lithium batteries, the separator is one of the key internal components. The performance of the separator determines the interfacial structure, internal resistance, etc. of the battery. The main function of the separator is to separate the positive electrode and the negative electrode of the battery and prevent the short circuit caused by the contact of the two electrodes, for the lithium battery series, because the electrolyte is an organic solvent system, most of the common separator materials at present are organic solvent-resistant separator materials, such as polyolefin porous membranes, and the common membrane cannot prevent the chemical reaction from occurring when the battery abnormally generates heat so as to cause danger, so that the separator material which can change along with the temperature rise needs to be found.

Disclosure of Invention

The invention aims to provide a micro-nano pore membrane with a controllable size, a preparation method and application thereof, and aims to solve the problems of fixed pore diameter and single shape of the micro-nano pore and obtain a porous membrane with temperature response.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a size-controllable micro-nano pore membrane comprises the following steps:

1) preparing a pore structure on the heat-shrinkable polymer film according to the required pore size;

2) sequentially immersing the prepared polymer film with the porous structure into a temperature environment capable of enabling the film to generate thermal deformation for heat treatment, wherein the thermal deformation temperature is determined according to the required aperture size; the polymer film is enabled to shrink and deform under the action of the ambient temperature environment, and the upper pore structure of the polymer film shrinks and deforms together to form the micro-nano pore channel with controllable shape.

As a further improvement of the invention, the heat treatment comprises heating the polymer film by a water bath, an oil bath or other methods for raising the ambient temperature.

The shape-controllable micro-nano pore channel which is further improved in the invention refers to the following steps:

the area of the pore channel shape formed by the shrinkage of the pore structure under the action of continuous temperature rise is continuously reduced.

The polymer film is a polyester PET film, a polycarbonate PC film, a polyimide PI film, a polyolefin POF film or a polyurethane TPU film which is further improved.

The pore structure is further improved by the invention and is prepared by a micro-nano processing method.

The micro-nano processing method serving as a further improvement of the invention comprises a track etching method, a laser drilling method, a focused ion beam engraving method, a focused electron beam engraving method or an electric shock penetrating method.

A size-controllable micro-nano pore membrane adopts a heat-shrinkable polymer film, a pore structure is processed on the polymer film according to the required pore size, and the shape of the pore structure changes along with the change of temperature.

As a further improvement of the present invention, the current through the two ends of the pore channel is reduced during the temperature rise and shrinkage process, and the electrical conductance is reduced.

As a further improvement of the invention, the membrane filters fluids with different temperatures, and the filtering time is controlled, so that the solution at a specific temperature is obtained.

Compared with the prior art, the method has the following advantages:

compared with the existing nanometer pore channels which are made of materials which are stable under the condition of temperature change, namely the size and the shape of the nanometer pore channels are not changed along with the change of the temperature, the invention utilizes the nuclear track technology to generate the micro-nanometer pore channels on the polymer film with the heat shrinkage performance, and the film has the characteristic of being capable of responding to the ambient temperature to realize shrinkage above the glass transition temperature, so that the size and the shape of the prepared nanometer pore channels can be controlled, and finally, the preparation of the micro-nanometer pore channel membrane with the controllable size is realized. By utilizing condition control, the pore canal can be prepared into a slit shape and an eye-like shape, and the structure has stronger Raman signal enhancement through detection, and has application prospect in the fields of monomolecular recognition and the like.

By utilizing the property of thermal shrinkage, the temperature response type filtering membrane can be prepared, and the safety protection is realized when the battery is overheated

And water purification, etc., which is a characteristic that the traditional pore membrane does not have. The results show that above 99.95% of the ion current and above 99.69% of the flow can be blocked when the ambient temperature rises to 90 degrees celsius.

Drawings

FIG. 1 is a schematic diagram of heat treatment in an embodiment;

FIG. 2 is a schematic view of a heat shrink film variation process;

FIG. 3 is a schematic view of the hole before and after heat shrinkage, in which the length of a white solid line is 1 um;

figure 4 is a current-voltage curve for a pore channel having a pore size of 1.5um after shrinkage at 60 c and 90 c.

Wherein, 1 is a film with holes; 2 is deionized water; 3 is a beaker; 4, a clamp (used for fixing the film); 5 is dimethyl silicone oil; 6 is an oil bath pan.

Detailed Description

The invention provides a preparation method of a size-controllable micro-nano pore membrane, which comprises the following steps:

1) preparing a hole: preparing holes with specific aperture size on the polymer film; the size of the pores can be all pores with the pore size of 1 nm-100 mu m;

2) and (3) heat treatment: heating the polymer film with the pore structure;

the specific steps of the heating treatment are to sequentially immerse the polymer film in a temperature environment (e.g. 50 ℃ to 100 ℃ water) capable of causing thermal deformation of the film, so as to ensure uniform temperature of the heating environment, and the specific heating schematic diagram is shown in fig. 1.

During the process of shrinking the film by heat treatment, the shapes of the pore channels formed by shrinking the micro-nano pore channels with different pore diameters on the film at different temperatures are different, and if the pore channel with the pore diameter smaller than 500nm shrinks, the pore shape is still round; the pore shape of the pore canal with the pore size between 500nm and 1.5um is changed into eye shape after the pore canal shrinks; the pore shape of the pore canal with the pore diameter larger than 1.5um is changed into an ellipse after the pore canal shrinks. The method can realize the controllability of the shapes of the micro-nano channels with different pore sizes. The specific deformation diagram is shown in fig. 3.

The initial pore size of the embodiments of the present invention is all pore channels larger than 1.5 um.

3) Cleaning and airing: and cleaning and airing the film after the heat treatment.

The method comprises the following specific steps:

1) preparing a porous film with a proper aperture size by utilizing various micro-nano processing methods;

2) immersing the prepared porous film into an environment (such as water at 50-100 ℃) capable of generating thermal deformation for heating, and stopping heating under a required condition after the porous film generates deformation;

3) taking out the film after the heat treatment, and cleaning the film by using deionized water;

4) and (3) placing the cleaned film in a dry and ventilated environment for airing.

The film is a polyester PET film, a polycarbonate PC film, a polyimide PI film, a polyolefin POF film, a polyurethane TPU film or other heat-shrinkable films.

The preparation method of the porous film is a track etching method, a laser punching method, a focused ion beam engraving method, a focused electron beam engraving method, an electric shock penetrating method and the like.

The application fields of the porous film are the fields of fluid filtration, temperature detection, chemical analysis, battery diaphragm and the like.

Example 1

1. Irradiation of radiation

And irradiating the polymer film by using a heavy ion accelerator to form a potential track.

2. Chemical etching

And (3) soaking the irradiated polymer film in a sodium hydroxide solution to form pores with the required pore size.

3. Cleaning and drying

Firstly, cleaning a film with holes after chemical etching by using a buffer solution to ensure that no etching solution is left on the surface of the film, then cleaning the film by using ultrapure water, and finally placing the cleaned film in a dry and ventilated environment for drying.

4. Thermal treatment

As shown in fig. 1, the PET film with the porous structure on the surface is sequentially placed in water bath heating treatment at different temperatures.

5. Cleaning and drying

And taking out the film after the heat treatment, cleaning, and then placing in a dry and ventilated environment for airing.

Example 2

PET film with holes is used as a filter element of a filter device, and the hole diameter is changed by changing the shrinkage temperature.

The specific embodiment is as follows:

1. the pore size required by a filter element in the filter device is determined;

2. determining the original pore diameter and the shrinkage temperature according to the required pore diameter;

3. a membrane with pores of the desired pore size was prepared according to the method described in example 1.

Example 3

It is another object of the present invention to provide a battery separator for preventing safety from occurring due to overheating of a battery.

As shown in fig. 4, the current through the ends of the cell during the contraction of the cell is significantly reduced and the conductance is reduced. The original PET film with holes can be used as a battery separator.

The specific embodiment is as follows:

1. adding a PET film with a specific aperture size between a positive tank and a negative tank of the electrolytic cell;

2. the abnormal temperature rise of the battery occurs in the process of electrochemical reaction;

3. the film shrinks, the aperture becomes small, the current is cut off, and the electrochemical reaction stops.

The original film with holes provided by the invention can be used as a battery diaphragm and placed between a positive electrolytic cell and a negative electrolytic cell, when the battery works abnormally, the film can shrink to cause the holes on the film to change, so that the current is blocked, and the battery is protected.

It is an object of the present invention to provide a temperature responder.

The preparation method provided by the invention can intercept high-temperature fluid, filter the fluid at different temperatures by using the film, and control the filtering time to obtain the solution at a specific temperature.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent changes and modifications made within the scope of the present invention should be considered as the technical scope of the present invention.

The embodiments of the present invention are merely exemplary and not intended to limit the scope of the patent, and those skilled in the art may make modifications to the embodiments without departing from the spirit and scope of the patent.

Claims

1. A preparation method of a size-controllable micro-nano pore membrane is characterized by comprising the following steps:

2) sequentially immersing the prepared polymer film with the porous structure into an environment with the temperature of 50-100 ℃ which can lead the film to generate thermal deformation for heat treatment, wherein the temperature of the thermal deformation is determined according to the required aperture size; the polymer film is caused to shrink and deform under the action of the ambient temperature environment, and the upper pore structure of the polymer film shrinks and deforms together to form a shape-controllable micro-nano pore channel;

the shape-controllable micro-nano pore channel refers to:

the area of the pore channel shape formed by the shrinkage of the pore structure under the action of continuous temperature rise is continuously reduced;

the polymer film is a polyester PET film, a polycarbonate PC film, a polyimide PI film, a polyolefin POF film or a polyurethane TPU film;

the heat treatment comprises heating the polymer film by a water bath, an oil bath or other methods for increasing the ambient temperature;

the pore structure is prepared by a micro-nano processing method;

the micro-nano processing method comprises a track etching method, a laser drilling method, a focused ion beam engraving method, a focused electron beam engraving method or an electric shock penetrating method.

2. A micro-nano pore membrane with controllable size, which is prepared by the method of claim 1.

3. The use of the size-controllable micro-nano pore membrane as claimed in claim 2 as a battery membrane, wherein the electrical conductance is reduced by reducing the current at the two ends of the pore during the temperature-rising shrinkage process of the pore structure.

4. The application of the micro-nano pore membrane with the controllable size as claimed in claim 2 as a temperature responder, wherein the membrane filters fluids with different temperatures, and the filtering time is controlled to obtain a solution at a specific temperature.