阅读说明：本技术 一种基于木切片的无孔tem载网支持膜及其制备方法和应用 (Non-porous TEM grid-supported supporting film based on wood slices and preparation method and application thereof ) 是由 刘贡钢 徐东年 胡进波 苌姗姗 李贤军 于 2020-12-14 设计创作，主要内容包括：本发明公开了一种基于木切片的无孔TEM载网支持膜,包括木切片和覆盖于木切片表面的一层或多层石墨烯或石墨烯的衍生物,其中木切片经过碱溶液处理。还公开了一种基于木切片的无孔TEM载网支持膜的制备方法和应用,该无孔TEM载网支持膜原料来源广、制备工艺简单、绿色环保,且能够替代现有的载网和支持膜的组合,大大降低了成本,简化了工艺,适用于大规模生产,同时该无孔TEM载网支持膜能够准确、清晰表征样品的形貌和结构,所测得数据具有很好的可靠性,且对苛刻条件的耐受性更强,可以广泛应用于透射电镜测试领域。(The invention discloses a pore-free TEM grid-supported supporting film based on a wood slice, which comprises the wood slice and one or more layers of graphene or graphene derivatives covering the surface of the wood slice, wherein the wood slice is treated by an alkali solution. The nonporous TEM grid-supported membrane has wide raw material source, simple preparation process, environmental protection, can replace the combination of the existing grid and the support membrane, greatly reduces the cost, simplifies the process, is suitable for large-scale production, can accurately and clearly represent the appearance and the structure of a sample, has good reliability of measured data, has stronger tolerance to harsh conditions, and can be widely applied to the field of transmission electron microscope testing.)

1. A nonporous TEM grid-carrying support film based on wood slices, which is characterized by comprising the wood slices and one or more layers of graphene or graphene derivatives covering the surfaces of the wood slices, wherein the wood slices are treated by an alkaline solution.

2. A wood-slice-based non-porous TEM grid support film according to claim 1, wherein the wood slices have a thickness of 100nm to 1000 μm;

the wood slices are made of coniferous wood or broadleaf wood;

the wood chip is obtained by slicing the wood chip along the direction perpendicular to the growth direction of the wood.

3. A wood-section-based non-porous TEM carrier support film according to claim 1 or 2, wherein the derivative of graphene is graphene oxide.

4. A preparation method of a nonporous TEM grid-supported supporting film based on a wood slice is characterized by comprising the following steps:

(1) softening the wood;

(2) slicing the softened wood;

(3) soaking the obtained wood slices in an alkali solution, and then washing and drying;

(4) cutting the dried wood slices into the size of a TEM grid-supported film;

(5) and forming one or more layers of graphene or graphene derivatives on the surface of the wood slice.

5. The method of making a wood-section-based nonporous TEM grid-supporting membrane as in claim 4, wherein step (5) comprises: preparing a graphene or graphene derivative solution, then dropwise adding the prepared solution onto the wood slices, and drying, or placing the wood slices on the graphene or graphene derivative for dipping or repeatedly lifting and then taking out for drying, or firstly preparing a graphene or graphene derivative film, then transferring the film to the surface of the wood slices, and drying to obtain the nonporous TEM grid-supported support film.

6. The method for preparing a non-porous wood-section-based TEM grid-supported membrane according to claim 5, wherein the concentration of the graphene or graphene derivative solution is 0.01-10 mg/ml.

7. The method for preparing a non-porous TEM grid-supporting film based on wood slices as claimed in any one of claims 4 to 6, wherein in step (1), the wood is softened by soaking in hot water;

in the step (2), slicing is performed along a direction perpendicular to the growth direction of the wood.

8. The method for preparing a non-porous TEM grid-supporting film based on wood slices as in any one of claims 4-6, wherein the graphene derivative is graphene oxide.

9. The method for preparing a non-porous TEM grid-supporting membrane based on wood slices as claimed in any one of claims 4 to 6, wherein in step (3), the alkali solution is a solution of sodium hydroxide, sodium thiosulfate, ammonia water or potassium hydroxide; the concentration of the alkali solution is 0.1-10 mol/L.

10. Use of a wood-section-based non-porous TEM grid-supporting film according to any one of claims 1 to 3 or a wood-section-based non-porous TEM grid-supporting film prepared by the preparation method according to any one of claims 4 to 9 in transmission electron microscopy tests.

Technical Field

The invention relates to a pore-free TEM grid-supported supporting film based on a wood slice, a preparation method and application thereof, and the pore-free TEM grid-supported supporting film can be applied to transmission electron microscope tests.

Background

In the transmission electron microscope technology, in order to more clearly and easily observe the structure and the morphology of a sample under a nanometer small scale and avoid the sample from falling, a carbon film is often required to cover the surface of a carrying net, and a nonporous supporting film material is obtained for TEM observation. In the preparation process of the prior commercialized nonporous support film for the transmission electron microscope, a metal material with a grid pore structure is selected as a support net, and then a layer of thin support film is covered on the surface of a metal material bare net through technologies such as precision carbon plating and the like to obtain the nonporous support film for the support net. The commonly used nonporous transmission electron microscope carrier net supporting film mainly comprises film materials such as a carbon supporting film, a pure carbon supporting film, an ultrathin carbon supporting film and the like, but because the coating technology is complex in process and difficult to accurately control the coating thickness, the cost of the nonporous carrier net supporting film is greatly increased, and the consumable material price of the transmission electron microscope carrier net supporting film with the diameter of about 3mm is higher.

The graphene or the derivative thereof is considered to be an ideal support film substitute material due to the advantages of good conductivity, high temperature resistance, corrosion resistance, electron beam bombardment resistance, low contrast and the like, and the characteristics of easy film formation and simple film coating operation. However, since the surface of the carrier net is usually hydrophobic and inert, it is not favorable for spreading of graphene and fixing of the film, and thus it is difficult to form a firm graphene-supported film. And the hydrophobic property of the surface of the bare net and the net-carrying supporting film is not beneficial to the adsorption of hydrophilic samples, and many samples are hydrophilic when observed by a transmission electron microscope, so that the oxygen-containing plasma technology is required to carry out hydrophilic treatment on the bare net and the net-carrying supporting film, and the test cost of the transmission electron microscope is undoubtedly further increased. On the other hand, the method is influenced by the metal material of the net of the bare net, and is difficult to be used under some harsh conditions, such as acidity and the like, and the skeleton of the net-carrying grid hole is easy to be corroded and damaged to influence the high-quality observation of the sample. Meanwhile, the consumption of the consumable materials of the supporting film of the grid of the transmission electron microscope is huge, and the consumable materials can not be recycled generally, so that resource waste and environmental pollution can be caused. Therefore, a novel, inexpensive, commercially useful, nonporous TEM support membrane is in need of development.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a pore-free TEM grid-supporting membrane based on wood slices, which has the advantages of low cost, simple preparation process, environmental protection and the like, the nonporous TEM grid-supported membrane can replace the combination of the prior grid and supported membrane, avoids a series of defects of complex process, high cost and the like in the prior art for independently preparing the grid and the supported membrane, has excellent hydrophilicity, has stronger tolerance to harsh conditions, simultaneously utilizes the characteristics of active functional groups such as rich hydroxyl and the like of the wood, the graphene or the derivatives thereof can be firmly covered on the wood slice carrying net through the interaction of hydrogen bonds and the like to form a supporting film, the appearance and the structure of the sample can be accurately and clearly represented, and the measured data has good reliability and can be widely applied to the field of transmission electron microscope testing.

In order to solve the technical problems, the invention adopts the following technical scheme.

The invention provides a pore-free TEM grid-supported supporting film based on a wood slice, which comprises the wood slice and one or more layers of graphene or graphene derivatives covered on the surface of the wood slice, wherein the wood slice is treated by an alkaline solution. In the scheme, the wood slices are obtained by slicing wood. In this embodiment, the multilayer means two or more layers.

The nonporous TEM grid-supporting film based on wood slices, preferably, the thickness of the wood slices is 100 nm-1000 μm; preferably 200nm to 500. mu.m, more preferably 10 to 300. mu.m, and still more preferably 10 to 100. mu.m;

preferably, the wood slices are obtained by slicing along a direction perpendicular to the growth direction of the wood;

optionally, the wood slice is made of coniferous wood or broadleaf wood, for example, fir, poplar, pine, etc.

Optionally, the derivative of graphene is graphene oxide.

As a general inventive concept, the present invention also provides a method for preparing a nonporous TEM mesh-supporting membrane based on wood chips, comprising the steps of:

(1) softening the wood;

(2) slicing the softened wood;

(3) soaking the obtained wood slices in an alkali solution, and then washing and drying;

(4) cutting the dried wood slices into the size of a TEM grid-supported film;

(5) and forming one or more layers of graphene or graphene derivatives on the surface of the wood slice.

In the above preparation method of the non-porous TEM mesh-supporting membrane based on wood slices, optionally, the derivative of graphene is graphene oxide.

In the above method for preparing the nonporous TEM grid-supported membrane based on wood slices, preferably, the thickness of the wood slices is 100 nm-1000 μm; preferably 200nm to 500. mu.m, more preferably 10 to 300. mu.m, and still more preferably 10 to 100. mu.m.

In the above method for preparing a non-porous TEM mesh-supporting membrane based on wood slices, preferably, step (5) comprises: preparing a graphene or graphene derivative solution, then dropwise adding the prepared solution onto a wood slice, and drying, or placing the wood slice into graphene or graphene derivative for dipping or repeatedly lifting and then fishing out for drying, or firstly preparing a graphene or graphene derivative film, then transferring the film to the surface of the wood slice, and naturally drying to obtain the nonporous TEM grid-supported membrane. In the step, the graphene or the graphene derivative can be obtained by dropping, dipping, pulling, transferring a graphene oxide film and the like, specifically, the graphene or the graphene derivative solution is prepared, dropped on the wood slice, and naturally dried; or preparing a solution of graphene or a derivative thereof, putting the wood slices into the solution, soaking the wood slices for a period of time, taking out the wood slices, and naturally drying the wood slices; or graphene or a graphene derivative solution, placing the wood slices in the solution, repeatedly lifting the wood slices, and naturally drying the wood slices; or preparing a solution of graphene or a derivative thereof, preparing a thin graphene or a derivative film thereof, transferring the thin graphene or the derivative film to the surface of the wood slice, and naturally drying.

In the preparation method of the nonporous TEM grid-supported membrane based on the wood slices, the concentration of the graphene or graphene derivative solution is preferably 0.01-10 mg/ml.

In the above method for preparing the non-porous TEM grid-supported membrane based on wood slices, preferably, in the step (1), the wood is softened by soaking in hot water;

in the step (2), slicing is performed along a direction perpendicular to the growth direction of the wood.

In the above method for preparing a nonporous TEM mesh-supporting membrane based on wood slices, preferably, in step (3), the alkali solution is a solution of sodium hydroxide, sodium thiosulfate, ammonia water or potassium hydroxide; the concentration of the alkali solution is 0.1-10 mol/L.

As a general inventive concept, the present invention also provides an application of the non-porous TEM mesh supporting film based on wood slice or the non-porous TEM mesh supporting film based on wood slice prepared by the above preparation method in a transmission electron microscope test.

Compared with the prior art, the invention has the advantages that:

the research of the inventor finds that after the thin wood slice is treated by the alkali solution, the thin wood slice has micron-sized mesh characteristics and excellent light transmittance in the growth direction when being tested by a TEM (transmission electron microscope), has no other visible structures under an electron microscope except a grid structure, and simultaneously has good hydrophilicity due to the fact that the wood is rich in oxygen-containing functional groups such as hydroxyl groups, so that graphene or derivatives thereof such as graphene oxide can easily form a firm graphene film on the surface through hydrogen bonding. The special nonporous TEM grid-supporting film is obtained by preparing the wood slices firstly and then covering the surfaces of the wood slices with the graphene or the derivative film thereof such as the graphene oxide film, has good acid and alkali resistance, easy processing property, good hydrophilicity, good strength, low price and easy obtaining, simple preparation process, renewable green biological resources, environmental protection and no harm to the environment due to abandonment; meanwhile, the nonporous TEM grid-supported membrane is equivalent to the conventional grid and support membrane, namely when the nonporous TEM grid-supported membrane is used for observing a sample, no additional grid or support membrane and other consumables are needed, so that the problems that in the prior art, when the nonporous grid-supported membrane is used for observing, both the grid and the support membrane are needed, and both the grid and the support membrane need to be prepared, complex processes are needed, the cost is high, meanwhile, the resistance to harsh conditions is poor, for example, the support membrane is easy to damage under the condition of hydrofluoric acid, and the conventional grid and support membrane are poor in hydrophilicity are avoided. The nonporous TEM grid-supported membrane has the advantages of good acid-base stability, good hydrophilicity, low cost, simple preparation process and convenient sample preparation, can be widely used for replacing the currently used TEM grid-supported membrane, greatly reduces the test cost of a transmission electron microscope sample, and has good industrial application prospect.

Drawings

FIG. 1 is a macroscopic TEM image of the non-porous TEM grid-supporting film obtained from example 1 and used for observing the halloysite nanotubes.

FIG. 2 is a high power TEM image of the non-porous TEM grid support film obtained from example 1 using fir as an example for observing the halloysite nanotubes.

Detailed Description

The existing TEM grid and support membrane preparation process is complex, the TEM grid and support membrane can not be recycled as consumable materials, the cost and the selling price are generally higher, many samples are hydrophilic when being observed by a transmission electron microscope, and the surfaces of various directly prepared various bare grids or grid support membranes are generally hydrophobic, so that the hydrophilicity of the grid-carrying membrane is realized by adopting a plasma technology, the process is complex, and the cost is increased. And the inventor needs to prepare samples under hydrofluoric acid condition during experimental process due to the observation of the transmission electron microscope samples, and finds that the existing grid structure is damaged when the commercial TEM grid supporting film is used for preparing samples, so that the supporting film structure is turned over, and therefore, the invention is difficult to be used for sample observation.

In view of the above technical problems, the inventors found through extensive research that, after thin wood slices are treated with an alkali solution, the thin wood slices have high light transmittance and micron-sized mesh characteristics in a TEM test, and have no other visible structure under an electron microscope except for a grid structure, and the structure of the thin wood slices is basically kept intact under a hydrofluoric acid environment, and the thin wood slices have good acid and alkali resistance, good processing characteristics and good strength, and simultaneously have good hydrophilicity, and can form a stable support film on the wood slices easily due to the fact that the wood surface is rich in hydroxyl functional groups and can form a strong hydrogen bonding effect with graphene or derivatives thereof such as graphene oxide, so that a special nonporous TEM support film is formed. Based on the above, by trying to form graphene or a derivative thereof such as graphene oxide on the surface of a thin wood slice treated by an alkali solution and using the graphene or the derivative as a nonporous TEM grid-supported supporting film for sample preparation and observation, it is found that a sample can be successfully observed at both low power and high power, and experiments prove that the use of the nonporous grid-supported supporting film based on the wood slice in the observation of a transmission electron microscope sample is simple in operation, the morphology and the structure of the sample can be accurately and clearly characterized, and the measured data have good reliability.

The invention will be described in further detail below with reference to the drawings and specific examples.

Example (b):

the invention relates to a nonporous TEM grid-supported membrane based on wood slices, which is prepared by the following steps:

1. firstly, 8mm by 10mm fir wood is soaked in boiling water for 30min for softening;

2. fixing the wet wood on a slicer, and slicing the wood along the direction perpendicular to the growth direction to obtain wood slices with the thickness of 20 mu m;

3. soaking the obtained wood slices in 0.5mol/L sodium hydroxide solution for 24h to remove resin and other inclusions in the wood holes, washing and drying for later use;

4. the obtained wood slices are cut into round pieces with the size of a TEM grid supporting film and the diameter of about 3mm, 0.5mg/ml graphene oxide ethanol solution 50 mu L is dripped into the round pieces for 2 times, and the round pieces are naturally dried.

A TEM grid nonporous support membrane of the present invention for TEM testing, comprising:

preparing a sample solution to be tested for TEM:

0.5mg/ml halloysite nanotube solution: weighing 1mg halloysite nanotube solid powder, adding 2ml ethanol, and performing ultrasonic treatment for 10min to disperse uniformly to be detected.

② observation of samples

And (3) dripping 10 mu L of halloysite nanotube solution of 0.5mg/ml on the obtained TEM mesh-supported nonporous support membrane, and naturally drying at normal temperature for 30 min. Then clamping the TEM mesh-loaded nonporous supporting membrane dripped with the sample by using tweezers, placing the TEM mesh-loaded nonporous supporting membrane in a sample rod of a transmission electron microscope for fixation, and carrying out TEM test observation.

Fig. 1 is a low-power TEM image of a graphene oxide wood slice TEM grid-supported film prepared by dropping a halloysite nanotube solution, and it can be clearly seen from the low-power TEM image that the graphene oxide film covers the mesh surface of a wood slice, and halloysite nanotubes are distributed on a graphene oxide film, and although halloysite has a small amount of large aggregates, the prepared TEM grid-supported nonporous support film can still clearly observe the nanotube-like structure of halloysite under high-power TEM (as shown in fig. 2), and has high resolution.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments to equivalent variations, without departing from the scope of the invention, using the teachings disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.