CN110589758B

CN110589758B - Large-area preparation and flexible transfer method of metal nanoparticle array

Info

Publication number: CN110589758B
Application number: CN201910827686.4A
Authority: CN
Inventors: 方靖淮; 吴静
Original assignee: Nantong University
Current assignee: Nantong University
Priority date: 2019-09-03
Filing date: 2019-09-03
Publication date: 2021-09-24
Anticipated expiration: 2039-09-03
Also published as: CN110589758A

Abstract

The invention belongs to the technical field of nano materials, and discloses a large-area preparation and flexible transfer method of a metal nano particle array, which comprises the following steps: evaporating a layer of metal film on the surface of a pore channel of a single-pass anodic alumina template, wherein the metal film forms metal nano particles in the pore channel through a high-temperature limited spheroidization process; and filling the pore channel with the polymer by using a hot melting or casting mode, wrapping the metal nanoparticles at the bottom of the pore channel, and finally removing the alumina template to obtain the metal nanoparticle array transferred to the surface of the flexible polymer. Compared with the prior art, the method realizes the one-step method for preparing the large-area metal nanoparticle array, obviously reduces the production cost of the large-area metal nanoparticle array, has simple and convenient operation and high transfer efficiency, and is suitable for batch production.

Description

Large-area preparation and flexible transfer method of metal nanoparticle array

Technical Field

The invention relates to the technical field of nano materials, in particular to a large-area preparation and flexible transfer method of a metal nano particle array.

Background

In the field of nanotechnology, nanoparticles are widely concerned due to their unique electrical and optical properties, and in particular, large-area uniform and ordered nanoparticle array structures have important research significance in plasma research, biosensing, and electrochemical energy storage. For example, in the aspect of surface enhanced raman scattering research, the sensitive, efficient and well-reproducible spectral signals strongly depend on the uniformity of the substrate structure, and the flexibility of the substrate is also an important factor for realizing the detection of objects with complex surface topography.

In order to prepare a large-area uniform and ordered nanoparticle array structure, currently, the existing nano-fabrication technologies mainly include photolithography technologies, such as electron lithography, focused ion beam lithography, interference lithography, and the like. The method can accurately control the size of the nano particles, the area and the shape of the array and the like, but the preparation process is complex, the cost is high, and the method has no universal applicability. In addition, due to the limitation of the limit of photolithography, the technology has difficulty in realizing the nanoparticle gap below 1nm, thereby limiting the further development thereof. In addition to photolithography, the preparation of nanoparticle arrays using a templating method has been receiving attention in recent years, wherein studies based on an anodized aluminum template have been relatively extensive. Usually, an alumina template is processed into a double-pass structure, and then metal nanoparticles are deposited into holes by evaporation or sputtering, so that the metal nanoparticles are directly attached to a solid substrate. And removing the bi-pass template to finally obtain the nanoparticle array. Compared with the photoetching technology, the template method reduces the preparation cost, but the preparation and removal processes of the bi-pass template are easy to generate defects, so that the area of the nanoparticle array is smaller, and the yield needs to be improved.

In addition, the nanoparticle array prepared by the above scheme cannot be transferred for the second time, which limits the practical application of the array structure to a certain extent. For example, in the research of surface enhanced raman scattering substrates and biosensors, the substrates are generally required to have the characteristics of flexibility and bendability, so as to be beneficial to adhering to the surfaces of objects with different morphologies.

Disclosure of Invention

In view of the above, the present invention is directed to a method for large-area preparation and flexible transfer of a metal nanoparticle array, wherein the method provided by the present invention has a simple operation process, and the prepared metal nanoparticle array has a flexible substrate, is easy to transfer for the second time, and has a wide application range.

The invention provides a large-area preparation and flexible transfer method of a metal nanoparticle array, which comprises the following steps:

step 1, evaporating a layer of metal film on the surface of a pore channel of a single-pass anodic alumina template;

step 2, forming metal nano particles at the bottom of the pore channel by the metal film through a high-temperature limited spheroidization process;

step 3, filling the pore channels with the polymer and wrapping the metal nanoparticles in the pore channels treated in the step 2 in a hot melting or casting mode;

and 4, removing the single-pass anodic alumina template to obtain the metal nanoparticle array transferred to the surface of the polymer.

Preferably, the pore diameter of the pore canal is 90 nm-400 nm; the depth of the pore channel is 50 nm-300 nm.

Preferably, the metal film is a gold film or a silver film; the thickness of the metal film is 5 nm-40 nm.

Preferably, the evaporation manner in step 1 is electron beam evaporation thermal deposition or magnetron sputtering deposition.

Preferably, the temperature of the high-temperature limited-area spheroidization process in the step 2 is 250-500 ℃ and the time is 1-3 h.

Preferably, the polymer is one of polystyrene, polycarbonate and polydimethylsiloxane.

Preferably, the removing the single-pass anodized aluminum template in the step 4 includes the following steps: and removing the aluminum layer on the back of the single-pass anodized aluminum template by using a copper chloride solution, and removing the barrier layer and the oxide layer of the single-pass anodized aluminum template by using a mixed solution of phosphoric acid and chromic acid.

Preferably, the copper chloride solution is a saturated solution; the concentration of phosphoric acid in the mixed solution of phosphoric acid and chromic acid is 5wt%, and the concentration of chromic acid is 1.8 wt%.

Compared with the prior art, the invention has the following advantages and effects:

(1) the invention can realize the one-step method for preparing the large-area metal nanoparticle array. The limited-area spheroidizing process enables the metal deposited in the holes of the template to be spheroidized into metal nanoparticles in situ at one time, and the nanoparticle array can be obtained without processing the template into a bi-pass structure. The particle size can be adjusted by deposition thickness and template size, and the array area depends only on the template size, thus can be made to 2cm above (i.e. commercial size).

(2) According to the invention, the polymer is filled in the pore canal and wraps the metal nano-particles in a hot melting or casting mode, the aluminum layer, the barrier layer and the oxide layer of the single-pass anodic alumina template are removed through solution soaking treatment, the transfer of the metal nano-particle array based on the flexible substrate from the template is realized, the operation is simple, the flexibility is high, the cost is low, the defect of the nano-particle array is avoided, the universality is realized, and the method is suitable for wide industrial application.

Drawings

Fig. 1 is a schematic diagram of a large-area preparation and flexible transfer method of a metal nanoparticle array according to the present invention.

FIG. 2 shows the characterization results of scanning electron microscope before and after transferring the gold nanoparticle array prepared in example 1 of the present invention.

FIG. 3 shows the characterization results of scanning electron microscope before and after transferring the gold nanoparticle array prepared in example 2 of the present invention.

Fig. 4 is a scanning electron microscope characterization result before and after the silver nanoparticle array prepared in example 3 of the present invention is transferred.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the present invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the present invention and is not intended to limit the scope of the claims which follow.

As shown in fig. 1, the present invention provides a method for preparing a metal nanoparticle array in a large area and flexibly transferring the metal nanoparticle array, comprising the following steps:

Specifically, the invention firstly evaporates and plates a layer of metal film on the surface of the pore channel of the single-pass anodic alumina template. In the invention, the aperture of the pore canal of the single-pass anodic alumina template is preferably 90 nm-400 nm; the depth of the pore channel is 50 nm-300 nm. The metal film is preferably a gold film or a silver film; the thickness of the metal film is preferably 5nm to 40 nm. The evaporation method is preferably electron beam evaporation thermal deposition or magnetron sputtering deposition.

After the surface of the pore canal of the one-way anodic alumina template is evaporated with a metal film, high-temperature limited spheroidization is carried out to form metal nano particles at the bottom of the pore canal. In the invention, the temperature in the high-temperature limited spheroidizing process is preferably 250-500 ℃, and the treatment time is preferably 1-3 h. The spheroidizing temperature and time can be adjusted according to the type and thickness of the metal film. Under the temperature and time conditions provided by the invention, the finally spheroidized metal nanoparticles have regular shapes and high surface smoothness.

After the metal nano-particles are formed at the bottom of the pore channel, the pore channel is filled with the polymer and the metal nano-particles are wrapped by the polymer in a hot melting or casting mode. In the present invention, one of polystyrene, polydimethylsiloxane and polycarbonate is preferably used as the polymer. The hot melting mode is that the polymer is placed on a heating table at 300 ℃ for hot melting, the side, with the holes, of the template is contacted with hot-melted polycarbonate, and after the polycarbonate is filled in the hole channels, the heating is stopped, and the template is naturally cooled to room temperature. The casting method is that the polymer stock solution is cast in the pore canal of the template and is placed in a blast drying oven at the temperature of 60-90 ℃ for curing, and the curing time is 2-4 h.

And (3) filling the pore channels with the polymer and wrapping the metal nanoparticles, and removing the single-pass anodic alumina template to obtain the metal nanoparticle array based on the flexible substrate.

In the invention, the following method is preferably adopted for removing the single-pass anodized aluminum template: and removing the aluminum layer on the back of the single-pass anodized aluminum template by using a copper chloride solution, and removing the barrier layer and the oxide layer of the single-pass anodized aluminum template by using a mixed solution of phosphoric acid and chromic acid. In the invention, the copper chloride solution is preferably a saturated solution; the concentration of phosphoric acid in the mixed solution of phosphoric acid and chromic acid is preferably 5wt%, and the concentration of chromic acid is preferably 1.8 wt%.

For further understanding of the present invention, the method provided by the present invention is described in detail below with reference to examples, and the scope of the present invention is not limited by the following examples.

Example 1

In this example, a single-pass anodized aluminum template with a pore diameter of 300nm and a pore depth of 300nm was selected as an initial template for preparing a nanoparticle array, the type of the metal film was a gold film, the deposition thickness of the gold film was 15nm, the spheroidization temperature was 450 ℃, the spheroidization time was 2 hours, and the gold nanoparticle array was transferred by casting polystyrene.

The method comprises the following specific steps:

firstly, a layer of gold film with the thickness of 15nm is deposited on the surface of a hole of a single-pass anodic alumina template with the aperture of 300nm and the hole depth of 300nm, then the template on which the gold film is deposited is placed in a high-temperature tube furnace, and is spheroidized for 2 hours at the temperature of 450 ℃, so that an array structure with one gold nanoparticle at the bottom of each hole is obtained. The results of the experiment are shown in FIGS. 2(a) and (b). Fig. 2(a) is a low-power scanning electron microscope characterization result before the gold nanoparticle array is transferred, and fig. 2(b) is a high-power scanning electron microscope characterization result before the gold nanoparticle array is transferred. And then, casting the polystyrene solution into the template, and curing the polystyrene solution by using a 90 ℃ blast drying oven after the pore channels are filled with the polystyrene solution for 2 hours. The polystyrene used in the present example has a molecular weight of 300000, the solvent is toluene, and the mass fraction is 2% to 5%. And finally, removing the template to obtain the gold nanoparticle array structure transferred to the polystyrene film. The results of the experiment are shown in FIGS. 2(c) and (d). Fig. 2(c) is a low-power scanning electron microscope characterization result after the gold nanoparticle array is transferred, and fig. 2(d) is a high-power scanning electron microscope characterization result after the gold nanoparticle array is transferred.

The template removing process comprises the following steps: removing an aluminum layer on the back of the template by using a saturated copper chloride solution, and removing a template barrier layer and an oxide layer by using a mixed solution of phosphoric acid and chromic acid; wherein the concentration of phosphoric acid is 5wt%, the concentration of chromic acid solution is 1.8wt%, and the used solvent is aqueous solution.

Example 2

The difference between the embodiment 2 and the embodiment 1 is that the aperture of the template is 100nm, the aperture depth is 100nm, the gold film deposition thickness is 7nm, the spheroidization temperature is 400 ℃, and the gold nanoparticle array is transferred by adopting a hot-melt polycarbonate mode.

The method comprises the following specific steps:

firstly, a layer of gold film with the thickness of 7nm is deposited on the surface of a template hole with the aperture of 100nm and the hole depth of 100nm, then the template on which the gold film is deposited is placed in a high-temperature tube furnace, and spheroidization is carried out for 2h at the temperature of 400 ℃, so as to obtain an array structure with one gold nanoparticle at the bottom of each hole. The experimental results are shown in fig. 3(a), and fig. 3(a) is the scanning electron microscope characterization results before the gold nanoparticle array is transferred. And then, placing the polycarbonate particles on a heating table at 300 ℃ for hot melting, contacting the side, with the holes, of the template with the hot-melted polycarbonate, stopping heating after the hole channels are filled with the polycarbonate, and naturally cooling to room temperature. The polycarbonate used in this example had a molecular weight of 30000 and was a transparent plastic pellet. And finally, removing the template to obtain the gold nanoparticle array structure transferred to the polycarbonate film. The results of the experiment are shown in FIG. 3 (b). Fig. 3(b) is a scanning electron microscope characterization result after the gold nanoparticle array is transferred. The template removing process comprises the following steps: removing an aluminum layer on the back of the template by using a saturated copper chloride solution, and removing a template barrier layer and an oxide layer by using a mixed solution of phosphoric acid and chromic acid; wherein the concentration of phosphoric acid is 5wt%, the concentration of chromic acid solution is 1.8wt%, and the used solvent is aqueous solution.

Example 3

The difference between this example 3 and example 1 is that the template pore diameter is 90nm, the pore depth is 50nm, the metal species is silver, the silver film deposition thickness is 13nm, the spheroidization temperature is 200 ℃, and the silver nanoparticle array is transferred by casting polydimethylsiloxane.

The method comprises the following specific steps:

firstly, depositing a layer of silver film with the thickness of 13nm on the surface of a template hole with the aperture of 90nm and the hole depth of 50nm, then placing the template on which the silver film is deposited in a high-temperature tube furnace, and spheroidizing for 2h at the temperature of 200 ℃ to obtain an array structure with one silver nanoparticle at the bottom of each hole. The experimental results are shown in fig. 4(a), and fig. 4(a) is a scanning electron microscope characterization result before the silver nanoparticle array is transferred. And then, casting the polydimethylsiloxane stock solution into the template, and curing the polydimethylsiloxane by using a 90-DEG C forced air drying oven after the pore channels are filled with the polydimethylsiloxane stock solution for 2 hours. The polydimethylsiloxane stock solution used in this example was prepared by mixing a monomer and a curing agent at a mass ratio of 10: 1. And finally, removing the template to obtain the silver nanoparticle array structure transferred to the polydimethylsiloxane film. The experimental results are shown in fig. 4(b), and fig. 4(b) is a scanning electron microscope characterization result after the silver nanoparticle array is transferred. The template removing process comprises the following steps: removing an aluminum layer on the back of the template by using a saturated copper chloride solution, and removing a template barrier layer and an oxide layer by using a mixed solution of phosphoric acid and chromic acid; wherein the concentration of phosphoric acid is 5wt%, the concentration of chromic acid solution is 1.8wt%, and the used solvent is aqueous solution.

While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A large-area preparation and flexible transfer method of a metal nanoparticle array is characterized by comprising the following steps:

step 3, filling the pore channels with polycarbonate and wrapping metal nanoparticles in the pore channels treated in the step 2 in a hot melting mode;

step 4, removing the single-pass anodic alumina template to obtain a metal nanoparticle array transferred to the surface of the polycarbonate;

the hot melting mode is as follows: placing the polycarbonate on a heating table at 300 ℃ for hot melting, contacting the side with the hole of the template with the hot-melted polycarbonate, stopping heating after the hole is filled with the polycarbonate, and naturally cooling to room temperature.

2. The large-area preparation and flexible transfer method of a metal nanoparticle array according to claim 1, wherein the pore diameter of the pore channel is 90nm to 400 nm; the depth of the pore channel is 50nm to 300 nm.

3. The method for large area fabrication and flexible transfer of metal nanoparticle arrays according to claim 1, wherein the metal film is a gold film or a silver film; the thickness of the metal film is 5 nm-40 nm.

4. The method as claimed in claim 1, wherein the evaporation in step 1 is electron beam evaporation thermal deposition.

5. The method for large-area preparation and flexible transfer of metal nanoparticle arrays according to claim 1, wherein the temperature of the high-temperature limited-area spheroidization process in the step 2 is 250 ℃ to 500 ℃ and the time is 1h to 3 h.

6. The method of claim 1, wherein the removing the single-pass anodized aluminum template in step 4 comprises the following steps: and removing the aluminum layer on the back of the single-pass anodized aluminum template by using a copper chloride solution, and removing the barrier layer and the oxide layer of the single-pass anodized aluminum template by using a mixed solution of phosphoric acid and chromic acid.

7. The method for large area fabrication and flexible transfer of metal nanoparticle arrays according to claim 6, wherein the copper chloride solution is a saturated solution; the concentration of phosphoric acid in the mixed solution of phosphoric acid and chromic acid is 5wt%, and the concentration of chromic acid is 1.8 wt%.