CN113387317B - A non-rotating axisymmetric bowl-shaped Janus micro-nano motor and its preparation method and application - Google Patents

Abstract

The invention discloses a non-rotation axis symmetrical bowl-shaped double-sided god micro-nano motor and a preparation method and application thereof. The non-rotation axis symmetrical bowl-shaped double-sided god micro-nano motor is composed of a hollow bowl-shaped structure and double-sided gods, has only one reflection plane, and has the characteristic of non-rotation symmetry. The preparation method comprises the following steps: dispersing hollow spherical double-sided particles in liquid 1 to fill liquid 1 with particles, and drying; or the particles filled with the liquid 1 are placed in the liquid 2 again for dispersion, and the micro-nano motor is obtained through stirring or drying or the combination of stirring and drying, wherein: the liquid 1 is ethanol, water or polydimethyl diallyl ammonium chloride aqueous solution; the liquid 2 is ethanol or water, and the two are different. The obtained micro-nano motor can realize multiple mechanism driving under a microscopic scale by regulating and controlling the composition of the double-sided god, has wide application prospect in the aspects of enhancing liquid mixing and mass transfer, and has simple preparation and better universality and repeatability.

Description

A non-rotating axisymmetric bowl-shaped Janus micro-nano motor and its preparation method and application

Technical field

The invention belongs to the technical field of micro-nano motors, and specifically relates to a non-rotating axis-symmetric bowl-shaped Janus micro-nano motor and its preparation method and application.

Background technique

Micro-nano motor is an active micro-nano device that can convert other forms of energy in the environment (chemical energy, light energy, electrical energy, magnetic energy, etc.) into its own kinetic energy. It has a wide range of applications in the fields of biomedicine, environmental purification, micro-nano processing, etc. application prospects. The movement behavior of micro-nano motors is highly dependent on the construction of asymmetric fields around them, mainly due to the asymmetry of their own structures or compositions and the asymmetric reactions induced by asymmetric external fields. Therefore, micro-nanoparticles with multiple asymmetries in structure and composition (non-rotational axial symmetry) may give motors more complex motion modes and enhanced driving force, thereby being used in applications related to mixing and mass transfer in liquid environments. showed enhanced performance.

In recent years, important progress has been made in the research on regulating the motion behavior of micro-nano motors through structural design. "Journal of American Chemical Society, 2020, Issue 5, Volume 142, Page 2213" reports a Au/ZnO double hexagonal rod-shaped micron motor with different end face diameters, which uses hydrogen peroxide. As fuel, it exhibits a multi-mode motion behavior that combines translation and rotation under ultraviolet light irradiation. However, at present, this kind of material with non-rotational axial symmetry is mainly obtained by hydrothermal synthesis combined with electrochemical deposition. The preparation process is cumbersome and the yield is not high, which limits its practical application.

Contents of the invention

The purpose of the present invention is to provide a non-rotating axis-symmetric bowl-shaped Janus micro-nano motor and its preparation method and application. The micro-nano motor can realize a variety of mechanism drives at microscopic dimensions by regulating the Janus composition. Preparation method It is simple, has good universality and repeatability, and can be widely used in the preparation of non-rotational axis-symmetric bowl-shaped micro-nanostructures.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A non-rotation axially symmetric bowl-shaped Janus micro-nano motor is provided, which is composed of a hollow bowl-shaped structure and a Janus. It has one and only one reflection plane and has the characteristics of non-rotation symmetry.

According to the above solution, the non-rotating axis-symmetric bowl-shaped Janus micro-nano motor is obtained by the collapse of hollow spherical Janus particles at the interface of different material compositions.

According to the above solution, the hollow spherical Janus particles include a hollow spherical matrix and a semi-coating layer on the surface of the matrix, wherein the particle size of the hollow spherical matrix is 1-1.2 μm, and the thickness of the semi-coating layer is 15 -30nm.

According to the above solution, the hollow spherical matrix material is a polymer, and the half-coating layer is a metal or non-metal oxide.

According to the above scheme, the polymer is polystyrene, the metal is any one of Au, Ag and Pt, and the non-metal oxide is any one of SiO ₂ and TiO ₂ .

According to the above solution, the semi-coating layer is coated on the surface of the hollow spherical substrate by magnetron sputtering.

A method for preparing the above-mentioned non-rotating axisymmetric bowl-shaped Janus micro-nano motor is provided, which specifically includes the following steps:

Disperse the hollow spherical Janus particles in the liquid 1 so that the liquid 1 is filled with the hollow spherical Janus particles, and then dry the Janus particles; or place the hollow spherical Janus particles filled with the liquid 1 in the liquid Dispersed in 2, obtained by stirring or drying or a combination of stirring and drying, wherein: the liquid 1 is ethanol, water or polydimethyldiallylammonium chloride aqueous solution; the liquid 2 is ethanol or water, The liquid 1 and liquid 2 are not the same. Preferably, the stirring is magnetic stirring.

According to the above scheme, the hollow spherical Janus particles are prepared from a hollow spherical matrix by magnetron sputtering and a semi-coating sputtering layer.

Preferably, the hollow spherical matrix material is a polymer, and the sputtering layer is a metal or metal oxide; more preferably, the polymer is polystyrene (PS), and the metal is Au, Ag, or Pt. Any one of them, the non-metal oxide is any one of SiO ₂ and TiO ₂ .

Preferably, the particle size of the hollow spherical matrix is 1-1.2 μm, and the thickness of the sputtering layer is 15-30 nm.

According to the above scheme, the volume percentage concentration of the polydimethyldiallylammonium chloride (PDADMAC) aqueous solution is 0.01-0.12%.

According to the above scheme, the stirring time is 24 to 120 hours.

According to the above plan, the drying time is 24-120h and the temperature is 30-60°C.

The above-mentioned non-rotating axisymmetric bowl-shaped double-faced micro-nano motor is provided as an "artificial rotor" for accelerating liquid mixing and mass transfer.

According to the above scheme, it is applied to enhance SERS sensing.

The micro-nano motor prepared by the present invention mainly utilizes the stress concentration at the junction of different compositions of the hollow spherical Janus ions, and then generates osmotic pressure inside and outside the hollow spherical Janus particles. Under the action of the osmotic pressure, the hollow spherical Janus ions are It is prepared by collapse due to stress concentration at the junction of different compositions of divine ions. Specifically: it provides different liquid environments inside and outside the cavity of hollow spherical Janus particles, and the liquids inside and outside the cavity can dissolve with each other, and mass transfer occurs inside and outside the cavity. Since the amount of liquid in the cavity is much smaller than the amount of liquid outside the cavity, the liquid in the cavity is Solute, mass transfer produces a mass flux directed outside the cavity, which in turn generates inward osmotic pressure. Under the action of osmotic pressure, the junction between the base and the semi-coating layer of the hollow spherical Janus particles is prone to collapse due to stress concentration. The bowl-shaped non-rotating axisymmetric Janus structure is described. What is more convenient is that the evaporation of liquid in the cavity of the hollow spherical Janus particles can also generate osmotic pressure, so direct drying of the hollow spherical Janus particles filled with liquid in the cavity can also be used to prepare the non-rotational axis symmetry. Bowl-shaped Janus micro-nano motor. The special asymmetric geometric structure of the resulting micro-nano motor can induce asymmetric physical or chemical reactions on its surface. Depending on the type of reaction, different gradient fields (such as bubbles, temperature, concentration, surface tension, magnetic field, etc.) are generated to drive the motor. sports.

The beneficial effects of the present invention are:

1. The present invention provides a Janus micro-nano motor with non-rotation axis symmetry, which has a hollow bowl-shaped structure and Janus composition characteristics, has one and only one reflection plane, and has the characteristics of non-rotation axis symmetry; by The composition of the Janus that regulates micro-nano motors can be driven by a variety of mechanisms at the microscopic scale. In a liquid environment, it exhibits enhanced oscillatory multi-motion behavior that is different from traditional Janus micro-nano motors, that is, it can take into account ballistic motion. With "self-rotating" motion, it has broad application prospects in enhancing liquid mixing and mass transfer.

2. In the preparation method provided by the present invention, a liquid osmotic pressure difference is formed in the inner and outer cavities of the hollow spherical Janus particles by stirring or drying or a combination of stirring and drying, so as to control the concentration of stress in the composition of the hollow spherical Janus particles. By collapsing at one point, a micro-nano motor with a hollow bowl-shaped structure and a Janus can be prepared; the preparation method is simple, has good universality and repeatability, has high yield, and has broad application prospects.

Description of drawings

Figure 1 is a field emission scanning electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 1 of the present invention.

Figure 2 is a transmission electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 1 of the present invention.

Figure 3 is an X-ray energy spectrum diagram of the PS-Ag non-rotating axis-symmetric bowl-shaped Janus micro-nanomotor synthesized in Example 1 of the present invention, in which Figure a represents Ag and Figure b represents C.

Figure 4 is a comparison of the motion behavior of the PS-Ag non-rotating axially symmetric bowl-shaped Janus micro-nano motor synthesized in Example 1 of the present invention and the traditional PS-Ag Janus micro-nano motor, where a is the PS-Ag non-rotating axis. Symmetrical bowl-shaped Janus micro-nano motor, b is a traditional PS-Ag Janus micro-nano motor.

Figure 5 shows the SERS performance characterization of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 1 of the present invention.

Figure 6 is a field emission scanning electron microscope image of the PS-Pt non-rotating axially symmetrical bowl-shaped Janus micro-nano motor synthesized in Example 2 of the present invention.

Figure 7 is the X-ray energy spectrum of the PS-Pt non-rotating axially symmetrical bowl-shaped Janus micro-nanomotor synthesized in Example 2 of the present invention, where a is Pt and b is C.

Figure 8 is a field emission scanning electron microscope image of the PS-Au non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 3 of the present invention.

Figure 9 is a field emission scanning electron microscope image of the PS-SiO ₂ -Ag non-rotational axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 4 of the present invention.

Figure 10 is an X-ray scanning energy spectrum of the PS-SiO ₂ -Ag non-rotational axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 4 of the present invention.

Figure 11 is a field emission scanning electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 5 of the present invention.

Figure 12 is a field emission scanning electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 6 of the present invention.

Figure 13 is a field emission scanning electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 7 of the present invention.

Figure 14 is a field emission scanning electron microscope image of the PS-Pt non-rotational axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 8 of the present invention.

Figure 15 is a field emission scanning electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 9 of the present invention.

Figure 16 is a field emission scanning electron microscope image of the PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motor synthesized in Example 10 of the present invention.

Detailed ways

The following examples further illustrate the technical solutions of the present invention, but are not intended to limit the scope of the present invention.

Example 1

A non-rotating axis-symmetric double-sided micro-nano motor is provided. The specific preparation steps are:

1) First, 1 mg polystyrene (PS) hollow microspheres (diameter 1 μm) are dispersed on a glass substrate, and subjected to Ag magnetron sputtering for 60 seconds. The resulting Ag layer is half-coated on the surface of the PS hollow microspheres. The thickness of the Ag layer With a diameter of 25 nm, PS-Ag hollow spherical Janus particles were obtained.

2) Disperse the PS-Ag hollow spherical Janus particles (diameter 1 μm, Ag layer thickness 25 nm) obtained in step 1) with ethanol and centrifuge for 3 times until the supernatant is clear. After removing the supernatant, the hollow cavity is filled with ethanol. PS-Ag hollow spherical Janus particles were then dispersed into 8 mL of water, magnetically stirred for 24 hours, centrifuged, and dried at 30°C for 48 hours. The resulting product was dispersed in water and stored.

From the field emission scanning electron microscope images and transmission electron microscope images of the product of this embodiment in Figures 1 and 2, it can be seen that the obtained product has a hollow bowl-shaped structure and a Janus composition, has one and only one reflection plane, and has the characteristics of non-rotational axis symmetry.

The X-ray energy spectrum scan results in Figure 3 further illustrate the asymmetric distribution of the Ag element on the motor. The collapse of the original hollow spherical Janus particles occurs at the PS-Ag interface, proving that the prepared micro-nano motor has non-rotating properties. Axisymmetric properties.

The prepared PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nanomotor was dispersed in a H ₂ O ₂ solution with a mass fraction of 1.7% and a KCl solution with a concentration of 600 μmol/L, and was used at an intensity of 500 mW/ cm ² of UV light irradiation, as shown in Figure 4, the performance of the bowl-shaped non-rotating axially symmetric micro-nano motor (Figure 4(a)) compared with the traditional PS-Ag double-faced micro-nano motor (Figure 4(b)) Enhanced oscillatory multiple motions are produced. The specific motion characteristics are as follows: (1) translational motion accompanied by rotation in the non-acceleration phase; (2) oscillatory speed mutation; (3) speed is larger than the Janus motor speed; (4) acceleration phase The direction of movement changes and there is a speed threshold.

The prepared PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nanomotor was prepared in a H ₂ O ₂ solution with a mass fraction of 1.7%, a KCl solution with a concentration of 600 μmol/L and 1×10 ^-8 M R6G. Evenly dispersed in the mixed solution, exposed to 500 mW/cm ² ultraviolet light for 30 minutes, and the recovered and dried motor was tested for Raman spectrum. As can be seen from Figure 5, PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nanomotors (Active NAJ-SPs) have better performance than traditional PS-Ag hollow spherical Janus particles (ActivePS-Ag Janus) and inert particles (Inactive NAJ -SPs) stronger Raman signal, proving its applicability in enhancing mass transfer. The traditional PS-Ag hollow spherical Janus particles are PS-Ag hollow spherical Janus particles prepared in Example 1, with a diameter of 1 μm and an Ag layer thickness of 25 nm. The inert particles are PS-Ag non-rotating axisymmetric bowl-shaped Janus micro-nano motors without applying fuel (H ₂ O ₂ , KCl).

Under ultraviolet light, the Ag-AgCl oscillation reaction occurs on the surface of the motor. Due to the restriction of ion diffusion by the bowl-shaped structure, an enhanced self-built electric field is formed around the motor, which acts on the negatively charged motor and provides a driving force deviating from the center of mass, thereby generating Torque, resulting in enhanced oscillatory multi-movement behavior. This enhanced motion increases the contact probability between the motor and the molecules of the substance to be detected, enhances the mass transfer of the motor in the liquid, and thereby improves the detection effect of the motor as a SERS substrate. At the same time, the AgCl-Ag composite structure on _the surface of the motor provides the motor with good chemical stability in _H2O2 .

Example 2

The hollow spherical PS-Ag Janus particles in Example 1 were adjusted to PS-Pt hollow spherical Janus particles (diameter 1 μm, Pt layer thickness 25 nm), and the above steps of Example 1 were repeated to obtain a product. Field emission scanning electron microscopy and X-ray energy spectroscopy were used to characterize the structure and composition of the product, as shown in Figures 6 and 7, indicating that the obtained product is a PS-Pt non-rotating axisymmetric bowl-shaped double-faced micro-nanomotor.

Example 3

The hollow spherical PS-Ag Janus particles in Example 1 were adjusted to PS-Au hollow spherical Janus particles (diameter 1 μm, Au layer thickness 25 nm), and the above steps of Example 1 were repeated to obtain a product. The structure of the product was characterized using field emission scanning electron microscopy, as shown in Figure 8, indicating that the obtained product is a PS-Au non-rotating axisymmetric bowl-shaped double-faced micro-nano motor.

Example 4

Adjust the hollow spherical PS-Ag Janus particles in Example 1 to PS-SiO ₂ -Ag hollow spherical Janus particles (diameter 1 μm, TiO ₂ layer thickness 4 nm, Ag layer thickness 15 nm), and repeat the above Example 1 steps to obtain the product. It should be noted that the purpose of sputtering an Ag layer on top of the SiO ₂ layer here is to facilitate SEM characterization of the product later. Field emission scanning electron microscopy and X-ray energy spectroscopy were used to characterize the structure and composition of the product, as shown in Figures 9 and 10, indicating that the obtained product is a PS-SiO ₂ -Ag non-rotating axisymmetric bowl-shaped double-sided God micro-nanomotor .

Example 5

The water in Example 1 was adjusted to a volume fraction of 0.12% PDADMAC aqueous solution, and the above steps of Example 1 were repeated to obtain a product. The structure of the product was characterized using field emission scanning electron microscopy, as shown in Figure 11, indicating that the obtained product is a PS-Ag non-rotating axisymmetric bowl-shaped double-faced micro-nano motor.

Example 6

Adjust the stirring time in Example 1 to 120 hours and omit the drying step. Repeat the steps of Example 1 above to obtain the product. The structure of the product is characterized by field emission scanning electron microscopy, as shown in Figure 12, illustrating the obtained product. It is a PS-Ag non-rotating axisymmetric bowl-shaped double-sided micro-nano motor.

Example 7

The thickness of the Ag layer in Example 1 was adjusted to 17 nm, and the steps of Example 1 were repeated to obtain a product. The structure of the product was characterized using field emission scanning electron microscopy, as shown in Figure 13, indicating that the obtained product was PS-Ag non-condensate. Rotation axis symmetrical bowl-shaped Janus micro-nano motor.

Example 8

1mg PS-Pt hollow spherical Janus particles (diameter 1μm, Pt layer thickness 25nm) were centrifuged and washed 3 times with water until the supernatant was clarified, the supernatant was removed, and the remaining precipitate was ultrasonically dispersed and dropped into the petri dish, at 30 Dry in ℃ environment for 24h to obtain the product. As shown in Figure 14, the obtained product is a PS-Pt non-rotational axisymmetric bowl-shaped Janus micro-nanomotor.

Example 9

The drying time in Example 1 was adjusted to 120 h, and the above steps of Example 1 were repeated to obtain a product. As shown in Figure 15, it is shown that the obtained product is a PS-Ag non-rotational axis-symmetric bowl-shaped Janus micro-nano motor.

Example 10

The drying temperature in Example 1 was adjusted to 60°C, and the above steps of Example 1 were repeated to obtain a product. As shown in Figure 16, it is shown that the obtained product is a PS-Ag non-rotational axis-symmetric bowl-shaped Janus micro-nano motor.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. within.

Claims (8)

1. A non-rotation axially symmetric bowl-shaped Janus micro-nano motor, which is characterized by having a hollow bowl-shaped structure and a Janus, with one and only one reflection plane, and has the characteristics of non-rotation symmetry; wherein: The non-rotating axisymmetric bowl-shaped Janus micro-nano motor is obtained by the collapse of hollow spherical Janus particles at the junction of different material compositions; The hollow spherical Janus particles include a hollow spherical matrix and a semi-coating layer on the surface of the hollow spherical matrix, wherein the particle diameter of the hollow spherical matrix is 1-1.2 μm, and the thickness of the semi-coating layer is 15-30 nm. 2. The micro-nano motor according to claim 1, wherein the hollow spherical matrix material is a polymer, and the half-coating layer is a metal or non-metal oxide. 3. The micro-nano motor according to claim 2, wherein the polymer is polystyrene, the metal is any one of Au, Ag and Pt, and the non-metal oxide is SiO ₂ and TiO ₂ any one. 4. A method for preparing the non-rotating axisymmetric bowl-shaped Janus micro-nano motor according to any one of claims 1-3, characterized in that it specifically includes the following steps: Disperse the hollow spherical Janus particles in liquid 1 so that the liquid 1 is filled with the hollow spherical Janus particles, and then dry the hollow spherical Janus particles to obtain a non-rotating axis-symmetrical bowl-shaped Janus micro-nano motor; Or the hollow spherical Janus particles filled with liquid 1 are then dispersed in liquid 2, and a non-rotating axis-symmetrical bowl-shaped Janus micro-nano motor is obtained by stirring or drying or a combination of stirring and drying, wherein: the liquid 1 is ethanol, water or polydimethyldiallylammonium chloride aqueous solution; the liquid 2 is ethanol or water, and the liquid 1 and liquid 2 are different. 5. The preparation method according to claim 4, characterized in that the hollow spherical Janus particles are prepared from a hollow spherical matrix through a magnetron sputtering semi-coating sputtering layer. 6. The preparation method according to claim 5, characterized in that the particle size of the hollow spherical matrix is 1-1.2 µm, and the thickness of the sputtering layer is 15-30 nm; the hollow spherical matrix material is a polymer. , the sputtered layer is metal or metal oxide. 7. The preparation method according to claim 4, characterized in that the volume percentage concentration of the polydimethyldiallyl ammonium chloride aqueous solution is 0.01-0.12%; the stirring time is 24~120 h; The drying time is 24 to 120 h, and the temperature is 30-60°C. 8. The application of the non-rotating axisymmetric bowl-shaped Janus micro-nano motor as claimed in any one of claims 1 to 3 as an artificial rotor in accelerating liquid mixing and mass transfer.