Microfluid control spinning head with capillary tube vertically penetrating through tank, spinning device nanofiber and preparation method

Abstract

The invention discloses a capillary tube vertical penetrating tank microfluid control spinning head, a spinning device nanofiber and a preparation method. The spinning head comprises a capillary tube gathering inlet pipe, a series of stainless steel capillary tubes and a storage tank. The capillary tube gathering inlet pipe is positioned above the tank body, and one end of the capillary tube gathering inlet pipe is connected with one end of each series of stainless steel capillary tubes; the other ends of all the series stainless steel capillary tubes are unfolded by taking the capillary tube gathering inlet tube as the center, the series stainless steel capillary tubes vertically penetrate through the tank body from the upper part of the tank body and penetrate out of the bottom of the tank body, and coaxial small holes are formed in the positions, penetrating out of the tank body, of the series stainless steel capillary tubes; the small holes and the series stainless steel capillary outlets form series coaxial outlets, and another inlet for injecting sheath fluid into the tank body and a tank body cleaning outlet are formed in the side face of the tank body. The spinning head is provided with a plurality of coaxial nozzle outlets, and a plurality of strands of coaxial spinning microfluid are stretched into the core-sheath structure nanofibers through the interaction of a high-voltage electrostatic field and fluid.

Description

Technical Field

[0001] This invention relates to nanomaterials and their preparation methods and apparatus, including a capillary vertical can-passing microfluidic controlled spinning head, a spinning device for nanofibers, and a preparation method. Background Technology

[0002] High-voltage electrospinning (HPE) is a top-down nanofabrication technology. It utilizes an external electric field to overcome the surface tension and viscoelasticity of the liquid droplets at the tip of the microfluidic-controlled spinneret, forming a jet. Under the combined action of electrostatic repulsion, Coulomb force, and surface tension (the electrospinning process may not involve atomization), the liquid jet is subjected to high-frequency bending, stretching, and splitting, being stretched millions of times within tens of milliseconds. Nanofibers are then obtained at the receiving end through solvent evaporation or melt cooling. This technology is simple to process, easy to operate, allows for a wide range of material selection, and offers strong controllability. Furthermore, it allows for the design and fabrication of nanofibers with microstructural characteristics through microfluidic control of the spinneret. It is considered one of the most promising methods for achieving continuous industrial production of nanofibers, and its application in the fabrication of functional nanofibers shows great promise.

[0003] The greatest advantage of electrospinning is its ability to efficiently prepare polymer micro / nanofibers with corresponding structural features in a single step through the design and modification of the spinneret structure, a feat difficult to achieve with other "bottom-up" chemical synthesis methods. The most common method is to use a coaxial capillary metal sheath as the spinneret to prepare core-sheath structured nanofibers (Polym. Rev. 2008, 48, 353-377; Science 2004, 304, 1917-1919). With the development of nanotechnology, the concept of simply reducing the micro / nano size of products to obtain corresponding nano-functionality has gradually become less mainstream. Currently, more attention is focused on nanodevices, complex micro / nano structures, and the structure-property relationships at the nanoscale. How to effectively prepare structurally complete micro / nanofibers with complex structural features, and how to design their functions based on these structural features, is both a research hotspot in nanotechnology and a key issue that needs to be addressed in the field of microfabrication and the production of novel micro / nanofiber products.

[0004] The molecule represents an interface; below the molecule level lies purely in chemical synthesis based on covalent and ionic bonds (corresponding to the chemical industry). Above the molecule level, below the visible scale (approximately 0.1 mm), lies the micro- and nanoscale realm. This is the richest source of knowledge about the world and the focal point for humanity's transformation of the material world (corresponding to the micro- and nano-fabrication of functional materials, and the aforementioned new chemical molecule synthesis also serves this purpose). In July 1990, the first International Conference on Nanoscience and Technology was held in Baltimore, USA, marking the formal birth of nanoscience and technology. By 1999, nanotechnology began to gradually enter the market. Over the past 20 years, many countries and regions have actively formulated relevant strategies or plans, investing heavily to seize the strategic high ground in nanotechnology, establishing nanomaterials research centers, and incorporating nanotechnology into the research and development priorities of basic science and technology plans. A search of Web of Science using "nano" as a keyword yields over 1.5 million articles and over 300,000 patents, but the number of nano-products benefiting the public on the market remains very limited. Essentially, globally, the proportion of nanotechnology research output is very low, and the industrialization of nanotechnology is far from expected! Compared to other technologies, the "valley of death" between nanoscience and industrialization is larger, which further highlights the importance and urgency of accelerating the industrial manufacturing of various functional micro and nanomaterials.

[0005] Therefore, developing new technologies and processes for functional nanomaterials with complex structural features that can be mass-produced on an industrial scale is of great practical significance. Summary of the Invention

[0006] Purpose of the invention: To address the shortcomings of existing technologies, this invention provides a capillary vertical canister-passing microfluidic controlled spinning head, spinning device, nanofibers, and preparation method, which enables the design, preparation, and commercialization of novel core-sheath structure-based nanofunctional materials, overcoming the difficulties in preparing structurally complete functional nanomaterials with complex structural features and achieving industrial-scale production.

[0007] Technical solution: The capillary vertical canister microfluidic control spinning head includes a capillary inlet tube, a series of stainless steel capillary tubes, and a horizontally placed canister.

[0008] The tank is a closed tank used for storing, delivering, and diverting liquid from the outer sheath;

[0009] The capillary inlet pipe is located at the top of the tank. One end of the capillary inlet pipe is connected to one end of all the series of stainless steel capillaries. The other ends of all the series of stainless steel capillaries extend from the capillary inlet pipe, entering the tank from the top and exiting from the bottom. The tank has a small hole at the exit point of the capillary tubes, which, together with the capillary outlets, forms a series of coaxial outlets (the series of coaxial outlets constitute a parallel guide outlet with two fluids flowing out coaxially. The core of the coaxial outlet is a metal needle-shaped nozzle, and the sheath is a polymer orifice). An inlet is located on the side of the tank for introducing sheath fluid into the tank, and a cleaning port is located on the other side; these two are interchangeable.

[0010] Some series of stainless steel capillaries are vertically and evenly distributed inside the tank.

[0011] The capillary vertical canister-penetrating microfluidic controlled spinning head of this invention features a rational structural design. The microfluidic controlled spinning head is equipped with multiple series of coaxial outlets, simultaneously guiding two different fluids into a high-voltage electrostatic field. Using the multiple coaxial nozzle outlets as macroscopic templates, under the high-voltage electrostatic field, through the interaction between the high-voltage electrostatic field and the fluids, multiple coaxial spinning fluids are stretched into solid nanofibers with clearly defined core-sheath structures within milliseconds. The numerous nozzles of the microfluidic controlled spinning head are needle-like metal tips combined with polymer holes in the canister structure, which facilitates the guiding effect of the "needle" and the "wall-attaching" effect of the liquid flowing out of the polymer holes. This ensures accurate "replication" from the macroscopic coaxial outlet template to the microscopic two-chamber core-sheath structure nanofibers under the high-voltage electrostatic field. It overcomes the limitations of traditional needle-type electrospinning technology in the laboratory-scale preparation of core-sheath structure nanofibers, providing the ability to prepare structurally complete core-sheath structure nanofibers effectively and in large quantities in a single step, showing promising application prospects.

[0012] As a preferred technical solution:

[0013] The capillary vertical canister microfluidic control spinning head described above has a canister that is a horizontally placed cylindrical structure.

[0014] Both the tank body and the capillary inlet pipe are made of polypropylene.

[0015] As described above, a capillary vertical can-penetrating microfluidic control spinning head has all series of stainless steel capillaries uniformly distributed within the length of the can.

[0016] As described above, a capillary vertical can-penetrating microfluidic control spinning head, wherein the series of stainless steel capillaries all pass vertically through the can body;

[0017] All the series of stainless steel capillaries and the tank form a microfluidic guiding and diversion mode that is "from main to branch".

[0018] As described above, in a capillary vertical can-penetrating microfluidic control spinning head, the series of stainless steel capillaries are fixed to the upper end of the can body with epoxy resin adhesive.

[0019] Another aspect of the present invention provides a spinning apparatus comprising a first injection pump, a first syringe, a second injection pump, a second syringe, a fiber receiving plate, a high-pressure generator, and a capillary vertical canister-passing microfluidic controlled spinning head of the aforementioned multi-fluid coaxial combination microfluidic controlled spinning head.

[0020] The first syringe is mounted on the first injection pump. The outlet of the first syringe is connected to the inlet on the side of the capillary tube that passes through the microfluidic control spinning head through a silicone tube. The second syringe is mounted on the second injection pump. The outlet of the second syringe is connected to the capillary tube inlet tube (away from the end of the series stainless steel capillary tube) through a silicone tube.

[0021] The fiber receiving plate is positioned directly below a series of coaxial outlets of the capillary vertical cannulation microfluidic controlled spinning head. The high-voltage generator is electrically connected to the capillary vertical cannulation microfluidic controlled spinning head. Through the cooperation of a first injection pump, a first syringe, a second injection pump, a second syringe, the fiber receiving plate, the high-voltage generator, and the capillary vertical cannulation microfluidic controlled spinning head, a high-voltage electrostatic field can be constructed in conjunction with the series of coaxial outlets of the capillary vertical cannulation microfluidic controlled spinning head to achieve large-scale production of core-sheath structured nanofibers.

[0022] As a preferred technical solution:

[0023] In the spinning device described above, the high-pressure generator and the capillary tube vertically pass through the microfluidic control spinning head are connected by alligator clips.

[0024] The fiber receiving board is a cardboard wrapped in aluminum foil;

[0025] Both the fiber receiving plate and the high-voltage generator are grounded.

[0026] Another aspect of the present invention provides a method for preparing nanofibers using the aforementioned spinning apparatus, wherein a first spinning solution (i.e., sheath solution) and a second spinning solution (i.e., core solution) are added to a first syringe and a second syringe, respectively, and a first injection pump, a second injection pump, and a high-voltage generator are started. Through the action of a high-voltage electrostatic field, nanofibers with core-sheath structure characteristics can be prepared in a single step in batches.

[0027] The above-mentioned method for mass production of nanofibers with core-sheath structure features is simple in steps, convenient in operation, and easy to control. Under a high-voltage electric field, it can effectively expand the scale of core-sheath structure nanofiber preparation, providing strong support for the development, production, and commercial application of nano-products based on core-sheath structure, and realizing the industrial-scale production of functional nanomaterials with complex structural features.

[0028] As a preferred technical solution:

[0029] The sheath fluid is an ethanol or methanol solution of polyvinylpyrrolidone with a mass percentage concentration of 7-13%.

[0030] The core fluid is an ethanol or methanol solution of ethyl cellulose with a mass percentage concentration of 18-28%.

[0031] The flow rate of the sheath fluid in the first syringe is 8–20 mL / h, and the flow rate of the second syringe is 8–20 mL / h.

[0032] As a preferred technical solution:

[0033] The output voltage of the high voltage generator is 30-40kV.

[0034] The sheath fluid is an ethanol solution of polyvinylpyrrolidone with a mass percentage concentration of 10%;

[0035] The core fluid is a 24% (w / w) ethyl cellulose ethanol solution.

[0036] As a preferred technical solution:

[0037] In the method described above, the sheath fluid is an ethanol solution of polyvinylpyrrolidone with a mass percentage concentration of 10%.

[0038] The flow rate of the sheath fluid in the first syringe is 10 mL / h, and the flow rate of the second syringe is 10 mL / h.

[0039] The fiberboard receiving distance is 20cm, and the output voltage of the high voltage generator is 34kV.

[0040] Another aspect of the present invention provides nanofibers prepared using the method described above.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The capillary vertical can-penetrating microfluidic control spinning head structure of the present invention is reasonably designed. The microfluidic control spinning head is equipped with multiple series of coaxial outlets, which synchronously guide two different fluids into the high voltage electrostatic field. Using multiple coaxial nozzle outlets as macro templates, under the high voltage electrostatic field, through the interaction between the high voltage electrostatic field and the fluid, multiple coaxial spinning fluids are stretched into solid nanofibers with clear core-sheath structure within a few milliseconds.

[0043] (2) The numerous nozzles of the capillary vertical can-penetrating microfluidic control spinning head of the present invention are needle-type metal tips plus polymer hole structure of the can body, which is conducive to giving full play to the guiding role of the "needle" and the "attachment" effect of the liquid flowing out of the polymer hole, ensuring accurate "replication" of the nanofibers with the characteristics of the macroscopic coaxial outlet template to the microscopic two-chamber core-sheath structure under high voltage electrostatic field.

[0044] (3) The capillary vertical canister-penetrating microfluidic control spinning head of the present invention overcomes the limitations of traditional needle-type electrospinning technology in preparing core-sheath structured nanofibers on a laboratory scale, and gives it the ability to prepare structurally complete core-sheath structured nanofibers in a single step, effectively and on a large scale.

[0045] (4) The preparation method of nanofibers with core-sheath structure features of the present invention has simple steps, convenient operation and easy control. Under high voltage electric field, the scale of preparation of core-sheath structure nanofibers can be effectively expanded, providing strong support for the development, production and commercial application of nano products based on core-sheath structure, realizing the industrial-scale production of functional nanomaterials with complex structural features, and has good application prospects. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of the capillary vertical can-penetrating microfluidic control spinning head of the present invention;

[0047] Figure 2 This is a schematic diagram of the multi-fluid high-voltage electrospinning device of the present invention, which uses capillary vertical can-penetrating microfluidic control of the spinning head.

[0048] Among them, 1-capillary inlet tube, 2-series stainless steel capillary tubes, 3-tank body, 4-inlet or cleaning port, 5-series coaxial outlet, 6-spinning head fixing support, 7-high pressure generator, 8-first injection pump, 9-second injection pump, 10-capillary vertical can-penetrating microfluidic control spinning head, 11-fiber receiving plate, 12-first syringe, 13-second syringe, 14-first high-elasticity silicone hose, 15-second high-elasticity silicone hose

[0049] Figure 3 This is a full view of the capillary vertical can-penetrating microfluidic control spinning head of the present invention;

[0050] Figure 4 This is a diagram showing the coaxial outlet of the capillary vertical can-penetrating microfluidic control spinning head section of the present invention;

[0051] Figure 5 This is a scanning electron microscope image of the nanofibers with core-sheath structure characteristics obtained in this invention.

[0052] Figure 6 This is a transmission electron microscope image of the nanofibers with core-sheath structure characteristics obtained in this invention. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0054] Example 1

[0055] In this embodiment, the capillary vertical can-penetrating microfluidic control spinning head, such as Figure 1 As shown, it includes a capillary inlet pipe 1, a series of stainless steel capillary tubes 2, and a tank body 3;

[0056] Tank 3 is a closed, horizontally placed tank with a cylindrical structure and made of polypropylene.

[0057] The capillary inlet pipe 1 (made of polypropylene) is located above the tank body 3. One end of the capillary inlet pipe 1 is connected to one end of all the series of stainless steel capillary tubes 2 (there are 6 series of stainless steel capillary tubes in total). The other ends of all the series of stainless steel capillary tubes 2 extend outward from the capillary inlet pipe 1, and all the series of stainless steel capillary tubes 2 are evenly distributed along the length of the tank body 3 (the spacing between adjacent series of stainless steel capillary tubes is uniform, all being 3.5 cm). The series of stainless steel capillary tubes 2 pass through the upper end of the tank body 3. The stainless steel capillary tube 2 is inserted into the tank body 3 and passes through the bottom of the tank body 3. The connection between the series stainless steel capillary tube 2 and the tank body 3 is fixed with epoxy resin. The series stainless steel capillary tube 2 is vertically downward on the inner wall of the tank body 3. There is a small hole in the tank body 3 at the position where the series stainless steel capillary tube 2 passes through the tank body 3. The small hole and the series stainless steel capillary tube outlet (the series stainless steel capillary tube outlet protrudes from the bottom of the tank body by about 1.0mm) form a series coaxial outlet 5. The side of the tank body 3 has an inlet 4 that communicates with the internal space of the tank body 3, which facilitates the introduction of spinning sheath liquid or is used for tank cleaning.

[0058] All the series of stainless steel capillaries 2 and tank 3 form a "from main to branch" diversion and guidance, and are given a microfluidic control guidance mode that enters the high voltage electrostatic field coaxially.

[0059] Example 2

[0060] This embodiment utilizes a multi-fluid high-voltage electrospinning device with capillary vertical can-penetrating microfluidic control of the spinning head, such as... Figure 2 As shown, it includes a spinning head fixing support 6, a high-pressure generator 7, a first injection pump 8, a second injection pump 9, a capillary vertical canister microfluidic control spinning head 10, a fiber receiving plate 11, a first syringe 12, a second syringe 13, a first high-elasticity silicone tube 14, and a second high-elasticity silicone tube 15.

[0061] The first syringe 12 is installed on the first injection pump 8. The outlet of the first syringe 12 is connected to the inlet on the side of the can of the capillary vertical can-penetrating microfluidic control spinning head 10 through the first high elasticity silicone hose 14. The second syringe 13 is installed on the second injection pump 9. The outlet of the second syringe 13 is connected to the end of the capillary collection inlet tube 1 away from the series stainless steel capillary tube 2 through the second high elasticity silicone hose 15.

[0062] The fiber receiving plate 11 is a cardboard wrapped in aluminum foil. The fiber receiving plate 11 is arranged directly below the series of coaxial outlets of the capillary vertical can-penetrating microfluidic control spinning head 10. The high voltage generator 7 is electrically connected to the capillary vertical can-penetrating microfluidic control spinning head 10 through alligator clips. Both the fiber receiving plate 11 and the high voltage generator 7 are grounded.

[0063] The installation and usage methods of the above-mentioned multi-fluid high-voltage electrospinning device are as follows:

[0064] First spinning solution (i.e., sheath solution) and second spinning solution (i.e., core solution) are added to the first syringe and the second syringe respectively. The first injection pump and the second injection pump are started to deliver the first spinning solution in the first syringe and the second spinning solution in the second syringe to the tank and the capillary collection inlet pipe. The high voltage generator is turned on, and nanofibers with core-sheath structure characteristics can be prepared in a single step through the action of the high voltage electrostatic field.

[0065] Application Example 1

[0066] The method of using the spinning apparatus as described in Example 2 includes the following steps:

[0067] (1) Prepare spinning solution;

[0068] The first spinning solution is a 10% polyvinylpyrrolidone ethanol solution, which is prepared as follows: 100g of polyvinylpyrrolidone is added to 900g of ethanol and stirred evenly to obtain a 10% polyvinylpyrrolidone ethanol solution.

[0069] The second spinning solution is a 24% ethyl cellulose ethanol solution, which is prepared as follows: 240g of ethyl cellulose is added to 760g of ethanol and stirred evenly to obtain a 24% ethyl cellulose solution, that is, the core solution has a 24% ethyl cellulose concentration.

[0070] (2) Add the first and second spinning solutions obtained in step (1) into the corresponding syringes, and then turn on the first injection pump and the second injection pump.

[0071] (3) Control the flow rate of the sheath fluid in the first syringe to 10 mL / h, control the flow rate of the second syringe to 10 mL / h, turn on the high voltage generator, adjust the fiberboard receiving distance to 20 cm, and raise the voltage to 34 kV for electrospinning. In this way, core-sheath structure nanofibers can be prepared in batches in a single step.

[0072] The core-sheath structure nanofibers prepared in Application Example 1 were observed using field scanning electron microscopy after surface sputtering with gold. The results are as follows: Figure 3 As shown, the prepared core-sheath structured nanofibers are uniformly collected and exhibit good linearity, with a diameter of 660±150 nm. The prepared coaxial structured nanofibers were observed using a high-resolution transmission electron microscope, and the results are as follows: Figure 4 As shown, the inner and outer parts of the nanofiber are composed of two gray-scale components, reflecting the structural characteristics of the nanocore-sheath.

[0073] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0074] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

[0075] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A capillary vertical can-penetrating microfluidic controlled spinning head, characterized in that: Includes capillary inlet tube, series of stainless steel capillary tubes, and tank; The capillary inlet pipe is located above the tank body. One end of the capillary inlet pipe is connected to one end of all the series of stainless steel capillaries. The other ends of all the series of stainless steel capillaries extend outward from the capillary inlet pipe. The series of stainless steel capillaries enter the tank body from the top and exit from the bottom of the tank body. The tank body has a small hole at the position where the series of stainless steel capillaries exit the tank body. The small hole and the outlet of the series of stainless steel capillaries form a series of coaxial outlets. The stainless steel capillaries are used to deliver the core liquid. The side of the tank body has an inlet and an outlet.

2. The capillary vertical can-penetrating microfluidic controlled spinning head according to claim 1, characterized in that: The tank is a closed, horizontally placed tank.

3. The capillary vertical can-penetrating microfluidic controlled spinning head according to claim 1, characterized in that: All series of stainless steel capillary tubes are vertically and evenly distributed inside the tank.

4. A spinning apparatus, characterized in that, It includes a first injection pump, a first syringe, a second injection pump, a second syringe, a fiber receiving plate, a high-pressure generator, and a capillary vertical canister-passing microfluidic control spinning head as described in any one of claims 1 to 3; The first syringe is mounted on the first injection pump, and the outlet of the first syringe is connected to the side inlet of the capillary vertically penetrating microfluidic control spinning head through a silicone tube for delivering sheath fluid; the second syringe is mounted on the second injection pump, and the outlet of the second syringe is connected to the capillary collection inlet tube through a silicone tube, away from the end of the series stainless steel capillary tube. The fiber receiving plate is arranged directly below the series of coaxial outlets of the capillary vertical can-penetrating microfluidic controlled spinning head, and the high-pressure generator is connected to the capillary vertical can-penetrating microfluidic controlled spinning head.

5. A method for preparing nanofibers using the spinning apparatus as described in claim 4, characterized in that, Sheath fluid and core fluid are added to the first and second syringes respectively. The first and second injection pumps and the high-voltage generator are started. Through the action of the high-voltage electrostatic field, nanofibers with core-sheath structure characteristics can be prepared in batches in a single step.

6. The method according to claim 5, characterized in that, The sheath fluid is an ethanol or methanol solution of polyvinylpyrrolidone with a mass percentage concentration of 7-13%. The core fluid is an ethanol or methanol solution of ethyl cellulose with a mass percentage concentration of 18-28%. The flow rate of the sheath fluid in the first syringe is 8–20 mL / h, and the flow rate of the second syringe is 8–20 mL / h.

7. The method according to claim 5, characterized in that, The output voltage of the high voltage generator is 30-40kV.

8. The method according to claim 5, characterized in that, The sheath fluid is an ethanol solution of polyvinylpyrrolidone with a mass percentage concentration of 10%; The core fluid is a 24% (w / w) ethyl cellulose ethanol solution.

9. A nanofiber prepared by the method according to any one of claims 5-8.

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