CN110409007A - A kind of electrospinning equipment and method for making micro-nano fiber support - Google Patents

Abstract

The invention discloses an electrostatic spraying equipment and method for making a micro-nano fiber support, wherein the equipment includes a hopper, a fiber nozzle, and a grounded fiber receiver, and a metal cylinder connected to a high-voltage direct current power supply is axially installed in the nozzle Fine needles; the preparation method enables the polymer solution to form a micro-nano polymer solution flow under the dispersion and drive of high-pressure gas, and form micro-nano fibers through high-pressure gas; DC high-voltage electricity ionizes the air and adsorbs it to the micro-nano polymer solution flow , form an electrostatic difference with the receiver to generate electrostatic force, the electrostatic force pulls the polymer chain to improve the chain orientation and crystallization, and improves the mechanical properties of the fiber through the electrostatic force; the processing speed of the present invention is obviously higher than that of electrospinning, which is equivalent to the air jet technology , and the mechanical properties of the obtained fibers are better than those obtained by traditional air-jet spinning; compared with traditional electrospinning technology and traditional air-jet technology, the micro-nano fiber bundles obtained in the present invention are looser, have higher porosity, and are more conducive to cell growth.

Description

A kind of electrospinning equipment and method for making micro-nano fiber support

technical field

The invention relates to a method and a device for manufacturing a uniform nanofibrous web, in particular to an electrostatic spray spinning device and a method for making a micro-nano fiber support.

Background technique

In the field of regenerative medicine, tissue engineering scaffolds play a pivotal role in the repair and reconstruction of missing or functionally damaged tissues and organs [1]. Nanofibrous scaffolds have attracted much attention because of their similar structure to natural collagen fiber extracellular matrix, and their advantages in promoting cell adhesion, proliferation, and differentiation[2-4]. Currently, the most commonly used processing methods for micro-nanofibrous scaffolds are electrospinning and air-brushing or air-blowing [5, 6]. Both techniques have their pros and cons. Electrospinning technology uses the formation of Tylor cone of polymer solution under high electrostatic effect to prepare micro-nano fibers. It has the advantages of simple operation and low cost, but its processing speed is slow, and the obtained scaffold has small pore size, low porosity, and difficult cell growth. Air spray technology is based on the principle of high-pressure air spraying, using high-pressure air as the dispersant and driving force of the polymer solution to promote the formation of micro-nano polymer solution flow, and the polymer solution flow forms micro-nano fibers with the volatilization of the solvent. Electrospinning technology and air-jet technology have different principles for preparing micro-nano fibers. Compared with electrospinning technology, the processing equipment of air-jet technology is simpler and the processing speed is faster (it can be increased by more than 10 times); due to the dispersion effect of high-pressure air, the processed micro-nano fibers are loosely arranged in bundles, Larger pore size and higher porosity are more conducive to cell growth, but the mechanical strength of the processed fiber scaffold is significantly lower than that of electrospun fibers [5].

After searching, it was found that the Chinese invention patent with the patent number CN02810669.5 (application time: 2002.11.20) disclosed an electroblowing method and preparation device for preparing non-woven fabrics with nanofiber structures by using high-voltage static electricity and high-pressure air at the same time. As shown in Figure 2, the preparation device includes several typical equipment units: a hollow spinning nozzle (104), which is connected to high-voltage static electricity; a high-pressure air nozzle (106), placed near the bottom of the spinning nozzle; Air suction collector (110). The device can be used to prepare nanofiber non-woven fabrics, and its typical process features are: the polymer solution is supplied to the spinning nozzle (104) with high voltage, and the polymer solution is spun while extruding from the spinning nozzle. The high-pressure air injected by the high-pressure air nozzle (106) below the nozzle is dispersed to form a fiber web, and finally the fiber web is collected by a grounded collector (110) to form a non-woven fiber cloth. According to the technical information disclosed in the patent, the spinning nozzle is hollow, and the polymer solution is pressed into the spinning nozzle and forms fibers under the action of electrostatic force, which is similar to the principle of electrospinning, and the effect of high-pressure air is to The formed fibers are dispersed into a fiber web, and the shape, air pressure and flow rate of the high-pressure air nozzle mainly affect the pattern and quality of the fiber web. Although the above technology uses high-voltage static electricity and high-pressure air at the same time, the formation of micro-nano fibers mainly depends on high-voltage static electricity, and high-pressure air does not directly participate in the formation of micro-nano fibers. type and quality.

In the search, it was found that the invention patent with the patent number CN200680013180.0 (publication number CN101163553A) discloses the process and device for forming a uniform nanofiber matrix, and high-pressure air is also used to affect the spray pattern and quality of the fiber.

Air-jet technology can use the dispersion and driving effect of high-pressure air to form micro-nano fibers by dispersing the polymer solution into a micro-nano polymer solution flow. Electricity, the high-voltage electrostatic force will have a pulling effect on the polymer chain, and at the same time improve the orientation and crystallinity of the polymer chain along the fiber axis, thereby improving the mechanical properties of the micro-nano fiber.

Contents of the invention

In view of this, the present invention provides a device for preparing micro-nano fibers using the principle of air jetting, using high-voltage electrostatic action to improve the mechanical properties of micro-nano fibers, and a method for producing micro-nano fibers using the device. The combination of the device and the method can obtain a Micro-nanofibrous scaffolds with various pore sizes, pores and mechanical properties that can meet the requirements of tissue repair.

Construct an electrospinning device for making micro-nano fiber scaffolds, including

a hopper for containing the polymer solution;

a fiber nozzle for discharging the polymer solution supplied from the hopper; and

a grounded fiber receiver for collecting said fibers;

The inside of the fiber nozzle is axially fixed with a metal cylindrical fine needle connected to a high-voltage direct current power supply. After the metal cylindrical fine needle is connected to a high-voltage direct current, a corona effect is generated to ionize the air around the fine needle, and the polymer solution adsorbs the metal cylindrical The charged ions around the fine needle form a voltage difference between the polymer solution after adsorbing the charged ions and the grounded metal fiber receiver, thereby generating electrostatic force;

The fiber nozzle is connected with a gas source for injecting high-pressure gas into it, and the polymer solution is dispersed and driven by the high-pressure gas to form a micro-nano polymer solution flow, and the solution flow forms micro-nano fibers with the volatilization of the solvent;

The electrostatic force produces a pulling effect on the polymer chains in the micro-nano polymer solution flow, improving the crystallinity of the polymer chains and the orientation of the polymer chains along the fiber axis, thereby improving the mechanical properties of the micro-nano fibers.

Preferably, an annular material channel is formed inside the fiber nozzle by a metal cylindrical fine needle, and the periphery of the limiting nozzle can be circular or rectangular; the annular material channel makes material delivery more uniform , and make the combination of materials and charged ions more uniform and better.

Preferably, the fiber receiver is a mesh structure made of metal material.

A method of using electrospinning equipment to manufacture a micro-nano fiber support, comprising the following steps,

Step 1. Place the polymer solution in the hopper and supply it to the fiber nozzle;

Step 2: Apply high-voltage direct current to the metal cylindrical fine needle inside the fiber nozzle, and at the same time feed high-pressure gas into the fiber nozzle, and the polymer solution forms a micro-nano polymer solution flow under the dispersion and drive of the high-pressure gas and sprays it out from the fiber nozzle ;

During this process, the flow of micro/nano polymer solution adsorbs the charged ions around the metal cylindrical fine needle, and a voltage difference is formed between the flow of charged micro/nano polymer solution and the grounded fiber receiver, thereby generating electrostatic force, and the charged micro/nano high The polymer chains in the molecular solution flow are pulled by the electrostatic force and volatilize with the solution to form micro-nano fibers;

Step 3. The micro-nano fibers in step 2 are received by a grounded fiber receiver to form a micro-nano fiber support.

In the method for processing the micro-nano fiber support, the dispersion and driving action of the high-pressure gas can make the polymer solution form a micro-nano polymer solution flow, and the micro-nano fiber flow forms a micro-nano fiber with the volatilization of the solvent. The principle of the fiber is the same as the principle of forming micro-nano fibers by air jet. However, in the electrostatic spraying process of the present invention, when the polymer solution passes through the metal cylindrical fine needle connected to the high-voltage direct current power supply, the charged ions around the metal cylindrical fine needle will be adsorbed and between the grounded fiber receiver A voltage difference is formed to generate electrostatic attraction; the polymer chains in the micro-nano polymer solution flow are arranged and oriented along the electric field force under the pulling of the electrostatic force, so that the arrangement of the polymer chains is more orderly, and the crystallinity of the crystalline polymer is improved. improve. This is conducive to improving the mechanical properties of micro-nano fibers. In addition, since the micro-nano polymer solution flow and the micro-nano fiber have the same charge, a looser fiber bundle is formed between the solution flow and the micro-nano fiber due to electrostatic repulsion.

Compared with the technologies disclosed in patent CN02810669.5 and patent CN101163553A, the present invention uses high-voltage static electricity and high-pressure air at the same time, but the application methods and effects of high-voltage static electricity and high-pressure air are completely different, resulting in micro-nano fibers There is also a noticeable difference in the performance of the stents. The formation of micro-nano fibers in the present invention mainly depends on high-pressure air, and one of the main functions of high-voltage static electricity is to generate high-voltage electrostatic force between the micro-nano fibers and the receiver, which produces a pulling effect on the micro-nano fibers and improves the stability of the polymer chain. The crystallinity and the orientation of polymer chains along the fiber axis can improve the mechanical properties of micro-nano fibers. In addition, the fiber nozzle of the present invention is a metal cylindrical needle inserted in the middle, and the metal cylindrical needle forms a circular material channel inside the fiber nozzle. High-voltage static electricity is applied to the metal cylindrical needle, and the metal cylindrical needle Under the action of high electrostatic voltage, halo discharge is generated to charge the air around the fine needle, and the charged ions are adsorbed on the micro-nano fiber solution flow, and the micro-nano fiber solution flow repels each other because of the same charge, thus forming a looser micro-nano fiber solution flow. fiber bundles.

Therefore, using the electrostatic spray spinning equipment of the present invention, the micro-nano fiber support processed by the electrostatic spray spinning process has the following advantages:

(1) The processing speed is significantly higher than that of electrospinning, which is comparable to that of air jet technology;

(2) However, the mechanical properties of the processed micro-nano fibers are significantly better than those processed by air-jet technology;

(3) Compared with the traditional electrospinning process and the traditional air-jet process, the micro-nano fiber bundle processed by the present invention is looser and has a higher porosity, which is more conducive to cell growth.

The main process conditions of the electrostatic spray spinning method of the present invention are as follows:

(1) Polymer type: The electrostatic spray spinning process described in the present invention is suitable for polymer solutions. Therefore, any polymer that can be dissolved in a solvent to form a polymer solution can theoretically use the electrospraying process of the present invention to prepare a micro-nano fiber scaffold. Like the electrospinning technology and the air jet technology, the concentration of the polymer solution also has an important influence on the formation of micro-nano fibers in the electrospinning process of the present invention. Therefore, when using the electrostatic spray spinning process of the present invention, it is also necessary to select a suitable polymer solution concentration according to the properties of the polymer.

(2) The diameter of the fiber nozzle: the diameter of the fiber nozzle is 0.1-1.0 mm, more preferably 0.3-0.8 mm, and most optimally 0.5-0.6 mm.

(3) High-pressure gas and its pressure: The role of high-pressure gas is as a dispersant and driving force for polymer solutions. Therefore, high-pressure gas can be air, nitrogen and other compressed gases. The pressure of the high-pressure gas is 0.15-0.8 MPa, preferably 0.20-0.5 MPa, more preferably 0.2-0.3 MPa.

(4) Voltage of high-voltage direct current: In order to ensure the effective ionization of air, the direct current voltage is 10-50 kV, and the optimized one is 15-30 kV.

(5) The distance between the fiber nozzle and the fiber receiver: The distance between the fiber nozzle and the receiver will affect the electric field strength and the flight path of the polymer solution flow. Under the condition of a certain voltage, the shorter the distance between the fiber nozzle and the receiver, the higher the electric field intensity and the greater the electrostatic pulling force on the polymer chain, but at the same time, the following disadvantages will also appear:

① The shorter the time that the electrostatic pulling force acts on the polymer chain, the polymer chain cannot be fully stretched and crystallized, which is not conducive to the enhancement of the mechanical properties of the fiber;

② The shorter the time available for solvent volatilization in the polymer solution flow, the too much residual solvent in the fiber when it reaches the fiber receiver is not conducive to the formation of a loose fiber scaffold;

③The residual pressure of the high-pressure gas reaching the fiber receiver is also greater, which may damage the micro-nano fibers on the receiver.

Therefore, the distance between the fiber nozzle and the fiber receiver is preferably 15-40 cm, and the optimal distance is 20-30 cm.

(6) The flow rate of the polymer solution: An important advantage of the electrostatic spray spinning process of the present invention is that the micro-nano fiber scaffold can be processed rapidly. Due to the dispersion and driving effect of the air, the flow rate of the polymer solution forming the micro-nanofibrous scaffold can reach up to 200 mL/h. Optimal flow requires a combination of air pressure, air flow and voltage adjustments.

Description of drawings

Fig. 1 is the schematic diagram of the electrospinning equipment for processing micro-nano fiber support in the present invention;

Fig. 2 is the accompanying drawing of the Chinese invention patent whose patent number is CN02810669.5 in the background technology;

Fig. 3 is a schematic diagram of the fiber nozzle of the present invention;

Fig. 4 is a schematic side view of the fiber nozzle of the present invention;

Fig. 5 is a stress-strain curve diagram of micro-nano fiber scaffolds prepared by different processes in the embodiment.

Detailed ways

In order to make the electrostatic spray spinning equipment and electrostatic spray spinning process described in the present invention easier to understand, the following takes the processing of polylactic acid micro-nano fiber scaffolds as an example to further clarify the use of electrostatic spray spinning equipment and the electrostatic spray spinning processing method:

Prepare a polymer solution, taking polylactic acid solution as an example: polylactic acid (M _w =100 kDa, PDI=1.4) was stirred and dissolved in 1,4-dioxane overnight to make a concentration of 8 wt%, 12 wt% %, 16 wt% polylactic acid solution.

Assemble the equipment as shown in Figure 1, the high-pressure air source is the high-pressure air provided by the air compressor; process the micro-nano fiber support according to the parameters set in Table 1, the specific process is: fix the spray gun 202 on the spray gun support 207, adjust the fiber nozzle 204 and the distance between the fiber receiver 208; the high-pressure air source 201 and the high-voltage DC power supply 200 are respectively connected to the corresponding air source interface 206 and power interface 205 on the spray gun, and the air pressure and the DC power supply voltage are adjusted to a certain value; Connect the hopper 203 to the hopper interface of the spray gun, pour the configured polylactic acid solution into the hopper; turn on the DC power supply, turn on the high-pressure air source, and start electrostatic spray spinning to prepare the micro-nano fiber support.

Using a polarizing microscope to initially observe the micro-nano fiber scaffold, it was found that the micro-nano fiber scaffold (shown in Table 2) can be obtained from Example 1 to Example 6. Among them, the diameter distribution of the micro-nano fiber obtained in Example 3 is relatively wide, ranging from 100 nm to 1000 nm, which may be related to the high concentration and high viscosity of the polylactic acid solution, resulting in uneven dispersion of high-pressure air to the polylactic acid solution; in addition, a small amount of micro-nano fibers obtained in Example 3 and Example 6 are broken The existence of the fibers should be caused by the residual air pressure reaching the receiving net due to too high air pressure to blow off the micro-nano fibers. Reduce the compressed air pressure to 0.22 MPa (Example 4), and there is no broken fiber in the obtained micro-nano fiber scaffold.

In order to more fully reflect the characteristics of the electrostatic spray spinning equipment and the electrostatic spray spinning process of the present invention, the air spray process (Example 7) and the Electrospinning process (Example 8) are used to process the micro-nano fiber support respectively, Example 7 and Example 8 is a traditional process, and the micro-nanofiber scaffolds obtained in Example 4, Example 7 and Example 8 were subjected to scanning electron microscope observation and mechanical tensile test. Scanning electron microscope observation shows that there are micron-scale bundled fibers in the micro-nano fibers obtained in Example 4 and Example 7, and the bundled fibers are composed of nano-scale fibers. loose.

The mechanical tensile test as shown in Figure 5 shows that the mechanical strength of the fiber support obtained in embodiment 8 (electrospinning process), embodiment 4 (electrospinning process of the present invention), and embodiment 7 (air spraying process) Intensity decreases sequentially. The above-mentioned scanning electron microscope observation and mechanical tensile test results prove that the electrospinning process of the present invention has the advantages of both the electrospinning process and the air spraying process, including:

(1) It has the advantages of rapid processing of loose micro-nano fiber scaffolds by air-jet process;

(2) It has the advantages of improved mechanical properties of the micro-nano fiber scaffold processed by the electrospinning process, thereby overcoming the disadvantage of poor mechanical properties of the micro-nano fiber processed by the air-jet process.

references

[1] Shao Jundong. Construction and modification of polylactic acid nanofiber scaffolds and research on their nanomechanical properties [D]. South China University of Technology, 2013.

[2] Elsdale T, Bard J. Collagen substrata for studies on cell behavior[J]. The Journal of cell biology. 1972, 54: 626-637.

[3] Ma P X, Langer R. Fabrication of Biodegradable Polymer Foams for CellTransplantation and Tissue Engineering[J]. Methods Mol Med. 1999, 18: 47-56.

[4] Palecek S P, Loftus J C, Ginsberg M H, et al. Integrin-ligand binding properties govern cell migration speed through cell-substratum adhesiveness[J]. Nature. 1997, 385(6616): 537-540.

[5] Tutak W, Sarkar S, Lin-Gibson S, et al. The support of bone marrowstromal cell differentiation by airbrushed nanofiber scaffolds[J]. Biomaterials. 2013, 34(10): 2389-2398.

[6] Yu Shaoyang, An Ying, Tan Jing, et al. Research Progress of Alternating Current Electrospinning Technology [J]. Application of Engineering Plastics. 2018(1): 115-118.

Claims (10)

1. An electrostatic spraying equipment for making micro-nano fiber support, comprising a hopper for containing the polymer solution; a fiber nozzle for discharging the polymer solution supplied from the hopper; and A grounded fiber receiver for collecting said fibers; characterized by: The inside of the fiber nozzle is axially fixed with a metal cylindrical fine needle connected to a high-voltage direct current power supply. After the metal cylindrical fine needle is connected to a high-voltage direct current, a corona effect is generated to ionize the air around the fine needle, and the polymer solution adsorbs the metal cylindrical The charged ions around the fine needle form a voltage difference between the polymer solution after adsorbing the charged ions and the grounded metal fiber receiver, thereby generating electrostatic force; The fiber nozzle is connected with a gas source for injecting high-pressure gas into it, and the polymer solution is dispersed and driven by the high-pressure gas to form a micro-nano polymer solution flow, and the solution flow forms micro-nano fibers with the volatilization of the solvent; The electrostatic force produces a pulling effect on the micro-nano fibers, increases the crystallinity of the polymer chains and the orientation of the polymer chains along the fiber axis, thereby improving the mechanical properties of the micro-nano fibers. 2. An electrostatic spraying device for making micro-nano fiber support according to claim 1, characterized in that: a circular material channel is formed inside the fiber nozzle by metal cylindrical needles. 3. The electrostatic spraying equipment for making micro-nano fiber support according to claim 1, characterized in that: the fiber receiver is a mesh structure made of metal material. 4 . The electrostatic spraying equipment for making micro-nano fiber support according to claim 1 , wherein the distance between the fiber nozzle and the fiber receiver is 15-40 cm. 5 . The electrostatic spraying equipment for making micro-nano fiber support according to claim 1 , characterized in that: the distance between the fiber nozzle and the fiber receiver is 20-30 cm. 6. A method for manufacturing a micro-nano fiber support using the electrostatic spraying equipment according to any claim of claim 1-5, characterized in that: comprising the following steps, Step 1. Place the polymer solution in the hopper and supply it to the fiber nozzle; Step 2: Apply high-voltage direct current to the metal cylindrical fine needle inside the fiber nozzle, and at the same time feed high-pressure gas into the fiber nozzle, and the polymer solution forms a micro-nano polymer solution flow under the dispersion and drive of the high-pressure gas and sprays it out from the fiber nozzle , During this process, the flow of micro/nano polymer solution adsorbs the charged ions around the metal cylindrical fine needle, and a voltage difference is formed between the flow of charged micro/nano polymer solution and the grounded fiber receiver, thereby generating electrostatic force, and the charged micro/nano high The polymer chains in the molecular solution flow are pulled by the electrostatic force and volatilize with the solution to form micro-nano fibers; Step 3. The micro-nano fibers in step 2 are received by a grounded fiber receiver to form a micro-nano fiber support. 7. The method according to claim 6, characterized in that: the electrostatic force produces a pulling effect on the micro-nano fibers, increasing the crystallinity of the polymer chains and the orientation of the polymer chains along the fiber axis. 8. The method according to claim 6, characterized in that: the high-voltage direct current voltage applied to the metal cylindrical fine needle in step 2 is 10-50 kV. 9. The method according to claim 6, characterized in that: the high-voltage direct current voltage applied to the metal cylindrical fine needle in step 2 is 15-30 kV. 10. The method according to claim 6, characterized in that: the pressure of the high-pressure gas fed into the fiber nozzle is 0.15-0.8 MPa.