CN107354516A - The method that porous silica Electrostatic spinning of fibres liquid and method of electrostatic spinning prepare porous silica silica fibre - Google Patents

Abstract

The invention discloses a kind of method that porous silica Electrostatic spinning of fibres liquid and method of electrostatic spinning prepare porous silica silica fibre, electrostatic spinning liquid is made up of silicon dioxide gel, polyvinyl alcohol, pore creating material etc., pore creating material is Nano carbon balls, polymethyl methacrylate nano ball, polystyrene nanospheres, silica/pore creating material/polyvinyl alcohol composite fiber is prepared by electrostatic spinning, realize the oxidation Decomposition of pore creating material and polyvinyl alcohol simultaneously by high-temperature calcination, inorganic porous silicon dioxide fibre structure is prepared.The porous silica silica fibre that the present invention is prepared has high temperature resistant, corrosion resistant feature, it is rendered as flexibility, good endurance, available in multiple environment such as acid, alkali simultaneously, it can be applied to adsorption and separate, catalyst carrier, ionic adsorption, sewage disposal etc..

Description

Porous silica fiber electrospinning solution and preparation of porous silica fiber by electrospinning Silicon Fiber Method

technical field

The invention belongs to the technical field of preparation of functional fibers, and relates to a preparation method of inorganic porous fibers, in particular to a preparation method of porous silica micro-nano fibers.

Background technique

Electrospinning technology is widely used to prepare one-dimensional fiber materials. The formed fibers have the advantages of large specific surface area, diverse components, and adjustable sizes. They are favored by researchers as biological substrates, electrode materials, catalysts, and environmental filter membranes. Among them, due to the characteristics of low density, large specific surface area, high adsorption capacity, and large surface roughness, the electrospun porous fiber greatly expands the application field of the electrospun fiber, making it suitable for filtration, adsorption, tissue growth, etc. The application performance in related fields has been significantly improved, and the preparation of porous fiber materials by electrospinning has broad development prospects in the future.

The existing methods for preparing porous fiber materials by electrospinning technology are mainly realized by phase separation (thermally induced phase separation, gas phase induced phase separation, non-solvent induced phase separation) or post-treatment. The post-treatment method removes some components of the fiber through ultraviolet irradiation, heat treatment, washing, etc., and forms a fiber containing holes. However, the above methods are mainly used to prepare porous fibers composed of organic polymer materials on the one hand. When preparing porous fibers from non-polar materials, it is difficult to maintain the flexibility of the material itself, and it is difficult to control the size of the fibers and their upper pore structures. On the other hand, The post-processing process requires more and tedious experimental steps.

Contents of the invention

The object of the present invention is to provide a porous silica fiber electrospinning solution and a method for preparing porous silica fibers by electrospinning.

To achieve the above object, the present invention adopts the following technical solutions:

A porous silica fiber electrospinning solution, the spinning solution is uniformly prepared by dispersion and mixing of silica sol, pore forming agent and polyvinyl alcohol (PVA) aqueous solution with a mass fraction of 10-30%. Mass sol/pore forming agent/polyvinyl alcohol metastable system, described silica sol: pore forming agent: the mass ratio of polyvinyl alcohol aqueous solution is 1:(0.04～0.2):(0.8～1.2), described forming The porogen is a nanoparticle whose thermal decomposition temperature is lower than 500°C.

The pore-forming agent is selected from one or more combinations of organic nanoparticles such as carbon nanospheres, polymethyl methacrylate (PMMA) nanospheres, polystyrene (PS) nanospheres, and the like.

A kind of electrospinning method prepares the method for porous silica fiber, comprises the following steps:

Step 1. Add the above-mentioned pore-forming agent into the silica sol, disperse by ultrasonic vibration for 0.5-1.0 h to obtain a mixture, then add an aqueous solution of polyvinyl alcohol with a mass fraction of 10-30% to the mixture, and stir for 2-6 h. The homogeneous sol/pore forming agent/polyvinyl alcohol metastable system is prepared, which is the electrospinning solution, and the mass ratio of the silica sol: pore forming agent: polyvinyl alcohol aqueous solution is 1: (0.04～0.2) :(0.8～1.2);

Step 2: Electrospinning the spinning solution to obtain composite fibers, drying the composite fibers and removing the pore-forming agent and polyvinyl alcohol by calcining to obtain porous silica (SiO ₂ ) fibers.

The preparation method of the silica sol comprises the following steps: using tetraethyl orthosilicate (TEOS) as the precursor of the silica sol, using water as the solvent, using H ₃ PO ₄ as the catalyst, and preparing tetraethyl orthosilicate Silica sol is produced through hydrolysis and condensation, and the mass ratio of ethyl orthosilicate: water: H ₃ PO ₄ is 1:(0.9～1.1):(0.01～0.02).

The reaction conditions for the hydrolysis and condensation are as follows: mix ethyl orthosilicate, water and H ₃ PO ₄ , control the adding speed of H ₃ PO ₄ during the mixing so that the addition is completed within 30-60 minutes, and then at 20-30°C Stir for 6-24 hours.

The electrospinning specifically includes the following steps: inject the spinning liquid into the syringe of the electrospinning equipment, prepare composite fibers by using the electrospinning equipment, connect the needle of the syringe to the positive pole of the power supply, and use tinfoil as the negative pole to collect the fibers; The distance between the poles is 10-15 cm, the spinning voltage is 10-20 kV, and the advancing speed of the syringe pump is 200-400 μL/min.

The drying condition of the composite fiber is: drying in an oven at 80-120° C. for 2-4 hours.

The calcination specifically includes the following steps: placing the dried composite fiber in a muffle furnace, then heating it to 750-900°C at a heating rate of 5-10°C/min, and holding it at this temperature for 2-4h, that is Porous silica fibers are available.

The beneficial effects of the present invention are reflected in:

In the present invention, the silica/nanosphere/PVA composite fiber is prepared by electrospinning the spinning solution containing the nanoparticle pore-forming agent, and then calcined at high temperature to oxidize and decompose the pore-forming agent under high temperature conditions, leaving Under the pore structure, the preparation of silica fibers and the thermal decomposition and removal of pore-forming agents and polymers (PVA) are realized in one step, and porous silica fibers are prepared. By controlling the mass ratio of silica sol, pore-forming agent and polyvinyl alcohol aqueous solution, the metastable system is guaranteed to meet the synthesis requirements of electrospinning fibers, so that the pore-forming agent is evenly distributed, and the difficulty of controlling the size of the fiber mesopore structure is reduced; through The size and content of the pore-forming agent in the electrospinning liquid are regulated to adjust the size and distribution of the internal pores of the fiber. The raw material is easy to obtain, and the method is simple and easy, and can be used to rapidly prepare porous silica fibers. The porous silica fiber prepared by the present invention has high purity, can give full play to the characteristics of high temperature resistance and corrosion resistance of silica, and at the same time, it still shows flexibility even after calcination, the fiber size is controllable, and the durability is good. It can be used in acid, In many environments such as alkali, it has good application prospects in the fields of surface adsorption and separation, catalyst carrier, ion adsorption, sewage treatment, etc.

Further, by controlling the addition rate of H ₃ PO ₄ to adjust the degree of hydrolysis of ethyl orthosilicate in the preparation of silica sol, the size of silica fibers can be controlled in the range of micronano.

Further, by controlling the parameters of the electrospinning process, the electrospinning solution forms composite fibers interwoven into a film, and better maintains the flexibility of the silica.

Furthermore, by drying the composite fiber before calcination, the moisture in the fiber is removed, and the shape of the fiber is better maintained.

Description of drawings

Fig. 1 is a scanning electron micrograph of the porous silica fiber prepared in Example 1 of the present invention.

Fig. 2 is an infrared spectrogram of the porous silica fiber prepared in Example 1 of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments. The examples are used to explain the present invention, but not to limit the protection scope of the present invention.

Example 1

Step 1, take 1g of silica sol and add 50mg of carbon nanospheres with an average diameter of 110nm, ultrasonically disperse evenly (0.5h), then add 1g of PVA aqueous solution with a mass fraction of 11% therein, stir until uniform (4h), and obtain The homogeneous sol/pore forming agent/polyvinyl alcohol metastable system is the electrospinning solution;

Wherein, the preparation method of silica sol is: use tetraethyl orthosilicate (TEOS) as the precursor of silica sol, use water as solvent, H ₃ PO ₄ (85%) as catalyst, and tetraethyl orthosilicate: Water: H ₃ PO ₄ was mixed according to the mass ratio of 1:1:0.01 (wherein, H ₃ PO ₄ needs to be added dropwise within 30-60 minutes), and then stirred at room temperature for 6 hours to fully hydrolyze the inorganic precursor, Condensation to form silica sol;

Wherein, the preparation of the PVA aqueous solution: add PVA to water, heat to dissolve and stir evenly to obtain the PVA aqueous solution, which is set aside. The degree of alcoholysis of PVA is 87-89%.

Step 2: Inject the electrospinning solution into a 1mL syringe with a stainless steel needle, control the spinning speed (i.e. the advancing speed of the syringe pump) to 200 μL/min, adjust the spinning voltage to 15kV, and adjust the nozzle (i.e. the stainless steel needle) to The distance between the receiving plate (covered with tin foil paper) is 15 cm, and the silica/carbon nanosphere/PVA composite fiber (fiber interwoven into a film) can be collected on the receiving plate.

Step 3. Dry the obtained composite fiber (membrane) in an oven at 80°C for 2 to 4 hours, then place it in a muffle furnace, heat it to 800°C in air at a heating rate of 5°C/min, and keep it warm at this temperature for 2 hours , that is, porous silica fibers (fiber interwoven into a film).

Referring to Fig. 1, the silica fiber prepared in this example has a porous structure, the diameter of the fiber is distributed in the range of 0.8-1.2 μm, and the diameter of the pores is 60-70 nm. Referring to Fig. 2, in the infrared spectrum of the silica fiber prepared in this example, there are only obvious Si-O-Si absorption peaks at 1078cm ^-1 , 790cm ^-1 and 455cm ^-1 , without other miscellaneous peaks.

Example 2

Step 1. Take 1 g of the silica sol prepared in Example 1 and add 75 mg of polymethyl methacrylate nanospheres with an average diameter of 300 nm. Ultrasonic dispersion is uniform (0.5 h), and then an aqueous PVA solution with a mass fraction of 11% is added thereto. 1g, stirred until uniform (4h), to obtain a homogeneous sol/pore forming agent/polyvinyl alcohol metastable system, which is the electrospinning solution.

Step 2. Inject the electrospinning solution into a 1mL syringe with a stainless steel needle, control the spinning speed to 250 μL/min, adjust the spinning voltage to 10kV, and adjust the nozzle (i.e., the stainless steel needle) to the receiving plate (covered with tinfoil) ) distance of 15cm, can be collected on the receiving plate to obtain silica/PMMA nanospheres/PVA composite fiber (fiber interweaving into film)

Step 3. Dry the obtained composite fiber (membrane) in an oven at 80°C for 2 to 4 hours, then place it in a muffle furnace, heat it to 850°C in air at a heating rate of 10°C/min, and keep it warm at this temperature for 3 hours , that is, porous silica fibers (fiber interwoven into a film).

The silica fiber prepared in this example has a porous structure, the diameter of the fiber is distributed in the range of 0.8-1.2 μm, and the diameter of the pores is 100-110 nm.

Example 3

Step 1. Take 1g of silica sol and add 100mg of polystyrene nanospheres with an average diameter of 200nm, ultrasonically disperse evenly (0.5h), then add 1g of PVA aqueous solution with a mass fraction of 11%, and stir until uniform (4h) , to obtain a homogeneous sol/pore forming agent/polyvinyl alcohol metastable system, which is the electrospinning solution.

Step 2. Inject the electrospinning solution into a 1mL syringe with a stainless steel needle, control the spinning speed to 250 μL/min, adjust the spinning voltage to 10kV, and adjust the nozzle (i.e., the stainless steel needle) to the receiving plate (covered with tinfoil) ) at a distance of 15 cm, the silica/PS nanosphere/PVA composite fiber (fiber interwoven into a film) can be collected on the receiving plate.

Step 3. Dry the obtained composite fiber (membrane) in an oven at 80°C for 2 to 4 hours, then place it in a muffle furnace, heat it to 750°C in air at a heating rate of 10°C/min, and keep it at this temperature for 2 hours , that is, porous silica fibers (fiber interwoven into a film).

The silica fiber prepared in this example has a porous structure, the diameter of the fiber is distributed in the range of 0.8-1.2 μm, and the diameter of the pores is 80-90 nm.

The present invention has the following advantages:

1. The porous silica fiber prepared by the present invention has the characteristics of high temperature resistance and corrosion resistance. At the same time, it still presents a flexible silica fiber film after electrospinning and calcination, which can be curled and folded without breaking, and has good durability. Can be used in many environments such as acid and alkali;

2. Through high-temperature calcination, the decomposition of the pore-forming agent and the removal of the polymer (PVA) are simultaneously realized, leaving a pore structure inside the fiber, the steps are simple, the preparation method of the porous silica fiber is simple, and mass production can be realized;

3. Porous silica fiber has adjustable pore size and a three-dimensional porous structure with large specific surface area, which can be applied to surface adsorption and separation, catalyst carrier, ion adsorption, sewage treatment, etc.

Claims (9)

1. A porous silica fiber electrospinning liquid, characterized in that: the spinning liquid is made of polyvinyl alcohol aqueous solution of 10 to 30% by dispersion and mixing by silica sol, pore forming agent and mass fraction The homogeneous sol/pore forming agent/polyvinyl alcohol metastable system formed, the silica sol: pore forming agent: the mass ratio of polyvinyl alcohol aqueous solution is 1:(0.04～0.2):(0.8～1.2), The pore-forming agent is nanoparticles with a thermal decomposition temperature lower than 500°C. 2. A kind of porous silica fiber electrospinning solution according to claim 1, characterized in that: the pore-forming agent is selected from carbon nanospheres, polymethyl methacrylate nanospheres, polystyrene nanospheres one or a combination of two or more. 3. A method for preparing porous silica fibers by electrospinning, characterized in that: comprise the following steps: Step 1. Add the pore-forming agent to the silica sol, disperse by ultrasonic vibration for 0.5-1.0 h to obtain a mixture, then add an aqueous polyvinyl alcohol solution with a mass fraction of 10-30% to the mixture, and stir for 2-6 hours to prepare Obtain a homogeneous sol/pore forming agent/polyvinyl alcohol metastable system, which is an electrospinning solution, and the mass ratio of the silica sol: pore forming agent: polyvinyl alcohol aqueous solution is 1: (0.04～0.2): (0.8～1.2); The pore-forming agent is a nanoparticle with a thermal decomposition temperature lower than 500°C; Step 2: Electrospinning the spinning liquid to obtain composite fibers, drying the composite fibers and removing the pore-forming agent and polyvinyl alcohol by calcining to obtain porous silica fibers. 4. according to the method for preparing porous silica fiber by a kind of electrospinning method according to claim 3, it is characterized in that: the preparation method of described silica sol comprises the following steps: using ethyl orthosilicate as the carbon dioxide Silica sol precursor, using water as solvent and H ₃ PO ₄ as catalyst, makes silica sol through hydrolysis and condensation of ethyl orthosilicate, the mass ratio of ethyl orthosilicate: water: H ₃ PO ₄ is 1:(0.9～1.1):(0.01～0.02). 5. The method for preparing porous silica fibers by electrospinning according to claim 4, characterized in that: the reaction conditions of the hydrolysis and condensation are: mixing ethyl orthosilicate, water and H ₃ PO ₄ During the mixing, control the adding speed of H ₃ PO ₄ to finish adding within 30-60 minutes, and then stir at 20-30°C for 6-24 hours. 6. The method for preparing porous silica fibers by electrospinning according to claim 3, characterized in that: said electrospinning specifically comprises the following steps: injecting said spinning solution into a syringe of an electrospinning device In this method, the composite fiber is prepared by electrospinning equipment, the needle of the syringe is connected to the positive pole of the power supply, and the tinfoil paper is used as the negative pole to collect the fiber; the distance between the positive and negative poles is 10-15cm, the spinning voltage is 10-20kV, and the injection pump advances at a speed of 200 ~400 μL/min. 7. A method for preparing porous silica fibers by electrospinning according to claim 3, characterized in that: the drying condition of the composite fibers is: oven drying at 80-120°C for 2-4 hours. 8. The method for preparing porous silica fibers by a kind of electrospinning method according to claim 3 is characterized in that: the calcination specifically comprises the following steps: placing the dried composite fibers in a muffle furnace, and then 5 Heating to 750-900°C at a heating rate of ~10°C/min, and holding the temperature for 2-4 hours at this temperature, the porous silica fiber can be obtained. 9. The method for preparing porous silica fibers according to claim 3, wherein the pore-forming agent is selected from carbon nanospheres, polymethyl methacrylate nanospheres, polystyrene One kind of nanospheres or a combination of two or more kinds.