阅读说明：本技术 一种同轴静电溶液喷射纺取向纳米中空纤维膜的制备方法 (Preparation method of coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane ) 是由 程博闻 厉宗洁 庄旭品 李磊 石磊 康卫民 李凯华 于 2020-12-11 设计创作，主要内容包括：本发明涉及一种同轴静电溶液喷射纺取向纳米中空纤维膜的制备方法,该制备方法包括以下步骤：(1)制备皮层纺丝液：将非水溶性聚合物溶解在有机溶剂中并添加不同类型的无机盐致孔剂；(2)制备芯层纺丝液：以水溶性极佳的聚合物溶液为芯层溶液；(3)制备同轴静电溶液喷射纺取向纳米中空纤维膜：将步骤(1)得到的皮层溶液和步骤(2)得到的芯层溶液分别注入不同的储液装置中,从喷丝头的同轴针头中挤出,纺丝溶液在高速喷射气流和静电场的作用下,牵伸细化,经溶剂挥发形成纳米纤维,通过辅助喷气装置喷射辅助气流,并采用框架接收以获取高度取向的皮芯结构纳米纤维,以溶解方式除去皮层无机盐和芯层溶液即得到定向排列的纳米中空纤维膜。(The invention relates to a preparation method of a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane, which comprises the following steps: (1) preparing a skin layer spinning solution: dissolving a water-insoluble polymer in an organic solvent and adding different types of inorganic salt pore-forming agents; (2) preparing a core layer spinning solution: taking a polymer solution with excellent water solubility as a core layer solution; (3) preparing a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the cortex solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding the solutions from coaxial needles of a spinning nozzle, drafting and refining the spinning solution under the action of high-speed jet airflow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary airflow through an auxiliary air jetting device, receiving the nano fibers by adopting a frame to obtain highly oriented skin-core structure nano fibers, and removing the cortex inorganic salt and the core layer solution in a dissolving mode to obtain the directionally arranged nano hollow fiber membrane.)

1. A preparation method of a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane is characterized by comprising the following steps:

(1) preparing a skin layer spinning solution: dissolving a water-insoluble polymer in an organic solvent, and adding different types of inorganic salt pore-forming agents to prepare a skin layer spinning solution;

the concentration of the skin layer spinning solution is between 5 and 35 percent; the hole making agent accounts for 0.1-5% of the mass percent of the skin layer spinning solution;

(2) preparing a core layer spinning solution: taking a polymer solution with excellent water solubility as a core layer solution;

the concentration of the core layer spinning solution is between 5 and 20 percent;

(3) preparing a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the skin layer solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding from a coaxial needle of a spinning nozzle at an extrusion speed of 5-50mL/h, drafting and refining the spinning solution under the action of high-speed jet airflow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary airflow through an auxiliary air jetting device at an airflow speed of 100-500 m/s, receiving by adopting a frame at a rotating speed of 200-2000 r/min to obtain highly oriented skin-core structure nano fibers, and removing the skin layer inorganic salt and the core layer solution in a dissolving mode to obtain the directionally arranged nano hollow fiber membrane.

Technical Field

The invention relates to a preparation technology of an oriented nano hollow fiber membrane, in particular to a preparation method of a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane.

Technical Field

Membrane separation technology is considered to be one of the most promising technologies from the end of the 20 th century to the beginning of the 21 st century. The technology can effectively purify waste water and recover some useful substances, and the continuously developed technologies such as microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane bioreactors and the like are widely applied to the industries such as chemical industry, environmental protection, energy, electronics, food, medicine, bioengineering and the like. Hollow fiber membranes have been widely used for water and wastewater treatment with their unique advantages, but the hollow fibers prepared by conventional spinning have large diameters, resulting in insufficient packing density, insufficient membrane specific surface area and water production efficiency, and meanwhile, to support the structural integrity of large-diameter fibers, a thick membrane wall is required, resulting in increased mass transfer resistance and decreased separation efficiency.

The coaxial electrostatic spinning is an effective method for preparing continuous superfine sheath-core or hollow fiber, and is different from the conventional electrostatic spinning in that the coaxial electrostatic spinning is a double-channel composite capillary nozzle with a concentric shaft and a single-channel capillary spinneret orifice. The hollow nano fiber is prepared by a coaxial electrostatic spinning technology, and the preparation principle is that water-soluble or volatile substances (such as mineral oil, methyl silicone oil and the like) are generally used as a core layer solution, and after spinning forming, the core layer solution is removed in a dissolving, heating or high-temperature calcining mode to obtain the hollow nano fiber. However, the current electrospinning technology has certain technical problems in popularization, such as relatively low yield of the current electrostatic spinning machine and large difficulty in large-scale application.

The electrostatic assistant solution jet technology is a novel micro-nano fiber preparation method disclosed in Chinese patent (patent No. 201410673678.6). according to the technology, high-speed jet air flow is introduced, so that spinning solution trickles are subjected to the action of the high-speed jet air flow and an electrostatic field of an annular induction electrode to prepare micro-nano fibers in a large scale. However, conventional drum or rotating disk collection fibers are typically deposited as a random network of non-woven aggregates, which is difficult to meet hollow fiber membrane module assembly requirements. The invention introduces an auxiliary air jet device to jet auxiliary air flow, adopts a frame to receive so as to obtain the skin-core structure nano fibers in highly oriented arrangement, and then removes inorganic salt of the skin layer and solution of the core layer in a dissolving mode to obtain the oriented nano hollow fiber membrane. The oriented nano hollow fiber membrane prepared by the method has obviously improved mechanical properties. The following is a detailed summary of the invention.

Disclosure of Invention

The invention relates to a preparation method of a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane, and the technical scheme of the invention can be used for preparing a high-orientation nano hollow fiber membrane. The oriented nano hollow fiber membrane prepared by the invention has excellent mechanical property and high specific surface area, and has wide application prospect in the field of membrane separation.

The invention provides a preparation method of a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane, which is characterized by comprising the following steps:

(1) preparing a skin layer spinning solution: dissolving a water-insoluble polymer in an organic solvent, and adding different types of pore-forming agents to prepare a skin layer spinning solution;

the concentration of the skin layer spinning solution is between 5 and 35 percent; the pore-foaming agent accounts for 0.1-5% of the mass of the skin layer spinning solution;

(2) preparing a core layer spinning solution: taking a polymer solution with excellent water solubility as a core layer solution;

the concentration of the core layer spinning solution is between 5 and 20 percent;

(3) preparing a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the skin layer solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding from a coaxial needle of a spinning nozzle at an extrusion speed of 5-50mL/h, drafting and refining the spinning solution under the action of high-speed jet airflow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary airflow through an auxiliary air jetting device at an airflow speed of 100-500 m/s, receiving by adopting a frame at a rotating speed of 200-2000 r/min to obtain highly oriented skin-core structure nano fibers, and removing the skin layer inorganic salt and the core layer solution in a dissolving mode to obtain the directionally arranged nano hollow fiber membrane.

The pore-forming agent is preferably NaCl, LiCl or AgNO₃And the like.

The water-soluble polymer in the core layer spinning solution of the present invention is preferably any one of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO).

The electrostatic solution jet spinning method is a preparation method of nano-micron fibers reported in Chinese patent ZL 201410673678.6.

According to the technical scheme, the specific surface area of the nano hollow fiber membrane prepared by adopting the coaxial electrostatic solution spraying method is obviously higher than that of the hollow fiber membrane prepared by the traditional spinning method. Meanwhile, the nanofibers are highly oriented by adding an auxiliary air jet and receiving with a frame.

Drawings

FIG. 1 is a schematic view of an auxiliary airflow and frame receiving directional array collection device employed in the present invention.

Fig. 2 is a schematic scanning electron microscope of the directionally aligned PAN nano hollow fiber prepared in example 1 of the present invention.

Fig. 3 is a schematic transmission electron microscope of the directionally aligned PAN nano hollow fiber prepared in example 1 of the present invention.

Detailed Description

The embodiments of the present invention relate to a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane, and several groups of embodiments are described in detail below.

Example 1

(1) Preparing a skin layer spinning solution: dissolving Polyacrylonitrile (PAN) with the average molecular weight of 380,000 in N, N-Dimethylformamide (DMF) according to the mass fraction of 16%, adding LiCl accounting for 2% of the mass of the PAN, and stirring until the mixture is uniformly mixed to prepare a sheath spinning solution;

(2) preparing a core layer spinning solution: dissolving polyvinylpyrrolidone (PVP) in DMF to prepare a core layer spinning solution with the concentration of 16%;

(3) preparing a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the skin layer solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding from a coaxial needle of a spinning nozzle at an extrusion rate of 20mL/h, drafting and refining the spinning solution under the action of high-speed jet airflow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary airflow through an auxiliary air jetting device at an airflow speed of 200m/s, receiving by adopting a frame at a rotating speed of 1000r/min to obtain highly oriented PAN/PVP skin-core structure nano fibers, and soaking in an ethanol solution to remove skin layer LiCl and the core layer to obtain the directionally arranged PAN nano hollow fiber membrane.

Fig. 2 is a schematic scanning electron microscope of the directionally aligned PAN nano hollow fiber prepared in example 1 of the present invention. Fig. 3 is a schematic transmission electron microscope of the directionally aligned PAN nano hollow fiber prepared in example 1 of the present invention.

Example 2

(1) Preparing a skin layer spinning solution: dissolving polyvinylidene fluoride (PVDF) with the average molecular weight of 500,000 in a mixed solvent of acetone and DMF with the volume ratio of 1: 3 according to the mass fraction of 18%, adding LiCl with the mass ratio of 5% relative to the PVDF, and stirring until the mixture is uniformly mixed to prepare a skin layer spinning solution;

(2) preparing a core layer spinning solution: dissolving polyvinyl alcohol (PVA) in deionized water to prepare a core layer spinning solution with the concentration of 10%;

(3) preparing a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the skin layer solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding from a coaxial needle of a spinning nozzle at an extrusion rate of 5mL/h, drafting and refining the spinning solution under the action of high-speed jet airflow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary airflow through an auxiliary air jet device at an airflow speed of 100m/s, receiving by adopting a frame at a rotating speed of 2000r/min to obtain highly oriented PVDF/PVA skin-core structure nano fibers, and soaking in an ethanol solution to remove skin layer LiCl and core layer PVA to obtain the oriented PVDF nano hollow fiber membrane.

Example 3

(1) Preparing a skin layer spinning solution: dissolving polyamide 6(PA6) with the average molecular weight of 100,000 in formic acid according to the mass fraction of 15%, adding NaCl accounting for 1% of the mass of PA6, and stirring until the mixture is uniformly mixed to prepare a skin layer spinning solution;

(2) preparing a core layer spinning solution: dissolving polyethylene oxide (PEO) in deionized water to prepare a core layer spinning solution with the concentration of 5%;

(3) preparing a coaxial electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the skin layer solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding from a coaxial needle of a spinning nozzle at an extrusion rate of 10mL/h, drafting and refining the spinning solution under the action of high-speed jet airflow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary airflow through an auxiliary air jetting device at an airflow speed of 400m/s, receiving by adopting a frame at a rotating speed of 500r/min to obtain highly oriented PA6/PEO skin-core structure nano fibers, and soaking in an ethanol solution to remove skin layer NaCl and core layer PEO to obtain the directionally arranged PA6 nano hollow fiber membrane.

Example 4

(1) Preparing a skin layer spinning solution: dissolving polylactic acid (PLA) with average molecular weight of 150,000 in a mass fraction of 10% in a mixed solvent of dichloromethane and DMF at a volume ratio of 7: 3, and adding AgNO at 3% relative to the mass of PLA₃Stirring until the mixture is uniformly mixed to prepare a skin layer spinning solution;

(2) preparing a core layer spinning solution: dissolving PVP in deionized water to prepare a core layer spinning solution with the concentration of 12%;

(3) coaxial cablePreparing an electrostatic solution jet spinning oriented nano hollow fiber membrane: respectively injecting the cortex solution obtained in the step (1) and the core layer solution obtained in the step (2) into different liquid storage devices, extruding from a coaxial needle of a spinning nozzle at an extrusion rate of 40mL/h, drafting and refining the spinning solution under the action of high-speed jet air flow and an electrostatic field, volatilizing the solvent to form nano fibers, jetting auxiliary air flow through an auxiliary air jet device at an air flow speed of 300m/s, receiving by adopting a frame at a rotating speed of 1000r/min to obtain highly oriented PLA/PVP skin-core structure nano fibers, and soaking in an ethanol solution to remove the cortex AgNO₃And the PLA nanometer hollow fiber membrane in the oriented arrangement can be obtained by the PVP of the core layer.