阅读说明：本技术 一种铜基金属有机框架/聚乙烯醇纤维复合膜及其制备方法 (Copper-based metal organic framework/polyvinyl alcohol fiber composite membrane and preparation method thereof ) 是由 王正帮 黄继明 张婧 于 2019-10-16 设计创作，主要内容包括：本发明公开了一种透明铜基金属有机骨架/PVA纤维复合膜的制备方法的制备方法。(1)以聚乙烯醇(PVA)和离子水为原料,高温搅拌得PVA纺丝溶液。以接地的金属板或者锟作为纤维接收装置,金属喷头和接收装置之间施加高压静电,真空干燥后可得纺丝膜样品；(2)以乙醇为溶剂,分别配置Cu(CH<Sub>3</Sub>COO)<Sub>2</Sub>溶液和均苯三甲酸(BTC)或者对苯二甲酸(BDC)溶液；(3)PVA膜固定在支架上,先用Cu(CH<Sub>3</Sub>COO)<Sub>2</Sub>溶液喷涂,再用乙醇喷涂,然后在室温下用BTC或者BDC溶液喷涂,再用乙醇喷涂,在给定数量的循环后,即可得到透明复合膜。与现有技术相比,本发明的制备的金属有机骨架/PVA纤维复合膜质量高,均匀透明,非常适合在光学中应用。(The invention discloses a preparation method of a transparent copper-based metal organic framework/PVA fiber composite membrane. (1) Polyvinyl alcohol (PVA) and ionized water are used as raw materials, and the PVA spinning solution is obtained by high-temperature stirring. A grounded metal plate or roller is used as a fiber receiving device, high-voltage static electricity is applied between a metal spray head and the receiving device, and a spinning film sample can be obtained after vacuum drying; (2) using ethanol as solvent to prepare Cu (CH) respectively 3 COO) 2 A solution and a trimesic acid (BTC) or terephthalic acid (BDC) solution; (3) the PVA film is fixed on the bracket by Cu (CH) 3 COO) 2 Spraying the solution, spraying with ethanol, and then spraying with BTC or BTC at room temperatureAnd (3) spraying the BDC solution, then spraying the BDC solution by using ethanol, and obtaining the transparent composite film after a given number of cycles. Compared with the prior art, the metal organic framework/PVA fiber composite membrane prepared by the invention has high quality, is uniform and transparent, and is very suitable for being applied in optics.)

1. A preparation method of a copper-based metal organic framework/polyvinyl alcohol fiber composite membrane is characterized by comprising the following steps:

(1) preparing PVA spinning solution by using PVA and water as raw materials; then, applying high-voltage static electricity between the spray head and the fiber receiving device for spinning to obtain a spinning PVA film sample;

(2) using ethanol as solvent to prepare Cu (CH) respectively₃COO)₂Solutions and BTC solutions or BDC solutions;

(3) fixing the spinning PVA film sample obtained in the step (1) on a bracket by using Cu (CH)₃COO)₂Spraying the solution, spraying with ethanol, spraying with BTC solution or BDC solution at room temperature, and spraying with ethanol to complete a spraying cycle; and circulating for a plurality of times according to the spraying sequence to obtain the copper-based metal organic framework/polyvinyl alcohol fiber composite membrane.

2. The method for preparing a copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein in the step (1), the concentration of the PVA spinning solution is in the range of 5-12 wt%.

3. The preparation method of the copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein in the step (1), the PVA is selected from 1788 or 1799, and is heated in a water bath at 80-95 ℃ for 2-6 hours under the stirring condition to prepare PVA spinning solution.

4. The preparation method of the copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein in the step (1), the spinning conditions in the step (1) are as follows: the environment temperature is 25-35 ℃, the humidity is 10-40%, the distance between the fiber receiving device and the spray nozzle is 10-18cm, the spinning voltage is 8-20kV, the spinning speed is controlled at 0.5-1mL/h, and the spinning time is 5-12 hours.

5. The method for preparing the copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein in the step (2), Cu (CH)₃COO)₂The concentration of the solution is in the range of 0.8-1 mmol/L; the concentration of the BTC solution or BDC solution is in the range of 0.16-0.2 mmol/L.

6. The preparation method of the copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein the specific conditions in the step (3) are as follows: the spinning PVA film sample is fixed on a bracket, the distance between a nozzle and the film is 6-12cm, the pressure of sprayed carrier gas is 1-1.5bar, the pressure of liquid is 0.1-0.3bar, and the flow rate of the liquid is 0.1-0.3 mL/s.

7. The method for preparing a copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein in the step (3), Cu (CH) is firstly used at room temperature₃COO)₂Spraying the solution for 10-15s, then dissolving and coating the solution for 8-12s by using an ethanol solvent, then spraying the solution for 20-25s by using a BTC solution or a BDC solution, and then spraying the solution for 8-12s by using the ethanol solvent, wherein the spraying interval is 10-40 s after each spraying, thus completing a spraying cycle.

8. The method for preparing the copper-based metal organic framework/polyvinyl alcohol fiber composite membrane according to claim 1, wherein in the step (3), the circulation is performed for 30-120 times.

9. A copper-based metal organic framework/polyvinyl alcohol fiber composite membrane prepared by the method of claim 1.

10. Use of the composite film according to claim 9 in the optical field as polarizer, scattering film, reflective polarizer, brightness enhancing film and sensor.

Technical Field

The invention belongs to the technical field of polymer composite film material manufacturing, and particularly relates to a preparation method of a copper-based metal organic framework/polyvinyl alcohol (PVA for short) fiber composite film with good light transmittance.

Background

PVA is a semi-crystalline PVA that contains mainly an amorphous phase and is composed of 1, 3-diol units or 1, 2-diol units. The properties of PVA are generally determined by its molecular weight, which is generally between 20,000 and 400,000, and by the degree of alcoholysis, which is generally between 80 and 99%. The PVA has many hydroxyl groups on its surface, which easily form hydrogen bonds in molecules, resulting in high durability and chemical stability. Blends and composites made from PVA are becoming increasingly popular for use in biomedical, cosmetic, food, pharmaceutical, and packaging industries, among others, because of their degradability and biocompatibility.

Metal-Organic Frameworks (MOFs) are a class of highly ordered porous network materials formed by self-assembly of multidentate Organic ligands and inorganic Metal ions or clusters through coordination bonds. Compared with the traditional porous materials such as zeolite, the MOF has the advantages of uniform pore diameter, large porosity, high specific surface area, rich active sites and the like, and is widely applied to potential applications in the aspects of gas storage and separation, catalytic reaction, proton conductors, medicine, sensing and the like. Metal Organic Framework (MOF) thin films are multilayer materials, ranging in thickness from nanometers to micrometers, physically or chemically bonded to (functionalized) substrates, and ideally exhibit low roughness and high uniformity. The MOF film prepared by liquid phase epitaxy layer-by-layer self-assembly has the advantages of adjustable thickness, high orientation degree, uniform surface and the like, and is more and more concerned by scientific researchers.

CN106832707A discloses a preparation method of a copper metal organic framework/polyvinyl alcohol nano composite film, and the obtained copper-based MOF (Cu-MOF)₃(BTC)₂) Mixing with polyvinyl alcohol solution, dripping and coating, and vacuum drying to obtain the composite membrane material. However, in the composite film, the copper-based MOF particles are not uniformly dispersed in the polyvinyl alcohol, or the polyvinyl alcohol wraps the copper-based MOF particles to block micropores of the particles, so that the properties of the film are influenced. CN107383725A discloses a preparation method of a gadolinium metal organic framework/polyvinyl alcohol nano composite membrane, and the composite membrane material is also obtained by mixing, coating and drying methods. The main disadvantages of this approach: aggregation of the MOF particles, and adverse interactions between the PVA matrix and the MOF particles, can lead to "sieve-in-a-cage" or PVA clogging of MThe fine pores OF the particles degrade the film properties.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a transparent copper-based Metal Organic Framework (MOF)/polyvinyl alcohol (PVA) fiber composite membrane and a preparation method thereof aiming at the defects in the prior art, the composite membrane has excellent mechanical strength and toughness and good light transmission performance, the condition that a mesh in a cage or PVA blocks MOF particle micropores is avoided, the MOF membrane is anchored on the surface of the PVA membrane, and the problem in the background technology can be effectively solved.

The technical scheme adopted by the invention for solving the problems is as follows:

a preparation method of a transparent copper-based MOF/PVA fiber composite membrane comprises the following steps:

(1) preparing PVA spinning solution by using polyvinyl alcohol (PVA) and water as raw materials; then, applying high-voltage static electricity between the spray head and the fiber receiving device for spinning to obtain a spinning PVA film sample;

(2) using ethanol as solvent to prepare Cu (CH) respectively₃COO)₂A solution and a trimesic acid (BTC) solution or a terephthalic acid (BDC) solution;

(3) fixing the spinning PVA film sample obtained in the step (1) on a bracket by using Cu (CH)₃COO)₂Spraying the solution, spraying with ethanol, spraying with BTC solution or BDC solution at room temperature, and spraying with ethanol to complete a spraying cycle; and circulating for several times according to the spraying sequence to obtain the transparent copper-based MOF/PVA fiber composite membrane.

According to the above scheme, in the step (1), the concentration of the PVA spinning solution is in the range of 5-12 wt%, preferably 8-10 wt%, so as to control the mechanical strength and toughness. PVA is usually selected from 1788 or 1799 type, and PVA spinning solution can be prepared by heating in water bath at 80-95 deg.C for 2-6h under stirring.

According to the scheme, in the step (1), the spinning conditions are as follows: the environment temperature is 25-35 ℃, the humidity is 10-40%, the distance between the fiber receiving device and the spray head is 10-18cm, the spinning voltage is 8-20kV (preferably 18kV-20kV), the spinning speed is controlled at 0.5-1mL/h, and the spinning time is 5-12 hours. Aluminium foil paper is preferred as the fibre receiving means. The thickness of the electrostatic spinning film can be controlled by the spinning time, and the spinning time is generally 5-12 hours.

According to the scheme, in the step (2), Cu (CH)₃COO)₂The concentration of the solution is in the range of 0.8-1 mmol/L; the concentration of the trimesic acid (BTC) solution or the terephthalic acid (BDC) solution is in the range of 0.16-0.2 mmol/L.

According to the scheme, in the step (3), the spinning PVA film sample is cut into a film with a certain size and fixed on a bracket, the distance between a nozzle and the film is 6-12cm, the pressure of sprayed carrier gas is 1-1.5bar, the pressure of liquid is 0.1-0.3bar, and the flow rate of the liquid is 0.1-0.3 mL/s.

According to the scheme, in the step (3), Cu (CH) is firstly used at room temperature₃COO)₂Spraying the solution for 10-15s, then dissolving and coating the solution for 8-12s by using an ethanol solvent, then spraying the solution for 20-25s by using a BTC solution or a BDC solution, and then spraying the solution for 8-12s by using the ethanol solvent, wherein the interval is 10-40 s after each spraying (the interval can be not be reserved after the ethanol solvent is sprayed), and thus, a spraying cycle is completed.

According to the scheme, in the step (3), 15-120 times of circulation is generally carried out.

The final product transparent copper-based MOF/polymer fiber composite membrane is a novel membrane material assembled by a PVA membrane obtained by electrostatic spinning and an MOF membrane through anchoring acting force, abundant hydroxyl strong polar groups on the PVA chelate metal ions, the metal ions and organic ligands are self-assembled through coordination bonds to form a highly ordered porous network, and the transparency and thickness of the final product are determined by the spraying times (the number of liquid phase epitaxy self-assembly layers). The MOF film grown on the surface of the electrostatic spinning film is used for anchoring polycrystalline MOF on the surface of the PVA spinning film, and the anchoring force is the acting force of forming hydrogen bonds, pi-pi bonds and the like between ligands or metal ions in the MOF and hydroxyl groups of PVA. The MOF membrane is constructed by self-assembling metal ions or clusters serving as nodes and organic ligands serving as connectors on the surface of the PVA membrane but not in the PVA membrane through anchoring force layer by layer, and the thickness of the MOF membrane can be controlled by the spraying cycle number.

Compared with the prior art, the invention has the beneficial effects that:

the copper-based MOF/PVA fiber composite membrane prepared by the invention adopts a liquid phase epitaxy layer-by-layer growth method, has the advantages that composite membrane materials obtained by other methods (such as mixing, coating and drying methods) do not have, (1) a substrate can grow uniform and highly oriented MOF thin films on a PVA substrate without chemical or physical modification, a certain number of growth cycles are selected, the thickness of the film is controllable, the film is transparent, the light transmittance is good, and the composite membrane can be applied to the optical field; (2) the MOF/PVA film has smooth surface and no roughness, allows heterogeneous multilayer deposition, is convenient for researching the growth orientation and mechanism of the metal organic framework compound, can be prepared at normal temperature, does not need high temperature and has low energy consumption; (3) PVA membrane and surface MOF are obtained through the equipment of one kind "anchoring force", have the advantage of two kinds of membranes respectively, sieve in the cage can not appear, more can not appear mixing drip and scribble into the membrane, the condition that PVA blockked up the MOF granule micropore.

Drawings

FIG. 1 shows a copper-based MOF/PVA fiber composite film and a PVA film obtained in example 1;

FIG. 2 is an ultraviolet-visible spectrum of the copper-based MOF/PVA fiber composite film and the pure PVA film obtained in example 1;

FIG. 3 is a Scanning Electron Microscope (SEM) of the copper-based MOF/PVA fiber composite film obtained in example 1; a, B are copper-based MOF/PVA fiber composite membranes under different magnification factors respectively; C. d, E are sections of copper-based MOF/PVA fiber composite membranes sprayed for different times of circulation respectively;

FIG. 4 is an X-ray diffraction (XRD) pattern of the copper-based MOF/PVA fiber composite film obtained in example 1 and copper-based MOF.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the following examples, the chemical reagents were all chemically pure or more.

In the following examples, a constant concentration of Cu (CH) was prepared₃COO)₂The procedure for the ethanol solution was as follows: calculation requires Cu (CH)₃COO)₂Mass, weighing Cu (CH) with balance₃COO)₂Pouring the solid into a beaker, adding a proper amount of ethanol into the beaker, and ultrasonically dissolving for 30min to restore to room temperature; mixing Cu (CH)₃COO)₂Transferring the solution into a volumetric flask by using a glass rod for drainage, washing a beaker and the glass rod for 2-3 times by using ethanol, and injecting a washing solution into the volumetric flask; adding ethanol to 1-2cm of the groove, dripping with rubber dropper, shaking, and labeling.

In the following examples, the procedure for preparing ethanol solutions of trimesic acid (BTC) and terephthalic acid (BDC) at a certain concentration is as follows: calculating a required BTC or BDC mass; weighing BTC or BDC solid by balance, pouring the BTC or BDC solid into a beaker, adding a proper amount of ethanol into the beaker, ultrasonically dissolving, draining the BTC or BDC solution by using a glass rod after the temperature is recovered to room temperature, transferring the BTC or BDC solution into a volumetric flask, washing the beaker and the glass rod by using ethanol for 2-3 times, and injecting a washing solution into the volumetric flask; adding ethanol to the 1-2cm position of the scribed line, dropwise adding with a rubber head dropper, and shaking up; subpackaging and labeling.