阅读说明：本技术 一种通过间接热致相分离制备多孔聚苯并咪唑材料的方法 (Method for preparing porous polybenzimidazole material through indirect thermally induced phase separation ) 是由 李文彬 于 2020-04-08 设计创作，主要内容包括：本发明涉及一种通过间接热致相分离制备多孔聚苯并咪唑材料的方法,首先将第一聚合物和第二聚合物溶解在第一溶剂中,然后在温度为T<Sub>1</Sub>(30～80℃)的条件下加入第二溶剂至第一聚合物和第二聚合物析出,接着升温至T<Sub>2</Sub>(140～180℃)至第一聚合物和第二聚合物溶解,最后降温至T<Sub>3</Sub>(0～40℃)至第二聚合物析出,整个体系形成凝胶后,除去除第一聚合物以外的所有物质得到多孔聚苯并咪唑材料；第一聚合物为聚苯并咪唑,第二聚合物为PVA、聚乙烯吡咯烷酮、聚乙二醇和聚马来酸酐中的一种以上,第一溶剂为NMP、DMAc和DMF中的一种以上,第二溶剂为醇类溶剂和醚类溶剂中的一种以上。本发明的方法,简单易行,应用前景广阔。(The invention relates to a method for producing porous polybenzimidazole materials by indirect thermally induced phase separation, first of all a first polymer and a second polymer are dissolved in a first solvent and then the solution is heated at a temperature T 1 Adding a second solvent under the condition of (30-80 ℃) until a first polymer and a second polymer are precipitated, and then heating to T 2 (140-180 ℃) until the first polymer and the second polymer are dissolved, and finally cooling to T 3 (0-40 ℃) until a second polymer is separated out, and removing all substances except the first polymer after the whole system forms gel to obtain a porous polybenzimidazole material; the first polymer is polybenzimidazole, the second polymer is more than one of PVA, polyvinylpyrrolidone, polyethylene glycol and polymaleic anhydride, the first solvent is more than one of NMP, DMAc and DMF, and the second solvent is more than one of alcohol solvents and ether solvents. The method is simple and feasible and has wide application prospect.)

1. A method for preparing a porous polybenzimidazole material by indirect thermally induced phase separation is characterized by comprising the following steps: first the first polymer and the second polymer are dissolved in a first solvent and then at a temperature T₁Adding a second solvent under the conditions of (1) until the first polymer and the second polymer are precipitated, and then heating to T₂Until the first polymer and the second polymer are dissolved, and finally, the temperature is reduced to T₃Until the second polymer is separated out, and after the whole system forms gel, removing all substances except the first polymer to obtain the porous polybenzimidazole material;

the first polymer is polybenzimidazole, the second polymer is more than one of PVA, polyvinylpyrrolidone, polyethylene glycol and polymaleic anhydride, and the first polymer is prepared from one or more of PVA, polyvinylpyrrolidone, polyethylene glycol and polymaleic anhydrideThe solvent is more than one of NMP, DMAc and DMF, and the second solvent is more than one of alcohol solvent and ether solvent; t is₁、T₂And T₃Respectively at 30-80 ℃, 140-180 ℃ and 0-40 ℃.

2. The method of claim 1, wherein the alcoholic solvent is cyclohexanol, terpineol, glycerol, butanediol, hexanediol, sorbitol, pentaerythritol, diethylene glycol or triethylene glycol, and the ether solvent is glycerol triglycidyl ether, ethylene glycol monoglycidyl ether, diethyl phthalate or ethylene glycol monoethyl ether.

3. The method for preparing the porous polybenzimidazole material by the indirect thermally induced phase separation according to claim 2, wherein the mass ratio of the first polymer to the second polymer to the first solvent to the second solvent is 5-15: 65-75: 8-15.

4. The method of claim 3, wherein the second solvent is added and the T is the temperature of the porous polybenzimidazole₁Keeping the temperature for 30-60 min under the temperature condition; heating to T₂Keeping the temperature for 80-150 min; cooling to T₃And keeping the temperature for 20-80 s.

5. The method for preparing a porous polybenzimidazole material by indirect thermally induced phase separation according to claim 3, wherein the temperature rise rate is 5-20 ℃/min; the cooling rate is 100-200 ℃/min.

6. A method of preparing a porous polybenzimidazole material by indirect thermally induced phase separation according to claim 1 where all but the first polymer is removed by extraction.

7. The method of claim 6, wherein the solvent used for extraction is water, methanol, ethanol, isopropanol, acetone, chloroform, dichloromethane or carbon tetrachloride.

8. The method of claim 1, wherein the porous polybenzimidazole material obtained by indirect thermally induced phase separation has an average pore size of 0.7 to 1.5 μm, a porosity of 45 to 65%, a tensile strength of 40 to 70MPa, and an elongation at break of 30 to 60%.

Technical Field

The invention belongs to the technical field of porous materials, and relates to a method for preparing a porous polybenzimidazole material by indirect thermally induced phase separation.

Background

Thermally induced phase separation (TPIS) is an effective method for manufacturing porous and microporous membranes, wherein a polymer is melted at high temperature to form a uniform solution phase with a high-boiling-point solvent, the whole solution phase is solidified by a rapid cooling method, and then the solvent is extracted to obtain porous membranes with various microstructures. The TPIS preparation process has few influencing factors and easily controlled structure; however, since the TPIS method requires a polymer having a definite melting point and a high-temperature solvent having a boiling point higher than that of the polymer, and the polymer and the solvent can form a uniform solution at a high temperature, the TPIS method can be used to prepare a porous film with less polymers, mainly polyolefins, PVDF, etc., such as: patents CN200810147491, CN200810172232, CN201710496247, etc. all use polysulfone, polyolefin or polyvinyl fluoride, etc. with low melting point to prepare membrane materials with porous structure by thermally induced phase separation.

Polybenzimidazole has a high melting point, is difficult to process, is difficult to find a small molecular solvent with a boiling point higher than the melting point of the polymer and also needs a good solubility for the polymer, and because polybenzimidazole can only be dissolved in a few polar aprotic solvents, and the solubility of polybenzimidazole is little changed along with the temperature rise, the polybenzimidazole cannot meet the requirements of a TIPS method, so that a porous structure cannot be formed by the traditional TPIS method.

Therefore, the research on a method for preparing the porous material by thermally induced phase separation of the polybenzimidazole is of great significance.

Disclosure of Invention

The invention aims to solve the problem that polybenzimidazole is difficult to form a porous structure by a TIPS method in the prior art, and provides a method for preparing a porous polybenzimidazole material by indirect thermally induced phase separation.

In order to achieve the purpose, the invention adopts the following scheme:

a process for preparing porous polybenzimidazole material by indirect thermally induced phase separation by first dissolving a first polymer and a second polymer in a first solvent and then heating at a temperature T₁Adding a second solvent under the conditions of (1) until the first polymer and the second polymer are precipitated, and then heating to T₂The addition of the second solvent results in a reduction in the dissolving capacity of the first solvent (a fixed amount of solvent, less mass of polymer that can be dissolved) because a portion of the first solvent will bind to the second solvent, the second polymer begins to dissolve in the second solvent after the temperature is raised, the second polymer dissolved in the first solvent begins to gradually transfer to the second solvent, the precipitated first polymer gradually dissolves in the first solvent, and after a certain period of time of equilibration, the first solvent is mainly composed of the first polymer and the second polymerThe first polymer and a small amount of the second polymer, and the second polymer is contained in the second solvent. ) Finally cooling to T₃Until the second polymer is separated out, and after the whole system forms gel, removing all substances except the first polymer to obtain the porous polybenzimidazole material;

the first polymer is polybenzimidazole, the second polymer is more than one of PVA, polyvinylpyrrolidone, polyethylene glycol and polymaleic anhydride, the first solvent is more than one of NMP, DMAc and DMF, and the second solvent is more than one of alcohol solvent and ether solvent; t is₁、T₂And T₃Respectively at 30-80 ℃, 140-180 ℃ and 0-40 ℃, T₁、T₂Setting in this range ensures the dissolution of the polymer, T₃And T₂When the temperature difference is larger, the higher the gelling speed is, the formed porous structure has certain strength, the subsequent processing is ensured, and if T is greater₃Too high a gel structure formed has no strength and subsequent processing is not guaranteed.

Polybenzimidazole does not have the characteristic of thermally induced phase separation, does not have a proper solvent to ensure that the solubility of polybenzimidazole changes along with the temperature, and cannot meet the requirements of a TIPS (TIPS process), and the polybenzimidazole forms a porous structure by a non-solvent induced phase separation or electrostatic spinning method in the prior art, so the polybenzimidazole has the following defects: the porous membrane prepared by non-solvent induced phase separation is difficult to obtain pores with a through structure, a compact structure is easily formed on the surface of the thin membrane in the preparation process, macropores are formed in the interior of the thin membrane, and the sizes of the pores are not uniform; the electrostatic spinning efficiency is low, the morphology of the pores is difficult to control, the pore diameter is large and uneven, and the porosity is high. The method takes polybenzimidazole as a first polymer (main polymer) and realizes phase separation transformation of the whole system through thermally induced phase separation of a second polymer, firstly, the polybenzimidazole and the second polymer are dissolved in a first solvent, and a certain proportion of the second solvent is added, so that the two dissolved polymers can be gradually precipitated along with the addition of the second solvent as the second solvent is a poor solvent for the polybenzimidazole and the second polymer at a low temperature (30-80 ℃); then, the temperature is raised to 140-180 ℃, the second solvent becomes a good solvent for the second polymer, but the second solvent is still a poor solvent for the polybenzimidazole, so the precipitated second polymer or the second polymer dissolved in the first solvent can be gradually dissolved in the second solvent, and the precipitated polybenzimidazole can be gradually dissolved back to the first solvent due to the reduction of the second polymer dissolved in the first solvent to form a uniform mixed solution; when the temperature is reduced to 0-40 ℃, the second polymer dissolved in the second solvent is rapidly separated out to cause gel of the whole solution system, and the separated second polymer plays a role in occupying space; finally, the first solvent and the second solvent are removed through extraction, water washing and the like, and the polybenzimidazole material with a porous structure can be obtained.

As a preferable scheme:

the method for preparing the porous polybenzimidazole material by the indirect thermally induced phase separation comprises the steps of using cyclohexanol, terpineol, glycerol, butanediol, hexanediol, sorbitol, pentaerythritol, diethylene glycol or triethylene glycol as the alcohol solvent, and using glycerol triglycidyl ether, ethylene glycol monoglycidyl ether, diethyl phthalate or ethylene glycol monoethyl ether as the ether solvent.

According to the method for preparing the porous polybenzimidazole material through indirect thermally induced phase separation, the mass ratio of the first polymer to the second polymer to the first solvent to the second solvent is 5-15: 65-75: 10-15, and due to the limited dissolving capacity of the solvent, if the dosage of the first polymer and the second polymer is too large or the dosage of the first solvent and the second solvent is too small, a uniform solution cannot be formed at a high temperature.

A method for preparing porous polybenzimidazole material by indirect thermal phase separation as described above, after adding the second solvent, at T₁Keeping the temperature for 30-60 min under the temperature condition; heating to T₂Keeping the temperature for 80-150 min; cooling to T₃Keeping the temperature for 20-80 s, T₁、T₂The holding time under temperature conditions is set in this range in order to ensure sufficient dissolution, T₃The holding time under temperature conditions is set within this range in order to ensure complete formation of the porous structure.

According to the method for preparing the porous polybenzimidazole material through indirect thermally induced phase separation, the heating rate is 5-20 ℃/min; the cooling rate is 100-200 ℃/min, the heating rate is not too high, the cooling rate influences the formed porous structure, and the faster the cooling is, the more symmetrical the holes on the front surface and the back surface are.

A method of preparing a porous polybenzimidazole material by indirect thermally induced phase separation as described above, by extraction with the exception of the first polymer.

The method for preparing the porous polybenzimidazole material by indirect thermally induced phase separation is characterized in that the solvent used for extraction is water, methanol, ethanol, isopropanol, acetone, chloroform, dichloromethane or carbon tetrachloride, the solvent is mutually soluble with the first solvent and the second solvent, part of the solvent can dissolve the second polymer, and other organic solvents meeting the requirement are also suitable for the invention.

According to the method for preparing the porous polybenzimidazole material through indirect thermally induced phase separation, the finally prepared porous polybenzimidazole material has the average pore diameter of 0.7-1.5 mu m, the porosity of 45-65%, the tensile strength of 40-70 MPa and the elongation at break of 30-60%.

Has the advantages that:

(1) according to the method for preparing the porous polybenzimidazole material through indirect thermally induced phase separation, polybenzimidazole which does not have thermally induced phase separation characteristics can form a porous structure through a TIPS method, so that the application range of the TIPS method is expanded;

(2) the method for preparing the porous polybenzimidazole material by indirect thermally induced phase separation is also suitable for some polymers which do not have thermally induced phase separation characteristics except the polybenzimidazole;

(3) the method for preparing the porous polybenzimidazole material through indirect thermally induced phase separation is simple and easy to implement, low in cost and wide in application prospect.

Detailed Description

The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.