200 results about "Diaminodiphenyl ether" patented technology

The invention relates to the technical field of organic chemical synthesis, in particular to a preparation method of 3, 4 '-diaminodiphenyl ether.The preparation method comprises the steps that S1, under inert gas and in a first solvent, m-dinitrobenzene and p-acetamidophenol are subjected to a heating reaction under the condition of a weak base catalyst, and 3-nitro-4-acetamido diphenyl ether is prepared; s2, in a second solvent, the 3-nitro-4-acetamido diphenyl ether is subjected to a hydrogenation reduction reaction, and 3-amino-4-acetamido diphenyl ether is prepared; and S3, dissolving the 3-amino-4-acetaminodiphenyl ether in an alcohol solvent system, adding an aqueous solution of alkali, controlling the reaction temperature, carrying out a hydrolysis reaction, and after the reaction is finished, carrying out post-treatment to obtain the 3, 4 '-diaminodiphenyl ether. The preparation method provided by the invention has the advantages of easily available raw materials, low price, good selectivity and high product yield, and is more suitable for industrial production by comprehensively considering economical efficiency and safety.

The invention relates to the technical field of aromatic polyamide high polymers, in particular to a modified poly-p-phenylene terephthamide fiber with high elongation at break and a preparation method of the modified poly-p-phenylene terephthamide fiber. According to the invention, a small amount of 3, 4-difluorobenzene is introduced According to the preparation method, the third monomer containing 4, 4 '-diaminodiphenyl ether and the fourth monomer containing a diaminophenoxy functional group are added, and the molar ratio of the third monomer and the fourth monomer in the total amount of the diamine monomer is controlled, so that the rigid molecular chain structure of the conventional para-aramid fiber is destroyed to a certain extent, the breaking strength of the fiber is maintained, the elongation at break of the polymer fiber is enhanced, and the service life of the polymer fiber is prolonged. The prepared modified poly-p-phenylene terephthamide can still adopt a dry-jet wet spinning process, the cost of a new production line of a factory is saved, the fiber with stable elongation at break index is obtained by optimizing process conditions and parameters, and the elongation at break of the prepared fiber is 3.6% or above.

The invention relates to the field of lithium battery diaphragms, and particularly discloses an aramid diaphragm for a lithium battery and a preparation method of the aramid diaphragm. The aramid diaphragm for the lithium battery comprises aramid slurry and a base membrane, the aramid slurry is coated on two sides of the base membrane to form an aramid coating, and the aramid slurry is prepared from the following raw materials in parts by weight: 20-40 parts of aramid polymer liquid, 5-10 parts of tencel fibrillation slurry, 1-3 parts of titanium aluminum lithium phosphate nanoparticles, 3-5 parts of nano ceramic particles and 8-15 parts of solvent; the aramid polymer liquid is prepared from the following raw materials in parts by weight: 1 to 3 parts of p-phenylenediamine, 60 to 80 parts of polar solvent, 5 to 10 parts of paraphthaloyl chloride, 1 to 3 parts of 3, 4 '-diaminodiphenyl ether, 1 to 3 parts of o-chloro-p-phenylenediamine and 0.5 to 1 part of polyether surfactant; the aramid polymer liquid is combined with the nano ceramic particles and the tencel fibrillation slurry component to form an intercommunicated porous three-dimensional network structure, so that the air permeability, the thermal stability and the porosity of the aramid diaphragm are improved.

The invention discloses a polyimide hollow fiber gas separation membrane and a preparation method thereof. The polyimide hollow fiber gas separation membrane is prepared from a mixture containing polyimide and an additive through a phase inversion method, the polyimide is prepared by using 2, 2 '-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride as a dianhydride monomer and 1, 3-phenylenediamine and 4, 4'-diaminodiphenyl ether as diamine monomers through solution polycondensation. The weight-average molecular weight of the polyimide is greater than or equal to 60000. The prepared polyimide hollow fiber gas separation membrane is suitable for being applied to multiple fields such as air separation, hydrogen separation, decarburization and rare gas concentration, and the application prospect is wide.

This invention relates to a method for synthesizing iron-cobalt alloy-doped carbon nanofibers for electrocatalysis using zinc oxide etching, belonging to the technical field of electrode materials and catalysts. The preparation method includes the following steps: 1) mixing DMF (dimethylformamide), PMDA (pyromellitic dianhydride), and ODA (4,4-diaminodiphenyl ether) in a certain proportion to prepare a PAA (polyamic acid) spinning solution; 2) preparing PAA nanofibers from the PAA spinning solution using an electrostatic melt-blowing device; 3) imidizing the PAA nanofibers using a programmed temperature rise method to obtain PI nanofibers; 4) impregnating the PI nanofibers in a salt solution; 5) carbonizing the impregnated PI nanofibers with a large number of metal ions on their surface in an inert atmosphere using a certain temperature rise program to obtain iron-cobalt alloy-doped carbon nanofibers. The iron-cobalt alloy-doped carbon nanofibers prepared by this method exhibit excellent performance as an ORR / OER bifunctional electrocatalyst and have wide applications.

The present invention relates to the field of solar-driven interfacial photothermal evaporation technology, and more particularly to a solar-driven interfacial evaporator based on TiN / polyimide aerogel, its preparation method, and application. The TiN / polyimide aerogel comprises a polyimide aerogel matrix with vertical channels connecting upper and lower surfaces, loaded with TiN nanoparticles. The aerogel is prepared by polycondensation, dehydration, and cyclization of the polyimide aerogel 4,4'-diaminodiphenyl ether and 4,4'-oxydiphthalic anhydride. The TiN / polyimide aerogel provided by the present invention, when used as a solar-driven interfacial evaporator, can not only improve the water transfer performance of a three-dimensional photothermal evaporator, but also increase the photothermal evaporation rate during seawater desalination.

The present invention discloses a yellow-green fluorescent COFs material, its preparation method and application, belonging to the fields of covalent organic framework materials and analytical detection. In the present invention, 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetraphenylaldehyde (ETBA) and a flexible organic monomer 4,4'-diaminodiphenyl ether (ODA) with chelating sites are used as raw materials, methanol and acetic acid are added and shaken for dispersion, frozen with liquid nitrogen, evacuated and reacted in a constant temperature oven, the product is collected by filtration, washed with anhydrous N,N-dimethylformamide and tetrahydrofuran respectively, and then centrifuged and washed with anhydrous acetone, the solid product is collected, dried in an oven to obtain yellow ETBA-ODA-COF powder. The present invention regulates the π-π interaction in the COF structure, synthesizes a kind of ETBA-ODA-COF material with yellow-green fluorescence, and can establish a fluorescent nanoprobe to realize the analysis and detection of metal Fe 3+ , Hg 2+ ions and folic acid small molecules.

The invention discloses a lithium ion battery diaphragm and a preparation method thereof, and relates to the technical field of battery diaphragms. When the lithium ion battery diaphragm is prepared, dianhydridized DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), 4, 4 '-diaminodiphenyl ether and 2-vinyl-4, 6-diamino-1, 3, 5-triazine are subjected to a reaction, and polyamide acid microspheres are prepared through electrostatic spraying; the preparation method comprises the following steps: sequentially reacting polyethylene with allylamine and allyl-1, 3-sultone to prepare modified polyethylene; mercaptopropyltrimethoxysilane and hydroxylated boron nitride are subjected to a reaction, and modified boron nitride is prepared; mixing polyvinylpyrrolidone, the modified polyethylene, the polyamide acid microspheres and the modified boron nitride, and performing hot pressing to form a film, so as to prepare the lithium ion battery diaphragm. The lithium ion battery diaphragm prepared by the invention has excellent ionic conductivity, flame retardance and mechanical property.

The invention discloses a preparation method of a polyimide-boron nitride nanosheet heat-conducting composite film. The preparation method comprises the following steps: firstly, dispersing boron nitride nanosheets into N, N-dimethylacetamide containing poly (diallyldimethylammonium chloride) to prepare slurry; meanwhile, 4, 4 '-diaminodiphenyl ether reacts with pyromellitic dianhydride to prepare a polyamide acid solution. And mixing the two materials, forming a layered structure through vertical and horizontal temperature gradients by adopting a bidirectional freezing casting technology, and freezing by liquid nitrogen to obtain the aerogel in oriented arrangement. And performing hot pressing and step-by-step thermal imidization treatment to obtain the heat-conducting composite film. According to the method, the highly-oriented arrangement of boron nitride nanosheets is constructed through bidirectional freezing casting, and the composite film has excellent heat-conducting property and keeps good mechanical strength and flexibility in combination with the surface modification effect. The process is simple and controllable, and is suitable for the fields of flexible electronics, 5G heat dissipation, battery thermal management and the like.

The invention discloses a light-emitting diode packaging material and a preparation method thereof, and relates to the technical field of light-emitting diodes. The method comprises the following steps: adding 4, 4 '-diaminodiphenyl ether into pyromellitic dianhydride for condensation polymerization to obtain a polyamic acid solution, and adding zinc borate nanowires and aluminum nitride powder to prepare an inorganic skeleton enhanced polyamic acid suspension; the preparation method comprises the following steps: reacting zirconium hydroxide sol with an aluminum sec-butoxide solution, and carrying out hydrothermal reaction and high-temperature calcination to obtain ZrO2at-alpha-Al2O3 core-shell particles; the preparation method comprises the following steps: pre-polymerizing 4, 4 '-diphenylmethane bismaleimide and bisphenol A cyanate ester to obtain a prepolymer; the preparation method comprises the following steps: mixing bisphenol A type epoxy resin, inorganic skeleton reinforced polyamide acid suspension, ZrO2at-alpha-Al2O3 core-shell particles and a prepolymer under vacuum, defoaming, injecting into a mold, heating, curing, cooling and demolding to obtain the product. Through the synergistic effect of triple modification, the high temperature resistance and lasting thermal stability of the packaging material are improved, and the packaging material is suitable for the field of light emitting diode packaging with high temperature resistance requirements.

The invention provides a plastic film for packaging a medical non-woven fabric and a preparation method of the plastic film. The plastic film comprises a polyimide layer, an ethylene-vinyl alcohol copolymer layer and a polypropylene layer from outside to inside, the polyimide layer is prepared from the following raw materials: 4, 4-diaminodiphenyl ether, pyromellitic dianhydride, a polyimide coated nano titanium dioxide / tetrapod-like zinc oxide whisker composite material and modified diatomite; the polyimide layer in the plastic film has excellent steam sterilization resistance and good radiation resistance, and after the polyimide layer is matched with the ethylene-vinyl alcohol copolymer layer and the polypropylene layer, the plastic film not only has excellent gas and microorganism barrier properties, but also can adapt to the modes of high-temperature steam sterilization, gamma ray irradiation sterilization and the like; the high mechanical property is kept for a long time, and the risk of damage caused by external force is reduced.

The invention discloses a fireproof flame-retardant battery diaphragm, a preparation method thereof and a fireproof flame-retardant battery, and relates to the technical field of battery diaphragms. When the fireproof flame-retardant battery diaphragm is prepared, boric acid diglyceride and chlorinated trimellitic anhydride mixed liquor react to prepare a flame-retardant monomer; the preparation method comprises the following steps: polymerizing 4, 4 '-diaminodiphenyl ether and a flame-retardant monomer, and carrying out electrostatic spraying to prepare polyamide acid microspheres; dehydrating and drying the polyamide acid microspheres to obtain polyimide microspheres; performing etching-acidification on the polyimide microspheres to prepare carboxylated polyimide microspheres; allyl phosphoric acid and acrylic acid are copolymerized and grafted on the surface of a polyethylene film to prepare a modified polyethylene film; and coating the surface of the modified polyethylene film with the carboxylated polyimide microspheres to prepare the fireproof flame-retardant battery diaphragm. The prepared fireproof flame-retardant battery diaphragm has excellent flame retardance, wetting performance and thermal stability.

The application discloses a preparation method and application of fluorine-containing cross-linkable polyimide-based carbon molecular sieve membrane and belongs to the technical field of gas separation membranes. 4,4'-(hexafluoroisopropyl) diphthalic anhydride is used as a dianhydride monomer, 3,5'-diaminobenzoic acid and 4,4'-diamino diphenyl ether are used as common diamine monomers to copolymerize a polyamide acid solution; the polyamide acid solution is prepared into a casting solution, and after standing and defoaming, a polyamide acid membrane is prepared by using a coating method, and the polyamide acid membrane is imidized to prepare a polyimide membrane; the polyimide membrane is used as a polymer precursor membrane of the carbon molecular sieve membrane, is placed in a programmed temperature carbonization furnace with a protective atmosphere and is high-temperature baked to obtain the fluorine-containing cross-linkable polyimide-based carbon molecular sieve membrane. The carbon molecular sieve membrane is not only easy to prepare but also excellent in anti-aging capacity; the carbon molecular sieve membrane is used for CO2 / N2 and CO2 / CH4 separation, and has a high CO2 permeation coefficient and CO2 / N2 and CO2 / CH4 separation factors.

The invention relates to the technical field of high-molecular polymerization and molding, in particular to a modified para-aramid stock solution, a preparation method and para-aramid fibers.The preparation method comprises the steps that under the inert gas condition, diamine and a chlorosilane polycondensation agent react in a weakly-alkaline polar aprotic solvent, and a silanization modified diamine solution is obtained; the diamine comprises diaminodiphenyl ether and p-phenylenediamine; adding paraphthaloyl chloride into the silanization modified diamine solution to carry out a copolymerization reaction, and after the reaction is finished, carrying out neutralization treatment to obtain the modified para-aramid stock solution. According to the preparation method of the modified para-aramid stock solution, the modified diamine does not need to be independently purified, the high-viscosity modified para-aramid stock solution can be directly obtained, and the modified para-aramid stock solution is high in polymer specific concentration logarithmic viscosity and high in molecular weight, so that a high-quality and stable-quality para-aramid fiber product is more favorably obtained.

According to the fluorine-containing polyimide resin and the epoxy resin adhesive based on the fluorine-containing polyimide resin, 2-trifluoromethyl-4, 4 '-diaminodiphenyl ether containing-CF3 is used as a raw material, and dianhydride containing a flexible group and dianhydride containing a rigid group are subjected to proportion optimization and compounding to synthesize the fluorine-containing polyimide resin. And mixing the epoxy resin with tetrafunctional epoxy resin, bifunctional epoxy resin and a curing agent to obtain the epoxy resin adhesive. According to the fluorine-containing polyimide resin, the glass transition temperature of the adhesive can be increased, the heat resistance of the adhesive is enhanced, meanwhile, due to the fact that the fluorine-containing polyimide resin contains-CF3, the solubility of the fluorine-containing polyimide resin in an epoxy system can be increased, and the water absorption rate and the dielectric constant of the adhesive are reduced.

The invention discloses a water treatment filtering material and a preparation method thereof, and relates to the technical field of water treatment. When the water treatment filtering material is prepared, alkaline lignin, epichlorohydrin and triethylenetetramine are subjected to a reaction through a reverse suspension cross-linking technology, and lignin porous microspheres are prepared; carrying out reaction on the lignin porous microspheres and picolinamide ligands to obtain modified lignin porous microspheres; 3-mercaptopropyltriethoxysilane and titanium dioxide are subjected to a reaction, and modified titanium dioxide is prepared; the preparation method comprises the following steps: reacting pyromellitic dianhydride, 1, 4-diaminobutylene and 4 ', 4-diaminodiphenyl ether to prepare functionalized polyamide; the functional polyamide, the modified lignin porous microspheres and the modified titanium dioxide are prepared into a spinning solution, and a polyamide membrane is prepared through electrostatic spinning; and carrying out liquid reaction on bromohexane on the polyamide membrane to obtain the water treatment filtering material. The prepared water treatment filtering material has excellent antibacterial property, heavy metal adsorption property, dye removal property and mechanical property.

The invention provides a gradient hydrophilic-hydrophobic diaphragm for an aqueous zinc ion battery, the gradient hydrophilic-hydrophobic diaphragm comprises a hydrophilic layer, a first hydrophobic layer and a second hydrophobic layer, the hydrophilic layer is located between the first hydrophobic layer and the second hydrophobic layer, so that the gradient hydrophilic-hydrophobic diaphragm with alternate hydrophobicity and hydrophilicity is formed; wherein the hydrophilic diaphragm layer is prepared by adopting an electrostatic spinning process and taking a mixed solution of 4, 4 '-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) as a hydrophilic precursor; the hydrophobic diaphragm layer is prepared by adopting an electrostatic spinning process and taking a mixed solution of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) as a hydrophobic precursor. The gradient hydrophilic-hydrophobic diaphragm disclosed by the invention can reduce a desolvation potential barrier so as to inhibit the occurrence of side reactions, inhibit disordered growth of zinc negative electrode dendrites, keep the electrochemical performance of the zinc ion battery unchanged, and improve the cycle performance of the battery.

This invention discloses an MPP pipe for power cables and its preparation method, relating to the field of polymer materials technology. The invention comprises, by weight, 80-90 parts of a toughening nucleating agent; 40-45 parts of an insulating nucleating agent obtained by in-situ composite and gradient temperature imidization treatment of a polyamic acid prepolymer prepared from hexagonal boron nitride nanosheets (prepared by surface modification with dopamine hydrochloride, followed by modification with octyltriethoxysilane) to obtain a silanized boron nitride suspension; 40-45 parts of melamine cyanurate; 2.1-2.4 parts of an antioxidant; 2.6-3 parts of a light stabilizer; 8-9 parts of a lubricant; and 1340-1500 parts of polypropylene. The introduction of the toughening nucleating agent and insulating nucleating agent in this invention effectively improves the flame retardancy, low-temperature rigidity-toughness balance, and aging resistance of the MPP pipe.

The invention relates to the technical field of nano materials, and provides a preparation method and application of a friction nano generator with high surface charge density. The invention aims to overcome the defects of low surface charge density, environmental influence, easy aging and the like in high-frequency mechanical energy collection of the existing friction nano-generator, and the application of the friction nano-generator in environmental mechanical energy collection is improved. The main scheme is as follows: 4, the preparation method comprises the following steps: dissolving 4, 4 '-diaminodiphenyl ether in N, N'-dimethylacetamide, adding diphenyl ether dianhydride into the solution to synthesize a polyamide acid solution, carrying out electrospinning and high-temperature treatment on the solution to obtain an imidized nanofiber membrane, treating the surface of the nanofiber membrane through a plasma sputtering instrument, selecting a fluorinated ethylene-propylene copolymer as an electric negative electrode material, and carrying out electrospinning and high-temperature treatment on the surface of the nanofiber membrane. And pasting an electrode and packaging to construct the friction nano generator. The invention is used in the fields of friction power generation, mechanical sensing and the like, and has the advantages of simple process, high preparation speed, high yield, low cost, good robustness, no environmental influence and high output performance.

The invention discloses a flame-retardant heat-insulating aluminum foil reinforced composite material and a preparation method thereof, and belongs to the technical field of aluminum foil reinforced composite materials. The flame-retardant heat-insulating aluminum foil reinforced composite material prepared by the invention sequentially comprises an aluminum foil layer, a reinforced net, kraft paper and a flame-retardant adhesive layer for bonding the aluminum foil layer and the reinforced net and bonding the reinforced net and the kraft paper from bottom to top, the flame-retardant adhesive layer comprises the following raw material components: a dianhydride monomer, an amine monomer and a heat-insulating filler; the amine monomer comprises 4, 4 '-diaminodiphenyl ether, flame-retardant diaminobenzimidazole and 4-aminobenzonitrile, the heat-insulating filler is prepared from hydroxyapatite nanowires, montmorillonite nanosheets and aminated polyvinyl alcohol, and the flame-retardant heat-insulating aluminum foil reinforced composite material prepared by the preparation method disclosed by the invention is relatively good in flame retardance and heat insulation.

The present invention provides a polyimide film comprising a copolymer in which an acid dianhydride monomer containing pyromellitic dianhydride (PMDA) is copolymerized with a diamine monomer containing 4,4'-diaminodiphenyl ether (ODA) and m-tolidine (m-TD), wherein the thermal expansion coefficient CTETD in the transverse direction (TD) of the film, measured under conditions of a temperature range of 50-200°C and a heating rate of 10°C / min, is -5 to 2.5ppm / °C, and the modulus thereof is 8GPa or more.

The application provides a porous carbon nanofiber electrocatalyst loaded with cobalt / lanthanum hydroxide heterojunction and a preparation method. The preparation method comprises the following steps: adding 4,4-diamino diphenyl ether and pyromellitic dianhydride into a solvent, uniformly mixing, and preparing a polyamide acid precursor spinning solution; electrospinning the prepared polyamide acid precursor spinning solution to prepare polyamide acid nanofibers; immersing the prepared polyamide acid nanofibers in a mixed metal salt solution containing cobalt salt, lanthanum salt and zinc salt to prepare polyamide acid nanofiber precursors loaded with metal ions; and performing programmed temperature heat treatment on the prepared polyamide acid nanofiber precursors loaded with metal ions in a protective atmosphere to prepare the porous carbon nanofiber electrocatalyst loaded with cobalt / lanthanum hydroxide heterojunction. The prepared porous carbon nanofiber electrocatalyst loaded with cobalt / lanthanum hydroxide heterojunction has excellent electrochemical oxygen reduction reaction and oxygen evolution reaction bifunctional catalytic activity.

The present invention discloses a polyimide vibrating film and a production process thereof, relating to the technical field of polyimides. By introducing 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl monomer as a fifth monomer into 4,4'-diaminodiphenyl ether, 3,3,4,4-diphenyl ether tetracarboxylic dianhydride, 3,3,4,4,-biphenyl dianhydride, and pyromellitic dianhydride monomers, the prepared polyimide film exhibits excellent mechanical properties, a low dielectric constant, a high elongation at break, and stable voltage breakdown resistance.

Provided is a polyimide resin powder which contains a tetracarboxylic acid component and a diamine component. The tetracarboxylic acid component includes 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and 2,3,3',4'-biphenyltetracarboxylic acid dianhydride. The diamine component includes p-phenylenediamine and m-phenylenediamine and / or 4,4'-diaminodiphenyl ether. The content of p-phenylenediamine is 70-98 mol% based on the total molar amount of the diamine component. The total content of m-phenylenediamine and 4,4'-diaminodiphenyl ether is 2-30 mol% based on the total molar amount of the diamine component.

The invention belongs to the technical field of polyimide materials, and particularly relates to an interpenetrating network type polyimide material as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out first polycondensation on pyromellitic dianhydride and 4, 4 '-diaminodiphenyl ether to obtain first polyamide acid; performing first cross-linking on the first polyamide acid under the action of a first cross-linking agent to obtain a first cross-linked network; carrying out second polycondensation on the amino-terminated poly (dimethyl siloxane) and 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride to obtain second polyamide acid; mixing the first polyamic acid and the second polyamic acid for pre-reaction, and then adding a second cross-linking agent for second cross-linking to obtain a precursor solution; and carrying out imidization on the precursor solution to obtain the interpenetrating network type polyimide material. The interpenetrating network type polyimide material obtained by the preparation method provided by the invention realizes synergistic enhancement of strength and toughness.

The invention discloses a polyimide vibration film and a production process thereof, and relates to the technical field of polyimide. According to the invention, a 2, 2-bis (trifluoromethyl)-4, 4-diaminodiphenyl monomer is introduced into 4, 4 '-diaminodiphenyl ether, 3, 3, 4, 4-diphenyl ether tetracarboxylic dianhydride, 3, 3, 4, 4-biphenyl dianhydride and pyromellitic dianhydride monomers as a fifth monomer to participate in copolymerization; the prepared polyimide film is excellent in mechanical property, low in dielectric constant, high in elongation at break and stable in voltage breakdown resistance.

The invention belongs to the field of intelligent materials, and discloses nanofiber-based shape memory aerogel as well as a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: adding 4, 4-diaminodiphenyl ether and 1, 2, 4, 5-pyromellitic dianhydride into N, N-dimethylformamide to prepare a polyamide acid solution; carrying out electrostatic spinning by taking the polyamide acid solution as a spinning solution to obtain a polyamide acid nanofiber membrane; cutting the polyamide acid nanofiber membrane into fibers with micron lengths, and carrying out amidation treatment to obtain polyimide nanofibers; the preparation method comprises the following steps: adding polyimide nanofibers, high-molecular-weight polyethylene glycol diacrylate and low-molecular-weight polyethylene glycol diacrylate into water, uniformly dispersing, and then adding ammonium persulfate and tetramethylethylenediamine to obtain a first mixed solution; performing freeze polymerization reaction on the first mixed solution, and performing freeze drying after the reaction is finished to obtain the nanofiber-based shape memory aerogel. The aerogel has excellent mechanical properties and shape memory properties, and can be widely applied to the industry.

The present application relates to the technical field of aromatic polyamide polymer, in particular to a modified poly-p-phenyleneterephthalamide fiber with high elongation at break and a preparation method thereof.The present application introduces a small amount of 3,4'-diamino diphenyl ether and a fourth monomer containing a bis-amino phenoxy functional group during polymerization, and controls the molar ratio of the third monomer and the fourth monomer in the total amount of diamine monomer, thereby to a certain extent, the rigid molecular chain structure of the conventional p-aramid is destroyed, while the breaking strength of the fiber is maintained, the elongation at break of the polymer fiber is enhanced, the modified poly-p-phenyleneterephthalamide can still be prepared by dry spraying wet spinning process, the cost of building a new production line in the factory is saved, the process conditions and parameters are optimized, the fiber with stable elongation at break index is obtained, and the prepared fiber has an elongation at break of more than 3.6%.

The invention records a fluorenyl polyimide film with a low dielectric constant and a preparation method and application thereof, and the polyimide is prepared by taking 9, 9-bis (4-(4-aminophenoxy) phenyl) fluorene and 4, 4 '-diaminodiphenyl ether diamine as diamine and aromatic dianhydride as dianhydride, and carrying out thermal imidization on the diamine and the dianhydride to obtain the PI film. The PI film provided by the invention has an asymmetric molecular structure, a fluorine-containing group and a fluorene group. The fluorine group has smaller dipole and lower polarizability, and can increase the free volume, and the free volume of the polymer material is increased, so that the number of polar groups in unit volume can be reduced, and the dielectric constant of the PI film can be reduced. The method can be applied to the high-tech fields of low-dielectric materials, gas separation membranes, fuel cell proton exchange membranes, outer space and the like.

The present invention provides a polyimide film comprising, as polymeric units, dianhydride monomers comprising pyromellitic dianhydride (PMDA), and diamine monomers comprising 4,4'-methylenedianiline (MDA), meta-phenylenediamine (MPD), 4,4'-diaminodiphenyl ether (ODA), and para-phenylenediamine (PPD), the tensile strength and percent elongation of the polyimide film being 180 MPa or greater and 90% or greater, respectively.