CN114633468A - Method for preparing three-dimensional aramid aerogel through suspension 3D printing and application - Google Patents

Abstract

The invention discloses a method and application for preparing three-dimensional aramid aerogel by suspension 3D printing. The preparation method includes: at least uniformly mixing aramid nanofibers, functional additives and solvents to form an aramid nanofiber dispersion as a 3D printing ink; The matrix is used as a suspension matrix; through the auxiliary action of the suspension matrix, suspension 3D printing is carried out by the direct-writing molding printing method to obtain a 3D printed three-dimensional aramid fiber gel component, which is stably placed in the suspension matrix; 3D printed stereo-aramid aerogels were obtained. The suspension 3D printing preparation method of the present invention can print three-dimensional aramid fiber gels of any size and shape, with low energy consumption, high printing precision, and simple process. Surface area, low thermal conductivity, structural designability, and broad application prospects.

Description

A method and application of suspension 3D printing to prepare three-dimensional aramid aerogel

technical field

The invention relates to a 3D printing method, in particular to a 3D printing three-dimensional aramid aerogel, and a method and application for preparing a 3D printing three-dimensional aramid aerogel by a novel suspension 3D printing method, belonging to 3D printing and nanoporous material technology field.

Background technique

3D printing technology, also known as additive manufacturing technology, is a rapid prototyping technology that began to emerge in the late 1980s. According to the precise design of objects by computer-aided design (CAD) or tomography (CT), it accurately 3D stacks ink materials and prints complex 3D components layer by layer. Compared with traditional manufacturing methods, 3D printing technology can not only greatly reduce production costs, but also break through the limitations of traditional manufacturing processes on complex shapes. As one of the most disruptive technologies in the future, 3D printing technology has attracted global attention and has been widely used in medical treatment, aerospace, construction and automobiles.

3D printing technology mainly includes fused deposition technology, inkjet printing technology, light curing technology, selective laser sintering, direct writing technology, etc. Among them, direct writing technology is an extrusion-based 3D printing technology, that is, the layer-by-layer deposition of liquid ink materials. The direct writing technology can be compatible with a variety of materials, and can print multiple materials at the same time, and the equipment is simple, the operation is simple, and the cost is relatively low.

Aerogel is a class of lightest solid materials listed in the Guinness Book of World Records, and is also hailed as a new material that has changed the world. It is a kind of gel material whose dispersion medium is gas, and is composed of nano-porous in which colloidal particles or polymer molecules are mutually accumulated into a network structure. Among them, aramid aerogel is widely used in protective equipment, infrared Stealth, thermal insulation, sports protection and other fields have shown extremely high application potential. Although 3D printing aramid aerogel has been prepared by the freezing-direct writing printing method (public number CN110982111A), the printing method has the following Defects: (1) Unable to print three-dimensional structures; (2) The printing height is limited; (3) There are requirements for the rheology of the ink, that is, the ink needs to have a certain viscosity and modulus, so that the ink can maintain a certain amount after extrusion. shape; (4) Sometimes a refrigeration system is required, and the energy consumption is high. Therefore, it is still a serious challenge to prepare aramid aerogels with three-dimensional structures by a 3D printing method with low energy consumption, high precision, and unlimited size and shape.

Based on this, it is an urgent problem to develop a new type of 3D printing technology to overcome the shortcomings of the existing direct writing technology and to prepare 3D printed three-dimensional aramid aerogels to meet the needs of practical applications.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a 3D printing three-dimensional aramid aerogel and a method for preparing a 3D printing three-dimensional aramid aerogel by a suspension 3D printing method, so as to overcome the deficiencies in the existing 3D printing technology and realize the three-dimensional structure of aramid fiber. The self-support of aerogel expands the application scope of 3D printing and aramid aerogel.

Another object of the present invention is to provide the use of the aforementioned 3D printing three-dimensional aramid aerogel.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

The embodiment of the present invention provides a method for preparing a three-dimensional aramid aerogel by suspension 3D printing, which includes:

At least uniformly mixing aramid nanofibers, functional additives and solvent to form aramid nanofiber dispersion;

Use a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion as a suspension matrix;

Through the auxiliary action of the suspension matrix, the direct-writing molding printing method is used to perform suspension 3D printing with the aramid nanofiber dispersion as a 3D printing ink to obtain a 3D printed three-dimensional aramid gel component, which is stably placed in the suspension in the matrix;

Then, the 3D-printed three-dimensional aramid fiber gel component is sequentially subjected to solvent replacement and drying treatment to obtain a 3D-printed three-dimensional aramid fiber aerogel.

In some embodiments, the suspending matrix includes the main ingredients and solvent, and preferably also includes auxiliary ingredients.

In some embodiments, the main components include but are not limited to cross-linked polyacrylic acid copolymer, polyacrylamide, polyvinyl alcohol, gelatin, sodium alginate, dimethacrylate modified polyethylene glycol, silica , Magnesium Lithium Silicate etc. any one or a combination of two or more.

In some embodiments, the auxiliary components include, but are not limited to, any one or a combination of two or more of potassium hydroxide, sodium hydroxide, triethanolamine, sodium bicarbonate, ammonia water, calcium chloride, and the like.

Further, the solvent includes one or a combination of two or more selected from water, ethanol, acetic acid, dimethyl sulfoxide, polyethylene glycol, glycerol, nitrogen methylpyrrolidone, acetone, and the like.

In some embodiments, the functional additives include, but are not limited to, carbon nanotubes, graphene, transition metal nitrides or carbides, metals, silica particles, etc., any one or a combination of two or more, so that Endows the final product with high electrical conductivity, high thermal conductivity/thermal insulation, light absorption, and electromagnetic shielding functions.

In some embodiments, the method specifically includes: transferring the 3D printing ink into a syringe of a 3D printer, and at room temperature, with the aid of the suspension matrix, and using a direct writing molding printing method, the aromatic The fiber nanofiber dispersion is directly extruded into the suspension matrix according to the set path, and finally a 3D printed three-dimensional aramid fiber gel component is obtained.

The embodiment of the present invention also provides a 3D printed stereo-aramid aerogel prepared by the aforementioned method, which has a three-dimensional structure and has a hierarchical porous aramid nanofiber network structure, and the hierarchical porous aramid nanofiber network structure is composed of pore diameters in Composed of micropores below 2nm, mesopores with pore diameters of 2nm to 50nm, and macropores with pore diameters of 50nm to 10cm, the 3D printed three-dimensional aramid aerogel has a porosity of 50 to 99.99% and a density of 0.1 to 1500mg/ cm ³ , the specific surface area is 50-2500 m ² /g, the pore volume is 0.1-15 cm ³ /g, and the thermal conductivity is 0.025-0.06 W/(m ^. K).

The embodiments of the present invention also provide applications of the aforementioned 3D printed three-dimensional aramid aerogel in the fields of thermal insulation, catalysis, separation/adsorption, seawater desalination, or electromagnetic shielding.

The embodiment of the present invention also provides a method for preparing a three-dimensional aerogel by suspension 3D printing, which includes:

At least the nanofibers, functional additives and solvent are uniformly mixed to form a nanofiber dispersion;

Use a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion as a suspension matrix;

Through the auxiliary action of the suspension matrix, using the direct writing molding printing method, the nanofiber dispersion liquid is used as a 3D printing ink for suspension 3D printing to obtain a 3D printed three-dimensional gel component, which is stably placed in the suspension matrix;

Then, the 3D printed three-dimensional gel component is sequentially subjected to solvent replacement and drying treatment to obtain a 3D printed three-dimensional aerogel.

Compared with the prior art, the advantages of the present invention include:

(1) The method for preparing three-dimensional aramid fiber aerogel by suspension 3D printing provided by the present invention does not require a refrigeration system, and can be printed at room temperature, with low energy consumption, and the suspension matrix is almost insensitive to temperature, and the system can be printed stably;

(2) The method for preparing three-dimensional aramid aerogel by suspension 3D printing provided by the present invention, because the ink can undergo rapid gelation after being extruded from the needle, and the viscosity and modulus of the ink are required while ensuring high printing accuracy. also low;

(3) The method for preparing three-dimensional aramid aerogel by suspension 3D printing provided by the present invention can print three-dimensional aramid aerogels of any size and shape, with low energy consumption, high printing accuracy, simple process, and general application to various materials. suitability;

(4) According to the method for preparing stereo-aramid aerogel by suspension 3D printing provided by the present invention, the obtained 3D-printed stereo-aramid aerogel has a pore size of micropores below 2 nm, mesopores of 2-50 nm and large pores of 50 nm-10 cm. Pore composition, porosity is 1-99.99%, with large specific surface area, low thermal conductivity, ultra-low density and designable three-dimensional structure, which can be used for thermal insulation, catalysis, separation/adsorption, seawater desalination, electromagnetic shielding, etc. In this field, the application scope of 3D printing and aramid aerogel has been greatly expanded.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

FIG. 1 is a schematic flowchart of the preparation of three-dimensional aramid aerogel by suspension 3D printing in a typical embodiment of the present invention;

2a and 2b are rheological curves of the suspended matrix obtained in Example 1 of the present invention.

3a-3c are microscope pictures of 3D printed single aramid hydrogel lines obtained in Example 2, Example 3, and Example 4 of the present invention, respectively;

4 is an optical photograph of the snail shell-shaped 3D printed three-dimensional aramid gel obtained in Example 5 of the present invention;

5 is an optical photo of the hose-shaped 3D printed three-dimensional aramid hydrogel obtained in Example 6 of the present invention;

6 is an optical photograph of a vase-shaped 3D printed three-dimensional aramid organogel obtained in Example 7 of the present invention;

7 is an optical photo of the pipe-shaped 3D printed three-dimensional aramid organogel obtained in Example 8 of the present invention;

8 is an optical photograph of a disc-shaped 3D printed three-dimensional aramid aerogel obtained in Example 9 of the present invention;

9 is a surface topography diagram of the 3D printed three-dimensional aramid aerogel obtained in Example 10 of the present invention;

Figures 10a and 10b show optical photographs of the obtained 3D printed aramid aerogels in Comparative Example 1 that were not printed with a suspended matrix;

FIG. 11 shows the surface topography of the obtained 3D printed aramid aerogel without adding silica particles in Comparative Example 2.

Detailed ways

In view of the deficiencies in the prior art, the inventor of this case has been able to propose the technical solution of the present invention after long-term research and extensive practice. In this case, for the first time, a method for preparing three-dimensional aramid aerogel by suspension 3D printing has been developed to expand 3D printing and The application range of aramid aerogel is shown in Figure 1. The method for preparing three-dimensional aramid aerogel by suspension 3D printing is mainly to uniformly mix aramid nanofibers, functional additives and solvents to form aramid nanofibers. The fiber dispersion is used as a 3D printing ink, and a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion is used as a suspension matrix, and the dispersion ink is suspended at room temperature by a direct writing printing method 3D printing, and then through solvent replacement and specific drying techniques, 3D printed three-dimensional aramid aerogels are obtained.

The technical solution, its implementation process and principle will be further explained as follows.

An aspect of the embodiments of the present invention provides a method for preparing a three-dimensional aramid aerogel by suspension 3D printing, comprising:

At least uniformly mixing aramid nanofibers, functional additives and solvent to form aramid nanofiber dispersion;

Use a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion as a suspension matrix;

Through the auxiliary action of the suspension matrix, the direct-writing molding printing method is used to perform suspension 3D printing with the aramid nanofiber dispersion as a 3D printing ink to obtain a 3D printed three-dimensional aramid gel component, which is stably placed in the suspension in the matrix;

Then, the 3D-printed three-dimensional aramid fiber gel component is sequentially subjected to solvent replacement and drying treatment to obtain a 3D-printed three-dimensional aramid fiber aerogel.

In some preferred embodiments, the preparation method specifically includes:

The aramid nanofiber dispersion formed by uniformly mixing aramid nanofibers, functional additives and solvent is used as 3D printing ink;

Use a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion as a suspension matrix;

After slicing the model designed by the software, the path is imported into the 3D printer;

Under normal temperature, through the auxiliary action of the suspension matrix, the 3D printing ink is suspended and 3D printed by the direct writing molding printing method to obtain a 3D printed three-dimensional aramid gel component;

After the 3D printed three-dimensional aramid fiber gel component is stabilized in the suspension matrix for a period of time, solvent replacement is performed;

The 3D printed three-dimensional aramid fiber gel after the solvent replacement is dried to obtain a 3D printed three-dimensional aramid fiber aerogel.

In some preferred embodiments, the suspending matrix includes a main ingredient and a solvent.

Further, the suspension base also includes auxiliary components.

In some preferred embodiments, the main components of the suspension matrix include cross-linked polyacrylic acid copolymer, polyacrylamide, polyvinyl alcohol, gelatin, sodium alginate, dimethacrylate modified polyethylene glycol, dioxide Any one or a combination of two or more of silicon, lithium magnesium silicate, etc., but not limited thereto.

In some preferred embodiments, the auxiliary components of the suspension matrix include any one or a combination of two or more of potassium hydroxide, sodium hydroxide, triethanolamine, sodium bicarbonate, ammonia water, calcium chloride, etc., but not limited to this.

Further, the solvent of the suspension matrix includes one or more combinations of water, ethanol, acetic acid, dimethyl sulfoxide, polyethylene glycol, glycerol, nitrogen methyl pyrrolidone, acetone, etc., but is not limited to this .

Further, the concentration of the main components in the suspension matrix is 0.01-60 wt %, preferably 0.5-30 wt %.

In some preferred embodiments, the functional additives include, but are not limited to, carbon nanotubes, graphene, transition metal nitrides or carbides, metals (such as gold particles, silver nanowires, etc.), silica particles, and the like. One or a combination of two or more, so that it can endow the final product with high electrical conductivity, high thermal conductivity/thermal insulation, light absorption, and electromagnetic shielding functions.

In some preferred embodiments, the 3D printing ink further includes auxiliary components.

Further, the aramid nanofibers have a diameter of 1 nm to 10 μm and a length of 5 nm to 1 mm.

Further, the solvent includes dimethyl sulfoxide, but is not limited thereto.

Further, the main component of the 3D printing ink is aramid nanofiber/dimethyl sulfoxide dispersion, and the auxiliary components include water, methanol, ethanol, acetone, n-hexane, nitrogen methyl pyrrolidone, potassium hydroxide and tert-butyl Any one or a combination of two or more of alcohol methyl alcohol, etc., but not limited to this.

In some preferred embodiments, the concentration of the aramid nanofiber dispersion liquid is 0.001-30 wt %, preferably 0.01-15 wt %.

In some preferred embodiments, the aramid nanofiber dispersion has a plateau storage modulus of 0.1-100 MPa, a plateau loss modulus of 0.1-100 MPa, a yield stress of 0.1-1000 Pa, and a shear rate of 1 s ^-1 , The apparent viscosity at 25℃ is 0.01～1000Pa.s ^.

In some preferred embodiments, the method specifically includes: after slicing the model designed by the software, the path is imported into a 3D printer, wherein the modeling software used includes but is not limited to AutoCAD, UG NX, Solidworks, ProE/Creo etc., the slicing software used includes but is not limited to any one of Cura, XBuilder, Makerbot, Simplify3D, Slic3r, etc.

In some preferred embodiments, the preparation method specifically includes: transferring the 3D printing ink into a syringe of a 3D printer, and at room temperature, through the auxiliary action of the suspension matrix, using a direct writing molding printing method, the The aramid nanofiber dispersion is directly extruded into the suspension matrix according to a set path, and finally a 3D printed three-dimensional aramid gel component is obtained.

In some embodiments, the preparation method of the 3D printing three-dimensional aramid aerogel is to place the 3D printing ink in the storage bin of the 3D printer at normal temperature, design the structure through a computer and import relevant programs, and print out different structures. 3D stereo-aramid gel.

Further, the inner diameter of the needle used in the 3D printing is 10 μm˜5 mm, preferably 50 μm˜1500 μm.

Further, the printing speed used in the 3D printing is 10mm/min～10000mm/min, preferably 500mm/min～5000mm/min.

Further, the structure of the 3D printed three-dimensional aramid fiber gel component includes any one or more than two of pipes, rings, pyramids, spheres, ellipsoids, cuboids, snail shells, hoses, discs, vases, etc. combination, but not limited to this.

In some preferred embodiments, the preparation method specifically includes: performing solvent replacement on the 3D printed 3D printed 3D aramid gel member with a replacement solvent at room temperature to obtain a 3D printed 3D aramid hydrogel or organogel .

Further, the replacement solvent includes, but is not limited to, any one or a combination of two or more of pure water, saline, phosphate buffer, ethanol, acetone, tert-butanol, nitrogen methylpyrrolidone, and the like.

In some preferred embodiments, the preparation method specifically includes: drying the 3D printed 3D aramid hydrogel or organogel to obtain a 3D printed 3D aramid aerogel.

In some preferred embodiments, the drying process includes freeze drying and/or supercritical fluid drying, etc., but is not limited thereto.

Further, the 3D printed 3D aramid aerogel was prepared by freeze-drying or supercritical drying.

Further, the temperature of the freeze-dried cold trap is -100～25°C, the vacuum degree is less than 0.1kPa, and the time is 10min～72h.

Further, the drying time of the supercritical fluid is 1 h to 48 h, and the supercritical fluid used includes any one or a combination of two or more of supercritical carbon dioxide, supercritical methanol and supercritical ethanol, etc., but is not limited thereto.

Another aspect of the embodiments of the present invention also provides a 3D printed stereo-aramid aerogel prepared by the aforementioned method, which has a three-dimensional structure and has a hierarchical porous aramid nanofiber network structure, the hierarchical porous aramid nanofiber network The structure is composed of micropores with a pore size of less than 2 nm, mesopores with a pore size of 2 nm to 50 nm, and macropores with a pore size of 50 nm to 10 cm. 0.1～1500mg/cm ³ , the specific surface area is 50～2500m ² /g, the pore volume is 0.1～15cm ³ /g, and the thermal conductivity is [0.025-0.06W/(m ^. K)].

Another aspect of the embodiments of the present invention also provides the application of the aforementioned 3D printed three-dimensional aramid aerogel in the fields of thermal insulation, catalysis, separation/adsorption, seawater desalination, electromagnetic shielding, and the like.

Specifically, in the application, at least some of its components use the aforementioned 3D printed three-dimensional aramid aerogel.

Another aspect of the embodiments of the present invention also provides a method for preparing a three-dimensional aerogel by suspension 3D printing, comprising:

At least the nanofibers, functional additives and solvent are uniformly mixed to form a nanofiber dispersion;

Use a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion as a suspension matrix;

Through the auxiliary action of the suspension matrix, using the direct writing molding printing method, the nanofiber dispersion liquid is used as a 3D printing ink for suspension 3D printing to obtain a 3D printed three-dimensional gel component, which is stably placed in the suspension matrix;

Then, the 3D printed three-dimensional gel component is sequentially subjected to solvent replacement and drying treatment to obtain a 3D printed three-dimensional aerogel.

In some preferred embodiments, the preparation method specifically includes:

The dispersion liquid formed by uniform mixing of nanomaterials, functional additives and solvents is used as 3D printing ink;

Use a matrix with thixotropic properties, shear thinning properties and fast solid-liquid conversion as a suspension matrix;

After slicing the model designed by the software, the path is imported into the 3D printer;

Under normal temperature, through the auxiliary action of the suspension matrix, the dispersion ink is suspended and 3D printed by the direct writing molding printing method to obtain a 3D printed three-dimensional gel component;

After the 3D printed three-dimensional gel component is stabilized in the matrix for a period of time, solvent replacement is performed;

The 3D printed three-dimensional gel after the solvent replacement is dried to obtain a 3D printed three-dimensional aerogel.

Further, the nanomaterials in the 3D printing ink include any one or a combination of two or more of aramid nanofibers, graphene oxide, sodium alginate, polyethylene glycols, collagen, etc., but not limited to this.

Further, the functional additives in the 3D printing ink include but are not limited to any one or a combination of two or more of carbon nanotubes, graphene, transition metal nitrides or carbides, metals, silica particles, etc., So that it gives the final product high electrical conductivity, high thermal conductivity/thermal insulation, light absorption, electromagnetic shielding function.

The method for preparing a three-dimensional aramid fiber aerogel by suspension 3D printing provided by the invention does not require a refrigeration system, can print at room temperature, has low energy consumption, and the suspension matrix is almost insensitive to temperature, and the system can be printed stably.

The method for preparing three-dimensional aramid fiber aerogel by suspension 3D printing provided by the present invention, because the ink can undergo rapid gelation after being extruded from the needle, while ensuring high printing accuracy, the requirements for the viscosity and modulus of the ink are also very low. .

The method for preparing three-dimensional aramid fiber aerogel by suspension 3D printing provided by the invention can print three-dimensional aramid fiber gel of any size and shape, with low energy consumption, high printing precision, simple process, and universal applicability to various materials.

According to the method for preparing stereo-aramid aerogel by suspension 3D printing provided by the present invention, the obtained 3D-printed stereo-aramid aerogel has a pore size consisting of micropores below 2 nm, mesopores of 2-50 nm and macropores of 50 nm-10 cm. The porosity is 1-99.99%, with a large specific surface area, low thermal conductivity, ultra-low density and a designable three-dimensional structure, which can be used in thermal insulation, catalysis, separation/adsorption, seawater desalination, electromagnetic shielding and other fields. Greatly expanded the application range of 3D printing and aramid aerogel.

To sum up, with the above technical solutions, the method for preparing three-dimensional aramid aerogel by suspension 3D printing provided by the present invention is to use the aramid nanofiber dispersion liquid formed by uniform mixing of aramid nanofibers, functional additives and solvents as 3D printing ink. , using a matrix with thixotropic properties, shear thinning properties and rapid solid-liquid conversion as a suspension matrix, at room temperature, using the direct-writing molding printing method, the dispersion ink is suspended for 3D printing, and then replaced by solvent. And specific drying technology, 3D printing stereo-aramid aerogel is obtained. The 3D printed three-dimensional aramid aerogel can be used in thermal insulation, catalysis, separation/adsorption, seawater desalination, electromagnetic shielding and other fields.

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in further detail below with reference to several preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention. , rather than all the embodiments, those skilled in the art can make adjustments according to the actual situation. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention. In the following examples, the test methods with no specific conditions are indicated, and the test methods in the examples are all carried out under normal conditions. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as there is no conflict with each other.

Example 1

(1) 30wt% aramid nanofiber/carbon nanotube/dimethyl sulfoxide/water mixed dispersion was used as 3D printing ink.

(2) 20wt% silica and polyethylene glycol are thoroughly mixed and used as a suspension base.

(3) Put the ink in the storage bin of the 3D printer, design the ring structure through the computer and import the relevant program, use a needle with an inner diameter of 5mm, the printing speed is 5000mm/min, and press the ink to the set path at room temperature. Print into suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced with water by solvent, freeze-dried at -100°C for 72 h to obtain 3D printed 3D aramid fiber aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 85%, a density of 50 mg/cm ³ , a specific surface area of 1500 m ² /g, a pore volume of 8 cm ³ /g, and a thermal conductivity of 0.04W/ (m.K) ^.

Figures 2a and 2b show the rheological curves of the suspended matrix obtained in step (2) of this example.

Example 2

(1) 1 wt% aramid nanofiber/graphene/dimethyl sulfoxide/ethanol mixed dispersion was used as 3D printing ink.

(2) 0.01wt% gelatin was fully swollen in water as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the spiral structure through the computer and import the relevant programs, use a needle with an inner diameter of 800 μm, the printing speed is 1000 mm/min, and print the ink according to the set path at room temperature. into the suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced with solvent by water, freeze-dried at -50°C for 10 min to obtain 3D printed 3D aramid fiber aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 80%, a density of 500 mg/cm ³ , a specific surface area of 1200 m ² /g, a pore volume of 2 cm ³ /g, and a thermal conductivity of 0.045W/ (m.K) ^.

Figure 3a is a microscope picture of a 3D printed single aramid hydrogel line obtained after solvent replacement with water in step (4) of this example.

Example 3

(1) 0.1 wt% aramid nanofiber/graphene/dimethyl sulfoxide/potassium hydroxide mixed dispersion was used as 3D printing ink.

(2) 0.5wt% polyacrylamide was fully swollen in acetic acid as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the spiral structure through the computer and import the relevant program, use a needle with an inner diameter of 500 μm, the printing speed is 3000 mm/min, and print the ink according to the set path at room temperature. into the suspension matrix.

(4) After solvent replacement of the 3D printed stereo-aramid gel with phosphate buffer, the 3D-printed stereo-aramid aerogel was obtained by freeze-drying at -50°C for 36 h.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 80%, a density of 100 mg/cm ³ , a specific surface area of 1000 m ² /g, a pore volume of 1 cm ³ /g, and a thermal conductivity of 0.047W/ (m.K) ^.

Figure 3b is a microscope picture of a 3D printed single aramid hydrogel line obtained after solvent replacement with phosphate buffer in step (4) of this example.

Example 4

(1) 0.01wt% aramid nanofiber/transition metal nitride/dimethyl sulfoxide/n-hexane mixed dispersion was used as 3D printing ink.

(2) 10wt% polyvinyl alcohol was fully swollen in glycerol as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the spiral structure through the computer and import the relevant program, use a needle with an inner diameter of 310 μm, the printing speed is 5000 mm/min, and print the ink according to the set path at room temperature. into the suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was solvent-replaced with saline, it was freeze-dried at -100°C for 72 h to obtain the 3D printed 3D aramid fiber aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 95%, a density of 1 mg/cm ³ , a specific surface area of 2000 m ² /g, a pore volume of 12 cm ³ /g, and a thermal conductivity of 0.035W/ (m.K) ^.

Figure 3c is a microscope picture of a 3D printed single aramid hydrogel line obtained after solvent replacement with saline in step (4) of this example.

Example 5

(1) 1wt% aramid nanofibers/gold particles/dimethyl sulfoxide/water mixed dispersion was used as 3D printing ink.

(2) 10wt% sodium alginate was fully swollen in dimethyl sulfoxide as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the snail shell structure through the computer and import the relevant program, use a needle with an inner diameter of 400 μm, and the printing speed is 2000 mm/min. The paths are printed into the suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced by solvent with ethanol, it was dried by supercritical carbon dioxide for 24 h to obtain 3D printed 3D aramid fiber aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 65%, a density of 1000 mg/cm ³ , a specific surface area of 50 m ² /g, a pore volume of 0.1 cm ³ /g, and a thermal conductivity of 0.055W /(m ^. K).

FIG. 4 is an optical photograph of the snail shell-shaped 3D printed three-dimensional aramid gel obtained in step (3) of this example.

Example 6

(1) 15wt% aramid nanofiber/silver nanowire/dimethyl sulfoxide/ethanol mixed dispersion was used as 3D printing ink.

(2) Fully dispersing 30wt% silicon dioxide in polyethylene glycol, adding a certain amount of ammonia water, and uniformly mixing it as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the hose-type structure through the computer and import the relevant program, use a needle with an inner diameter of 10 μm, and the printing speed is 10 mm/min. The paths are printed into the suspension matrix.

(4) The 3D printed 3D aramid fiber aerogel was obtained by solvent replacement of the 3D printed 3D aramid fiber with water, and then freeze-dried at -50°C for 24 h.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 75%, a density of 1200 mg/cm ³ , a specific surface area of 1000 m ² /g, a pore volume of 5 cm ³ /g, and a thermal conductivity of 0.05W/ (m.K) ^.

5 is an optical photograph of a hose-shaped 3D printed three-dimensional aramid hydrogel obtained after solvent replacement with water in step (4) of this example.

Example 7

(1) 0.05wt% aramid nanofibers/silica particles/dimethyl sulfoxide/nitrogen methyl pyrrolidone mixed dispersion was used as 3D printing ink.

(2) Fully dispersing 5wt% lithium magnesium silicate in water, adding a certain amount of sodium bicarbonate, and uniformly mixing it as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the vase-shaped structure through the computer and import the relevant programs, use a needle with an inner diameter of 330 μm, and the printing speed is 1000 mm/min. Print into suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced with tert-butanol, freeze-dried at 25°C for 72 h to obtain the 3D printed 3D aramid fiber aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 99.99%, a density of 0.1 mg/cm ³ , a specific surface area of 2500 m ² /g, a pore volume of 15 cm ³ /g, and a thermal conductivity of 0.025W /(m ^. K).

6 is an optical photograph of the vase-shaped 3D printed three-dimensional aramid organogel obtained after solvent replacement with tert-butanol in step (4) of this example.

Example 8

(1) 0.5wt% aramid nanofiber/transition metal carbide/dimethyl sulfoxide/ethanol mixed dispersion was used as 3D printing ink.

(2) Fully dispersing 20wt% silicon dioxide in polyethylene glycol, adding a certain amount of triethanolamine, and uniformly mixing it as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the pipeline structure through the computer and import the relevant programs, use a needle with an inner diameter of 810 μm, and the printing speed is 10000 mm/min. Print into suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced with ethanol solvent, it was dried by supercritical carbon dioxide for 1 h to obtain the 3D printed 3D aramid fiber aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 90%, a density of 10 mg/cm ³ , a specific surface area of 1800 m ² /g, a pore volume of 10 cm ³ /g, and a thermal conductivity of 0.037W/ (m.K) ^.

FIG. 7 is an optical photograph of the pipe-type 3D printed three-dimensional aramid organogel obtained after solvent replacement with ethanol in step (4) of this example.

Example 9

(1) 1 wt% aramid nanofiber/silver nanowire/dimethyl sulfoxide/tert-butanol methyl mixed dispersion was used as 3D printing ink.

(2) 1 wt% cross-linked polyacrylic acid copolymer is fully swollen in glycerin, a certain amount of potassium hydroxide is added, and the mixture is uniformly mixed to serve as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the disc-shaped structure through the computer and import the relevant program, use a needle with an inner diameter of 810 μm, and the printing speed is 8000 mm/min. The paths are printed into the suspension matrix.

(4) After replacing the 3D printed stereo-aramid gel with acetone, it was dried by supercritical carbon dioxide for 36 h to obtain the 3D-printed stereo-aramid aerogel.

The 3D printed stereo-aramid aerogel obtained in this example has a porosity of 50%, a density of 1500 mg/cm ³ , a specific surface area of 100 m ² /g, a pore volume of 0.1 cm ³ /g, and a thermal conductivity of 0.06W /(m ^. K).

FIG. 8 is an optical photograph of the disc-shaped 3D printed three-dimensional aramid aerogel obtained in this example.

Example 10

(1) 0.001wt% aramid nanofibers/silica particles/dimethyl sulfoxide/potassium hydroxide mixed dispersion was used as 3D printing ink.

(2) 60wt% cross-linked polyacrylic acid copolymer is fully swollen in water, a certain amount of sodium hydroxide is added, and the mixture is uniformly mixed to serve as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the cylindrical structure through the computer and import the relevant program, use a needle with an inner diameter of 330 μm, and the printing speed is 3000 mm/min. Print into suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced with acetone by solvent, it was dried by supercritical methanol for 48 h to obtain 3D printed 3D aramid fiber aerogel.

The 3D printed three-dimensional aramid aerogel obtained in this example has a porosity of 98%, a density of 100 mg/cm ³ , a specific surface area of 2000 m ² /g, a pore volume of 12 cm ³ /g, and a thermal conductivity of 0.03W/ (m.K) ^.

FIG. 9 is a surface topography diagram of the 3D printed three-dimensional aramid aerogel obtained in this example.

Through Examples 1-10, it can be found that the suspension 3D printing preparation method obtained by the above technical solution of the present invention has the advantages of being able to print any size and shape, low energy consumption, high printing precision, simple process, and universal applicability to various materials. The obtained 3D printed three-dimensional aramid aerogel has a hierarchical porous structure, ultra-low density, large specific surface area, low thermal conductivity, and structural designability.

In addition, the inventors of the present application also carried out experiments with other raw materials and conditions listed in this specification with reference to the methods of Examples 1-10, and also obtained products with hierarchical porous structure, ultra-low density, large specific surface area and low thermal conductivity. Efficiency, structural designability of 3D printed stereo-aramid aerogels. The suspension 3D printing method provided by the invention has the advantages of being able to print any size and shape, low energy consumption, high printing precision, simple process, and having excellent performances such as universality to various materials.

Comparative Example 1

(1) 1wt% aramid nanofibers/gold particles/dimethyl sulfoxide/water mixed dispersion was used as 3D printing ink;

(2) Put the ink in the storage bin of the 3D printer, design the pyre-type structure through the computer and import the relevant program, use a needle with an inner diameter of 400 μm, and the printing speed is 2000 mm/min. Paths are printed directly onto the substrate.

(3) After the 3D printed three-dimensional aramid fiber gel was replaced with ethanol by solvent, it was dried by supercritical carbon dioxide for 24 h to obtain the 3D printed aramid fiber aerogel.

Compared with Example 5, this control example is different in that no suspension matrix is used. The method of this comparative example cannot print a three-dimensional snail shell-shaped structure, so a pyre-shaped structure is used.

10a and 10b are optical photos of the pyre-type 3D printed aramid aerogel obtained in step (3) of this comparative example.

Comparative Example 2

(1) 0.001wt% aramid nanofiber/dimethyl sulfoxide/potassium hydroxide mixed dispersion is used as 3D printing ink;

(2) 60wt% cross-linked polyacrylic acid copolymer is fully swollen in water, a certain amount of potassium hydroxide is added, and the mixture is uniformly mixed to serve as a suspension matrix.

(3) Put the ink in the storage bin of the 3D printer, design the cylindrical structure through the computer and import the relevant program, use a needle with an inner diameter of 330 μm, and the printing speed is 3000 mm/min. Print into suspension matrix.

(4) After the 3D printed 3D aramid fiber gel was replaced with acetone by solvent, it was dried by supercritical methanol for 48 h to obtain 3D printed 3D aramid fiber aerogel.

The difference between this control example and Example 10 is that no functional additive silica particles are added. The 3D printed aramid aerogel obtained in this control example has a porosity of 40%, a density of 1800 mg/cm ³ , a specific surface area of 30 m ² /g, a pore volume of 0.01 cm ³ /g, and a thermal conductivity of 0.1 W/ (m.K) ^.

FIG. 11 is a surface topography diagram of the cylindrical 3D printed three-dimensional aramid aerogel obtained in step (4) of this comparative example.

The aspects, embodiments, features, and examples of the present invention are to be considered in all respects illustrative and not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

The use of headings and sections in this application is not meant to limit the invention; each section is applicable to any aspect, embodiment or feature of the invention.

Throughout this specification, where a composition is described as having, comprising or including particular components, or where a process is described as having, comprising or including particular process steps, it is contemplated that the compositions of the present teachings will also be substantially The above consists of or consists of the recited components, and the processes taught herein also consist essentially of, or consist of, the recited process steps.

It should be understood that the order of the steps or the order in which the particular actions are performed is not critical so long as the present teachings remain operable. Furthermore, two or more steps or actions may be performed simultaneously.

Although the present invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions and/or additions and the like may be made without departing from the spirit and scope of the invention Effects replace elements of the described embodiments. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is not intended herein to limit the invention to the particular embodiments disclosed for carrying out the invention, but it is intended that this invention include all embodiments falling within the scope of the appended claims.

Claims (10)

1. A method for preparing three-dimensional aramid aerogel through suspension 3D printing is characterized by comprising the following steps:

at least uniformly mixing aramid nano-fiber, a functional additive and a solvent to form an aramid nano-fiber dispersion liquid;

taking a substrate with thixotropic property, shear thinning property and rapid solid-liquid conversion as a suspension substrate;

by the aid of the auxiliary effect of the suspension matrix, the aramid nanofiber dispersion liquid is used as 3D printing ink to perform suspension 3D printing by a direct-writing forming printing method, so that a 3D-printed three-dimensional aramid gel component is obtained and is stably placed in the suspension matrix;

and then sequentially carrying out solvent replacement and drying treatment on the 3D printed three-dimensional aramid gel member to obtain the 3D printed three-dimensional aramid aerogel.

2. The method of claim 1, wherein: the suspension matrix comprises a main component and a solvent, and preferably, the suspension matrix also comprises an auxiliary component; preferably, the main component comprises any one or a combination of more than two of a cross-linked polyacrylic acid copolymer, polyacrylamide, polyvinyl alcohol, gelatin, sodium alginate, dimethacrylate modified polyethylene glycol, silicon dioxide and lithium magnesium silicate; preferably, the auxiliary component comprises one or more of potassium hydroxide, sodium hydroxide, triethanolamine, sodium bicarbonate, ammonia water and calcium chloride; preferably, the solvent comprises one or a combination of more than two of water, ethanol, acetic acid, dimethyl sulfoxide, polyethylene glycol, glycerol, nitrogen methyl pyrrolidone and acetone; preferably, the concentration of the main component in the suspension matrix is 0.01 to 60 wt%, preferably 0.5 to 30 wt%.

3. The method of claim 1, wherein: the functional additive comprises any one or the combination of more than two of carbon nano tubes, graphene, transition metal nitride or carbide, metal and silicon dioxide particles;

and/or the diameter of the aramid nano fiber is 1 nm-10 mu m, and the length of the aramid nano fiber is 5 nm-1 mm;

and/or the concentration of the aramid nanofiber dispersion liquid is 0.001-30 wt%, preferably 0.01-15 wt%; preferably, the aramid nanofiber dispersion liquid has a platform storage modulus of 0.1-100 MPa, a platform loss modulus of 0.1-100 MPa, a yield stress of 0.1-1000 Pa and a shear rate of 1s^-1And an apparent viscosity at 25 ℃ of 0.01 to 1000Pa_.s；

And/or, the 3D printing ink further comprises an auxiliary component; preferably, the auxiliary component comprises any one or a combination of more than two of water, methanol, ethanol, acetone, n-hexane, N-methylpyrrolidone, potassium hydroxide and methyl tert-butoxide;

and/or, the solvent comprises dimethyl sulfoxide.

4. The method according to claim 1, characterized in that it comprises in particular: after a model designed by software is sliced, a path is led into a 3D printer, wherein the adopted modeling software comprises any one of AutoCAD, UG NX, Solidworks and ProE/Creo, and the adopted slicing software comprises any one of Cura, XBuilder, Makerbot, Simplify3D and Slic3 r.

5. The method according to claim 4, characterized in that it comprises in particular: transferring the 3D printing ink into an injector of a 3D printer, and directly extruding the aramid nano-fiber dispersion liquid into the suspension matrix according to a set path by using a direct-writing forming printing method under the auxiliary action of the suspension matrix at normal temperature to finally obtain a 3D printed three-dimensional aramid gel component; preferably, the inner diameter of the needle head used for 3D printing is 10-5 mm, preferably 50-1500 μm; preferably, the printing speed adopted by the 3D printing is 10 mm/min-10000 mm/min, preferably 500 mm/min-5000 mm/min; preferably, the structure of the 3D printed three-dimensional aramid gel member comprises any one or a combination of more than two of a pipeline, a ring, a pyramid, a sphere, an ellipsoid, a cuboid, a snail shell, a hose, a disc and a vase.

6. The method according to claim 1, comprising: at normal temperature, carrying out solvent replacement on the 3D printed three-dimensional aramid gel component by using a replacement solvent to obtain 3D printed three-dimensional aramid hydrogel or organogel; preferably, the substitution solvent includes any one or a combination of two or more of pure water, saline, phosphate buffer, ethanol, acetone, t-butanol, and N-methylpyrrolidone.

7. The method according to claim 6, comprising: drying the 3D printed three-dimensional aramid hydrogel or organogel to obtain a 3D printed three-dimensional aramid aerogel;

and/or, the drying process comprises freeze drying and/or supercritical fluid drying; preferably, the temperature of the freeze-dried cold trap is-100-25 ℃, the vacuum degree is less than 0.1kPa, and the time is 10 min-72 h; preferably, the drying time of the supercritical fluid is 1-48 h, and the adopted supercritical fluid comprises any one or the combination of more than two of supercritical carbon dioxide, supercritical methanol and supercritical ethanol.

8. 3D printed stereoscopic aramid aerogel prepared by the method of any one of claims 1 to 7, having a stereoscopic structure and having a hierarchical porous aramid nanofiber network structureThe hierarchical porous aramid nanofiber network structure is composed of micropores with the pore diameter of below 2nm, mesopores with the pore diameter of 2 nm-50 nm and macropores with the pore diameter of 50 nm-10 cm, the porosity of the 3D printing three-dimensional aramid aerogel is 50-99.99%, and the density of the 3D printing three-dimensional aramid aerogel is 0.1-1500 mg/cm³The specific surface area is 50-2500 m²The pore volume is 0.1-15 cm³The thermal conductivity is 0.025-0.06W/(m)^.K)。

9. The 3D printed stereoscopic aramid aerogel of claim 8, in applications in the fields of thermal insulation, catalysis, separation/adsorption, seawater desalination, or electromagnetic shielding.

10. A method for preparing three-dimensional aerogel through suspension 3D printing is characterized by comprising the following steps:

at least uniformly mixing the nano-fibers, the functional additive and the solvent to form nano-fiber dispersion liquid;

taking a substrate with thixotropic property, shear thinning property and rapid solid-liquid conversion as a suspension substrate;

by the aid of the auxiliary effect of the suspension matrix, the nanofiber dispersion liquid is used as 3D printing ink to perform suspension 3D printing by a direct-writing forming printing method, so that a 3D-printed three-dimensional gel component is obtained and is stably placed in the suspension matrix;

then sequentially carrying out solvent replacement and drying treatment on the 3D printed three-dimensional gel component to obtain a 3D printed three-dimensional aerogel;

preferably, the nanofiber comprises any one or a combination of more than two of aramid nanofiber, graphene oxide, sodium alginate, polyethylene glycol and collagen.

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