Nylon aerogel for 3D printing and preparation method and application thereof

Abstract

The application belongs to the technical field of aerogel, and particularly relates to a nylon aerogel for 3D printing and a preparation method and application thereof. The preparation of the aerogel comprises the following steps: (1) adding aniline monomer and ice micro-powder into pre-cooled deionized water to obtain a monomer mixed solution; (2) under the condition of stirring at no less than 400 rpm, dropping an initiator into the monomer mixed solution in batches to obtain a curved polyaniline after reaction; (3) preparing a nylon mixed solution containing the curved polyaniline; and (4) freeze-drying to obtain the nylon aerogel for 3D printing. The ice crystal template method is combined with the freeze-drying method to adjust the microstructure of the nylon aerogel containing polyaniline, and the nylon-based aerogel conductive polymer material is prepared. The conductive aerogel material can greatly improve the elongation at break and conductivity of polyurethane material, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerogels, and particularly relates to a nylon aerogel for 3D printing, a preparation method and application thereof. BACKGROUND

[0002] 3D printing technology is also known as additive manufacturing, and its basic principle is to first draw a three-dimensional structure diagram of a formed product with the aid of computer three-dimensional drawing software, then convert the drawn three-dimensional structure diagram into a corresponding digital model in a related 3D printing software, and finally use a 3D printer to directly form a three-dimensional structure of the product by using liquid, powder, filament and other materials based on the digital model in a bottom-up layer-by-layer manner.

[0003] In recent years, with the wide application of various 3D printing technologies in various fields, the types of 3D printing raw materials have also become more and more diverse. Thermoplastic polyurethane materials are widely used in the 3D printing of various parts due to their excellent performance and great adjustability of hardness, strength, melting temperature and other properties. The 3D printing forming technology of thermoplastic polyurethane materials currently mainly includes light curing forming, fused deposition forming technology and selective laser sintering technology. Thermoplastic polyurethane material parts printed by the selective laser sintering technology are relatively excellent in product precision and strength, but the printing cost is high, and they are generally mainly used for the printing of small-sized and high-precision thermoplastic polyurethane material parts. Light curing forming and fused deposition forming technology are more widely used in the application of thermoplastic polyurethane material parts due to their simple operation, low equipment cost and wide raw materials. As a common thermoplastic resin, thermoplastic polyurethane has high mechanical properties, but poor electrical conductivity, which easily causes charge accumulation and static electricity when used as a device part material, and is not conducive to the safe operation of the device. The existing technologies all use different templates to prepare special-shaped conductive polymers to solve the compatibility problem. Among them, the ice template is a kind of green and environmentally friendly technology widely used in recent years. For example, patent technologies such as CN118681506A, CN105597622A, CN103191019A, CN106860403A and CN119701808A disclose the preparation of ice templates and the preparation of corresponding biomaterials, but there is no report on the preparation of conductive materials by using ice templates in the prior art. SUMMARY

[0004] The purpose of the present application is to provide a nylon aerogel for 3D printing, a preparation method and application thereof. The prepared nylon aerogel has a three-dimensional multi-channel network structure, excellent flexibility, and can be used as a conductive and reinforcing filler of thermoplastic polyurethane to greatly increase the mechanical properties and antistatic ability of thermoplastic polyurethane. Moreover, the preparation process is simple, the cost is low, it is safe and environmentally friendly, and it has a wide application potential in the field of 3D printing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0007] (1) Under ice-salt bath conditions, aniline monomer and ice powder were added to deionized water while stirring to obtain a monomer mixed solution;

[0008] (2) Under stirring conditions of not less than 400 rpm, the initiator is added dropwise to the monomer mixture solution in batches. After the addition is completed, the reaction is stirred and the reaction is continued. After post-treatment, curved polyaniline is obtained. The initiator added for the first time accounts for 10-20 wt% of the total initiator. After the reaction is carried out for 0.5-1 h, the remaining initiator is added dropwise.

[0009] (3) Dissolve nylon in an acidic solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution;

[0010] (4) Freeze-dry the nylon mixture to obtain nylon aerogel for 3D printing.

[0011] Polyaniline (POA) is composed of oxidizing and reducing units, and possesses advantages such as low cost, ease of preparation, chemical stability, high electrical conductivity, excellent magnetic properties, and unique optical properties, making it widely used in the polymer field. Due to the presence of chemically flexible amino groups on both sides of the benzene ring in POA, its excellent processability distinguishes it from other conductive polymers. Its electrical properties can be controlled to a relatively ideal degree by changing the reaction conditions and synthesis process. Furthermore, POA has many advantages, including widely available and inexpensive raw materials, mild synthesis conditions, safety and environmental friendliness, good oxidation resistance in natural environments, adjustable electrical conductivity, and ideal film-forming effect. However, the rigid structure within the POA molecule limits its application as a conductive filler to some extent; in addition, its insolubility and infusibility significantly restrict the practical applications of conductive POA polymers. Therefore, combining conductive polymers with other easily moldable and processed common polymers to prepare functional polymers with special applications has become the main approach to broadening the application fields of conductive POA polymers.

[0012] Nylon, a common engineering plastic, has good processing properties and, like polyurethane, contains nitrogen-containing functional groups, exhibiting good compatibility. It holds promise as a matrix for conductive polyaniline molecules used in the preparation of conductive fillers for polyurethane. In previous work (CN120818176A, CN120865604A), the inventors prepared core-shell structured polyaniline microspheres through in-situ polymerization in polyamide solution using inorganic solid or hollow nanoparticles as templates. However, this process requires the addition of inorganic nanoparticles as templates and must be carried out in a polyamide solution, making the in-situ polymerization process complex and subject to harsh reaction conditions, hindering its market adoption. More importantly, due to the viscosity limitations of the polyamide solution, the product contains a large number of unreacted small aniline monomer molecules, which not only fails to meet the requirements of green chemistry development but also affects the improvement of the mechanical properties of aerogels and 3D printed products.

[0013] To address the issue of needing to add an additional non-conductive template during the preparation of polyaniline with special morphology, this invention uses ice micron powder as a template for the synthesis of aniline monomers to prepare polyaniline with an arc-shaped structure.

[0014] Ice-templating is a widely used material preparation technique. This invention combines ice-templating with freeze-drying to adjust the microstructure of polyaniline-containing nylon aerogels, thereby preparing nylon-based conductive polymer materials with a multi-level structure.

[0015] The key to preparing antistatic materials lies in ensuring good compatibility between the conductive filler and the matrix to achieve uniform dispersion. This can then be achieved through simple mechanical stirring and ultrasonic dispersion, requiring no complex equipment or processes, making it suitable for large-scale production. Previously, the inventors constructed zero-dimensional spherical polyaniline particles within a nylon matrix. Due to the presence of inorganic particles, these particles are dense and difficult to distribute within the nylon matrix, hindering the construction of conductive pathways and requiring a large proportion to achieve antistatic properties. Furthermore, the presence of inorganic nanoparticles also affects the pore structure of nylon aerogels, which is detrimental to the construction of high-porosity aerogel materials. Common two-dimensional sheet-like polyaniline structures (such as common polyaniline nanosheets) have a planar structure, resulting in a small interaction area with the nylon matrix resin, making them prone to breakage and peeling under stress. The curved polyaniline prepared in this invention has an arc-shaped curved surface structure, which significantly disperses the stress on the polyaniline. Meanwhile, the curved arc structure has a large specific surface area, enabling it to form numerous contact points with nylon resin, which helps construct conductive pathways. Furthermore, its curved structure makes it less prone to aggregation, facilitating the formation of continuous conductive paths in the planar direction, thereby improving the overall conductivity of the material. The arc-shaped polyaniline exhibits a three-dimensional spatial structure, forming a randomly arranged conductive network structure when blended with the nylon solution. This not only makes the composite material less prone to breakage under impact but also allows it to better embed itself within the gaps of the nylon aerogel, forming stress-transfer channels and constructing a more complex three-dimensional network structure. This not only helps reduce the amount of polyaniline filler but also disperses the stress, preventing stress concentration and improving toughness.

[0016] Furthermore, the particle size of the ice micropowder mentioned in step (1) is not particularly limited, and micron-sized particles are acceptable. Further, it can be micropowder with an average particle size of 100 nm-50 μm and a spherical structure. The preparation process of the ice micropowder is not particularly limited, and it can be prepared using common existing technologies such as spray freezing or freeze-milling. Using ice micro / nano particles as templates for aniline monomers, polyaniline with an arc-shaped structure can be prepared. The inventors analyzed that, as a solid substance of water, the nucleation effect of ice particles themselves is limited. However, under strong stirring, the solvent flow rate is relatively fast, and there is a certain rate difference between its flow and the movement of solid ice particles. Moreover, during stirring, ice particles exhibit both revolution around the center and rotation around themselves. There is a large rate difference between the macroscopic revolution and microscopic rotation of the ice micropowder, and the shear effect caused by this speed difference leads to uneven adhesion of aniline. Furthermore, due to the volume change after water crystallization, a large number of micro-cracks exist on the surface of the ice micropowder, which is beneficial for the adhesion of aniline. As stirring proceeds, more aniline monomers use the preferentially attached aniline as nuclei, gradually undergoing polymerization and forming a curved polyaniline structure on the surface of the ice micropowder. As polymerization continues, the curved polyaniline structure gradually increases in size. When the curved polyaniline structure grows to a certain curvature, its area becomes too large, reducing its interaction with the ice micropowder while increasing the impact force from the solvent. Under the centrifugal force of the ice micropowder's rotation, it detaches from the surface, forming an arc-shaped polyaniline structure. It is worth noting that the nucleation effect of the ice micropowder is mainly observed in the early stages of the reaction. At lower temperatures, the ice micropowder dissolves slowly, while the initial polymerization rate is faster, quickly forming the initial curved structure. The reaction temperature should be controlled during the initial reaction to prevent premature dissolution of the ice particles due to excessively high temperatures. In the later stages of the reaction, the surface of the ice micropowder has already formed a curved arc-shaped structure. Subsequent reaction temperatures are not strictly limited; even if the initial curved structure detaches, aniline monomers can continue to polymerize on this basis, promoting the formation of the arc-shaped structure. In particular, in order to improve the regularity of hollow arc-shaped polyaniline, the reaction system can be kept below 0°C during the polymerization process. Specifically, the present invention adopts an ice-salt bath reaction system.

[0017] Furthermore, the aniline monomer and deionized water in step (1) and the initiator in step (2) are all pre-cooled at a temperature of -10 to 0°C. The pre-cooling process can lower the temperature of the solution system and prevent damage to the ice template structure. During the pre-cooling process, stirring can be performed to prevent freezing. The polyaniline preparation process uses an ice-salt bath system, which can control the reaction temperature below 0°C, specifically -20 to 0°C, and further controllable temperatures of (-10) to (-1°C) or (-6) to (-1°C).

[0018] Furthermore, the mass ratio of ice micropowder to aniline monomer in step (1) is 5-20:1. Specifically, it can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, or 15:1. In particular, it can be 8-15:1. An appropriate amount of ice micropowder can fully exert its nucleation effect, preventing excessive ice micropowder from causing disturbance in the solution, which is detrimental to the dispersion, adhesion, and polymerization process of aniline monomer.

[0019] Furthermore, in step (1), the mass ratio of aniline monomer to deionized water is (0.1-2):100. Alternatively, it can be (0.5-1):100. The addition of a large amount of deionized water can improve the stability of the ice micron powder and promote the formation of the arc-shaped structure.

[0020] Furthermore, the stirring rate in step (1) is not particularly limited, but can be 400-600 rpm. More specifically, the stirring rate is 500-600 rpm. Stirring promotes the dispersion of the components and facilitates the full binding of the ice micro powder with the aniline monomer.

[0021] Furthermore, in step (1), aniline monomer is added first and mixed evenly, and then ice powder is added. The mixing of ice powder and aniline monomer is promoted by stirring.

[0022] Furthermore, the stirring rate in step (2) is 400-650 rpm. The initiator is one or more of ammonium persulfate, potassium persulfate, and ferric chloride. The mass ratio of the initiator to the aniline monomer is (2-4):1. In particular, ferric chloride, which has a doping effect, is selected. Lewis acid doping can greatly improve the conductivity of polyaniline. Specifically, it can be added dropwise in the form of an aqueous solution of ferric chloride, and the mass-volume ratio of ferric chloride to water in the aqueous solution of ferric chloride can be (0.01-0.5):1. In particular, it can be 0.1:1.

[0023] Furthermore, the batch addition mentioned in step (2) refers to adding the initiator in two batches. Specifically, the initial addition of initiator accounts for 12-18 wt% of the total initiator. After reacting for 0.6-0.8 hours, the remaining initiator is added until the addition is complete. The dropping rate is not specifically limited. Further, the initial addition of initiator accounts for 13-18 wt% of the total initiator; even further, it is 14-15 wt%. In particular, by adjusting the amount of the first batch of initiator added to control the reaction rate, the nucleation effect of the ice micro powder can be better utilized, promoting the formation of curved surface morphology. In order to minimize the impact of temperature changes on the ice micro powder, the first batch of initiator is added rapidly after the addition of materials in step (1). The dropping rate of the first batch of initiator is the same as that of the second batch of initiator, and the total dropping time is 10-30 minutes. By adding the initiator in batches, the polymerization process of aniline monomer can be reasonably controlled. After the initial addition of 12-18 wt% initiator, a reaction period is allowed. This small amount of initiator controls the polymerization rate of aniline monomers, facilitating their attachment to the sides of ice particles and promoting nucleation. Furthermore, after the first batch of initiator is added, the aniline monomers quickly polymerize on the sides of the ice powder, promoting the formation of the initial curved surface morphology of polyaniline and preventing random polymerization of aniline due to continuous initiator addition. On one hand, the initially formed curved arc structure eliminates the morphological changes caused by melting during the ice powder reaction, promoting the formation of the curved structure. On the other hand, the batch addition and segmented polymerization of the initiator reduce the influence of polar substances on the solution system, improving the stability of the ice powder.

[0024] Furthermore, the total reaction time described in step (2), i.e., the time from the initial addition of the initiator to the completion of the reaction, is 10-20 hours. After the reaction is complete, the mixture can be brought back to room temperature, and the ice powder will dissolve. The post-treatment process includes filtration, washing, and drying at room temperature. Specifically, washing can be done with deionized water, and drying can be carried out in a vacuum oven.

[0025] Furthermore, the nylon mentioned in step (3) is an aliphatic nylon. Specifically, the aliphatic nylon is one or more of nylon 6, nylon 66, nylon 56, and nylon 12. Aliphatic nylons have good solubility and dispersibility in acidic solvents, making them suitable for freeze-drying processes.

[0026] Furthermore, the acidic solvent used to dissolve the nylon in step (3) is a formic acid solution; specifically, an 88wt% formic acid aqueous solution can be used. The nylon dissolution process can be appropriately heated to accelerate the dissolution rate. Adding the curved polyaniline back into the acidic solvent containing nylon can perform a secondary doping effect on the polyaniline. Secondary doping can promote the expansion of the polyaniline backbone, enhance the interaction of charge carriers, and further improve the conductivity and mechanical properties of the polyaniline.

[0027] Furthermore, in step (3), the mass ratio of nylon to acid solvent is 1-10 wt%.

[0028] Furthermore, in step (3), the mass ratio of curved polyaniline to nylon is (0.1-1):1.

[0029] On the other hand, the present invention also provides a nylon aerogel for 3D printing prepared by the above method. Using nylon resin as the aerogel matrix resin, both nylon and polyaniline contain nitrogen-containing groups, exhibiting good compatibility. Furthermore, nylon is soluble in acidic solvents, which facilitates secondary doping of polyaniline. More importantly, the nylon solution is easily freeze-dried, promoting aerogel formation.

[0030] On the other hand, the present invention also provides an application of nylon aerogel for 3D printing and a 3D printing polyurethane material reinforced with it. Specifically, the nylon aerogel for 3D printing is used in photopolymerization, selective laser sintering, fused deposition modeling, or layered solid fabrication technologies in 3D printing. Specifically, the 3D printing polyurethane material comprises polyurethane resin material and nylon aerogel for 3D printing. Further, photopolymerization or fused deposition modeling can be used. Specifically, fused deposition modeling is used to prepare the polyurethane material. The printing temperature in fused deposition modeling is not particularly limited, generally between 190-220°C, and can be adjusted according to the production process. Furthermore, the 3D printing polyurethane material may also contain various reinforcing fillers, flow modifiers, lubricants, antioxidants, UV stabilizers, hydrolysis inhibitors, colorants, and other additives. Specifically, the type of reinforcing filler is not particularly limited, and may include granular, fibrous, or sheet-like fillers. It should be noted that the types of raw materials used in the present invention are not particularly limited; they can be prepared using conventional processes in the art or commercially available. For example, the thermoplastic polyurethane can be the commonly used Wanhua Q / 0600, and the nylon 66 can be the commonly used EPR27, etc.

[0031] Beneficial Effects: To address the issue of requiring additional non-conductive templates during the preparation of polyaniline with special morphologies, this invention utilizes ice micron powder as a template for the synthesis of aniline monomers to prepare arc-shaped polyaniline; and uses nylon as the matrix resin to prepare nylon aerogel for 3D printing. The curved polyaniline prepared by this invention possesses an arc-shaped curved surface structure, which significantly disperses the stress on the polyaniline. Simultaneously, the arc-shaped structure has a large specific surface area, enabling the formation of numerous contact points with the nylon resin, facilitating the construction of conductive pathways. Furthermore, its curved structure reduces the likelihood of agglomeration, promoting the formation of continuous conductive paths in the planar direction, thereby improving the material's conductivity. Moreover, the arc-shaped polyaniline exhibits a three-dimensional spatial structure, forming a randomly arranged conductive network structure when blended with the nylon solution. This not only makes the composite material less prone to breakage under impact but also allows for better embedding within the gaps of the nylon aerogel, forming stress-transfer channels and constructing a more complex three-dimensional network structure. This not only helps reduce the amount of polyaniline required but also disperses the stress, preventing stress concentration and improving toughness. The nylon aerogel for 3D printing prepared by this invention, used as an antistatic reinforcing filler for thermoplastic polyurethane, not only has a simple preparation process, low cost, safety and environmental protection, but also greatly reduces the amount of polyaniline added, thereby increasing the mechanical properties and antistatic properties of thermoplastic polyurethane products. Attached Figure Description

[0032] Figure 1 Scanning electron microscope image of the curved polyaniline prepared in Example 10;

[0033] Figure 2 Here is a scanning electron microscope image of the polyaniline prepared in Comparative Example 1;

[0034] Figure 3 The image shows a scanning electron microscope (SEM) image of the polyaniline prepared in Comparative Example 2. Detailed Implementation

[0035] In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the specific embodiments of the present invention will be described in further detail below with reference to specific examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] The performance testing method for the nylon aerogels for 3D printing prepared in the following examples and comparative examples is as follows: Under the same conditions, the effect of the nylon aerogels for 3D printing prepared in Examples 1-10 and Comparative Examples 1-2 on the performance of 3D printed polyurethane products is tested.

[0037] Specifically, the 3D printing polyurethane material comprises 100 parts thermoplastic polyurethane, 15 parts nylon aerogel for 3D printing, and 3 parts zinc stearate. The 3D printing polyurethane material is printed into specimens, and the elongation at break of the specimens is tested according to GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber," and its conductivity is tested using a conductivity meter.

[0038] Example 1

[0039] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0040] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 400 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 800 nm; the mass ratio of ice powder to aniline monomer was 5:1; the mass ratio of aniline monomer to deionized water was 0.4:100.

[0041] (2) Under stirring at 400 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed, and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 2.5:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 10 wt% of the total initiator mass. After reacting for 0.5 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 25 min. The total time for the stirring reaction was 10 h.

[0042] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and disperse evenly by ultrasonication to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3wt%; the mass ratio of curved polyaniline to nylon 66 is 0.45:1;

[0043] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 566%, and its electrical conductivity was 30.36 × 10⁻⁶. -4 S / cm.

[0044] Example 2

[0045] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0046] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 600 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 15 μm; the mass ratio of ice powder to aniline monomer was 15:1; the mass ratio of aniline monomer to deionized water was 0.6:100.

[0047] (2) Under stirring at 650 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 3.2:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 18 wt% of the total initiator mass. After reacting for 1 hour, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 30 minutes. The total time for the stirring reaction was 15 hours.

[0048] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 4.2 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.8:1;

[0049] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 528%, and its electrical conductivity was 34.85 × 10⁻⁶. -4 S / cm.

[0050] Example 3

[0051] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0052] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 4 μm; the mass ratio of ice powder to aniline monomer was 20:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0053] (2) Under stirring at 500 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 3:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 15 wt% of the total initiator mass. After reacting for 0.7 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 20 min. The total time for the stirring reaction was 13 h.

[0054] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.6 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.7:1;

[0055] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 531%, and its electrical conductivity was 32.69 × 10⁻⁶. -4 S / cm.

[0056] Example 4

[0057] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0058] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 430 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 15 μm; the mass ratio of ice powder to aniline monomer was 8.5:1; the mass ratio of aniline monomer to deionized water was 0.55:100.

[0059] (2) Under stirring at 520 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 2.7:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 16 wt% of the total initiator mass. After reacting for 0.5 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 20 min. The total time for the stirring reaction was 14 h.

[0060] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 2.8 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.65:1;

[0061] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 537%, and its electrical conductivity was 33.81 × 10⁻⁶. -4 S / cm.

[0062] Example 5

[0063] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0064] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 4 μm; the mass ratio of ice powder to aniline monomer was 12:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0065] (2) Under stirring at 500 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 3:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 10 wt% of the total initiator mass. After reacting for 0.7 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 20 min. The total time for the stirring reaction was 13 h.

[0066] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.6 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.7:1;

[0067] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 524%, and its electrical conductivity was 31.27 × 10⁻⁶. -4 S / cm.

[0068] Example 6

[0069] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0070] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 450 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 800 nm; the mass ratio of ice powder to aniline monomer was 9:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0071] (2) Under stirring at 450 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 2.7:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 13 wt% of the total initiator mass. After reacting for 0.6 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 17 min. The total time for the stirring reaction was 11 h.

[0072] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.2 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.5:1;

[0073] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 556%, and its electrical conductivity was 31.64 × 10⁻⁶. -4 S / cm.

[0074] Example 7

[0075] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0076] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 4 μm; the mass ratio of ice powder to aniline monomer was 12:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0077] (2) Under stirring at 500 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 3:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 20 wt% of the total initiator mass. After reacting for 0.7 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 20 min. The total time for the stirring reaction was 13 h.

[0078] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.6 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.7:1;

[0079] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 534%, and its electrical conductivity was 30.75 × 10⁻⁶. -4 S / cm.

[0080] Example 8

[0081] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0082] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 15 μm; the mass ratio of ice powder to aniline monomer was 13:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0083] (2) Under stirring at 550 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 3.1:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 17 wt% of the total initiator mass. After reacting for 0.8 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 22 min. The total time for the stirring reaction was 13 h.

[0084] (3) Nylon 66 was dissolved in formic acid solvent, and then curved polyaniline was added and ultrasonically dispersed to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent was 4.3 wt%; the mass ratio of curved polyaniline to nylon 66 was 0.6:1.

[0085] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 548%, and its electrical conductivity was 32.17 × 10⁻⁶. -4 S / cm.

[0086] Example 9

[0087] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0088] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice micro powder were added to deionized water at a stirring speed of 580 rpm to obtain a monomer mixed solution; the ice micro powder had a particle size of 800 nm; the mass ratio of ice micro powder to aniline monomer was 10.5:1; the mass ratio of aniline monomer to deionized water was 0.45:100.

[0089] (2) Under stirring at 470 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed, and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 2.9:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 14 wt% of the total initiator mass. After reacting for 0.9 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 26 min. The total time for the stirring reaction was 13 h.

[0090] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and disperse evenly by ultrasonication to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 4.1 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.75:1;

[0091] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 525%, and its electrical conductivity was 34.73 × 10⁻⁶. -4 S / cm.

[0092] Example 10

[0093] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0094] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 4 μm; the mass ratio of ice powder to aniline monomer was 12:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0095] (2) Under stirring at 500 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain curved polyaniline. The mass ratio of the initiator to the aniline monomer was 3:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 15 wt% of the total initiator mass. After reacting for 0.7 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 20 min. The total time for the stirring reaction was 13 h.

[0096] (3) Dissolve nylon 66 in formic acid solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.6 wt%; the mass ratio of curved polyaniline to nylon 66 is 0.7:1;

[0097] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 563%, and its electrical conductivity was 35.14 × 10⁻⁶. -4 S / cm.

[0098] Comparative Example 1

[0099] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0100] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 4 μm; the mass ratio of ice powder to aniline monomer was 12:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0101] (2) Under stirring at 500 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was continuously added dropwise to the monomer mixture solution over 20 min. After the addition was completed, the reaction was stirred and reacted. The mixture was filtered, washed, and dried at room temperature to obtain polyaniline. The mass ratio of the initiator to the aniline monomer was 3:1. The total stirring reaction time was 13 h.

[0102] (3) Dissolve nylon 66 in formic acid solvent, then add polyaniline, and disperse evenly by ultrasonication to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.6 wt%; the mass ratio of polyaniline to nylon 66 is 0.7:1;

[0103] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 513%, and its electrical conductivity was 1.56 × 10⁻⁶. -4 S / cm.

[0104] Comparative Example 2

[0105] A method for preparing nylon aerogel for 3D printing includes the following steps:

[0106] (1) Under ice-salt bath conditions, the pre-cooled aniline monomer and ice powder were added to deionized water at a stirring speed of 550 rpm to obtain a monomer mixed solution; the ice powder had a particle size of 4 μm; the mass ratio of ice powder to aniline monomer was 12:1; the mass ratio of aniline monomer to deionized water was 0.5:100.

[0107] (2) Under stirring at 200 rpm, the pre-cooled ferric chloride aqueous solution of the initiator was added dropwise to the monomer mixture in batches. After the addition was completed, the reaction was stirred and the mixture was filtered, washed and dried at room temperature to obtain polyaniline. The mass ratio of the initiator to the aniline monomer was 3:1. The batch addition was to add the initiator in two batches at a uniform rate. Specifically, the first batch was 15 wt% of the total initiator mass. After reacting for 0.7 h, the remaining initiator was added dropwise until the addition was completed. The total time for the two additions was 20 min. The total time for the stirring reaction was 13 h.

[0108] (3) Dissolve nylon 66 in formic acid solvent, then add polyaniline, and disperse evenly by ultrasonication to obtain a nylon mixed solution; the mass ratio of nylon 66 to formic acid solvent is 3.6 wt%; the mass ratio of polyaniline to nylon 66 is 0.7:1;

[0109] (4) The nylon mixture solution was freeze-dried to obtain nylon aerogel for 3D printing. When used as a conductive reinforcing filler for thermoplastic polyurethane, its elongation at break was tested to be 518%, and its electrical conductivity was 2.12 × 10⁻⁶. -4 S / cm.

[0110] Figure 1 The image shows a scanning electron microscope (SEM) image of the curved polyaniline prepared in Example 10. As can be seen from the image, the polyaniline exhibits a distinct hollow curved arc structure. The presence of this curved structure helps to disperse the stress and promotes the stability of the polyaniline's morphology. Furthermore, the curved arc structure also facilitates thorough wetting with the nylon resin solution, and the nylon resin infused inside the arc enhances the bonding force between the polyaniline and the matrix resin.

[0111] Figure 2 The scanning electron microscope image of polyaniline prepared for Comparative Example 1 shows a clearly aggregated blocky structure. This is because the initiator is added continuously in one drop, which is not conducive to the formation of the initial curved structure. Moreover, the polymerization rate is too fast, and the aniline monomers do not have time to bind to the surface of the ice micro powder before the polymerization reaction occurs, thus failing to form a curved arc structure.

[0112] Figure 3 The scanning electron microscope image of polyaniline prepared for Comparative Example 2 shows an irregular morphology. Due to the excessively slow stirring rate, the difference in motion rates between the solid and liquid was too small, which was detrimental to the nucleation effect of the ice micropowder.

[0113] Combining the mechanical and electrical conductivity data from various embodiments and comparative examples, it can be seen that the presence of the curved surface structure of the polyaniline can significantly disperse the stress on the polyaniline. This is because the curved arc structure has a large specific surface area, which can form more contact points with the nylon resin, facilitating the construction of conductive pathways. Simultaneously, the curved structure of polyaniline makes it less prone to aggregation, helping to form continuous conductive paths in the planar direction, thereby improving the overall conductivity of the material. Furthermore, the arc-shaped polyaniline exhibits a three-dimensional spatial structure, forming a randomly arranged conductive network structure when blended with the nylon solution. This not only makes the composite material less prone to breakage under impact but also allows it to better embed itself between the gaps in the nylon aerogel, forming channels for stress transmission and constructing a more complex three-dimensional network structure. This not only helps reduce the amount of polyaniline filling material but also disperses the stress, prevents stress concentration, and improves toughness.

[0114] Specifically, compared to Example 10, the initiator in Comparative Example 1 was not added in batches, resulting in an excessively fast polymerization rate. The aniline monomers did not have enough time to bind to the surface of the ice micropowder before polymerization occurred, preventing the formation of a curved, arc-shaped structure and hindering the improvement of conductivity and mechanical properties. In Comparative Example 2, the stirring rate was too low during the polymerization reaction, preventing the ice micropowder from playing a heterogeneous nucleation role and thus failing to prepare an arc-shaped polyaniline structure. With the same mass addition of polyaniline, the contact area with the nylon aerogel decreased, hindering the effective construction of a conductive, reinforcing, and dispersing network, leading to a reduction in electrical conductivity and elongation at break.

[0115] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for preparing nylon aerogel for 3D printing, characterized in that, Includes the following steps: (1) Under ice-salt bath conditions, aniline monomer and ice powder were added to deionized water while stirring to obtain a monomer mixed solution; (2) Under stirring conditions of not less than 400 rpm, the initiator is added dropwise to the monomer mixture solution in batches. After the addition is completed, the reaction is stirred and the reaction is continued. After post-treatment, curved polyaniline is obtained. The initiator added for the first time accounts for 10-20 wt% of the total initiator. After the reaction is carried out for 0.5-1 h, the remaining initiator is added dropwise. (3) Dissolve nylon in an acidic solvent, then add curved polyaniline, and ultrasonically disperse to obtain a nylon mixed solution; (4) Freeze-dry the nylon mixture solution to obtain nylon aerogel for 3D printing; In step (2), the mass ratio of the initiator to the aniline monomer is (2-4):

1.

2. The method for preparing nylon aerogel for 3D printing as described in claim 1, characterized in that, In step (1), the mass ratio of ice micro powder to aniline monomer is 5-20:

1.

3. The method for preparing nylon aerogel for 3D printing as described in claim 1, characterized in that, In step (1), the mass ratio of aniline monomer to deionized water is (0.1-2):

100.

4. The method for preparing nylon aerogel for 3D printing as described in claim 1, characterized in that, The stirring rate in step (1) is 400-600 rpm.

5. The method for preparing nylon aerogel for 3D printing as described in claim 1, characterized in that, In step (2), the initiator is added in batches by adding the initiator in two separate additions. The first addition of the initiator accounts for 12-18 wt% of the total initiator. After reacting for 0.6-0.8 hours, the remaining initiator is added until the addition is complete.

6. The method for preparing nylon aerogel for 3D printing as described in claim 1, characterized in that, In step (3), the nylon is aliphatic nylon.

7. A nylon aerogel for 3D printing, characterized in that, It is prepared by the method of any one of claims 1-6 for 3D printing nylon aerogel.

8. An application of the nylon aerogel for 3D printing as described in claim 7, characterized in that, The nylon aerogel for 3D printing is used in photopolymerization, selective laser sintering, fused deposition modeling, or layered solid manufacturing technologies in 3D printing.

9. A 3D printing polyurethane material, characterized in that, It comprises a polyurethane resin material and a nylon aerogel for 3D printing; the nylon aerogel for 3D printing is the nylon aerogel for 3D printing as described in claim 7.

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