Naphthalene-containing polyamide elastomer for flexible electronic printing basement membrane, and preparation method and application thereof

Abstract

The invention relates to a naphthalene-containing polyamide elastomer for a flexible electronic printing basement membrane, which is characterized in that an aliphatic polyamide chain segment is used as a hard segment, polyether is used as a soft segment, a naphthalene ring monomer is introduced into a polyamide elastomer molecular chain, a conjugate plane structure forms a pi-pi stack, and amide hydrogen bonds are arranged at two ends; the naphthalene-containing polyamide elastomer has a spider-thread-like multilevel structure. The naphthalene-containing polyamide elastomer has the beneficial effects that the naphthalene-containing polyamide elastomer has excellent mechanical strength and toughness, and when the flexible electronic printing substrate film adopting the naphthalene-containing polyamide elastomer is applied to a flexible strain sensing device, the mechanical performance, thermal stability, sustainability and the like of the flexible strain sensing device are greatly improved. The flexible electronic printing substrate is comprehensively superior to a flexible electronic printing substrate prepared from an existing material; and the naphthalene-containing polyamide elastomer film can be recycled, so that the manufacturing cost of the flexible electronic device is reduced while environmental protection is considered.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis, and particularly relates to a naphthalene-containing polyamide elastomer for flexible electronic printing substrate films, its preparation method, and its application. Background Technology

[0002] Flexible printed electronics (FPCB) technology, as a cutting-edge manufacturing process, deposits conductive functional materials onto flexible substrates through printing to fabricate electronic devices. This technology combines the advantages of large-area, low-cost printing with the lightweight, thin, flexible, and transparent characteristics of flexible substrates, demonstrating enormous application potential in wearable devices, smart textiles, medical monitoring, and automotive electronics. As the technology carrier, the performance of the flexible substrate directly determines the reliability and application boundaries of the final electronic device. An ideal flexible printed substrate must possess both excellent mechanical durability (withstanding repeated bending, folding, and even rolling deformation) and thermal stability (withstanding high-temperature processes such as thermosetting of conductive pastes without significant dimensional changes, shrinkage, deformation, or decomposition). Currently, flexible substrates are mainly divided into two categories: polymer elastomers and polymer films, both of which have performance limitations.

[0003] Polymer elastomers: Represented by thermoplastic polyurethane elastomers, although they have excellent elasticity, toughness and processability, they have poor thermal stability and are difficult to be compatible with precious metal electronic pastes that require high-temperature curing (>100 ℃); in addition, the synthesis process of some thermoplastic polyurethane elastomers depends on organic solvents, which will bring environmental burden.

[0004] Polymer films, such as polyethylene terephthalate and polycarbonate, are transparent and impact-resistant, but their mechanical durability is insufficient under dynamic bending conditions, which can easily lead to failure. Polyimide films, although ultra-thin and flexible, lack sufficient elasticity and are expensive, which limits the large-scale application and promotion of polyimide films.

[0005] Nature provides remarkable biomimetic inspiration for material design: spider silk achieves a perfect balance of strength and toughness through a combination of "multi-layered microstructure + dynamic sacrificial bonds"—in its protein backbone, rigid alanine-rich regions (forming β-sheet nanocrystals) and flexible glycine-rich regions alternate, forming a natural "microphase separation structure" at the nanoscale that combines rigidity and flexibility; among them, β-sheet crystals act as physical cross-linking points, giving the material strength, while the hydrogen bond network between crystals acts as reversible sacrificial bonds, effectively dissipating energy under stress through reversible fracture and recombination, giving spider silk extremely high toughness. Inspired by this biomimetic principle, thermoplastic polyamide elastomers (composed of polyamide hard segments and polyether soft segments) have demonstrated excellent properties: combining mechanical strength, rubber-like elasticity, and a wide temperature range (-50℃ to 200℃), making them suitable as flexible printed circuit board materials; and the mainstream "melt polycondensation" synthesis process adopts an environmentally friendly approach, avoiding the use of organic solvents, which aligns with the requirements of green manufacturing. However, if the molecular design of existing thermoplastic polyamide elastomers can further draw on the biomimetic principle of "multi-level structure + dynamic cross-linking" of spider silk, it is expected to achieve breakthroughs in mechanical properties, thermal stability and sustainability, solve the current technical bottlenecks faced by flexible printed circuit boards, and promote technological innovation in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a naphthalene-containing polyamide elastomer for flexible electronic printing substrate films, its preparation method, and its application.

[0007] This naphthalene-containing polyamide elastomer is used for flexible electronic printing substrate films:

[0008] The polymer chain structure of naphthalene-containing polyamide elastomer is as follows:

[0009] ;

[0010] The polymer chains of naphthalene-containing polyamide elastomers include rigid sequence stacking portions, rigid regions, and flexible regions;

[0011] In the above formula, a is the number of repeating units in the rigid sequence stacking part of the polymer chain containing naphthalene polyamide elastomer, b is the number of repeating units in the rigid region part of the polymer chain containing naphthalene polyamide elastomer, and n is the number of repeating units in the flexible region part of the polymer chain containing naphthalene polyamide elastomer.

[0012] On a molar percentage basis, the naphthalene-containing polyamide elastomer is a terpolymer obtained by melt polycondensation of the following components:

[0013] Component A, 20–60 mol%,

[0014] Component B, ranging from 10 to 45 mol%, and

[0015] 25–50 mol% of component C,

[0016] Component A includes equimolar amounts of aliphatic dicarboxylic acids with 6 to 14 carbon atoms in their molecular backbone and aliphatic diamines with 6 to 14 carbon atoms in their molecular backbone;

[0017] Component B includes equimolar amounts of naphthalic acid / naphthalene diester and an aliphatic diamine whose molecular chain contains 6 to 14 carbon atoms;

[0018] Component C includes equimolar amounts of aliphatic dicarboxylic acid and polyether containing 6 to 14 carbon atoms in the molecular chain backbone, or component C includes equimolar amounts of naphthalic acid / naphthalene diester and polyether.

[0019] As a preferred embodiment, the naphthalene-containing polyamide elastomer, by molar percentage, is a terpolymer obtained by melt polycondensation of the following components:

[0020] Component A,

[0021] Component B,

[0022] Component C, and

[0023] An additional 0.1–0.3 mol% of catalyst was added;

[0024] The catalyst is a mixture of hypophosphite and tetrabutyl titanate, or a mixture of hypophosphite and tetrabutyl titanate.

[0025] Preferably, the polyether is any one of the following: polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran, polyetheramine, and polyether diamine with a molecular weight of 400 g / mol to 2000 g / mol.

[0026] As a preferred option:

[0027] Naphthalic acid is 2,6-naphthalenedicarboxylic acid;

[0028] Naphthalene diester is one of dimethyl 2,6-naphthalenedicarboxylate and diethyl 2,6-naphthalenedicarboxylate;

[0029] Aliphatic dicarboxylic acids are any one of the following: adipic acid, octanoic acid, sebacic acid, dodecanoic acid, and tetradecanoic acid;

[0030] The aliphatic diamine is any one of the following: hexanediamine, octanediamine, decanediamine, dodecanediamine, and tetradecanediamine.

[0031] As a preferred option:

[0032] Hypophosphite is any one of the following: sodium hypophosphite, potassium hypophosphite, magnesium hypophosphite, calcium hypophosphite, and zinc hypophosphite;

[0033] The phosphite is sodium phosphite.

[0034] The method for preparing this naphthalene-containing polyamide elastomer for flexible electronic printing substrate films includes the following steps:

[0035] Step 1: Weigh out components A, B, C and catalyst according to the above-mentioned proportions of the naphthalene-containing polyamide elastomer, and add them to the reactor. With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at the first pressure value, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at the first pressure value as the reaction protective gas.

[0036] Step 2: Heat the reactor to the first target temperature, and continue stirring the material in the reactor for the set time at the first target temperature;

[0037] Step 3: Heat the reactor to the second target temperature, continue stirring the material in the reactor at the second target temperature for a set time, then release the gas pressure in the reactor to atmospheric pressure within a certain time, open the nitrogen connection passage, and continue to introduce nitrogen into the reactor; heat the reactor to the third target temperature, and continue stirring the material in the reactor at the third target temperature for a set time.

[0038] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside reaches the second pressure value. Heat the reactor to the fourth target temperature. Continue stirring the material in the reactor at the fourth target temperature for the set time, then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain a biomimetic spider silk naphthalene-containing polyamide elastomer.

[0039] In the above steps:

[0040] First target temperature < Second target temperature < Third target temperature < Fourth target temperature;

[0041] First air pressure value > 0 MPa > Second air pressure value.

[0042] As preferred options: the first target temperature is 60–80 ℃, the second target temperature is 180–220 ℃, the third target temperature is 240–260 ℃, and the fourth target temperature is 270–290 ℃.

[0043] Preferably, the first air pressure value is 0.2 MPa, and the second air pressure value is -0.1 MPa.

[0044] This application of naphthalene-containing polyamide elastomers involves using them as flexible electronic printing substrate films in flexible strain sensor devices. In practice, the naphthalene-containing polyamide elastomers are processed through polymer casting or flat vulcanization equipment to obtain biomimetic spider silk-like naphthalene-containing polyamide elastomer films of a specific thickness. Conductive paste is then deposited onto the naphthalene-containing polyamide elastomer films via screen printing and cured at a certain temperature to form conductive circuits.

[0045] As a preferred option, a flexible strain sensor device using naphthalene-containing polyamide elastomer as the flexible electronic printing substrate film exhibits a stable electrical signal output under cyclic bending strain; the conductive circuit can be removed by wiping after immersion in anhydrous ethanol, enabling the recycling and reuse of the naphthalene-containing polyamide elastomer film.

[0046] The beneficial effects of this invention are:

[0047] (1) The present invention adopts a simple and efficient melt polycondensation method, using aliphatic polyamide segments as hard segments and polyethers as soft segments to construct a primary microphase separation structure. At the same time, naphthalene ring monomers are introduced into the polyamide elastomer molecular chain, and secondary microphase separation structure is constructed by using the π-π stacking formed by its conjugated planar structure and the amide hydrogen bonds at both ends. A thermoplastic naphthalene-containing polyamide elastomer with a multi-level structure similar to spider silk is synthesized.

[0048] (2) The conjugated planar structure of the thermoplastic naphthalene-containing polyamide elastomer enhances the mechanical strength of the polymer through π-π stacking and amide hydrogen bonds at both ends. At the same time, the amide hydrogen bonds between polymer molecular chains can act as dynamic sacrificial bonds similar to spider silk (which can achieve repeated breaking and recombination under stress, similar to spider silk), further improving the toughness of the polymer under dynamic strain. According to calculations, the hydrogen bond density of the naphthalene-containing polyamide elastomer of the present invention is as high as 51.70%. The energy released by these hydrogen bonds during tensile fracture can serve as the energy required by the polymer, making the toughness of the naphthalene-containing polyamide elastomer material as high as 134.61 MJ / m. 3 Furthermore, the hierarchical structure constructed in the molecular chain after the introduction of the naphthalene ring provides the polymer with excellent mechanical properties: tensile strength up to 68.32 MPa, elongation at break up to 688.37%, and cyclic elastic recovery rate exceeding 84.26%.

[0049] (3) The present invention uses a flexible electronic printing substrate film containing naphthalene polyamide elastomer to screen print flexible strain sensor devices, which makes up for the defects of poor thermal stability of thermoplastic polyurethane, insufficient temperature resistance of the substrate in the later stage of electronic paste printing, difficulty in curing, and reliance on organic solvent polymerization. It overcomes the shortcomings of polyethylene terephthalate and polycarbonate materials in poor mechanical durability and easy failure of devices under dynamic bending conditions, and overcomes the problems of poor elastic recovery performance and high cost of polyimide. The flexible strain sensor device using this flexible electronic printing substrate film has comprehensively surpassed the flexible electronic printing substrate prepared with existing materials in terms of mechanical performance, thermal stability and sustainability (which shows stable electrical signal output under cyclic bending strain), and overcomes the technical bottleneck of the prior art.

[0050] (4) The conductive lines formed by the conductive paste deposition on the flexible strain sensor can be wiped off after soaking in anhydrous ethanol for 12 hours, realizing the recycling and reuse of naphthalene-containing polyamide elastomer film, reducing the manufacturing cost of flexible electronic devices while taking into account environmental protection. Attached Figure Description

[0051] Figure 1 Image (a) shows a schematic diagram of the multi-layered microstructure and dynamic sacrificial bonds of spider silk in nature. Figure 1 (b) is a schematic diagram of the multi-level structure of the naphthalene-containing polyamide elastomer of the present invention and the amide hydrogen bonds between polymer molecular chains;

[0052] Figure 2 The figure shows the test results of the electrical signal output by the flexible strain sensor under cyclic bending strain. Detailed Implementation

[0053] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0054] In this invention: component A comprises an equimolar amount of an aliphatic dicarboxylic acid containing 6 to 14 carbon atoms in its molecular backbone and an aliphatic diamine containing 6 to 14 carbon atoms in its molecular backbone; component B comprises an equimolar amount of naphthalic acid / naphthalene diester and an aliphatic diamine containing 6 to 14 carbon atoms in its molecular backbone; component C comprises an equimolar amount of an aliphatic dicarboxylic acid containing 6 to 14 carbon atoms in its molecular backbone and a polyether, or component C comprises an equimolar amount of naphthalic acid / naphthalene diester and a polyether; the catalyst is a mixture of hypophosphite and tetrabutyl titanate, or the catalyst is a mixture of phosphite and tetrabutyl titanate.

[0055] Example 1

[0056] Step 1: Weigh 60 mol% of component A, 10 mol% of component B, 30 mol% of component C, and 0.1 mol% of catalyst, and add them to the reactor. Specifically: naphthalic acid is 2,6-naphthalenedicarboxylic acid, aliphatic dicarboxylic acid is adipic acid, aliphatic diamine is hexamethylenediamine, polyether is polyethylene glycol with a molecular weight of 400 g / mol, and catalyst is a mixture of sodium hypophosphite and tetrabutyl titanate. With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0057] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0058] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0059] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0060] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0061] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0062] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0063] Example 2

[0064] Step 1: Weigh 40 mol% of component A, 10 mol% of component B, 50 mol% of component C, and 0.2 mol% of catalyst, and add them to the reactor. Specifically, the following are used: naphthalene diester (dimethyl 2,6-naphthalenedicarboxylate), aliphatic dicarboxylic acid (octanoic acid), aliphatic diamine (octanediamine), polyether (polypropylene glycol with a molecular weight of 400 g / mol), and catalyst (a mixture of sodium phosphite and tetrabutyl titanate). With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0065] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0066] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0067] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0068] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0069] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0070] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0071] Example 3

[0072] Step 1: Weigh 40 mol% of component A, 20 mol% of component B, 40 mol% of component C, and 0.3 mol% of catalyst, and add them to the reactor. Specifically, the following are used: naphthalene diester (diethyl 2,6-naphthalenedicarboxylate), aliphatic dicarboxylic acid sebacic acid, aliphatic diamine decanediamine, polybutane glycol with a molecular weight of 400 g / mol, and catalyst a mixture of potassium hypophosphite and tetrabutyl titanate. With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0073] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0074] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0075] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0076] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0077] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0078] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0079] Example 4

[0080] Step 1: Weigh 35 mol% of component A, 20 mol% of component B, 45 mol% of component C, and 0.3 mol% of catalyst, and add them to the reactor. Specifically, the following mixtures are used: naphthalic acid (2,6-naphthalenedicarboxylic acid), aliphatic dicarboxylic acid (dodecanoic acid), aliphatic diamine (dodecanediamine), polyether (polytetrahydrofuran with a molecular weight of 400 g / mol), and catalyst (a mixture of magnesium hypophosphite and tetrabutyl titanate). With the reactor sealed, start the stirring device to stir the materials inside the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0081] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0082] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0083] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0084] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0085] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0086] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0087] Example 5

[0088] Step 1: Weigh 30 mol% of component A, 20 mol% of component B, 50 mol% of component C, and 0.2 mol% of catalyst, and add them to the reactor. Specifically, the following mixtures are used: naphthalic acid (2,6-naphthalenedicarboxylic acid), aliphatic dicarboxylic acid (tetradecanoic acid), aliphatic diamine (tetradecanediamine), polyether (400 g / mol molecular weight polyetheramine), and catalyst (a mixture of calcium hypophosphite and tetrabutyl titanate). With the reactor sealed, start the stirring device to stir the materials inside the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0089] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0090] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0091] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0092] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0093] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0094] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0095] Example 6

[0096] Step 1: Weigh 20 mol% of component A, 35 mol% of component B, 45 mol% of component C, and 0.2 mol% of catalyst, and add them to the reactor. Specifically, the following are used: naphthalic acid (2,6-naphthalenedicarboxylic acid), aliphatic dicarboxylic acid (dodecanoic acid), aliphatic diamine (decanediamine), polyether (polyethylene glycol with a molecular weight of 1000 g / mol), and catalyst (a mixture of zinc hypophosphite and tetrabutyl titanate). With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0097] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0098] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0099] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0100] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0101] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0102] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0103] Example 7

[0104] Step 1: Weigh 30 mol% of component A, 45 mol% of component B, 25 mol% of component C, and 0.2 mol% of catalyst, and add them to the reactor. Specifically, the following are used: naphthalic acid (2,6-naphthalenedicarboxylic acid), aliphatic dicarboxylic acid (dodecanoic acid), aliphatic diamine (decanediamine), polyether (polyethylene glycol with a molecular weight of 2000 g / mol), and catalyst (a mixture of sodium hypophosphite and tetrabutyl titanate). With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0105] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0106] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0107] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0108] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0109] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0110] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0111] Comparative Example

[0112] Step 1: Weigh 75 mol% of component A, 25 mol% of component C, and 0.2 mol% of catalyst, and add them to the reactor. Specifically: the aliphatic dicarboxylic acid is adipic acid, the aliphatic diamine is hexamethylenediamine, the polyether is polyethylene glycol with a molecular weight of 400 g / mol, and the catalyst is a mixture of sodium hypophosphite and tetrabutyl titanate. With the reactor sealed, start the stirring device to stir the materials in the reactor. At the same time, open the nitrogen connection to introduce nitrogen into the reactor. After the nitrogen gradually replaces the residual air inside the reactor and the pressure inside the reactor is maintained at 0.2 MPa, close the nitrogen connection to stop the introduction of nitrogen. Use the nitrogen at a pressure of 0.2 MPa as the protective gas for the reaction.

[0113] Step 2: After all components have been added and mixed, heat the reactor to 80 ℃ and continue stirring the material in the reactor at a stirring rate of 50 r / min for 2 h at 80 ℃.

[0114] Step 3: Heat the reactor to 220 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 220 ℃. Then, release the gas pressure in the reactor to atmospheric pressure within 1.5 hours, open the nitrogen connection, and continue to introduce nitrogen into the reactor. Heat the reactor to 240 ℃, and continue stirring the material in the reactor at 50 r / min for 2 hours at 240 ℃.

[0115] Step 4: Close the nitrogen connection and stop supplying nitrogen into the reactor. Extract the gas from the reactor until the pressure inside the reactor reaches -0.1 MPa. Heat the reactor to 280 ℃ and continue stirring the material inside the reactor at a stirring rate of 50 r / min for 2 hours at 280 ℃. Then stop stirring. Open the nitrogen connection and continue supplying nitrogen into the reactor until the pressure inside the reactor returns to atmospheric pressure. Discharge the reaction product from the bottom of the reactor and granulate it to obtain biomimetic spider silk naphthalene-containing polyamide elastomer.

[0116] Step 5: Obtain a 0.1 mm thick biomimetic spider silk naphthalene-containing polyamide elastomer film by polymer casting or flat vulcanization equipment. Deposit conductive paste onto the naphthalene-containing polyamide elastomer film by screen printing and cure it at 150 °C to form conductive lines on the surface of the naphthalene-containing polyamide elastomer film. After encapsulation, the naphthalene-containing polyamide elastomer film with conductive lines on the surface is applied to a flexible strain sensor device.

[0117] Step 6: Acquire the electrical signal output by the flexible strain sensor under cyclic bending strain;

[0118] Step 7: Immerse the naphthalene-containing polyamide elastomer film in anhydrous ethanol for 12 hours, then wipe off the printed circuit on its surface and recycle the naphthalene-containing polyamide elastomer film.

[0119] The thermal properties (glass transition temperature and melting point), relative viscosity, density, tensile strength, elongation at break and elastic recovery of the biomimetic spider silk naphthalene polyamide elastomers obtained in Examples 1-7 and the comparative examples were tested under the following conditions. The test results are shown in Table 1 below.

[0120] The specific test conditions for various properties of biomimetic spider silk-containing naphthalene polyamide elastomer are as follows:

[0121] The thermal properties were tested using differential scanning calorimetry and dynamic thermomechanical analysis.

[0122] The relative viscosity was measured using a relative viscosity meter in concentrated sulfuric acid at a concentration of 1 g / dL.

[0123] Density was tested using a true density meter.

[0124] Tensile strength and elongation at break were measured according to GB / T 2918-2018.

[0125] The elastic recovery rate is determined by testing the 50% recovery rate after 10 tensile strain cycles.

[0126] Table 1. Performance test results of the biomimetic spider silk naphthalene-containing polyamide elastomers prepared in Examples 1-7 and comparative examples.

[0127] Performance Examples Glass transition temperature (°C) Melting point (°C) relative viscosity Density (g / ml) Tensile strength (MPa) Elongation at break (%) Elastic recovery rate (%) Example 1 56 265 2.37 1.14 56.36 237.91 38.49 Example 2 53 237 2.41 1.13 54.41 341.85 67.14 Example 3 43 201 2.29 1.11 55.26 421.67 74.26 Example 4 46 176 2.33 1.11 57.46 544.39 78.41 Example 5 54 181 2.21 1.12 56.11 688.37 84.26 Example 6 62 243 2.52 1.14 61.33 289.54 46.21 Example 7 73 268 2.63 1.15 68.32 314.26 51.63 Comparative Example 55 258 2.46 1.12 53.21 240.63 40.17

[0128] Based on the glass transition temperature, melting point, relative viscosity, density, tensile strength, elongation at break, and elastic recovery rate data of Examples 1-7 and the comparative examples shown in Table 1 above, it can be seen that the performance of the spider silk-like naphthalene-containing polyamide elastomer used in flexible electronic printing is closely related to the composition ratio of the feed components. Specifically, compared to the comparative examples, the 10 mol% component B in Example 1 improved the glass transition temperature, melting point, density, and tensile strength of the polymer. Compared to Example 1, the proportion of component C in Example 2 was increased to 50 mol%, thereby improving the elongation at break and elastic recovery rate of the polymer. Further, compared to Examples 1-2, the proportion of component B in Example 3 was increased to 20 mol%, resulting in an elongation at break and elastic recovery rate of 421.67% and 74.26%, respectively. Compared to Example 3, in Examples 4 and 5, with the further increase of component C, the elongation at break and elastic recovery rate of the polymer also increased accordingly. Compared to Example 6, the proportions of components A and B are increased in Example 7. The glass transition temperature, melting point, relative viscosity, density, and tensile strength of the polymer in this example are also enhanced. In summary, the spider silk-like naphthalene-containing polyamide elastomer synthesized in this invention exhibits a wide range of tunable thermal and mechanical properties and significant characteristic differences, meeting the needs of various application scenarios within its applicable scope and demonstrating broad application prospects.

[0129] Furthermore, the test results of the electrical signal output by the flexible strain sensor device of the present invention under cyclic bending strain are shown in [the figure]. Figure 2 , Figure 2 In this context, R represents the resistance of the printed substrate (i.e., a naphthalene-containing polyamide elastomer film with conductive lines on its surface) under bending strain, R0 represents the initial resistance of the printed substrate, and (R-R0) / R0 represents the rate of change of resistance of the printed substrate under strain. Figure 2 This demonstrates that the fabricated flexible printed circuit can achieve stable electrical signal output performance under 90° cyclic bending and folding test conditions.

[0130] In summary, as Figure 1As shown, this invention is inspired by the multi-level structure and dynamic sacrificial bonds of spider silk. It employs a simple and efficient melt polycondensation method, utilizing aliphatic polyamide segments as hard segments and polyethers as soft segments to construct a primary microphase separation structure. Simultaneously, naphthalene ring monomers (such as naphthalene dicarboxylic acid) are introduced into the polyamide elastomer molecular chain. The π-π stacking formed by its conjugated planar structure and the amide hydrogen bonds at both ends are used to construct a secondary microphase separation structure, synthesizing a thermoplastic naphthalene-containing polyamide elastomer with a multi-level structure similar to spider silk. Its conjugated planar structure enhances the mechanical strength of the polymer through π-π stacking and amide hydrogen bonds at both ends. Furthermore, the amide hydrogen bonds between polymer molecular chains can act as dynamic sacrificial bonds similar to spider silk (allowing for repeated breakage and recombination under stress), further improving the polymer's toughness under dynamic strain. When the naphthalene-containing polyamide elastomer is used as a flexible substrate film for printing conductive paste, it exhibits stable electrical signal output under cyclic bending strain. Moreover, the printed circuit can be removed by wiping after soaking in anhydrous ethanol for 12 hours, thus enabling the polymer film to be recycled and reused.

Claims

1. A naphthalene-containing polyamide elastomer for flexible electronic printing substrate films, characterized in that: The polymer chain structure of the naphthalene-containing polyamide elastomer is as follows: ； The polymer chain of the naphthalene-containing polyamide elastomer includes a rigid sequence stacking portion, a rigid region portion, and a flexible region portion; In the above formula, a is the number of repeating units in the rigid sequence stacking portion of the polymer chain containing naphthalene polyamide elastomer, b is the number of repeating units in the rigid region portion of the polymer chain containing naphthalene polyamide elastomer, and n is the number of repeating units in the flexible region portion of the polymer chain containing naphthalene polyamide elastomer. By molar percentage, the naphthalene-containing polyamide elastomer is a terpolymer obtained by melt polycondensation of the following components: Component A, 20–60 mol%, Component B, ranging from 10 to 45 mol%, and 25–50 mol% of component C, Component A includes equimolar amounts of aliphatic dicarboxylic acids containing 6 to 14 carbon atoms in the molecular chain backbone and aliphatic diamines containing 6 to 14 carbon atoms in the molecular chain backbone. Component B includes equimolar amounts of naphthalic acid / naphthalene diester and an aliphatic diamine whose molecular chain contains 6 to 14 carbon atoms. The component C comprises an equimolar amount of an aliphatic dicarboxylic acid containing 6 to 14 carbon atoms in the molecular chain backbone and a polyether, or the component C comprises an equimolar amount of naphthalic acid / naphthalene diester and a polyether.

2. The naphthalene-containing polyamide elastomer for flexible electronic printing substrate film according to claim 1, characterized in that: By molar percentage, the naphthalene-containing polyamide elastomer is a terpolymer obtained by melt polycondensation of the following components: The component A, The component B, The component C, and An additional 0.1–0.3 mol% of catalyst was added; The catalyst is a mixture of hypophosphite and tetrabutyl titanate, or the catalyst is a mixture of hypophosphite and tetrabutyl titanate.

3. The naphthalene-containing polyamide elastomer for flexible electronic printing substrate film according to claim 1, characterized in that, The polyether is any one of the following: polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran, polyetheramine, and polyetherdiamine with a molecular weight of 400 g / mol to 2000 g / mol.

4. The naphthalene-containing polyamide elastomer for flexible electronic printing substrate film according to claim 1, characterized in that: The naphthalic acid is 2,6-naphthalenedicarboxylic acid; The naphthalene diester is one of dimethyl 2,6-naphthalenedicarboxylate and diethyl 2,6-naphthalenedicarboxylate; The aliphatic dicarboxylic acid is any one of the following: adipic acid, octanoic acid, sebacic acid, dodecanoic acid, and tetradecanoic acid; The aliphatic diamine is any one of the following: hexanediamine, octanediamine, decanediamine, dodecanediamine, and tetradecanediamine.

5. The naphthalene-containing polyamide elastomer for flexible electronic printing substrate film according to claim 2, characterized in that: The hypophosphite is any one of the following: sodium hypophosphite, potassium hypophosphite, magnesium hypophosphite, calcium hypophosphite, and zinc hypophosphite; The phosphite is sodium phosphite.

6. A method for preparing a naphthalene-containing polyamide elastomer for flexible electronic printing substrate film as described in any one of claims 2 to 5, characterized in that, Includes the following steps: Step 1: Weigh out component A, component B, component C and catalyst according to the above-mentioned proportions of the naphthalene-containing polyamide elastomer, and add them to the reactor; stir the material in the reactor while it is sealed, and simultaneously introduce nitrogen into the reactor. After the nitrogen gradually replaces the air inside the reactor and the pressure inside the reactor is maintained at a first pressure value, stop introducing nitrogen and use the nitrogen at the first pressure value as a protective gas. Step 2: Heat the reactor to the first target temperature, and continue stirring the material in the reactor for the set time at the first target temperature; Step 3: Heat the reactor to the second target temperature, and continue stirring the material in the reactor at the second target temperature for a set time. After a certain period of time, release the gas pressure in the reactor to atmospheric pressure and continue to introduce nitrogen into the reactor. Heat the reactor to the third target temperature, and continue stirring the material in the reactor at the third target temperature for a set time. Step 4: Stop supplying nitrogen into the reactor and extract the gas from the reactor until the gas pressure inside the reactor reaches the second pressure value; heat the reactor to the fourth target temperature, and continue stirring the material in the reactor at the fourth target temperature for a set time, then stop stirring; continue supplying nitrogen into the reactor until the gas pressure inside the reactor returns to atmospheric pressure; discharge the reaction product from the bottom of the reactor and granulate it to obtain naphthalene-containing polyamide elastomer; In the above steps: The first target temperature < the second target temperature < the third target temperature < the fourth target temperature; The first air pressure value is greater than 0 MPa, which is greater than the second air pressure value.

7. The preparation method according to claim 6, characterized in that: The first target temperature is 60–80 °C, the second target temperature is 180–220 °C, the third target temperature is 240–260 °C, and the fourth target temperature is 270–290 °C.

8. The preparation method according to claim 6, characterized in that: The first air pressure value is 0.2 MPa, and the second air pressure value is -0.1 MPa.

9. An application of the naphthalene-containing polyamide elastomer as described in claim 1 or claim 6, characterized in that: The naphthalene-containing polyamide elastomer is used as a flexible electronic printing substrate film in flexible strain sensor devices. In application: the naphthalene-containing polyamide elastomer is subjected to polymer casting treatment or flat vulcanization treatment to obtain a naphthalene-containing polyamide elastomer film of a specific thickness. The conductive paste is deposited on the naphthalene-containing polyamide elastomer film by screen printing and cured at a certain temperature to form a conductive circuit.

10. The application of the naphthalene-containing polyamide elastomer according to claim 9, characterized in that: The flexible strain sensor, which uses naphthalene-containing polyamide elastomer as a flexible electronic printing substrate film, exhibits a stable electrical signal output under cyclic bending strain; the conductive lines can be removed by wiping after immersion in anhydrous ethanol.

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