Preparation method of boron-based polymer based on strong-weak dynamic bonds

Abstract

The invention belongs to the technical field of protective materials, and particularly relates to a preparation method of a boron-based polymer based on a'strong-weak 'dynamic bond, which comprises the following steps: destroying intermolecular force of a boron-based siloxane material and another supramolecular material through a polar solvent, and then fully blending to recombine into a dual-network structure, thereby obtaining the boron-based polymer based on the'strong-weak' dynamic bond. And fully evaporating the solvent to obtain the boron-based polymer based on the strong-weak dynamic bond. According to the invention, the strong-bond silicon-based supramolecular material and the weak-bond silicon-based supramolecular material are subjected to structural interpenetration under the driving of an intermolecular acting force, so that the compatible integration of the two components is promoted, and the novel shear thickening material is formed; by constructing a composite system of a boron-based siloxane material (component A) and siloxane containing a strong dynamic bond (component B), dual-function optimization is realized: a dynamic bond network of the component B not only effectively inhibits the intrinsic cold fluidity defect of the component A, but also inhibits the intrinsic cold fluidity defect of the component B through a dynamic bond synergistic effect on the premise of maintaining the shear thickening characteristic of the system; the mechanical property and the environmental stability of the composite material are obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of protective materials, and particularly relates to a preparation method of a boron-based polymer based on "strong-weak" dynamic bonds. Background Art

[0002] Shear thickening effect, as a non-Newtonian fluid behavior, its core feature is that above the critical strain rate threshold, the material viscosity or modulus is positively correlated with the strain rate, showing a unique mechanical response characteristic of "getting stronger when encountering strength". This effect has important application value in the field of protective materials. The most representative one is the D3O intelligent protective material developed by British engineer Richard Palmer in 2004 (American Journal of Aerospace Engineering Volume 10, Issue 1). The "soft armor" material composed of a special polymer system is listed as one of the top ten innovative materials in the future. Its excellent protective performance stems from the unique shear thickening effect of its matrix polymer. In recent years, the academic community has carried out systematic research on the preparation process, action mechanism and mechanical behavior of shear thickening materials. Among them, the shear thickening gel (STG) based on borosiloxane has attracted much attention due to its significant shear hardening characteristics.

[0003] Although STG shows broad application prospects in the field of human protection, its inherent cold flowability defect severely restricts its practical application. The current main solutions include: (1) Sandwich structure design: Encapsulating the STG core material in a sandwich structure composed of high-performance fabrics, aluminum plates or rubber plates; (2) Porous matrix composite: Diluting STG with organic solvents and then composite with a polyurethane foam matrix through an impregnation-drying process; (3) Dual network construction: Combining the STG dynamic network with a specific siloxane static network. The former endows the material with shear thickening characteristics, and the latter provides structural stability support. It should be noted that the first two methods essentially belong to mechanical encapsulation strategies. In practical applications, the long-term sealing reliability of the encapsulation system needs to be ensured, which poses severe challenges to the interfacial bonding strength and fatigue resistance of the material. For the dual network construction strategy, the compatibility of the two components and the performance manifestation after the combination of the two components are also unknown. Summary of the Invention

[0004] The present invention discloses a preparation method of a boron-based polymer based on "strong-weak" dynamic bonds. Driven by intermolecular forces, through the structural interpenetration of a silicon-based supramolecular material with the cooperation of strong / weak bonds, the compatibility and integration of a two-component system are realized, and a novel shear thickening material is formed. By constructing a composite system of a boron-based siloxane material (component A) and a siloxane material containing strong dynamic covalent bonds (component B), dual-functional optimization is achieved: the dynamic bond network of component B not only effectively inhibits the intrinsic cold flowability defect of component A, but also significantly improves the mechanical properties and environmental stability of the composite material through the dynamic bond synergistic effect while maintaining the shear thickening characteristics of the system.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A preparation method of a boron-based polymer based on "strong-weak" dynamic bonds is to disrupt the intermolecular forces of a boron-based siloxane material and another supramolecular material through a polar solvent, and then recombine them into a double-network structure through sufficient blending. After fully evaporating the solvent, a boron-based polymer based on "strong-weak" dynamic bonds is obtained.

[0007] Preferably, in the preparation method, the double-network structure is poured into a mold and the solvent is first evaporated under normal pressure, then the mold is placed in a low-pressure environment for further evaporation of the solvent, and then placed in an oven for heating to reorganize the intermolecular forces, obtaining a boron-based polymer based on "strong-weak" dynamic bonds.

[0008] Preferably, in the preparation method, after the mold is placed in a low-pressure environment for further evaporation of the solvent, it is placed in an oven at 75 °C for heating for 8 h to reorganize the intermolecular forces.

[0009] Preferably, the boron-based siloxane material refers to at least one of linear polyborosiloxane and hyperbranched polyborosiloxane.

[0010] Preferably, the supramolecular material refers to at least one of a D-A bond-based supramolecular material, an S-S bond-based supramolecular material, a multiple hydrogen bond-based supramolecular material, and a metal coordination bond-based supramolecular material.

[0011] Preferably, the mass ratio of the boron-based siloxane material to the supramolecular material is between 10:1 and 1:10.

[0012] Preferably, the polar solvent is at least one of ethanol, DMSO, pyridine, acetone, and DMF.

[0013] The beneficial effects of the preparation method of a boron-based polymer based on "strong-weak" dynamic bonds of the present invention are:

[0014] (1) By constructing a composite system of a boron-based siloxane material (Component A) and a siloxane material with strong dynamic covalent bonds (Component B), this study achieved dual-functional optimization: The dynamic bond network of Component B not only effectively suppressed the intrinsic cold flowability defect of Component A, but also significantly improved the mechanical properties and environmental stability of the composite material through the dynamic bond synergistic effect while maintaining the shear thickening characteristics of the system.

[0015] (2) Adopting the supramolecular network design strategy, dynamic reversible action sites were introduced into the material system. This strategy endows the material with three advantages: 1. The self-healing ability based on non-covalent bonds can restore the mechanical integrity of the damaged interface; 2. The network topology reconstruction characteristics enable the material to have thermoplastic processability; 3. The inverse depolymerization-recombination mechanism realizes the closed-loop recycling of the material, which conforms to the concept of sustainable material design. 4. Using the boron-based siloxane material as Component A and another siloxane material with strong dynamic covalent bonds as Component B can achieve the restraint of the cold flowability of Component A and improve the overall performance while retaining the shear thickening property. 5. Taking the supramolecular network strategy as the synthesis strategy ensures that the material can improve its lifespan through self-healing and endows it with recyclability.

[0016] (3) Although conventional boron-based siloxane materials have excellent impact resistance, the cold flowability and irreversible deformation problems caused by their unstable topological structures seriously restrict their application and development; In this invention, a double-network interpenetrating structure was constructed by introducing a supramolecular network, and while effectively maintaining the shear thickening characteristics of the material, the controllable regulation of mechanical properties and morphology was successfully achieved. It is particularly worth pointing out that this invention uses a siloxane-based polymer with excellent biocompatibility as the raw material, which not only ensures that the material is non-toxic and harmless to the human body, but also provides an important guarantee for its large-scale popularization and application; This preparation method of the double-network interpenetrating structure based on the regulation of intermolecular forces has the advantages of simple process, environmentally friendly and reliable materials, and controllable performance, and shows broad application prospects in the field of intelligent materials. Description of the Drawings

[0017] Figure 1 It is a schematic flow chart of the preparation of the new material provided by this invention;

[0018] Figure 2 It is a tensile-strain characterization result diagram of the new material provided by Example 8 at a tensile rate of 100 mm / min;

[0019] Figure 3 It is a tensile-strain characterization result diagram of the new material provided by Example 9 at a tensile rate of 100 mm / min;

[0020] Figure 4 It is a tensile-strain characterization result diagram of the new material provided by Example 10 at a tensile rate of 100 mm / min. Detailed implementation manners

[0021] As described below, it is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0022] In general, the following embodiments can be understood as explaining the present invention step by step, or can be understood as separately expressing a part of the local structure or method of the present invention, or can also be understood as the combination of embodiments explaining the connotation of a larger range of the structure or method of the present invention.

[0023] Embodiment 1

[0024] A preparation method of a boron-based polymer based on "strong-weak" dynamic bonds is to disrupt the intermolecular forces of a boron-based siloxane material and another supramolecular material through a polar solvent, and then recombine them into a double-network structure through sufficient blending, and obtain a boron-based polymer based on "strong-weak" dynamic bonds after fully evaporating the solvent.

[0025] In this embodiment, the double-network structure refers to constructing a bicontinuous phase structure that penetrates each other but does not undergo covalent crosslinking to achieve synergistic enhancement of material properties. This strategy can effectively improve the mechanical properties, interfacial compatibility, and functional stability of materials, while maintaining the inherent characteristics of each component, providing a new idea for the design of multifunctional composite materials.

[0026] Embodiment 2

[0027] In the described preparation method, the double-network structure is poured into a mold, and the solvent is first evaporated under normal pressure, and then the mold is placed in a low-pressure environment to further evaporate the solvent to obtain a boron-based polymer based on "strong-weak" dynamic bonds.

[0028] Embodiment 3

[0029] The boron-based siloxane material refers to linear polyborosiloxane.

[0030] The supramolecular material refers to a D-A bond-based supramolecular material.

[0031] The mass ratio of the boron-based siloxane material to the supramolecular material is 10:1.

[0032] The polar solvent is ethanol.

[0033] Embodiment 4

[0034] The boron-based siloxane material refers to hyperbranched polyborosiloxane.

[0035] The supramolecular material refers to an S-S bond-based supramolecular material.

[0036] The mass ratio of the boron-based siloxane material to the supramolecular material is 1:10.

[0037] The polar solvent described is DMSO.

[0038] Example 5

[0039] The supramolecular material mentioned refers to a multiple hydrogen bond-based supramolecular material.

[0040] The polar solvent described is pyridine.

[0041] Example 6

[0042] The supramolecular material mentioned refers to a metal coordination bond-based supramolecular material.

[0043] The polar solvent described is acetone.

[0044] Example 7

[0045] The polar solvent described is DMF.

[0046] Example 8

[0047] First, react a certain amount of hydroxyl-terminated polydimethylsiloxane with a certain amount of boric acid at high temperature to generate component A. Second, react hydroxyl-terminated polydimethylsiloxane, upy, hexamethylene diisocyanate, and BDTDL under argon protection and stirring at 85 °C overnight to generate component B (multiple hydrogen bond-based supramolecular material). Dissolve components A and B in ethanol at a weight ratio of 4:3, stir overnight to fully dissolve and mix evenly, then pour into a mold and place in an oven at 75 °C to evaporate the solvent for 1 hour. Immediately place in a vacuum oven at 60 °C and dry overnight, and then place in an oven at 75 °C and heat for 8 h to reorganize the intermolecular forces. Take out to obtain a new material.

[0048] Perform rheological tests on the prepared new material. Specifically, use an RSO rotational rheometer to test the modulus of the material, and perform a frequency sweep on the material. Stress: 500 N, frequency: 0.1 - 20 Hz, temperature: 25 °C, as Figure 2 shown. It can be found from the figure that the new material still maintains shear thickening properties.

[0049] Example 9

[0050] First, a certain amount of hydroxyl-terminated polydimethylsiloxane reacts with a certain amount of boric acid at high temperature to generate component A. Second, hydroxyl-terminated polydimethylsiloxane, 3,3'-dihydroxydiphenyl disulfide, hexamethylene diisocyanate and BDTDL are stirred and reacted overnight under argon protection at 85 °C to generate component B (S-S group supramolecular material). Components A and B are dissolved in ethanol at a weight ratio of 4:3, stirred overnight to dissolve them fully and mix them evenly, then poured into a mold and placed in an oven at 75 °C to evaporate the solvent for 1 hour. Immediately, it is placed in a vacuum oven at 60 °C and dried overnight, and then placed in an oven at 75 °C and heated for 8 h to reorganize the intermolecular forces. After taking it out, a new material is obtained.

[0051] The rheological properties of the prepared new material are tested. Specifically, an RSO rotational rheometer is used to test the modulus of the material. The material is subjected to frequency scanning with a stress of 500 N, a frequency of 0.1 - 20 Hz, and a temperature of 25 °C, as Figure 3 shown. It can be found from the figure that the new material still maintains shear thickening properties.

[0052] Example 10

[0053] First, a certain amount of hydroxyl-terminated polydimethylsiloxane reacts with a certain amount of boric acid at high temperature to generate component A. Second, bis(3-aminopropyl)polydimethylsiloxane, hexamethylene diisocyanate and BDTDL are stirred and reacted overnight under argon protection at 85 °C to generate component B (hydrogen bond-based supramolecular material). Components A and B are dissolved in acetone at a weight ratio of 4:3, stirred overnight to dissolve them fully and mix them evenly, then poured into a mold and placed in an oven at 75 °C to evaporate the solvent for 1 hour. Immediately, it is placed in a vacuum oven at 60 °C and dried overnight, and then placed in an oven at 75 °C and heated for 8 h to reorganize the intermolecular forces. After taking it out, a new material is obtained.

[0054] The rheological properties of the prepared new material are tested. Specifically, an RSO rotational rheometer is used to test the modulus of the material. The material is subjected to frequency scanning with a stress of 500 N, a frequency of 0.1 - 20 Hz, and a temperature of 25 °C, as Figure 4 shown. It can be found from the figure that the new material still maintains shear thickening properties.

Claims

1. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond, characterized in that: The intermolecular forces between the boron-based siloxane material and another supramolecular material are destroyed by a polar solvent, and then reorganized into a double network structure after sufficient blending. After sufficient evaporation of the solvent, a boron-based polymer based on "strong-weak" dynamic bonds is obtained.

2. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond as claimed in claim 1, characterized in that: In the preparation method, the double network structure is poured into a mold to evaporate the solvent at normal pressure, and then the mold is placed in a low-pressure environment to further evaporate the solvent, and then placed in an oven for heating to reorganize the intermolecular forces to obtain a boron-based polymer based on "strong-weak" dynamic bonds.

3. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond as claimed in claim 2, characterized in that: In the preparation method, the mold is placed in a low-pressure environment to further evaporate the solvent, and then placed in a 75° C. oven and heated for 8 hours to reorganize the intermolecular forces.

4. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond as claimed in claim 1, characterized in that: The boron-based siloxane material refers to at least one of linear polyborosiloxane and hyperbranched polyborosiloxane.

5. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond as claimed in claim 1, characterized in that: The supramolecular material refers to at least one of a DA bond-based supramolecular material, an SS bond-based supramolecular material, a multiple hydrogen bond-based supramolecular material, and a metal coordination bond-based supramolecular material.

6. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond as claimed in claim 1, characterized in that: The mass ratio of the boron-based siloxane material to the supramolecular material is between 10:1 and 1:

10.

7. A method for preparing a boron-based polymer based on a "strong-weak" dynamic bond as claimed in claim 1, characterized in that: The polar solvent is at least one of ethanol, DMSO, pyridine, acetone and DMF.

Images