Radiation-sensitive cross-linking agent and preparation method thereof

Abstract

The invention discloses a radiation-sensitive cross-linking agent which is characterized in that radiation-sensitive dynamic bonds contained in the cross-linking agent are easy to break after being subjected to high-energy irradiation, and stable free radicals are generated. The irradiation cross-linking bond of the polymer can be balanced, so that the structural performance stability of the polymer during irradiation is kept. A cross-linked structure of the material contains phenyl conjugated acylhydrazone bonds sensitive to high-energy irradiation and phenylboronic acid groups sensitive to radiation product active oxygen free radicals; at room temperature, the gel is irradiated by high-energy rays, and when a broken dynamic covalent bond and a cross-linking point generated by radiation are balanced, the performance stability can be macroscopically maintained.

Description

Technical Field

[0001] The invention relates to the field of radiation self-repairing materials, and in particular to a radiation-sensitive crosslinking agent and a preparation method thereof. Background Art

[0002] After being irradiated by high-energy rays, radiation-crosslinked polymer materials show aging phenomena such as hardening and reduced mechanical properties. This is because the material is irradiated to produce macromolecular free radicals, which then recombine to form more crosslinking points inside the material, that is, the crosslinking density increases. For example, polyvinyl alcohol aqueous solution undergoes crosslinking after being irradiated with gamma rays. As the absorbed dose increases, the crosslinking density increases, and the polyvinyl alcohol hydrogel shrinks severely and hardens [Chang, S.; Wang, B.; Liu, Y.; Li, Z.; Hu, X.; Zhang, X.; Zhang, H., Radiation-assistant preparation of highly conductive, transparent and self-healing hydrogels with triple-network structure. Polymer 2020, 188, 122156.] The usual practice to improve the radiation resistance of materials is to introduce radiation-resistant additives into the polymer, such as compounds containing fused ring structures, compounds containing heavy metal elements such as lead and tungsten, compounds with free radical capture functions, etc.; or directly introduce radiation-resistant structures into the polymer molecular chain. However, the existing methods have limited effect on improving the radiation resistance of materials, and the introduction of additives will have adverse effects on the original structural properties of the materials.

[0003] There have been reports on the use of radiation-sensitive dynamic bonds for the recycling of epoxy resins [CN 110218294 A], but there is still a lack of research on the use of radiation-sensitive dynamic bonds for the self-repair of material aging caused by high-energy radiation.

[0004] Starting from molecular design, a high-energy radiation-sensitive cross-linker is designed, and dynamic covalent bonds are introduced into the cross-linking network, so that the number of covalent cross-linking structures maintains a dynamic balance during continuous irradiation, thereby maintaining the mechanical properties of the material. Summary of the invention

[0005] To achieve the above object, the present invention provides a radiation-sensitive crosslinking agent and a preparation method thereof.

[0006] The present invention provides a radiation-sensitive crosslinking agent, characterized in that the crosslinking agent contains radiation-sensitive dynamic bonds that are prone to breaking after being irradiated with high energy, generating stable free radicals. The radiation crosslinking bonds of the polymer can be balanced, thereby maintaining the stability of the structural performance of the polymer during irradiation. The crosslinking structure of the material contains phenyl conjugated acylhydrazone bonds that are sensitive to high-energy radiation and phenylboronic acid groups that are sensitive to active oxygen free radicals produced by radiation; at room temperature, when the gel is irradiated with high-energy rays, the broken dynamic covalent bonds reach equilibrium with the crosslinking points generated by radiation, and the stability of the performance can be maintained macroscopically.

[0007] Furthermore, the crosslinking agent contains a phenyl conjugated acylhydrazone bond and a phenylboronic acid group; and contains a structure sensitive to radiation product reactive oxygen free radicals (ROS). The molecular structure of the crosslinking agent is as follows:

[0008]

[0009] Further, R1 is one of cycloalkylene, alkylene cycloalkylene, heterocycloalkylene, alkylene heterocycloalkylene, alkylene heterocycloalkylene alkylene, cycloalkenylene, alkylene cycloalkenylene, alkylene cycloalkenylene alkylene, heterocycloalkenylene, alkylene heterocycloalkenylene, aromatic radical, alkylene aromatic radical, alkylene aromatic radical alkylene, heteroaromatic radical, alkylene heteroaromatic radical, secondary amine alkylene secondary amine group, secondary amine cycloalkylene secondary amine group, secondary amine heterocycloalkylene secondary amine group, secondary amine cycloalkylene secondary amine group, secondary amine heterocycloalkylene secondary amine group, secondary amine aromatic radical secondary amine group, secondary amine heteroaromatic radical secondary amine group, secondary amide heterocycloalkylene secondary amide group, secondary amide cycloalkylene secondary amide group, secondary amide aromatic radical secondary amide group, secondary amide heteroaromatic radical secondary amide group, oxyalkylene oxide group, oxycycloalkylene oxide group, oxyheterocycloalkylene oxide group, oxycycloalkylene oxide group, oxyaromatic radical oxy group, and disulfide bond.

[0010] Further, R2 is one of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocyclic group, a heterocycloalkyl group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, an alkane heteroalkyl group, an alkynyl group, an alkylene group, an alkylene heteroalkylene group, an alkenylene group, an alkylene heteroalkenylene group, an alkynylene group or an alkylene heteroalkynylene group.

[0011] Furthermore, the phenylboronic acid group is located at any substitution position of the phenyl group.

[0012] In addition, the present invention also provides a method for preparing the aforementioned radiation-sensitive crosslinking agent, characterized in that the crosslinking agent is produced by an amine-aldehyde condensation reaction between a hydrazine derivative and a benzoyl derivative.

[0013] Further, the hydrazine derivative is compound I, and compound I is: The benzoyl derivative is compound II, and compound II is: The molar ratio of compound I to compound II is 1:2.

[0014] Furthermore, the solvent used in the reaction is at least one of water, ethanol, methanol, butanol, tetrahydrofuran and dimethyl sulfoxide.

[0015] Furthermore, the reaction temperature is: 40-120°C.

[0016] The molecular structure of the high-energy radiation sensitive crosslinking agent of the present invention contains two radiation-sensitive phenyl conjugated acylhydrazone bonds, which improves the responsiveness of the crosslinking agent to high-energy radiation; introducing high-energy radiation sensitive dynamic bonds such as acylhydrazone bonds and disulfide bonds into the polymer as crosslinking structures is a dynamic dissipation strategy for aging of radiation crosslinked polymer materials due to excessive crosslinking during radiation.

[0017] In addition, the present invention also provides a high-energy ray irradiation self-repairing material based on the aforementioned radiation-sensitive crosslinking agent, comprising a crosslinking agent and a polymer substrate, the crosslinking agent and the polymer substrate are crosslinked in a certain ratio, the crosslinking structure contains radiation-sensitive dynamic bonds, and the substrate is crosslinked through chemical dynamic bonds to generate a radiation-sensitive self-repairing polymer material; at room temperature, when exposed to high-energy radiation, the material maintains stable properties and performance. The crosslinking structure is:

[0018]

[0019] Furthermore, the cross-linking structure is a dynamic phenylboronic acid bond. The hydroxyl group of the polymer substrate undergoes an ester exchange reaction with the phenylboronic acid group of the cross-linking agent, or the epoxy structure of the substrate undergoes a condensation reaction with the phenylboronic acid group of the cross-linking agent, to obtain a radiation self-healing material with phenylboronic acid ester as the cross-linking structure. Furthermore, the polymer substrate is a radiation cross-linking polymer material with at least one of hydroxyl, epoxy, and electron-rich nitrogen atom structures in the main chain.

[0020] Furthermore, the polymer substrate is at least one of cellulose, chitosan, hyaluronic acid, sodium alginate, agar, polyvinyl alcohol, 1,3-diethoxybutylene, and epoxy resin.

[0021] Furthermore, the molar ratio of the boronic acid groups of the crosslinking agent to the polymer reactive groups is 1:1-1:1000.

[0022] In addition, the present invention also provides a radiation self-repairing hydrogel, characterized in that it comprises the aforementioned high-energy ray irradiation self-repairing material.

[0023] In addition, the present invention also provides a method for preparing a radiation self-healing hydrogel, which is characterized in that the crosslinking agent in the aforementioned high-energy ray irradiation self-healing material and the polymer substrate are mixed in a solvent in an appropriate proportion and cross-linked to obtain the hydrogel.

[0024] In addition, the present invention also provides a radiation self-healing aerogel, characterized in that it comprises the aforementioned radiation self-healing hydrogel.

[0025] In addition, the present invention also provides a method for preparing a radiation self-healing aerogel, which is characterized in that the radiation self-healing hydrogel is freeze-dried or supercritically dried to obtain the aerogel.

[0026] The principles and beneficial effects of the present invention are:

[0027] 1. The crosslinker molecule contains two radiation-sensitive phenyl conjugated acylhydrazone bonds, which improves the responsiveness of the crosslinker to high-energy radiation. 2. The crosslinker structure contains phenylboric acid, and the hydroxyl group of the borate bond has good compatibility with polymer substrates containing epoxy groups and hydroxyl groups. At the same time, the reaction conditions are mild and the bond formation is rapid. 3. The present invention uses radiation-sensitive dynamic bonds to modify radiation-crosslinked polymer materials. Introducing radiation-sensitive dynamic bonds such as acylhydrazone bonds into polymers as crosslinking structures is aimed at the dissipation of crosslinking aging. 4. The borate structure is selected as a crosslinking point. It has good compatibility with gel precursors containing hydroxyl groups, epoxy groups, and electron-rich nitrogen atom structures. It can be used as a crosslinking structure to introduce radiation-sensitive dynamic bonds into them, thereby extending the service life of the material. 5. Materials crosslinked using borate bonds are easy to shape and can be made into different shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the results of H NMR spectrum detection of the cross-linking agent I prepared in Example 1 of the present invention;

[0029] Figure 2 Schematic diagram of the paramagnetic resonance spectrum of the cross-linking agent prepared in Example 1 of the present invention before and after irradiation and the cross-linking agent used in the comparative example;

[0030] Figure 3 A schematic diagram showing the mechanical properties comparison between the radiation self-repairing gel I prepared in Example 3 of the present invention and the comparative hydrogel I prepared in Comparative Example 1;

[0031] Figure 4 This is a schematic diagram of infrared spectrum detection of cross-linking agent I in Example 1 of the present invention before and after γ-ray irradiation. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below with reference to examples to make the implementation purpose, technical solution and advantages clearer. The reagents or instruments used, if not specifically described, are regarded as conventional products that can be purchased commercially.

[0033] The high-energy radiation self-repairing hydrogel and aerogel materials of the present invention contain radiation-sensitive conjugated acylhydrazone bond structures and radiation product ROS-sensitive phenylboronic acid structures as crosslinking points. When the material is irradiated, the broken dynamic covalent bonds and the crosslinking points generated by radiation reach a balance, and it is expected that the polymer material can maintain stable performance on a macro scale, thereby achieving the purpose of self-repair of radiation aging and extending the service life of the material under continuous irradiation environment.

[0034] The present invention provides a radiation-sensitive crosslinking agent, characterized in that the crosslinking agent contains radiation-sensitive dynamic bonds that are prone to breaking after being irradiated with high energy, generating stable free radicals. The radiation crosslinking bonds of the polymer can be balanced, thereby maintaining the stability of the structural performance of the polymer during irradiation. The crosslinking structure of the material contains phenyl conjugated acylhydrazone bonds that are sensitive to high-energy radiation and phenylboronic acid groups that are sensitive to active oxygen free radicals produced by radiation; at room temperature, when the gel is irradiated with high-energy rays, the broken dynamic covalent bonds reach equilibrium with the crosslinking points generated by radiation, and the stability of the performance can be maintained macroscopically.

[0035] Furthermore, the crosslinking agent contains a phenyl conjugated acylhydrazone bond and a phenylboronic acid group; and contains a structure sensitive to radiation product reactive oxygen free radicals (ROS). The molecular structure of the crosslinking agent is as follows:

[0036]

[0037] Further, R1 is one of cycloalkylene, alkylene cycloalkylene, heterocycloalkylene, alkylene heterocycloalkylene, alkylene heterocycloalkylene alkylene, cycloalkenylene, alkylene cycloalkenylene, alkylene cycloalkenylene alkylene, heterocycloalkenylene, alkylene heterocycloalkenylene, aromatic radical, alkylene aromatic radical, alkylene aromatic radical alkylene, heteroaromatic radical, alkylene heteroaromatic radical, secondary amine alkylene secondary amine group, secondary amine cycloalkylene secondary amine group, secondary amine heterocycloalkylene secondary amine group, secondary amine cycloalkylene secondary amine group, secondary amine heterocycloalkylene secondary amine group, secondary amine aromatic radical secondary amine group, secondary amine heteroaromatic radical secondary amine group, secondary amide heterocycloalkylene secondary amide group, secondary amide cycloalkylene secondary amide group, secondary amide aromatic radical secondary amide group, secondary amide heteroaromatic radical secondary amide group, oxyalkylene oxide group, oxycycloalkylene oxide group, oxyheterocycloalkylene oxide group, oxycycloalkylene oxide group, oxyaromatic radical oxy group, and disulfide bond.

[0038] Further, R2 is one of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocyclic group, a heterocycloalkyl group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, an alkane heteroalkyl group, an alkynyl group, an alkylene group, an alkylene heteroalkylene group, an alkenylene group, an alkylene heteroalkenylene group, an alkynylene group or an alkylene heteroalkynylene group.

[0039] Furthermore, the phenylboronic acid group is located at any substitution position of the phenyl group.

[0040] In addition, the present invention also provides a method for preparing the aforementioned radiation-sensitive crosslinking agent, characterized in that the crosslinking agent is produced by an amine-aldehyde condensation reaction between a hydrazine derivative and a benzoyl derivative.

[0041] Further, the hydrazine derivative is compound I, and compound I is: The benzoyl derivative is compound II, and compound II is: The molar ratio of compound I to compound II is 1:2.

[0042] Furthermore, the solvent used in the reaction is at least one of water, ethanol, methanol, butanol, tetrahydrofuran and dimethyl sulfoxide.

[0043] Furthermore, the reaction temperature is: 40-120°C.

[0044] The molecular structure of the high-energy radiation sensitive crosslinking agent of the present invention contains two radiation-sensitive phenyl conjugated acylhydrazone bonds, which improves the responsiveness of the crosslinking agent to high-energy radiation; introducing high-energy radiation sensitive dynamic bonds such as acylhydrazone bonds and disulfide bonds into the polymer as crosslinking structures is a dynamic dissipation strategy for aging of radiation crosslinked polymer materials due to excessive crosslinking during radiation.

[0045] In addition, the present invention also provides a high-energy ray irradiation self-repairing material based on the aforementioned radiation-sensitive crosslinking agent, comprising a crosslinking agent and a polymer substrate, the crosslinking agent and the polymer substrate are crosslinked in a certain ratio, the crosslinking structure contains radiation-sensitive dynamic bonds, and the substrate is crosslinked through chemical dynamic bonds to generate a radiation-sensitive self-repairing polymer material; at room temperature, when exposed to high-energy radiation, the material maintains stable properties and performance. The crosslinking structure is:

[0046]

[0047] Furthermore, the cross-linking structure is a dynamic phenylboronic acid bond. The hydroxyl group of the polymer substrate undergoes an ester exchange reaction with the phenylboronic acid group of the cross-linking agent, or the epoxy structure of the substrate undergoes a condensation reaction with the phenylboronic acid group of the cross-linking agent, to obtain a radiation self-healing material with phenylboronic acid ester as the cross-linking structure. Furthermore, the polymer substrate is a radiation cross-linking polymer material with at least one of hydroxyl, epoxy, and electron-rich nitrogen atom structures in the main chain.

[0048] Furthermore, the polymer substrate is at least one of cellulose, chitosan, hyaluronic acid, sodium alginate, agar, polyvinyl alcohol, 1,3-diethoxybutylene, and epoxy resin.

[0049] Furthermore, the molar ratio of the boronic acid groups of the crosslinking agent to the polymer reactive groups is 1:1-1:1000.

[0050] In addition, the present invention also provides a radiation self-repairing hydrogel, characterized in that it comprises the aforementioned high-energy ray irradiation self-repairing material.

[0051] In addition, the present invention also provides a method for preparing a radiation self-healing hydrogel, which is characterized in that the crosslinking agent in the aforementioned high-energy ray irradiation self-healing material and the polymer substrate are mixed in a solvent in an appropriate proportion and cross-linked to obtain the hydrogel.

[0052] In addition, the present invention also provides a radiation self-healing aerogel, characterized in that it comprises the aforementioned radiation self-healing hydrogel.

[0053] In addition, the present invention also provides a method for preparing a radiation self-healing aerogel, which is characterized in that the radiation self-healing hydrogel is freeze-dried or supercritically dried to obtain the aerogel.

[0054] Example 1

[0055] Preparation of cross-linking agent Ⅰ

[0056]

[0057] 4-Acetylphenylboronic acid (3.279 g, 20 mmol) and carbohydrazide (0.901 g, 10 mmol) were mixed, and ethanol was used as solvent. After the reaction was refluxed at 55°C for 14 hours, hydrochloric acid was added dropwise to produce a white precipitate. The white precipitate was then washed with water, methanol, and water in sequence, and then vacuum dried to constant weight to obtain pure cross-linking agent I.

[0058] Example 2

[0059] Preparation of cross-linking agent II

[0060]

[0061] The synthesis experiment was carried out using a Schlenk reaction flask under nitrogen protection. Dimethyl 3,3'-dithiodipropionate (1.0 g, 4.2 mmol) was dissolved in 50 ml of ethanol, stirred at room temperature and hydrazine hydrate (1.25 eq, 0.525 g, 10.5 mmol) was added dropwise. After stirring at room temperature for 4 hours, the mixture was heated to 60°C in a water bath and refluxed for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, and a white solid precipitated. A filter cake was obtained by suction filtration using a glass sand funnel. The filter cake was washed twice with a mixed solvent of methanol and ether. The obtained product was vacuum dried at 40°C to constant weight to obtain 3,3'-dithiodipropionic acid dihydrazide.

[0062] 3,3'-dithiodipropionic acid dihydrazide (1 eq) and 4-acetylphenylboronic acid (2 eq) were mixed, and refluxed at 55°C for 14 h using an ethanol-tetrahydrofuran mixed solvent, and then rotary evaporated until there was no solvent, and vacuum dried to constant weight to obtain crosslinker II.

[0063] Example 3

[0064] This embodiment provides a mixed preparation method of radiation self-repairing gel material

[0065] The radiation self-healing gel can be prepared by a mixing method: a crosslinking agent I aqueous solution and a polyvinyl alcohol aqueous solution are quickly mixed in a certain proportion and allowed to stand to obtain a gel.

[0066] 5 g of crosslinker I was dissolved in 100 ml of 0.35 mol / L sodium hydroxide aqueous solution, and then 5 ml of the crosslinker solution was mixed with 5 ml of 15 wt % polyvinyl alcohol aqueous solution to obtain radiation self-healing hydrogel I.

[0067] Furthermore, the cross-linking agent solution preparation method is as follows: a certain mass of the cross-linking agent is dissolved in a 4g / L NaOH aqueous solution to prepare a solution with a cross-linking agent mass fraction of 5%.

[0068] Furthermore, the mass fraction of the gel precursor is 10%.

[0069] Further, the crosslinker solution and the gel precursor are mixed in equal volumes.

[0070] Furthermore, the crosslinking reaction temperature was 80°C.

[0071] 5 g of crosslinker I was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and then 5 ml of the crosslinker solution was quickly mixed and stirred with 5 ml of 10 wt% polyvinyl alcohol aqueous solution to obtain radiation self-healing hydrogel I, wherein the molar ratio of the hydroxyl group of the crosslinker to the molar number of the hydroxyl group of the gel precursor was 1:10.

[0072] The elongation at break of the irradiated self-healing hydrogel I material of Example 3 shows an upward trend. When the absorbed dose is 20 kGy, the elongation at break is 107% of the initial value, and when the absorbed dose is 50 kGy, the elongation at break is 144% of the initial value.

[0073]

[0074] Example 4

[0075] This embodiment provides a mixed preparation method of radiation self-repairing hydrogel material

[0076] 6.9399 g of crosslinker II was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and then 2 ml of the crosslinker solution was mixed with 5 ml of 10 wt% polyvinyl alcohol aqueous solution to obtain radiation self-healing gel II. The molar ratio of the hydroxyl group of the crosslinker to the hydroxyl group of the gel precursor was 1:10.

[0077] The elongation at break of the radiation self-healing hydrogel II material of Example 4 can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 93% of the initial value, and when the absorbed dose is 50 kGy, the elongation at break is 88% of the initial value.

[0078] Example 5

[0079] This embodiment provides a mixed preparation method of radiation self-repairing hydrogel material

[0080] 5g of crosslinker I was dissolved in 100ml of 0.1mol / L sodium hydroxide aqueous solution, and then 5ml of the crosslinker solution was quickly mixed and stirred with 5ml of 20wt% hyaluronic acid (HA) aqueous solution to obtain radiation self-healing hydrogel III. The molar ratio of the hydroxyl group of the crosslinker to the molar number of the hydroxyl group of the gel precursor was 1:100.

[0081] The elongation at break of the radiation self-healing hydrogel III material of Example 5 can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 103% of the initial value. When the absorbed dose is 50 kGy, the elongation at break is 91% of the initial value.

[0082] Example 6

[0083] This embodiment provides a mixed preparation method of radiation self-repairing hydrogel material

[0084] 6.9399g of crosslinker II was dissolved in 100ml of 0.1mol / L sodium hydroxide aqueous solution, and then 5ml of the crosslinker solution was quickly mixed and stirred with 5ml of 20wt% hyaluronic acid (HA) aqueous solution to obtain radiation self-healing hydrogel IV. The molar ratio of the hydroxyl group of the crosslinker to the molar number of the hydroxyl group of the gel precursor was 1:100.

[0085] The elongation at break of the radiation self-healing hydrogel IV material of Example 6 can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 107% of the initial value. When the absorbed dose is 50 kGy, the elongation at break is 95% of the initial value.

[0086] Example 7

[0087] This embodiment provides a mixed preparation method of radiation self-repairing hydrogel material

[0088] 1 g of crosslinker I was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and 5 ml of the crosslinker solution was quickly mixed and stirred with 5 ml of 30 wt% agar aqueous solution at 60°C to obtain radiation self-healing hydrogel V. The molar ratio of the hydroxyl group of the crosslinker to the molar number of the hydroxyl group of the gel precursor was 1:1000.

[0089] The elongation at break of the radiation self-healing hydrogel V material of Example 7 can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 104% of the initial value. When the absorbed dose is 50 kGy, the elongation at break is 90% of the initial value.

[0090] Example 8

[0091] This embodiment provides a mixed preparation method of radiation self-repairing hydrogel material

[0092] 1.39 g of crosslinker II was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and 5 ml of the crosslinker solution was quickly mixed and stirred with 5 ml of 30 wt% agar aqueous solution at 60°C to obtain radiation self-healing hydrogel VI. The molar ratio of the hydroxyl group of the crosslinker to the molar number of the hydroxyl group of the gel precursor was 1:1000.

[0093] The elongation at break of the radiation self-healing hydrogel VI material of Example 8 can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 104% of the initial value. When the absorbed dose is 50 kGy, the elongation at break is 114% of the initial value.

[0094] Example 9

[0095] This embodiment provides a method for preparing radiation self-healing epoxy hydrogel

[0096] Add crosslinker I to a round-bottom flask, stir with 0.1 mol / L sodium hydroxide solution at room temperature until crosslinker I is completely dissolved, then add difunctional epoxy monomer BDE to the system; after sufficient stirring and mixing, react in a 65°C water bath for 1 hour to obtain radiation self-healing hydrogel VII. The molar ratio of the hydroxyl group of the crosslinker to the molar number of the epoxy group of the gel precursor is 2:3.

[0097] The elongation at break of the radiation self-healing hydrogel VII of Example 9 can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 123% of the initial value. When the absorbed dose is 50 kGy, the elongation at break is 95% of the initial value.

[0098] Example 10

[0099] This embodiment provides a method for preparing a radiation self-healing epoxy resin

[0100] The self-healing epoxy resin can be prepared as follows: in a mixed solvent of N,N-dimethylformamide (DMF) and tetrahydrofuran (THF), a crosslinking agent I and a bisphenol A type epoxy resin are sequentially added, heated for reaction, poured into a mold, and heated and cured after removing the residual solvent to obtain a radiation self-healing epoxy resin.

[0101] Furthermore, the mass ratio of DMF to THF in the mixed solvent is 1:4.

[0102] Furthermore, the molar ratio of the epoxy group of the bisphenol A epoxy resin to the hydroxyl group of the crosslinking agent is 1:1.

[0103] Furthermore, the temperature of the heating reaction system is 80-90°C.

[0104] Furthermore, the heating curing temperature is 120° C. and the curing time is 2 hours.

[0105] 0.9583g of crosslinker I was added to 5g of DMF and 20g of THF, and stirred at room temperature until the crosslinker I was completely dissolved. Then 0.9058g of bisphenol A epoxy resin (DGEBA, E51) was added to the system, the system was heated to 90°C, and stirred for 5 hours to obtain a light yellow prepolymer solution. After the solvent THF was removed by rotary evaporation, part of the prepolymer liquid was taken into the mold, and vacuumed in a 70°C vacuum drying oven for 1 hour to remove the residual DMF in the prepolymer, and then placed in a 100°C forced air oven for reaction and curing for 2 hours to obtain modified epoxy resin I. The molar number of hydroxyl groups of the crosslinker and the molar number of epoxy groups of the resin prepolymer were 1:1.

[0106] The elongation at break of the modified epoxy resin I can remain stable. When the absorbed dose is 20 kGy, the elongation at break is 98% of the initial value. When the absorbed dose is 50 kGy, the elongation at break is 94% of the initial value.

[0107]

[0108] Embodiment 11

[0109] This embodiment provides a method for preparing a radiation self-repairing foam material

[0110] 5g of crosslinker I was dissolved in 100ml of 0.1mol / L sodium hydroxide aqueous solution, and then 5ml of the crosslinker solution was quickly mixed and stirred with 5ml of 10wt% polyvinyl alcohol aqueous solution, and the molar ratio of the hydroxyl group of the crosslinker to the hydroxyl group of the gel precursor was 1:30. The obtained hydrogel was quickly frozen at -196℃ until the ice crystals grew completely, and vacuum dried at room temperature until completely freeze-dried. Radiation self-healing foam material I was obtained.

[0111] The compression modulus of the self-repairing foam material I remains stable after irradiation. When the absorbed dose is 20 kGy, the compression modulus is 90% of the initial value, and when the absorbed dose is 50 kGy, it is 85% of the initial value.

[0112] Example 12

[0113] This embodiment provides a method for preparing a radiation self-repairing foam material

[0114] 5g of crosslinker I was dissolved in 100ml of 0.1mol / L sodium hydroxide aqueous solution, and then 5ml of the crosslinker solution was quickly mixed and stirred with 5ml of 20wt% hyaluronic acid (HA) aqueous solution, and the molar ratio of the hydroxyl group of the crosslinker to the hydroxyl group of the gel precursor was 1:100. The obtained hydrogel was quickly frozen at -196℃ until the ice crystals grew completely, and vacuum dried at room temperature until completely freeze-dried. Radiation self-healing foam material II was obtained.

[0115] The compression modulus of the self-repairing foam material II remains stable after irradiation. When the absorbed dose is 20 kGy, the compression modulus is 93% of the initial value, and when the absorbed dose is 50 kGy, it is 84% ​​of the initial value.

[0116] Example 13

[0117] This embodiment provides a method for preparing a radiation self-repairing foam material

[0118] Dissolve 1g of crosslinker I in 100ml of 0.1mol / L sodium hydroxide aqueous solution. Quickly mix and stir 5ml of crosslinker solution with 5ml of 30wt% agar aqueous solution at 60°C. The molar ratio of the hydroxyl group of the crosslinker to the hydroxyl group of the gel precursor is 1:1000. Quickly freeze the obtained hydrogel at -196°C until the ice crystals grow completely, and vacuum dry at room temperature until completely freeze-dried. Radiation self-healing foam material III is obtained.

[0119] The compression modulus of the self-repairing foam material III remains stable after irradiation. When the absorbed dose is 20 kGy, the compression modulus is 91% of the initial value, and when the absorbed dose is 50 kGy, it is 88% of the initial value.

[0120] Embodiment 14

[0121] This embodiment provides a method for preparing a radiation self-repairing foam material

[0122] Add crosslinker I to a round-bottom flask, stir with 0.1 mol / L sodium hydroxide solution at room temperature until crosslinker I is completely dissolved, and then add difunctional epoxy monomer 1,3-diethoxybutane to the system; after thorough stirring and mixing, react in a 65°C water bath for 1 hour, and the ratio of the molar number of hydroxyl groups of the crosslinker to the molar number of epoxy groups of the gel precursor is 2:3.

[0123] The obtained hydrogel was quickly frozen at -196°C until ice crystals were fully grown, and then vacuum dried at room temperature until completely freeze-dried. Radiation self-repairing foam material IV was obtained. The compression modulus of self-repairing foam material IV remained stable after irradiation, and when the absorbed dose was 20 kGy, the compression modulus was 86% of the initial value, and when the absorbed dose was 50 kGy, it was 80% of the initial value.

[0124] Comparative Example 1

[0125] 4.525 g of 4-acetophenylboronic acid was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and then 5 ml of 4-acetophenylboronic acid solution was quickly mixed and stirred with 5 ml of 10 wt% polyvinyl alcohol aqueous solution to obtain comparative example gel I. The molar ratio of the hydroxyl group of the crosslinking agent to the molar number of the hydroxyl group of the gel precursor was 1:10.

[0126] When the absorbed dose is 20 kGy, the elongation at break is 57% of the initial elongation at break, and when the absorbed dose is 50 kGy, the elongation at break is 30% of the initial elongation, and the tensile strength decreases significantly.

[0127] Comparative Example 2

[0128] 5 g of 4-acetylphenylboronic acid was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and then 5 ml of 4-acetylphenylboronic acid solution was quickly mixed and stirred with 5 ml of 20 wt% hyaluronic acid (HA) aqueous solution to obtain comparative gel II. The molar ratio of the hydroxyl group of the crosslinking agent to the molar number of the hydroxyl group of the gel precursor was 1:100.

[0129] The elongation at break of the comparative gel II showed a rapid downward trend. When the absorbed dose was 20 kGy, the elongation at break was 52% of the initial value. When the absorbed dose was 50 kGy, the sample had broken and its elongation at break could not be measured.

[0130] Comparative Example 3

[0131] 0.838 g of 4-acetylphenylboronic acid was dissolved in 100 ml of 0.1 mol / L sodium hydroxide aqueous solution, and 5 ml of 4-acetylphenylboronic acid solution was quickly mixed and stirred with 5 ml of 30 wt% agar aqueous solution at 60° C. to obtain comparative example gel III. The molar ratio of the hydroxyl group of the crosslinking agent to the molar ratio of the hydroxyl group of the gel precursor was 1:1000.

[0132] The elongation at break of the comparative example gel III showed a rapid downward trend. When the absorbed dose was 20 kGy, the elongation at break was 40% of the initial value. When the absorbed dose was 50 kGy, the sample had broken and its elongation at break could not be measured.

[0133] Comparative Example 4

[0134] Add 4-acetylphenylboronic acid to a round-bottom flask, stir with 0.1 mol / L sodium hydroxide solution at room temperature until completely dissolved, then add difunctional epoxy monomer BDE to the system; after sufficient stirring and mixing, react in a 65°C water bath for 1 hour to obtain comparative gel IV. The molar ratio of the hydroxyl group of the crosslinking agent to the molar number of the epoxy group of the gel precursor is 2:3.

[0135] The elongation at break of the comparative gel IV showed a rapid downward trend. When the absorbed dose was 20 kGy, the elongation at break was 30% of the initial value. When the absorbed dose was 50 kGy, the sample had broken and its elongation at break could not be measured.

[0136] Comparative Example 5

[0137] 40 g of bisphenol A epoxy resin E51 was put into a container, and then 10 g of a commercial cross-linking agent was added. After the two were mixed and stirred evenly, the mixture was poured into a mold and allowed to stand for 4 hours to obtain a comparative epoxy resin.

[0138] The materials prepared in the examples were selected for analysis and processing:

[0139] 1. Nuclear magnetic resonance spectroscopy characterization:

[0140] The cross-linking agent I prepared in Example 1 was dissolved in deuterated DMSO solvent at a concentration of 10 mg / ml, and then detected by H-NMR spectrum.

[0141] The results of H NMR spectrum detection of the cross-linking agent I prepared in Example 1 are as follows Figure 1 As shown: 1H NMR (400 MHz, DMSO) δ10.29 (s, 4H), 9.53 (s, 2H), 7.73 (q, J = 8.4 Hz, 8H), 2.14 (s, 6H), the chemical structure of cross-linker I was confirmed, and cross-linker I was obtained by synthesis.

[0142] 2. Paramagnetic resonance characterization:

[0143] The crosslinking agent I prepared in Example 1 was irradiated with radiation, and paramagnetic resonance test was performed on the crosslinking agent before and after irradiation.

[0144] Test results: The paramagnetic resonance spectra of the crosslinking agent prepared in Example 1 and the crosslinking agent used in the comparative example before and after irradiation are as follows: Figure 2 As shown. The higher the free radical content in the irradiated material, the larger the peak area of ​​its paramagnetic resonance spectrum. The peak area of ​​the sample with an absorption dose of 540kGy is larger than that of the sample with an absorption dose of 20kGy. This is because after the cross-linking agent is irradiated, the NN bond of the phenyl conjugated acylhydrazone bond structure breaks to generate phenylimine conjugated free radicals. The phenylimine conjugated group can stabilize the free radicals generated by the ray break and inhibit the free radicals from electron aggregation through the electron-withdrawing effect, thereby reducing the cross-linking and recombination of the molecular chain segments.

[0145]

[0146] 3. Characterization of mechanical properties:

[0147] Take the radiation self-healing gels prepared in Examples 2 to 8 and the comparative hydrogel prepared in Comparative Example 1 and cut the samples into dumbbell shapes with dimensions of 35 mm×2 mm×0.6 mm; irradiate them with γ-rays of 0 KGy, 20 KGy, and 50 KGy, respectively, and perform tensile tests on the materials before and after irradiation.

[0148] Tensile test:

[0149] The tensile test was carried out on a tensile testing machine produced by Instron, USA. The sensor selected was a 1kN sensor. The experiment was carried out at room temperature. Dumbbell-shaped specimens were tested with a size of 35mm×2mm×0.6mm. All samples were tested at a strain rate of 500mm / min. The tensile strength and ultimate elongation at break were obtained from the stress-strain curve. Samples treated with different irradiation doses were tested in the same time period.

[0150] Under the action of radiation irradiation with an absorbed dose of 0-100 kGy, the mechanical properties of the radiation self-repairing gel I prepared in Example 3 and the comparative hydrogel I prepared in Comparative Example 1 are compared. Figure 3 shown.

[0151] When the cross-linking agent concentration is 10%, the elongation at break of hydrogel Ⅰ and comparative hydrogel Ⅰ are similar, and the tensile strength of hydrogel Ⅰ is slightly higher than that of comparative hydrogel Ⅰ. Figure 3 The changes in mechanical properties of the two hydrogels at different absorbed doses were compared. The results showed that the tensile strength and elongation at break of the control sample hydrogel material decreased significantly under the action of γ radiation. When the absorbed dose was 20kGy, the elongation at break was 57% of the initial elongation at break, and when the absorbed dose was 50kGy, the elongation at break was 30% of the initial elongation at break, and the tensile strength decreased significantly. The elongation at break of the irradiated self-healing hydrogel I material of Example 3 showed an upward trend. When the absorbed dose was 20kGy, the elongation at break was 107% of the initial elongation at break, and when the absorbed dose was 50kGy, the elongation at break was 144% of the initial elongation at break.

[0152] 4. Fourier infrared characterization:

[0153] The crosslinking agent I prepared in Example 1 and the crosslinking agent II prepared in Example 2 were irradiated with 100 KGy of gamma rays, and then the crosslinking agents were detected by Fourier transform infrared spectroscopy.

[0154] The radiation self-healing gels prepared in Examples 2 to 6 and the comparative hydrogel prepared in Comparative Example 1 were irradiated with γ-rays of 0 kGy, 20 kGy, 50 kGy, and 100 kGy, respectively. After the materials were freeze-dried, Fourier transform infrared spectroscopy was performed on the materials before and after irradiation.

[0155] Peak positions of each group in infrared spectrum

[0156] Wavenumbers / cm-1 Group 3300 Ph-B-OH 3350 Ph-OH 1690 C=O 1600 C=N 1280 CN

[0157] in, Figure 4 The infrared spectra of crosslinker I before and after γ-ray irradiation show that when the absorbed dose is 20 kGy, the infrared signals at ~1600 cm-1 and ~3090 cm-1 disappear, which correspond to the stretching signals of C=N and NH groups, indicating that the NN bond in Ph-C(CH3)=N-NH- has broken. The infrared signal at ~3030 disappears, which corresponds to the stretching signal of B-hydroxyl in Ph-B-OH; a new infrared signal appears at ~3350, which corresponds to the stretching signal of hydroxyl in Ph-OH, indicating that the phenylboronic acid structure generates phenol structure and boronic acid structure after oxidation in response to ROS.

[0158] The present invention is described in detail above in combination with specific implementation methods and exemplary examples. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments; the above description cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, the technical solution of the present invention and its implementation methods may be subjected to a variety of equivalent substitutions, modifications or improvements, all of which fall within the scope of the present invention; the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A radiation-sensitive crosslinking agent, characterized in that The cross-linking agent contains radiation-sensitive dynamic bonds which are prone to bond breaking after being irradiated with high energy, thereby generating stable free radicals.

2. A radiation-sensitive crosslinking agent according to claim 1, characterized in that: The cross-linking agent contains a phenyl conjugated acylhydrazone bond and a phenylboronic acid group; the molecular structure of the cross-linking agent is as follows:

3. A radiation-sensitive crosslinking agent according to claim 2, characterized in that: R1 is one of cycloalkylene, alkylenecycloalkylene, heterocycloalkylene, alkyleneheterocycloalkylene, alkyleneheterocycloalkylene alkylene, cycloalkenylene, alkylenecycloalkenylene, alkylenecycloalkenylene, heterocycloalkenylene, alkyleneheterocycloalkenylene, aromatic radical, alkylene aromatic radical, alkylene aromatic radical alkylene, heteroaromatic radical, alkylene heteroaromatic radical, secondary amine alkylene secondary amine group, secondary amine cycloalkylene secondary amine group, secondary amine heterocycloalkylene secondary amine group, secondary amine cycloalkylene secondary amine group, secondary amine heterocycloalkylene secondary amine group, secondary amine aromatic radical secondary amine group, secondary amine heteroaromatic radical secondary amine group, secondary amide heterocycloalkylene secondary amide group, secondary amide cycloalkylene secondary amide group, secondary amide aromatic radical secondary amide group, secondary amide heteroaromatic radical secondary amide group, oxyalkyleneoxy group, oxycycloalkyleneoxy group, oxyheterocycloalkyleneoxy group, oxycycloalkyleneoxy group, oxyaromatic radical oxy group, and disulfide bond.

4. A radiation-sensitive crosslinking agent according to claim 2, characterized in that: R2 is one of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocyclyl group, a heterocyclylalkyl group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, an alkynyl group, an alkylene group, an alkylene heteroalkylene group, an alkenylene group, an alkylene heteroalkenylene group, an alkynylene group or an alkylene heteroalkynylene group.

5. A radiation-sensitive crosslinking agent according to claim 2, characterized in that: The phenylboronic acid group is located at any substitution position of the phenyl group.

6. A method for preparing a radiation-sensitive crosslinking agent as claimed in any one of claims 1 to 5, characterized in that: The cross-linking agent is produced by an amine-aldehyde condensation reaction between a hydrazine derivative and a benzoyl derivative.

7. The method for preparing a crosslinking agent according to claim 6, characterized in that: The hydrazine derivative is compound I, and the compound I is: The benzoyl derivative is compound II, and the compound II is: The molar ratio of the compound I to the compound II is 1:

2.

8. The method for preparing a crosslinking agent according to claim 6, characterized in that: The solvent used in the reaction is at least one of water, ethanol, methanol, butanol, tetrahydrofuran and dimethyl sulfoxide.

9. The method for preparing a crosslinking agent according to claim 8, characterized in that: The reaction temperature is: 40-120℃.

10. A high-energy ray irradiation self-healing material comprising the radiation-sensitive crosslinking agent according to any one of claims 1 to 5, characterized in that: The high-energy ray irradiation self-healing material comprises the cross-linking agent and the polymer substrate, the cross-linking agent and the polymer substrate are cross-linked in a certain ratio, the cross-linking structure contains radiation-sensitive dynamic bonds, and the cross-linking structure is:

11. The high-energy ray irradiation self-repairing material according to claim 10, characterized in that: The cross-linking structure is a dynamic phenyl borate bond.

12. The high-energy ray irradiation self-repairing material according to claim 10, characterized in that: The polymer substrate is a radiation cross-linked polymer material whose main chain contains at least one of a hydroxyl group, an epoxy group and an electron-rich nitrogen atom structure.

13. The high-energy ray irradiation self-repairing material according to claim 10, characterized in that: The polymer substrate is at least one of cellulose, chitosan, hyaluronic acid, sodium alginate, agar, polyvinyl alcohol, 1,3-diepoxybutane, and epoxy resin.

14. The high-energy ray irradiation self-repairing material according to claim 10, characterized in that: The molar ratio of the boric acid group of the crosslinking agent to the polymer reaction group is 1:1-1:1000.

15. A radiation self-repairing hydrogel, characterized in that: A high-energy ray irradiation self-healing material comprising any one of claims 10-14.

16. A method for preparing a hydrogel to obtain the radiation self-healing hydrogel according to claim 15, characterized in that: The crosslinking agent in the high-energy ray irradiation self-healing material is mixed with the polymer substrate in a solvent in an appropriate ratio and then cross-linked to obtain the material.

17. A radiation self-healing aerogel, characterized in that: Comprising the radiation self-healing hydrogel as claimed in claim 15.

18. A method for preparing an aerogel to obtain the radiation self-healing aerogel as claimed in claim 17, characterized in that: The radiation self-repairing hydrogel is obtained by freeze-drying or supercritical drying.

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