CN108641043B

CN108641043B - Self-repairing graft copolymer based on hydrogen bond effect and preparation method thereof

Info

Publication number: CN108641043B
Application number: CN201810320582.XA
Authority: CN
Inventors: 王雯雯; 王栋; 张志锋; 徐得立; 刘轲; 鲁振坦; 王跃丹
Original assignee: Wuhan Textile University
Current assignee: Wuhan Textile University
Priority date: 2018-04-11
Filing date: 2018-04-11
Publication date: 2021-02-26
Anticipated expiration: 2038-04-11
Also published as: CN108641043A

Abstract

The invention discloses a self-repairing graft copolymer based on hydrogen bond effect and a preparation method thereof, belonging to the technical field of high polymer materials. The preparation method comprises the following steps: 1) preparing a polymer macromonomer with double bonds as end groups; 2) preparing a self-repairing graft copolymer: taking a second monomer and the polymer macromonomer with the end group of double bond prepared in the step 1) to carry out free radical polymerization reaction under the action of a free radical polymerization initiator to prepare the self-repairing graft copolymer with a comb-shaped or centipede-shaped or three-chain or barbed wire structure, wherein the graft copolymer has better thermodynamic property and self-repairing function.

Description

Self-repairing graft copolymer based on hydrogen bond effect and preparation method thereof

Technical Field

The invention relates to a thermoplastic elastomer, belongs to the technical field of high polymer materials, and particularly relates to a self-repairing graft copolymer based on a hydrogen bond effect and a preparation method thereof.

Background

The thermoplastic elastomer is a special high polymer material, has elasticity and plasticity, and can be widely applied to the important fields of national economy such as packaging materials, automobile parts, adhesives, clothes, biomedicine and the like. However, thermoplastic elastomers are subjected to alternating stresses over a long period of time during use, which causes fatigue cracks in the elastomer and leads to early failure of the elastomer, shortening the service life of the elastomer.

The polymer self-repairing material simulates the principle of organism injury healing, finds cracks automatically and heals automatically through a certain mechanism, and is a polymer intelligent material with wide application requirements. In recent years, the research direction of polymer self-repairing materials extends from composite materials to elastomers, and scientists try to adopt self-repairing technology to reduce the early damage of polymer elastomer materials so as to improve the service life of elastomers.

The early self-repairing high-molecular elastomer material mainly focuses on microcapsules and microtubules to break to initiate repolymerization to realize external aid type repair of damage, and the self-repairing property can be usually realized only twice and cannot repeatedly repair the damage. However, the polymer material has an adjustable chemical structure, and the control of the material performance can be easily realized by controlling the polymerization process and then designing the chain segment structure of the polymer material.

Therefore, the current research focuses more on the structural design of the high polymer elastomer material to realize intrinsic self-repair of material damage, that is, the material starts the structural change of the material to adaptively realize dynamic adjustment without external stimulation or energy input. Guan et al introduced designing and synthesizing a diblock copolymer, polystyrene-b-poly (n-butyl acrylate) (PS-b-PnBA) by RAFT method, and modifying the chain transfer agent by using a hydrogen bonding unit UPy so that four hydrogen bonds can be formed between chain ends of poly (n-butyl acrylate) to obtain a triblock thermoplastic elastomer with self-repairing function (Angew Chem Int Ed 2012,124, 10713-10717.). However, compared with the PS-b-PnBA-PS thermoplastic elastomer, the thermoplastic elastomer has better self-repairing function, but the soft micro-region is connected with each other by non-covalent bond-hydrogen bond, so the breaking strength and the breaking elongation are greatly reduced.

Furthermore, Zhang et al describe the RAFT method to synthesize a diblock copolymer containing liquid crystal units and amide structures, and hydrogen bonds can be formed between the amide structures in the soft segment of the polymer, and multiple hydrogen bonds exert the effect of "crosslinking", so that the polymer exhibits the properties of a thermoplastic elastomer (J Mater Chem C2015, 3, 8526-. But the introduction of multiple hydrogen bonds reduces the orderliness of the microphase separation morphology of the diblock copolymer, thereby reducing the mechanical property of the copolymer.

Meanwhile, Guan et al introduced that ABA type triblock copolymer with polymethyl methacrylate (PMMA) as hard segment and polyacetylaminoacrylate as soft segment was synthesized by ATRP method, and the mechanical properties of the copolymer were greatly improved without decreasing the self-repairing property (Chem Commun 2014,50, 10868-10870.). Furthermore, Guan et al have designed and synthesized brush copolymer elastomers with polystyrene or polymethyl methacrylate as the main chain and polyacrylamide as the side chain by ATRP and grafting from methods, and the copolymer can form a soft and hard multiphase structure, including a relatively hard and strong stationary phase (polystyrene phase) which can maintain the skeleton structure of the material when applied with force, and a relatively soft mobile phase (polyacetylaminoacrylate) which generates certain deformation to relieve the stress of the material itself (Nature Chem2012,4, 467-. Meanwhile, reversible assembly hydrogen bonds formed in the mobile phase contribute to realizing the self-repairing function of the material. Therefore, the elastomer chain structure can extend from linear to nonlinear (brush type), so that the elastomer has certain elastic property and self-repairing function, but the elastic property and other mechanical properties are relatively lower than those of the commercial thermoplastic elastomer.

Although Mays et al have shown that "comb", "centipede" and "barbed wire" multi-point graft copolymers (PI-g-PS) with Polyisoprene (PI) as the main chain and Polystyrene (PS) as the side chain were synthesized by high vacuum anionic polymerization in combination with the "grafting onto" method, the "centipede" graft copolymers had an elongation at break of about twice that of the commercial thermoplastic elastomer Kraton (20% PS) up to 2100% and a tensile strength of 21MPa, slightly lower than that of Kraton, when the number of grafting points was 10 and the polystyrene content was 21%, and they were used as thermoplastic superelastomer materials (Macromolecules, 2002,35, 7182; Macromolecules, 34, 6333). However, the high vacuum anionic polymerization has higher requirements on reaction environment, and more importantly, the thermoplastic super-elastomer material prepared by the method has no self-repairing function.

Disclosure of Invention

In order to solve the technical problems, the invention discloses a graft copolymer which is prepared by adopting an active/controllable free radical polymerization technology and has a main chain as a soft segment and a branched chain as a segment with a self-repairing function based on a hydrogen bond effect.

In order to realize the purpose, the invention discloses a preparation method of a self-repairing graft copolymer based on hydrogen bond effect, which is characterized by comprising the following steps: it comprises the following steps:

1) preparing a polymer macromonomer with double bonds as end groups;

2) preparing a self-repairing graft copolymer: and (2) carrying out free radical polymerization reaction on a second monomer and the polymer macromonomer with the double bond as the end group prepared in the step 1) under the action of a free radical polymerization initiator to prepare the self-repairing graft copolymer.

Further, the process of preparing the self-repairing graft copolymer in the step 2) is as follows:

in the presence of a free radical polymerization initiator, controlling the reaction temperature to be 60-80 ℃, and performing free radical polymerization on a second monomer and a polymer macromonomer with a double bond as a terminal group in a mass ratio of 6: 3-10: 3 for 6-12 hours to prepare the self-repairing graft copolymer.

Still further, the polymer macromonomer with the double bond as the terminal group comprises at least one polymerization chain connected to the double bond, and the molecular weight of the polymer macromonomer with the double bond as the terminal group is 3000-15000 g/mol.

The preferred terminal double bond-containing polymeric macromers of the present invention have a molecular weight of 4000 g/mol.

The molecular weight of the preferred terminal double bond-containing polymer macromers of the present invention is 6000 g/mol.

The preferred terminal double bond-containing polymeric macromers of the present invention have a molecular weight of 8000 g/mol.

The preferred terminal double bond-containing polymeric macromonomers of the present invention have a molecular weight of 12000 g/mol.

The preferred terminal double bond-containing polymeric macromonomers of the present invention have a molecular weight of 15000 g/mol.

Preferred terminal double-bond polymer macromers of the present invention comprise a polymer chain attached to a double bond, i.e., the structure of the polymer macromonomer is a single tail structure.

Preferred terminal double bond polymer macromers of the present invention comprise two polymer chains attached to a double bond, i.e., the structure of the polymer macromonomer is a double tail structure.

Preferred terminal double-bond polymer macromers of the present invention comprise three polymer chains attached to a double bond, i.e., the structure of the polymer macromonomer is a trinodal structure.

Preferred double-terminated polymeric macromers of the present invention comprise four polymer chains attached to the double bond, i.e., the polymeric macromonomer is of a four-tailed structure.

Further, the polymer macromonomer with the terminal group being a double bond is at least one of poly-2-acetamidoacrylate macromonomer, poly-2- (3- (6-methyl-oxy-1, 4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate macromonomer and poly-2- (3- (3-aminophenyl) ureido) ethyl methacrylate macromonomer.

The preferred polymer macromonomer with double bonds at the terminal group in the invention is poly (2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate macromonomer.

The preferred polymer macromonomer with double bonds at the terminal group in the invention is poly-2-acetamido methyl acrylate macromonomer.

The preferred polymer macromonomer with double bonds at the terminal group in the invention is poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate.

Still further, the second monomer is at least one of n-butyl acrylate, isoprene, or butadiene.

The preferred second monomer of the present invention is n-butyl acrylate.

The preferred second monomer of the present invention is isoprene.

The preferred second monomer of the present invention is butadiene.

Further, the radical polymerization initiator is at least one of azobisisobutyronitrile, dibenzoyl peroxide, potassium persulfate and ammonium persulfate.

The preferred free radical polymerization initiator of the present invention is azobisisobutyronitrile.

The preferred free radical polymerization initiator of the present invention is potassium persulfate.

The preferred free radical polymerization initiator of the present invention is dibenzoyl peroxide.

Further, the process of preparing the polymer macromonomer having a terminal double bond in step 1) is as follows:

the process of the polymer macromonomer with double bond as the end group is as follows:

preparing a macromolecular initiator by adopting an atom transfer radical polymerization mode or preparing a macromolecular chain transfer agent by adopting a reversible-addition-fragmentation chain transfer polymerization mode, and modifying the macromolecular initiator or the macromolecular chain transfer agent to obtain a polymer macromolecular monomer with a double-bond end group; the tail ends of the macromolecular initiator and the macromolecular chain transfer agent contain functional groups.

Further, the functional group is at least one of a bromine-terminated group, a chlorine-terminated group, a carboxyl group, a hydroxyl group, an amino group, an isocyanate group or a mercapto group.

The preparation process of the preferable polymer macromonomer with double bonds at the end group of the invention is polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester macromonomer:

(1) atom Transfer Radical Polymerization (ATRP): 2-ethyl bromopropionate is used as an initiator, cuprous bromide/N, N, N, N, N-pentamethyl divinyl triamine is used as a catalytic system, the bromo-terminated polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl ester macroinitiator is prepared through an ATRP reaction, and then the bromo-terminated polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl ester macroinitiator and allyl trimethyl silane react to prepare the polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl ester macromonomer with.

(2) Reversible-addition-fragmentation chain transfer polymerization (RAFT) mode was used: the method comprises the steps of adopting 2- (dodecyl trithiocarbonate) -2-methylpropanoic acid as a chain transfer agent, adopting azodiisobutyronitrile as an initiator, adopting an RAFT (reversible addition fragmentation chain transfer) method to prepare carboxyl-terminated poly (2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl methacrylate, and then reacting the carboxyl-terminated poly (2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl methacrylate with p-chloromethyl styrene to obtain a poly (2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl methacrylate macromonomer with double.

In order to better achieve the purpose of the invention, the invention also discloses a self-repairing graft copolymer based on hydrogen bonding effect, which is prepared by adopting the preparation method, wherein the self-repairing graft copolymer comprises a main chain and branched chains, each main chain comprises a plurality of randomly spaced branch points, and each branched chain is connected to the main chain at each of the plurality of randomly spaced branch points.

Furthermore, the main chain is a chain segment obtained by polymerization reaction of a second monomer, the branched chain is a chain segment with a self-repairing function based on hydrogen bond effect obtained by polymerization of a polymer macromonomer with a double bond at the end group, and the chain segment with the self-repairing function accounts for 20-40% of the total mass of the self-repairing graft copolymer.

In the invention, preferably, a branch chain is connected to each of a plurality of randomly spaced branch points on the main chain, and the self-repairing graft copolymer formed by the branch chains is of a comb-shaped macromolecular structure.

In the invention, two branched chains are preferably connected at each of a plurality of randomly spaced branched points on the main chain, and the self-repairing graft copolymer formed by the two branched chains is of a centipede-type macromolecular structure.

In the invention, three branched chains are preferably connected to each of a plurality of randomly spaced branched points on the main chain, and the self-repairing graft copolymer formed by the three branched chains is of a three-chain type macromolecular structure.

In the invention, four branched chains are preferably connected at each of a plurality of randomly spaced branched points on the main chain, and the self-repairing graft copolymer formed by the four branched chains is of a 'barbed wire type' macromolecular structure.

The principle that the graft copolymer of the present invention has a self-repairing function is as follows:

the reversible breakage and formation of the hydrogen bond endow the graft copolymer with self-repairing performance, avoid the expansion of microcracks inside the polymer and prolong the service life of the polymer.

Has the advantages that:

1. the preparation method designed by the invention adopts a free radical polymerization mode, prepares the graft copolymer by carrying out polymerization reaction on more than two monomers, has mild reaction conditions, is easy to operate in experiments, has simple and convenient preparation process, and is beneficial to realizing batch production.

2. The self-repairing graft copolymer prepared by the preparation method is of a comb-type macromolecular structure or a centipede-type macromolecular structure or a three-chain-type macromolecular structure or a barbed wire-type macromolecular structure, when the structure is subjected to microphase separation, a plurality of branched chains in a graft copolymer macromolecular chain can be simultaneously distributed in a plurality of dispersed phase micro-regions, and a plurality of micro-regions are connected by a main chain, so that when the polymer is subjected to external force, the intermolecular force is stronger, the mechanical strength is better, and the elastic recovery rate is higher.

3. The main chain of the self-repairing graft copolymer prepared by the preparation method is a soft segment, the branched chain is a self-repairing hard segment containing an amide bond, a dynamic reversible assembly structure (hydrogen bond) containing the amide bond is integrated in the branched chain of the multi-point graft copolymer, and the synergistic effect of the elastomer material on the mechanical property and the self-repairing efficiency can be realized by regulating and controlling the structure of the branched chain.

4. The self-repairing graft copolymer prepared by the preparation method provided by the invention is used as a thermoplastic elastomer material with excellent self-repairing performance, can still maintain the excellent mechanical property of the thermoplastic elastomer under a long-term alternating stress field, and has great market prospect in the fields of gaskets, sealing rings and the like.

Drawings

FIG. 1 is a schematic diagram of the structure of a polymer macromonomer with terminal double bonds;

FIG. 2 is a schematic diagram of the structure of a polymer macromonomer with terminal double bonds;

FIG. 3 is a schematic diagram of the structure of a polymer macromonomer with terminal double bonds;

FIG. 4 is a schematic diagram of the structure of a polymer macromonomer with terminal double bonds;

FIG. 5 is a schematic diagram of the structure of a "comb" graft copolymer;

FIG. 6 is a schematic diagram of the structure of a graft copolymer of the "centipede type";

FIG. 7 is a schematic diagram of the structure of a "three-chain" graft copolymer;

FIG. 8 is a schematic structural view of a "barbed wire" graft copolymer.

Detailed Description

In order to better explain the invention, the following further illustrate the main content of the invention in connection with specific examples, but the content of the invention is not limited to the following examples.

Example 1

1) Preparation of a Polymer macromonomer with end groups of double bonds: the preparation process of the poly-2-acetamido methyl acrylate macromonomer with a single tail structure is as follows:

firstly, preparing a macroinitiator by adopting an atom transfer radical polymerization mode, and specifically comprising the following steps: 0.13g of initiator ethyl 2-bromopropionate, 0.12g of catalyst cuprous bromide, 0.12g of ligand N, N, N, N, N-pentamethyldiethylenetriamine, 5g of 2-acetamido methyl acrylate and 15g of N, N-dimethylformamide are respectively weighed, the reactants are added into a reactor, the reactants in the reactor are sealed after being deoxidized, then the reactor is transferred into an oil bath with the temperature of 100 ℃, and after reaction for 8h, the bromine-terminated poly-2-acetamido methyl acrylate macroinitiator with the molecular weight of about 6400g/mol is obtained.

Respectively taking 4g of the prepared bromo-terminated poly-2-acetamido methyl acrylate macroinitiator and 30g of N, N-dimethylformamide, adding the reactants into a reactor, then carrying out deoxygenation treatment, then placing the reactor in an ice bath at 0 ℃, then weighing 0.5g of allyl trimethylsilane and 1g of titanium tetrachloride, adding the allyl trimethylsilane and the titanium tetrachloride into the reactor, and terminating the reaction after 1h to obtain the poly-2-acetamido methyl acrylate macromonomer with the single-tail structure shown in figure 1.

2) Preparing a self-repairing graft copolymer:

respectively weighing 10g of N-butyl acrylate, 3g of poly-2-acetamido methyl acrylate macromonomer with a single tail structure prepared in the step 1), 0.15g of azodiisobutyronitrile and 30g of N, N-dimethylformamide, adding the obtained mixture into a reactor, introducing nitrogen to remove oxygen, placing the reactor in an oil bath at 70 ℃, reacting for 8 hours to obtain the poly-N-butyl acrylate-g-poly-2-acetamido methyl acrylate graft copolymer with a comb-type structure shown in figure 5, wherein the mass fraction of the poly-2-acetamido methyl acrylate is about 22 wt%, and testing the tensile strength of the copolymer: the tensile strength is 9MPa and the elongation at break is 1500% at room temperature. The polymer was prepared into a 3cm × 1cm × 0.5cm sample, and the sample was cut from the middle portion and repaired at room temperature for 24 hours to have a tensile strength of 6MPa and an elongation at break of 880%.

Example 2

1) Preparation of a Polymer macromonomer with end groups of double bonds: the preparation process of the poly-2-acetamido methyl acrylate macromonomer with a double tail structure is as follows:

firstly, preparing a macroinitiator by adopting an atom transfer radical polymerization mode, and specifically comprising the following steps: 0.2g of initiator ethyl 2-bromopropionate, 0.1g of catalyst cuprous bromide, 0.12g of ligand N, N, N, N, N-pentamethyldiethylenetriamine, 5g of 2-acetamido methyl acrylate and 15g of N, N-dimethylformamide are respectively weighed, the reactants are added into a reactor, the reactants in the reactor are sealed after being deoxidized, then the reactor is transferred into an oil bath with the temperature of 100 ℃, and after reaction for 8h, the bromine-terminated poly-2-acetamido methyl acrylate macroinitiator with the molecular weight of about 4500g/mol is obtained.

4g of terminal bromo poly-2-acetamido methyl acrylate macroinitiator, 100mL of N, N-dimethylformamide, 4.5g of ethanolamine and 0.8g of triethylamine are respectively taken, the reactants are added into a reactor and then placed into a 90 ℃ oil bath pot for reaction for 8 hours, and after the reaction is finished, the product is purified, so that the terminal hydroxy poly-2-acetamido methyl acrylate is obtained. Taking 3g of hydroxyl-terminated poly-2-acetamido methyl acrylate to dissolve in 30mL of N, N-dimethylformamide, weighing 0.5g of 5- (4-vinylbenzyloxy) isophthalic acid, 0.1g of 4-dimethylaminopyridine and 0.1g of N, N-dicyclohexylcarbodiimide, adding the 5- (4-vinylbenzyloxy) isophthalic acid, the 4-dimethylaminopyridine and the N, N-dicyclohexylcarbodiimide into a reactor together, placing the reactor in an ice-water bath at 0 ℃ for reacting for two hours, and purifying the product to obtain the poly-2-acetamido methyl acrylate macromonomer with a double-tail structure shown in figure 2.

2) Preparing a self-repairing graft copolymer:

respectively weighing 6g of N-butyl acrylate, respectively weighing 2.5g of poly-2-acetamido methyl acrylate macromonomer with a double-tail structure prepared in the step 1), 0.1g of azodiisobutyronitrile and 30g of N, N-dimethylformamide, then adding the obtained mixture into a reactor, introducing nitrogen to remove oxygen, placing the reactor into an oil bath at 70 ℃, and reacting for 8 hours to obtain the centipede type poly-N-butyl acrylate-g-poly-2-acetamido methyl acrylate graft copolymer shown in the figure 6, wherein the mass fraction of the poly-2-acetamido methyl acrylate is about 25 wt%, and testing the tensile strength of the copolymer: the tensile strength is 10MPa and the elongation at break is 1400% at room temperature. The polymer was prepared into a 3cm × 1cm × 0.5cm sample strip, and the sample strip was cut from the middle portion and repaired at room temperature for 24 hours to have a tensile strength of 8MPa and an elongation at break of 1000%.

Example 3

1) Preparation of a Polymer macromonomer with end groups of double bonds: the preparation process of the poly-2-acetamido methyl acrylate macromonomer with a three-tail structure is as follows:

firstly, preparing a macromolecular chain transfer agent by adopting a reversible-addition-fragmentation chain transfer polymerization mode, and specifically comprising the following steps: respectively weighing 0.6g of chain transfer agent 2- (dodecyl trithiocarbonate) -2-methylpropanoic acid, 5g of 2-acetamido methyl acrylate, 0.11g of azodiisobutyronitrile and 40g of N, N-dimethylformamide, adding the adopted reactants into a reactor, carrying out oxygen removal treatment on the reactants in the reactor, sealing the reactants, transferring the reactor into an oil bath at 70 ℃, and reacting for 8 hours to obtain the carboxyl-terminated poly-2-acetamido methyl acrylate macromolecular chain transfer agent with the molecular weight of about 3100 g/mol.

4g of carboxyl-terminated poly-2-acetamido methyl acrylate macroinitiator and 20g of N, N-dimethylformamide are respectively taken, the reactants are added into a reactor and then subjected to deoxidization treatment, then the reactor is placed in a water bath with the temperature of 30 ℃, then 0.1g of 3-vinyloxypropyl trichloroacetamide is weighed and added into the reactor, and the reaction is terminated after 24h, so that the poly-2-acetamido methyl acrylate macromonomer with the three-tail structure shown in the figure 3 is obtained.

2) Preparing a self-repairing graft copolymer:

respectively weighing 7g of N-butyl acrylate, 3g of poly-2-acetamido methyl acrylate macromonomer with a three-tail structure, 0.2g of azodiisobutyronitrile and 50g of N, N-dimethylformamide, adding the obtained mixture into a reactor, introducing nitrogen to remove oxygen, placing the reactor in an oil bath at 70 ℃, and reacting for 8 hours to obtain the three-chain poly-N-butyl acrylate-g-poly-2-acetamido methyl acrylate graft copolymer shown in the figure 7, wherein the mass fraction of the poly-2-acetamido methyl acrylate is about 30 wt%. The tensile strength test was carried out on it: the tensile strength was about 12MPa and the elongation at break was 1100% at room temperature. The polymer was prepared into a 3cm × 1cm × 0.5cm sample, and the sample was cut from the middle part, and after 24 hours of room-temperature repair, the tensile strength was 10MPa and the elongation at break was 1000%.

Example 4

1) Preparation of a Polymer macromonomer with end groups of double bonds: the preparation process of the poly-2-acetamido methyl acrylate macromonomer with four tail structures is as follows:

firstly, preparing a macroinitiator by adopting an atom transfer radical polymerization mode, and specifically comprising the following steps: 0.3g of initiator ethyl 2-bromopropionate, 0.1g of catalyst cuprous bromide, 0.12g of ligand N, N, N, N, N-pentamethyldiethylenetriamine, 5g of 2-acetamido methyl acrylate and 15g of N, N-dimethylformamide are respectively weighed, the reactants are added into a reactor, the reactants in the reactor are sealed after being deoxidized, then the reactor is transferred into an oil bath with the temperature of 100 ℃, and after reaction for 8h, the terminal bromo poly-2-acetamido methyl acrylate macroinitiator with the molecular weight of about 3000g/mol is obtained.

4g of terminal bromo poly-2-acetamido methyl acrylate macroinitiator, 100mL of N, N-dimethylformamide, 4.5g of ethanolamine and 0.8g of triethylamine are respectively taken, the reactants are added into a reactor and then placed into a 90 ℃ oil bath pot for reaction for 8 hours, and after the reaction is finished, the product is purified, so that the terminal hydroxy poly-2-acetamido methyl acrylate is obtained. Taking 3g of hydroxyl-terminated poly-2-acetamido methyl acrylate to dissolve in 30mL of N, N-dimethylformamide, weighing 0.15g of 5 '- (5- (4-vinylbenzyloxy) isophthalamide) isophthalic acid, 0.05g of 4-dimethylaminopyridine and 0.05g of N, N-dicyclohexylcarbodiimide, adding the 5' - (5- (4-vinylbenzyloxy) isophthalamide) isophthalic acid and the N, N-dicyclohexylcarbodiimide into a reactor together, placing the reactor in an ice-water bath at 0 ℃ for reaction for two hours, and purifying the product to obtain the poly-2-acetamido methyl acrylate macromonomer with a four-tail structure shown in figure 4.

2) Preparation of self-healing graft copolymers

Respectively weighing 7g of N-butyl acrylate, 3g of poly-2-acetamido methyl acrylate macromonomer with a four-tail structure, 0.2g of azodiisobutyronitrile and 50g of N, N-dimethylformamide, adding the obtained mixture into a reactor, introducing nitrogen to remove oxygen, placing the reactor in an oil bath at 70 ℃, and reacting for 8 hours to obtain the barbed wire type poly (N-butyl acrylate) -g-poly-2-acetamido methyl acrylate graft copolymer shown in the figure 8, wherein the mass fraction of the poly-2-acetamido methyl acrylate is about 27 wt%. The tensile strength test was carried out on it: the tensile strength was about 12MPa and the elongation at break was 1800% at room temperature. The polymer was prepared into a 3cm × 1cm × 0.5cm sample strip, and the sample strip was cut from the middle portion and repaired at room temperature for 24 hours to have a tensile strength of 10.5MPa and an elongation at break of 1600%.

Example 5

1) Preparation of a Polymer macromonomer with end groups of double bonds: polymethacrylic acid-2- (3- (6-methyl-oxo-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester macromonomer with single tail structure:

firstly, preparing a macroinitiator by adopting an atom transfer radical polymerization mode, and specifically comprising the following steps: 0.13g of initiator ethyl 2-bromopropionate, 0.12g of catalyst cuprous bromide, 0.12g of ligand N, N, N, N, N-pentamethyldiethylenetriamine and 5g of methacrylic acid-2- (3- (6-methyl-oxy-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester and 20g of N, N-dimethylformamide are weighed respectively and added into a reactor, deoxidizing the reactant in the reactor, sealing the reactant, transferring the reactor into an oil bath at 100 ℃, after 8h of reaction, the terminal bromo polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester macroinitiator with the molecular weight of about 6000g/mol is obtained.

Respectively taking 4g of the prepared bromo-terminated poly (2- (3- (6-methyl-oxy-1, 4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate macroinitiator and 30g of N, N-dimethylformamide, adding the reactants into a reactor, then carrying out deoxidization treatment, then placing the reactor in an ice bath at 0 ℃, then weighing 0.5g of allyl trimethylsilane and 1g of titanium tetrachloride, adding the weighed allyl trimethylsilane and titanium tetrachloride into the reactor, and terminating the reaction after 1h to obtain the poly (2- (3- (6-methyl-oxy-1, 4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate macromonomer with a single-tail structure shown in figure 1.

2) Preparing a self-repairing graft copolymer:

respectively weighing 10g of N-butyl acrylate, 3g of the polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester macromonomer with the single tail structure prepared in the step 1), 0.14g of azodiisobutyronitrile and 30g of N, N-dimethylformamide, adding the monomers into a reactor, introducing nitrogen to remove oxygen, placing the reactor in an oil bath at 70 ℃, and reacting for 8h to obtain the comb-type poly (N-butyl acrylate) -g-polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester graft copolymer shown in the figure 5, wherein the polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidin-2-yl) ureido) ethyl ester, the mass fraction of which is about 23% by weight, and the tensile strength test is carried out: the tensile strength at room temperature was 9.5MPa and the elongation at break was 1450%. The polymer was prepared into a 3cm × 1cm × 0.5cm sample strip, and the sample strip was cut from the middle portion and repaired at room temperature for 24 hours to obtain a sample strip having a tensile strength of 6.5MPa and an elongation at break of 1180%.

Example 6

1) Preparation of a Polymer macromonomer with end groups of double bonds: the preparation process of the polymethacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester macromonomer with a single tail structure comprises the following steps:

firstly, preparing a macroinitiator by adopting an atom transfer radical polymerization mode, and specifically comprising the following steps: 0.15g of initiator ethyl 2-bromopropionate, 0.13g of catalyst cuprous bromide, 0.13g of ligand N, N, N, N, N-pentamethyldiethylenetriamine, 5g of methacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester and 20g of N, N-dimethylformamide are respectively weighed, the reactants are added into a reactor, the reactants in the reactor are sealed after being deoxidized, then the reactor is transferred into an oil bath at 100 ℃, and after the reaction is carried out for 8h, the terminal bromo polymethacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester macromolecular initiator with the molecular weight of about 5500g/mol is obtained.

Respectively taking 4g of the prepared bromo-terminated poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate macro-initiator and 30g of N, N-dimethylformamide, adding the reactants into a reactor, then carrying out deoxidization treatment, then placing the reactor in an ice bath at 0 ℃, then weighing 0.6g of allyl trimethylsilane and 1.1g of titanium tetrachloride, adding the allyl trimethylsilane and the titanium tetrachloride into the reactor, and terminating the reaction after 1h to obtain the poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate macro-monomer with the single-tail structure shown in the figure 1.

2) Preparing a self-repairing graft copolymer:

respectively weighing 8g of N-butyl acrylate and 3g of poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate macromonomer with a single tail structure prepared in the step 1), 0.13g of azodiisobutyronitrile and 30g of N, N-dimethylformamide, adding the obtained mixture into a reactor, introducing nitrogen to remove oxygen, placing the reactor in an oil bath at 70 ℃, reacting for 8 hours to obtain a comb-type poly (N-butyl acrylate) -g-poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate graft copolymer shown in figure 5, wherein the mass fraction of poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate is about 27 wt%, and testing the tensile strength of the copolymer: the tensile strength at room temperature was 10.5MPa, and the elongation at break was 1500%. The polymer was prepared into a 3cm × 1cm × 0.5cm sample, and the sample was cut from the middle portion and repaired at room temperature for 24 hours to have a tensile strength of 7.5MPa and an elongation at break of 1100%.

Example 7

1) Preparation of a Polymer macromonomer with end groups of double bonds: the preparation process of the polymethacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester with the single tail structure comprises the following steps:

firstly, preparing a macromolecular chain transfer agent by adopting a reversible-addition-fragmentation chain transfer polymerization mode, and specifically comprising the following steps: respectively weighing 0.3g of chain transfer agent 2- (dodecyl trithiocarbonate) -2-methylpropanoic acid, 6g of methacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester, 0.1g of azodiisobutyronitrile and 40g of toluene, adding the reactants into a reactor, deoxidizing the reactants in the reactor, sealing the reactants, transferring the reactor into an oil bath at 70 ℃, and reacting for 8 hours to obtain the carboxyl-terminated polymethacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester macromolecular chain transfer agent with the molecular weight of about 7200 g/mol.

Taking 5g of carboxyl-terminated poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate) macroinitiator and 30g of N, N-dimethylformamide respectively, adding the reactants into a reactor, then carrying out deoxygenation treatment, then placing the reactor into a water bath at 30 ℃, then weighing 0.1g of p-chloromethyl styrene, adding the p-chloromethyl styrene into the reactor, and terminating the reaction after 24 hours to obtain the poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate macromonomer with a single-tail structure shown in the figure 1.

2) Preparation of self-healing graft copolymers

Respectively weighing 8g of N-butyl acrylate and 4g of poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate macromonomer with a single tail structure prepared in the step 1), 0.13g of azodiisobutyronitrile and 30g of N, N-dimethylformamide, adding the obtained mixture into a reactor, introducing nitrogen to remove oxygen, placing the reactor in an oil bath at 70 ℃, reacting for 8 hours to obtain a comb-type poly (N-butyl acrylate) -g-poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate graft copolymer shown in figure 5, wherein the mass fraction of poly (2- (3- (3-aminophenyl) ureido) ethyl methacrylate is about 32 wt%, and testing the tensile strength of the copolymer: the tensile strength at room temperature was 11MPa and the elongation at break was 1300%. The polymer was prepared into a 3cm × 1cm × 0.5cm sample strip, and the sample strip was cut from the middle portion and repaired at room temperature for 24 hours to have a tensile strength of 8.5MPa and an elongation at break of 900%.

From the embodiment, the comb-type macromolecular structure or the centipede-type macromolecular structure or the three-chain-type macromolecular structure or the barbed wire-type macromolecular structure prepared by the method has a good self-repairing function, even if the macromolecular chains are broken and spliced together at room temperature for a period of time, the macromolecular chains can be bonded again based on the hydrogen bond acting force between the amido bonds on the branched chains, and certain elasticity of the macromolecular chains is ensured, so that the normal macromolecular chains are easier to recover to a normal state under the condition that the conventional macromolecular chains are compressed or elongated; therefore, the graft copolymer can realize the synergistic effect of the elastomer material on the mechanical property and the self-repairing efficiency.

The above examples are merely preferred examples and are not intended to limit the embodiments of the present invention. In addition to the above embodiments, the present invention has other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a self-repairing graft copolymer based on hydrogen bond effect is characterized in that: it comprises the following steps:

1) preparing a polymer macromonomer containing amido bond and having double bond as an end group;

2) preparing a self-repairing graft copolymer: and (2) carrying out free radical polymerization reaction on a second monomer and the polymer macromonomer which contains amido bond and has double bond at the end group and is prepared in the step 1) under the action of a free radical polymerization initiator to prepare the self-repairing graft copolymer.

2. The preparation method of the self-repairing graft copolymer based on hydrogen bonding effect, according to claim 1, is characterized in that: the process for preparing the self-repairing graft copolymer in the step 2) is as follows:

in the presence of a free radical polymerization initiator, controlling the reaction temperature to be 60-80 ℃, and performing free radical polymerization on a second monomer and a polymer macromonomer containing amido bonds and having a double bond as an end group in a mass ratio of 6: 3-10: 3 for 6-12 hours to prepare the self-repairing graft copolymer.

3. The method for preparing the self-repairing graft copolymer of claim 1 or 2, wherein: the polymer macromonomer containing amido bond and the end group of which is double bond is at least one of poly-2-acetamido methyl acrylate macromonomer, polymethacrylic acid-2- (3- (6-methyl-oxygen-1, 4-dihydropyrimidine-2-yl) ureido) ethyl ester macromonomer and polymethacrylic acid-2- (3- (3-aminophenyl) ureido) ethyl ester macromonomer.

4. The preparation method of the self-repairing graft copolymer based on hydrogen bonding effect, according to claim 3, is characterized in that: the molecular weight of the polymer macromonomer containing amido bond and the end group of which is double bond is 3000-15000 g/mol.

5. The preparation method of the self-repairing graft copolymer based on hydrogen bonding as claimed in claim 1 or 2, wherein: the process of the polymer macromonomer containing amido bond and having double bond as the end group is as follows:

preparing a macromolecular initiator by adopting an atom transfer radical polymerization mode or preparing a macromolecular chain transfer agent by adopting a reversible-addition-fragmentation chain transfer polymerization mode, and modifying the macromolecular initiator or the macromolecular chain transfer agent to obtain a polymer macromolecular monomer containing amido bonds and having double bonds as end groups; the tail ends of the macromolecular initiator and the macromolecular chain transfer agent contain functional groups.

6. The preparation method of the self-repairing graft copolymer based on hydrogen bonding effect, according to claim 5, is characterized in that: the functional group is at least one of a bromine-terminated group, a chlorine-terminated group, a carboxyl group, a hydroxyl group, an amino group, an isocyanate group or a mercapto group.

7. The method for preparing the self-repairing graft copolymer of claim 1 or 2, wherein: the second monomer is at least one of n-butyl acrylate, isoprene or butadiene.

8. The method for preparing the self-repairing graft copolymer of claim 1 or 2, wherein: the free radical polymerization initiator is at least one of azobisisobutyronitrile, dibenzoyl peroxide, potassium persulfate and ammonium persulfate.

9. The self-repairing graft copolymer based on hydrogen bonding effect prepared by the preparation method of any one of claims 1-8, which is characterized in that: the self-healing graft copolymer includes a backbone and branches, each of the backbone including a plurality of randomly spaced branch points, each of the branches being attached to the backbone at each of the plurality of randomly spaced branch points.

10. The hydrogen bonding based self-healing graft copolymer of claim 9, wherein: the main chain is a soft segment obtained by polymerization reaction of a second monomer, the branched chain is a segment with a self-repairing function based on hydrogen bond effect, which is obtained by polymerization of a polymer macromonomer containing amido bonds and having a double bond at the end group, and the segment with the self-repairing function accounts for 20-40% of the total mass of the self-repairing graft copolymer.