阅读说明：本技术 一种本征型自修复和可回收的聚硫脲聚合物及其制备方法和应用 (Intrinsic self-repairing and recyclable polythiourea polymer and preparation method and application thereof ) 是由 张泽平 李艳梅 容敏智 章明秋 于 2019-08-06 设计创作，主要内容包括：本发明涉及一种本征型自修复和可回收的聚硫脲聚合物及其制备方法和应用。所述聚硫脲聚合物由如下重量份数的组分组成：二元胺单体1.9～24.5份,二异硫氰酸酯单体3.7～5.9份,胺单体交联剂0.07～2.2份；所述胺单体交联剂的官能度大于2。本发明提供的聚硫脲聚合物含有特征的动态可逆硫脲键单元,赋予聚硫脲聚合物材料热致可逆自修复和可固态粉碎或溶剂降解回收的性能,从而增强材料的使用稳定性和延长服役期限。本发明提供的制备方法工艺简单,且硫脲键的热可逆温度范围宽(35～120℃),无需外加催化剂。(The invention relates to an intrinsic self-repairing and recyclable polythiourea polymer, and a preparation method and application thereof. The polythiourea polymer comprises the following components in parts by weight: 1.9-24.5 parts of diamine monomer, 3.7-5.9 parts of diisothiocyanate monomer and 0.07-2.2 parts of amine monomer cross-linking agent; the amine monomer crosslinker has a functionality greater than 2. The polythiourea polymer provided by the invention contains a characteristic dynamic reversible thiourea bond unit, and endows the polythiourea polymer material with the properties of thermoreversible self-repairing and solid crushing or solvent degradation recovery, thereby enhancing the service stability of the material and prolonging the service life. The preparation method provided by the invention is simple in process, the thermoreversible temperature range of the thiourea bond is wide (35-120 ℃), and no catalyst is required to be added.)

1. An intrinsic self-repairing and recyclable polythiourea polymer is characterized by comprising the following components in parts by weight:

1.9 to 24.5 portions of diamine monomer,

3.7 to 5.9 parts of diisothiocyanate monomer,

0.07-2.2 parts of amine monomer crosslinking agent;

the amine monomer crosslinker has a functionality greater than 2.

2. The polythiourea polymer of claim 1 which is comprised of the following components in parts by weight:

2.6 to 20.7 portions of diamine monomer,

5.0 parts of diisothiocyanate monomer,

0.1-1.8 parts of amine monomer crosslinking agent.

3. The polythiourea polymer of claim 1 wherein the polythiourea polymer comprises dynamically reversible thiourea linkage units having the characteristics shown in formula I:

Wherein R ₁ is methylene or phenyl, R ₂ is hydrogen, phenyl or alkyl, and R ₃ is methylene or phenyl.

4. The polythiourea polymer of claim 1 wherein the diamine monomer is a diamine containing a primary or secondary amine structure; the diamine monomer is one or more of the substances shown in the following structural formula:

Wherein n is 2-5; m is 30 to 32.

5. The polythiourea polymer of claim 4 wherein the diamine monomer is one or more of 1, 2-bis (2-aminoethoxy) ethane, diethylene glycol bis (3-aminopropyl) ether, polyetheramine, bis (3-aminopropyl) terminated polyethylene glycol, 1, 6-hexanediamine, 4 '-methylenebis (cyclohexylamine), or N, N' -diethylethylenediamine.

6. The polythiourea polymer of claim 1 wherein the diisothiocyanate monomer is one or more of the following structures:

7. The polythiourea polymer of claim 1 wherein the amine monomer crosslinker is one or more of the following structures:

r is H or dimer acid.

8. a process for preparing a polythiourea polymer of any of claims 1 to 7 comprising the steps of: dissolving diisothiocyanate monomers, adding diamine monomers for polycondensation, adding an amine monomer cross-linking agent for continuous reaction, and curing to obtain the polythiourea polymer.

9. Use of the polythiourea polymer of any of claims 1 to 7 in the preparation of self-healing and recyclable polymeric materials.

10. The use of claim 9, wherein the polythiourea polymer is self-healing by: butting the fracture surfaces of polythiourea polymers fractured by mechanical damage and placing the polythiourea polymers at 35-120 ℃ until the polythiourea polymers are recovered; the recoverable method comprises crushing the polythiourea polymer and then carrying out hot press molding; or with the assistance of diamine monomer, degrading polythiourea polymer in polar solvent, adding diisothiocyanate with the same molar ratio as diamine monomer, and casting to form film.

Technical Field

the invention belongs to the technical field of intelligent polymer materials, and particularly relates to an intrinsic self-repairing and recyclable polythiourea polymer, and a preparation method and application thereof.

Background

The polymer material, the metal material and the inorganic material are arranged in parallel as three pillars in a material structure, and the polymer material has wide application prospect. However, in the processing and using processes of the polymer material, the performance of the polymer material is often reduced due to internal microcracks and local damage, the service life of the polymer material is shortened, and even potential safety hazards are caused. The self-repairing high polymer material simulates the principle of organism injury healing, self-heals through a certain mechanism, and is a high polymer intelligent material with the greatest prospect for solving the key problems.

The self-repairing high polymer material comprises intrinsic self-repairing and external self-repairing. The external self-repairing system is repaired by embedding a micro-container for encapsulating a repairing agent or a catalyst, but has the problem that the same part is difficult to repair repeatedly. The intrinsic self-repairing high polymer material is generally repaired by utilizing a dynamic reversible bond, and the problem of repeated repair of the same part can be well solved. The dynamic reversible bonds used for constructing self-repairing polymer materials are generally classified into dynamic reversible noncovalent bonds and covalent bonds. At present, reported non-covalent bond systems mainly comprise hydrogen bonds, host-guest interactions, pi-pi stacking interactions, electrostatic interactions and the like; the covalent bond system mainly comprises Diels-Alder bond, C-ON bond, disulfide bond, acylhydrazone bond, carbamate bond, urea bond and the like. Among them, the self-repairing polymer material based on the dynamic reversible covalent bond has higher structural stability and mechanical strength, and is receiving wide attention.

In recent years, people utilize the reversible characteristics of urethane bonds and urea bonds to prepare a series of intrinsic self-repairing materials. However, the following disadvantages, for example: the thermoreversible temperature of the common urethane bond is higher, even a high content of toxic catalyst is needed; on the other hand, in order to reduce the temperature of the thermoreversible reaction, a special electronegativity (such as an oxime bond) and a large steric hindrance (such as tert-butyl) group are introduced into a reversible bond molecular structure, which generally needs to synthesize a specific monomer, so that the use of the commercialized conventional monomer is limited, and the popularization and application of the conventional polyurethane and polyurea are not facilitated. From the viewpoint of bond energy, the bond energy of thiourea bond is lower than that of urea bond of the same type, and dynamic reversibility can be exhibited over a wide temperature range without the need for a catalyst and without the need for introduction of a specific electronegative group or a large steric hindrance substituent. Therefore, it is necessary to develop a self-repairing chemistry based on a dynamic thermoreversible thiourea bond to prepare a self-repairing material with higher mechanical strength and repairing efficiency.

Disclosure of Invention

The invention aims to overcome the defects or shortcomings that the intrinsic self-repairing material in the prior art has higher thermoreversible temperature, needs to use high-content toxic catalyst and synthesize specific monomer, and limits the use of commercial conventional monomer; an intrinsically self-healing and recyclable polythiourea polymer is provided. The polythiourea polymer provided by the invention contains a characteristic dynamic reversible thiourea bond unit, and endows the polythiourea polymer material with the properties of thermoreversible self-repairing and solid crushing or solvent degradation recovery, thereby enhancing the service stability of the material and prolonging the service life.

Another object of the present invention is to provide a process for the preparation of polythiourea polymers as described above.

another object of the present invention is to provide the use of the polythiourea polymer described above for the preparation of self-healing and recyclable polymeric materials.

In order to achieve the purpose, the invention adopts the following technical scheme:

an intrinsic self-repairing and recoverable polythiourea polymer comprises the following components in parts by weight:

1.9 to 24.5 portions of diamine monomer,

3.7 to 5.9 parts of diisothiocyanate monomer,

0.07-2.2 parts of amine monomer crosslinking agent;

the amine monomer crosslinker has a functionality greater than 2.

In the polythiourea polymer provided by the invention, diamine monomer reacts with diisothiocyanate to obtain a linear polymer containing a characteristic dynamic reversible thiourea bond unit, and then the linear polymer reacts with an amine monomer crosslinking agent to obtain the polythiourea polymer.

The structural formula of the dynamic reversible thiourea bond unit is shown as the formula (I):

Wherein R ₁ is methylene and phenyl, R ₂ is hydrogen, phenyl and alkyl, and R ₃ is methylene and phenyl.

In the thiourea bond unit structure, because the number of electron layers of the sulfur atom is large, the capability of attracting electrons is weaker than that of oxygen atoms, and the p-pi conjugation effect of lone-pair electrons on the N atom and C ═ S double bonds is reduced, so that the bond energy of C-N bonds is lower, and finally, the thiourea bond has dynamic reversibility. The repair mechanism of the polythiourea polymer with the thiourea bond-containing structure is that C-N bonds connected with thiocarbonyl carbons and a fatty chain on a polymer molecular chain are broken to cause the formation of reaction end groups, and reactive groups are contacted with each other along with the full movement or diffusion of chain segments, so that exchange and recombination reactions of macromolecular chains among damaged surfaces or broken particles of the polymer occur, and the repair and the recycling of a polymer network are realized.

The process of polymer self-repair by using dynamic reversible covalent bonds has the core that the breakage-recombination of the covalent bonds is realized, and even if the related polymer materials are broken in a fragment mode, new covalent bonds can be formed among the fragments to recover the mechanical property, which actually means that the reversible reaction based on the covalent bonds can realize the solid recovery and the recycling of the polymer materials. In actual operation, the abandoned polymer products can be crushed and then the block polymer with (or close to) the original mechanical property can be prepared again by adopting the compression molding or solid phase extrusion molding technology and through the exchange recombination of macromolecular chains among polymer particles at the temperature of the thermal reversible reaction and under certain pressure. The recovery process is carried out under the condition of all solid state, so the method is simple to operate, low in energy consumption and promising in development prospect. On the other hand, the general thermosetting material cannot be dissolved, but can be controllably degraded to obtain a uniform solution by utilizing the dissociation of a thermal reversible bond under the assistance of a small amount of micromolecule monomers forming a reversible unit, and the solution method is utilized to degrade and recover the thermosetting material, so that the original molecular structure of the material is more favorably kept.

according to the invention, a thiourea structure with a dynamic reversible carbon-nitrogen bond is introduced into the polymer material, so that the polymer material is endowed with the properties of thermoreversible self-repairing and solid-state crushing or solvent degradation and recovery, thereby enhancing the use stability of the material and prolonging the service life.

Preferably, the polythiourea polymer consists of the following components in parts by weight:

2.6 to 20.7 portions of diamine monomer,

3.7 to 5.9 parts of diisothiocyanate monomer,

0.07-2.2 parts of amine monomer crosslinking agent.

Preferably, the polythiourea polymer contains dynamic reversible thiourea bond units characterized by formula I:

Wherein R ₁ is methylene or phenyl, R ₂ is hydrogen, phenyl or alkyl, and R ₃ is methylene or phenyl.

More preferably, the alkyl group is methyl, methylene, isopropyl, tert-butyl or cyclohexyl.

preferably, the polythiourea polymer consists of the following components in parts by weight:

1.9 to 24.5 portions of diamine monomer,

3.7 to 5.9 parts of diisothiocyanate monomer,

0.07-2.2 parts of amine monomer crosslinking agent;

Preferably, the diamine monomer is one or more of the following diamines containing primary amine or secondary amine structures:

Wherein n is 2-5, and m is 30-32.

More preferably, the diamine monomer is one or more of 1, 2-bis (2-aminoethoxy) ethane, diethylene glycol bis (3-aminopropyl) ether, polyether amine, bis (3-aminopropyl) terminated polyethylene glycol or 1, 6-hexamethylene diamine, 4 '-methylene bis (cyclohexylamine) or N, N' -diethyl ethylene diamine.

Most preferably, the polyetheramine has M _n ═ 230 or M _n ═ 400.

most preferably, the bis (3-aminopropyl) capped polyethylene glycol has M _n ═ 1500.

Preferably, the diisothiocyanate monomer is one or more of the following substances:

More preferably, the diisothiocyanate monomer is terephthalocyanate.

Preferably, the amine monomer crosslinking agent is one or more of the substances shown in the following structural formula:

r is H or dimer acid.

More preferably, the amine monomer crosslinking agent is one or more of pentaethylenehexamine, polyamide curing agent or tri (2-aminoethyl) amine.

the preparation method of the polythiourea polymer comprises the following steps: dissolving diisothiocyanate monomers, adding diamine monomers for polycondensation, adding an amine monomer cross-linking agent for continuous reaction, and curing to obtain the polythiourea polymer.

the preparation method provided by the invention has the advantages of simple process, low temperature of thermal reversibility of the thiourea bond and no need of additional catalyst. The obtained polythiourea polymer has high mechanical strength.

Preferably, the reaction time after the diamine monomer is added is 16-24 h.

Preferably, the curing process is as follows: pouring the mixture into a mold, and curing at 60-80 ℃ for 12-24 h.

The application of the polythiourea polymer in the preparation of self-repairing and recyclable polymer materials is also within the protection scope of the invention.

the polythiourea polymer provided by the invention has the advantages of short repair time and high repair efficiency; the recovery efficiency is high.

preferably, the self-healing method of the polythiourea polymer is as follows: the polythiourea polymer which is broken by mechanical damage is butted with the broken surface and is placed at 35-120 ℃ until recovery.

More preferably, the standing time is 0.5-24 h.

Preferably, the polythiourea polymer is recoverable by a process comprising: crushing the polythiourea polymer, and then carrying out hot press molding;

More preferably, the hot press forming process comprises the following steps: and carrying out hot press molding on the polythiourea polymer powder for 5-12 h at 35-120 ℃ and under the pressure of 3-10 MPa.

the invention herein provides another recoverable process for polythiourea polymers.

Preferably, the polythiourea polymer is recoverable by a process comprising: with the assistance of diamine monomer, the polythiourea polymer is degraded in polar solvent, and diisothiocyanate with the same molar ratio as the diamine monomer is added for reaction and then is cast into a film.

after casting into a film, a block material similar to the tensile strength of the original sample can be obtained.

Preferably, the diamine monomer is one or more of N, N '-diethyl ethylenediamine, diethylene glycol di (3-aminopropyl) ether or 4,4' -methylene bis (cyclohexylamine).

Preferably, the diisothiocyanate is terephthalocyanate.

More preferably, the polar solvent is one or more of DMF or DMSO.

Compared with the prior art, the invention has the following beneficial effects:

The polythiourea polymer provided by the invention contains a characteristic dynamic reversible thiourea bond unit, and endows the polythiourea polymer material with the properties of thermoreversible self-repairing and solid crushing or solvent degradation recovery, thereby enhancing the service stability of the material and prolonging the service life.

The preparation method provided by the invention has simple process, wide thermoreversible temperature range (35-120 ℃) of thiourea bonds, and no additional catalyst.

Drawings

FIG. 1 is a photograph of a crack repair of a self-healing polythiourea prepared in example 6 (a, c are the original cracks, respectively; b, d are micrographs of a treatment at 80 ℃ for 2.5h and 5h, respectively);

FIG. 2 is an infrared spectrum of a polythiourea polymer prepared by example 6.

Detailed Description

The invention is further illustrated by the following examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. Experimental procedures without specific conditions noted in the examples below, generally according to conditions conventional in the art or as suggested by the manufacturer; the raw materials, reagents and the like used are, unless otherwise specified, those commercially available from the conventional markets and the like. Any insubstantial changes and substitutions made by those skilled in the art based on the present invention are intended to be covered by the claims.

In the invention, the repairing effect of the material is qualitatively evaluated by adopting microcrack repairing (as shown in figure 1); in addition, the polymer sample bars are made into dumbbell-type sample bars (l is 25mm, b is 2mm, h is 0.5mm) and subjected to a repair test, i.e., after the sample bars are cut from the middle, the cross sections of the sample bars are butted and heat-treated at 35 to 120 ℃ to test the tensile strength of the polymer, and the tensile strength is calculated as follows:

σ＝F/(b·l)

In the formula: f, the maximum load of the tensile failure of the sample; b, the width of the butt joint surface of the sample; l, sample butt joint face length. The repair efficiency is defined as the ratio of the tensile strength or elongation at break or elastic modulus of the repair sample to the original sample:

Eta-sigma _recycled/sigma _virgin, eta-epsilon _recycled/epsilon _virgin, eta-E _recycled/E _virgin

The recovery efficiency of the material was evaluated by a tensile test method: polythiourea materials prepared in examples 1 to 11 were subjected to a tensile test to obtain an original mechanical strength, and then a polymer material was pulverized under liquid nitrogen quenching, and the obtained polymer powder was hot-pressed at 35 to 120 ℃ and 5MPa for a certain period of time to obtain a recovered sample (a rectangular film of 20X 40 mm) and subjected to a tensile test. Recovery efficiency is defined as the ratio of the tensile strength or elongation at break or elastic modulus of the recovered sample to the original sample.

similarly, a tensile test is adopted to evaluate the solvent degradation recovery effect, after the polythiourea material prepared in examples 1 to 11 is subjected to a tensile test to obtain original mechanical strength, the polymer is dissolved in a DMF solvent containing a certain amount of diamine monomer (N, N '-diethylethylenediamine in examples 1 to 9, diethylene glycol di (3-aminopropyl) ether in example 10, and 4,4' -methylenebis (cyclohexylamine) in example 11) at 35 to 120 ℃, diisothiocyanate (p-phenylene diisothiocyanate in each example) in a corresponding proportion is added for reaction for 24 hours, then casting molding is carried out again to prepare a polythiourea bulk material, and the recovery efficiency is defined as the tensile strength, or the ratio of the elongation at break, or the elastic modulus of the recovered sample to the original sample.