A dynamic slip-ring supramolecular polymer network, and a preparation method and application thereof

Abstract

The application discloses a kind of dynamic slip ring supramolecular polymer network and preparation method and application thereof, belong to supramolecular polymer technical field, preparation method is: acrylic ester monomer, initiator, accelerator and poly (caprolactone) single propylene modified column [5] areocenes The polyrotaxane of initiator and accelerator occurs RAFT polymerization under inert gas atmosphere, and the dynamic slip ring supramolecular polymer network of the preparation method is obtained;This method is simple, and reaction condition is mild, easy to implement;Compared with traditional covalent polymer network, the supramolecular polymer network prepared by the method has dynamic, more excellent mechanical mechanical property and energy dissipation, and has application potential in preparation of adhesive and / or toughening agent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supramolecular polymers, and particularly relates to a dynamic sliding ring supramolecular polymer network and a preparation method and application thereof. BACKGROUND

[0002] Supramolecular sliding ring polymer network (SRN) is a kind of non-covalently cross-linked polymer material, which has dynamic characteristics and structural integrity under external stimulation. This characteristic endows the material with excellent toughness, damping capacity, tensile property and reversible plasticity. Compared with the covalent cross-linking of traditional polymer networks, the sliding cross-linking points of the sliding ring polymer material can move freely on the polymer chain, providing an efficient energy dissipation path for the material. At the same time, the mechanical interlocking structure can effectively maintain the stability of the entire polymer network, which is an ideal topological form for constructing polymer materials with dynamic and mechanical properties.

[0003] Although some progress has been made in the research of SRN materials in adhesives in recent years, and most of the sliding ring materials are based on cyclodextrin as a macrocycle, there is still some space for the research of other sliding ring toughening agents. For example, the Chinese patent document with the publication number CN115895072A discloses the application of a supramolecular polymer in the modification of carboxyl nitrile rubber. The invention aims to solve the technical problems of difficult filler dispersion and complex interface design in the existing filler reinforced and toughened carboxyl nitrile rubber. The supramolecular polymer is used to modify the carboxyl nitrile rubber, thereby significantly improving the strength and toughness of the carboxyl nitrile rubber. The research group of Professor Qu Dahui of East China University of Technology introduced a zipper-like ring cross-linking agent into a polyurethane network with rich hydrogen bond stacking domains, obtaining a supramolecular polymer network with both host-guest interaction and hydrogen bond interaction. A small amount (0.5 mol%) of zipper-like ring cross-linking agent can increase the mechanical strength of polyurethane by 950%, the elongation by 650%, and the breaking energy by 4470% (An Ultrastrong and Highly Stretchable Polyurethane Elastomer Enabled by a Zipper-Like Ring-Sliding Effect [J]. Advanced Materials, 2020, 32 (23)).

[0004] Currently, the construction of the slip-ring polymer is based on the formation of interpenetrating structure by hydrophilic and hydrophobic interaction, thus, the core construction process must be carried out in aqueous phase, which greatly limits the use of traditional polymers which are insoluble in water for constructing the slip-ring material. Due to the limitation of material selection, the current slip-ring polymer material is difficult to meet the complex practical application requirements. As a classic structure of macrocyclic aromatic hydrocarbons, since 2008, when it was first reported by Ogoshi group of Kyoto University in Japan, the synthesis method of the pillar [5] arene is simple, and the unique cavity structure and easy functionalization characteristics endow it with rich host-guest chemical properties, thus injecting new blood into the field of supramolecular chemistry, especially host-guest chemistry. So far, in addition to Ogoshi group, Meier group of Mainz University in Germany and other well-known research groups at home and abroad have made great contributions to the synthesis and host-guest chemistry research of pillar [5] arene and its derivatives.

[0005] Traditional acrylate adhesives have poor toughness, low elongation at break after curing and poor impact resistance, which limits their application fields. The intramolecular sliding of the pillar [5] arene slip-ring polymer can bring rich mechanical properties to the material. The combination of the pillar [5] arene slip-ring polymer and the traditional covalent polymer can construct a new system of synergistic slip-ring and covalent polymer, which will provide a new idea for the design and construction of functional polymer materials. SUMMARY

[0006] The application provides a preparation method of a dynamic slip-ring supramolecular polymer network, which is simple, mild in reaction conditions and easy to implement; compared with a traditional covalent polymer network, the supramolecular polymer network prepared by the method has dynamicity, more excellent mechanical properties and energy dissipation, and has application potential in the preparation of adhesives and / or toughening agents.

[0007] The specific technical solutions are as follows:

[0008] A preparation method of a dynamic slip-ring supramolecular polymer network, in which a RAFT polymerization reaction of an acrylate monomer, an initiator, a promoter and a polyrotaxane of a polycaprolactone monopropylene modified pillar [5] arene occurs in an inert gas atmosphere in an organic solvent to obtain the dynamic slip-ring supramolecular polymer network.

[0009] The polyrotaxane of the polycaprolactone monopropylene modified pillar [5] arene has the following structural formula:

[0010]

[0011] In the formula, n and m are respectively independent positive integers, and R is ethyl.

[0012] Preferably, the polyhedral oligomeric nylons of the polycaprolactone mono-acryl modified pillar[5]arene have a molecular weight of 1000-200000, n is a positive integer of 2-1000, and m is a positive integer of 2-1000.

[0013] The present application uses the polyhedral oligomeric nylons of the polycaprolactone mono-acryl modified pillar[5]arene as a toughening agent and acrylate monomers to obtain a slip ring and covalent polymer synergistic polymer network through reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymer network has dynamicity (dynamicity mainly comes from the host-guest recognition of the pillar[5]arene derivative and polycaprolactone), and compared with the performance of the network formed by traditional acrylate monomer polymerization, the mechanical mechanical performance and energy dissipation are significantly improved. The addition of the polyhedral oligomeric nylons of the polycaprolactone mono-acryl modified pillar[5]arene can significantly improve the toughness and elasticity of the acrylate polymer, and promote the maximum elongation and ductility without sacrificing the mechanical strength of the polymer.

[0014] Preferably, the preparation method of the polyhedral oligomeric nylons of the polycaprolactone mono-acryl modified pillar[5]arene comprises the following steps:

[0015] (1) Under the protection of nitrogen at -6 to -15℃, boron tribromide is added dropwise into a solution of alkoxy pillar[5]arene in chloroform and the reaction is completed. After quenching the reaction, the organic phase is separated and dried to obtain a single-elimination alkoxy pillar[5]arene. The alkoxy pillar[5]arene is ethoxy pillar[5]arene.

[0016] (2) A solution of the single-elimination alkoxy pillar[5]arene and triethylamine in dichloromethane or chloroform is prepared, and a solution of methacryloyl chloride in dichloromethane is added dropwise into the solution under ice bath. The reaction is carried out at room temperature. After the reaction is completed, the filtrate is obtained by solid-liquid separation, washed with saturated sodium bicarbonate solution, separated into layers, and the organic phase is dried and separated to obtain a single-olefin substituted alkoxy pillar[5]arene.

[0017] (3) A solution of the single-olefin substituted alkoxy pillar[5]arene and polycaprolactone diol in chloroform is prepared. After stirring at room temperature for a period of time, the solution is continuously stirred at -30 to -40℃ for a period of time to form a stable quasi-polyhedral oligomeric. Then, a solution of the capping agent 3,5-bis(trifluoromethyl)phenyl isocyanate in chloroform is added dropwise into the solution at -30 to -40℃ and the reaction is continued at this temperature. The mixture after the reaction is completed is dropped into ice methanol for sedimentation and drying to obtain the polyhedral oligomeric nylons of the polycaprolactone mono-acryl modified pillar[5]arene.

[0018] Preferably, the acrylate monomer comprises methyl acrylate, ethyl acrylate, butyl acrylate or acrylate derivatives.

[0019] Preferably, the initiator comprises azobisisobutyronitrile.

[0020] Preferably, the accelerator comprises diisopropyl xanthogen disulfide.

[0021] Preferably, the molar ratio of the acrylate monomer, the initiator, the accelerator and the polyhedral oligomeric nanocarbons of the poly(caprolactone) monopropylene modified pillar[5]arene is 100-2000:1:1-10:0.1-200. Too much addition of the polyhedral oligomeric nanocarbons of the poly(caprolactone) monopropylene modified pillar[5]arene will make the dynamic property of the polymer network stronger, the brittleness increase and the toughening performance decrease.

[0022] Further preferably, the acrylate monomer is ethyl acrylate, the initiator is azobisisobutyronitrile and the accelerator is diisopropyl xanthogen disulfide; the molar ratio of the acrylate monomer, the initiator, the accelerator and the polyhedral oligomeric nanocarbons of the poly(caprolactone) monopropylene modified pillar[5]arene is 1000-2000:1:1:1-2.

[0023] Preferably, the organic solvent comprises, but is not limited to, 1,4-dioxane, tetrahydrofuran, toluene, ethanol and other common organic solvents.

[0024] Further preferably, the volume ratio of the organic solvent to the substance amount of the acrylate monomer is 0.1-10 L:1 mol.

[0025] Preferably, the inert gas atmosphere is a nitrogen atmosphere.

[0026] Preferably, the RAFT polymerization reaction is carried out at a temperature of 0-120℃ for 2-72 hours.

[0027] Further preferably, the RAFT polymerization reaction is carried out at a temperature of 80℃ for 6 hours.

[0028] The application also provides the dynamic slip-ring supramolecular polymer network prepared by the preparation method of the dynamic slip-ring supramolecular polymer network.

[0029] The application also provides the application of the dynamic slip-ring supramolecular polymer network in preparing adhesives and / or toughening agents.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] (1) This invention provides a dynamic slip ring supramolecular polymer network with excellent performance, easy synthesis and mild synthesis conditions. The dynamic slip ring supramolecular polymer network has dynamic properties, which mainly come from the host-guest recognition of columnar aromatic hydrocarbons and polycaprolactone. It can improve the mechanical properties and energy dissipation of the network formed by the polymerization of acrylate monomers, and make the network formed by the polymerization of acrylate monomers have better elasticity and toughness. It can promote the maximum elongation and extensibility without sacrificing mechanical strength, and has application potential in the preparation of adhesives and / or toughening agents.

[0032] (2) The dynamic slip ring supramolecular polymer network provided by this invention can achieve a tensile strength of 4.2 MPa, an elongation of 1600%, and a toughness of 3500 MJ / m under the condition that the polyrotaxane of the columnar aromatic hydrocarbon modified with polycaprolactone monopropylene [5] is added at 0.1 mol%. 3 Compared with traditional acrylate monomer polymer networks, it has 400 times higher tensile strength, 10 times higher elongation, and 10 times higher toughness. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the preparation of a dynamic slip ring supramolecular polymer network.

[0034] Figure 2 The infrared spectra of the polymer networks obtained in Examples 2-4 and Comparative Example 1 are shown.

[0035] Figure 3 Thermogravimetric curves of the polymer networks obtained in Examples 2-4 and Comparative Example 1 are shown.

[0036] Figure 4 Differential scanning calorimetry (DSC) curves of the polymer networks obtained in Examples 2-4 and Comparative Example 1 are shown.

[0037] Figure 5 The stress-strain curves are for the polymer networks obtained in Examples 2-4 and Comparative Example 1.

[0038] Figure 6 The toughness statistics of the polymer networks obtained in Examples 2-4 and Comparative Example 1 are shown.

[0039] Figure 7 The image shows the cyclic tensile curves of the toughened acrylic adhesives prepared in Examples 2-3 and Comparative Example 1. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to the embodiments and accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0041] Example 1

[0042] The synthesis method of polyrotaxane of polycaprolactone mono-acryl modified pillar[5]arene is as follows:

[0043] (1) The synthesis route of mono-acryl substituted ethoxyl pillar[5]arene is as follows:

[0044]

[0045] Diethoxybenzene (6.00 g, 36 mmol) was added to 300 mL of chloroform, and paraformaldehyde (2.16 g, 144 mmol) and boron trifluoride etherate (4.00 mL, 35 mmol) were added. The mixture was stirred at room temperature for 15 minutes. After the raw material completely disappeared, saturated sodium bicarbonate solution was added to stop the reaction. After standing and separation, the organic phase was washed twice with saturated sodium bicarbonate solution, and concentrated under reduced pressure to obtain the crude product. The crude product was purified by flash column chromatography (eluent: petroleum ether / dichloromethane, volume ratio = 1:1) to obtain compound ethoxyl pillar[5]arene 1 (white powder, 3.28 g, yield 51.0%). It was dried in a vacuum oven at 140°C overnight for standby use.

[0046] Ethoxyl pillar[5]arene 1 (3.00 g, 3.37 mmol) was added to 50 mL of chloroform, and stirred at -6.9°C for 30 min. Under nitrogen protection, boron tribromide solution (0.78 g, 1.55 mmol) was slowly added dropwise. Stirring was continued at -6 to -15°C for 10 min. After the raw material completely reacted, 20 mL of ice water was slowly added to the reaction solution to quench the reaction. After separation, the organic phase was dried, filtered, and rotary evaporated to obtain red crude product. The crude product was separated by column chromatography (eluent: petroleum ether / ethyl acetate = 20:1, v / v) to obtain white solid powder mono-elimination ethoxyl pillar[5]arene 2 (0.400 g), yield 13.78%.

[0047] Mono-elimination ethoxyl pillar[5]arene 2 (1.20 g, 1.39 mmol) and triethylamine (196 mg, 1.94 mmol) were added to 20 mL of anhydrous dichloromethane. Methyl acryloyl chloride (188 μL, 1.94 mmol) diluted with anhydrous dichloromethane was slowly added dropwise under ice bath. After the temperature rose to room temperature, the reaction was continued for 12 h. After stopping the stirring, the insoluble material in the reaction solution was filtered off. The filtrate was washed with saturated sodium bicarbonate solution, separated, dried, filtered, and rotary evaporated to obtain white solid. The crude product was separated by column chromatography (eluent: petroleum ether / ethyl acetate = 45:1, v / v) to obtain white solid mono-acryl substituted ethoxyl pillar[5]arene 3 (1.05 g), yield 81.0%.

[0048] The characterization data of mono-acryl substituted ethoxyl pillar[5]arene 3 are as follows:1 H NMR (600 MHz, CDC13, 298 K) δ ppm 6.92 (s, 1H), 6.71-6.73 (M, J = 13.92 Hz, 5H), 6.69 (s, 1H), 6.66-6.67 (d, J = 4.92 Hz, 2H), 6.52 (s, 1H), 6.31 (s, 1H), 5.72 (s, 1H), 3.82-3, 85 (q, J = 20.82 Hz, 8H), 3.75-3.80 (m, J = 33.60 Hz, 18H), 3.64 (s, 2H), 1.23-1.28 (m, J = 29.04 Hz, 18H), 1.19-1.22 (m, J = 17.58 Hz, 8H), 1.16-1.18 (t, J = 14.10 Hz, 4H).

[0049] (2) Synthesis of polyrotaxane of polycaprolactone mono-acryl modified pillar[5]arene (R is ethyl) as shown in the following formula

[0050]

[0051] The mono-acryl substituted ethoxyl pillar[5]arene 3 (1.82 g, 1.96 mmol) and polycaprolactone diol PCL-OH (0.4 g, Mn: 4000, 0.1 mmol) were added to 10 mL of anhydrous chloroform, protected by nitrogen, stirred at room temperature for 6 h, then stirred at -35 °C for 6 h, and then slowly added dropwise 3,5-bis(trifluoromethyl)phenyl isocyanate (0.20 mL, 1.16 mmol) diluted with anhydrous chloroform at low temperature, and continued to react at -35 °C for 72 h. Stop stirring, slowly drop the reaction solution into ice methanol, stand for half an hour, then filter, wash the residue with ice methanol, then dissolve the residue in chloroform again, and then drop the obtained liquid into ice methanol, filter, and spin dry to obtain 0.56 g of white powder solid, with a yield of 62.5%.

[0052] The structure of the synthesized polyrotaxane of polycaprolactone mono-acryl modified pillar[5]arene was characterized. An appropriate amount of the final product was weighed into a nuclear magnetic tube, dissolved with deuterated chloroform, and tested at 25 °C using a nuclear magnetic resonance instrument. From the nuclear magnetic resonance spectrum of the polyrotaxane of polycaprolactone mono-acryl modified pillar[5]arene, it can be seen that the chemical shift, integration, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product is obtained, and the spectrum has no impurity peak, proving that the product reaches a high purity.

[0053] The characterization data of the polyrotaxane of polycaprolactone mono-acryl modified pillar[5]arene are as follows:

[0054] 1H NMR (600 MHz, CDC13, 298 K) δ ppm 8.01-8.07 (t, 3H), 7.51-7.57 (t, 3H), 7.05 (m, 17H), 6.93 (m, 60H), 6.50-6.56 (t, 8H), 6.69 (m, 8H), 5.80 (s, 7H), 3.78-4.06 (m, 252H), 2.17 (s, 32H), 1.50 (s, 190H), 1.42 (m, 28H), 1.26 (s, 9H).

[0055] Example 2

[0056] A schematic diagram of the preparation of the dynamic slip-ring supramolecular polymer network is shown in Figure 1

[0057] Ethyl acrylate (2.0 g, 20.0 mmol), polywheel of polycaprolactone mono-acrylate modified pillar[5]arene prepared in Example 1 (180.0 mg, Mn=9000, 0.02 mmol), azobisisobutyronitrile (1.6 mg, 0.01 mmol) and diisopropyl xanthate disulfide (2.7 mg, 0.01 mmol) were mixed in a 100 mL reaction flask, and 4 mL of 1,4-dioxane was added. The oxygen in the reaction flask was removed by three cycles of freeze-pump-thaw and filled with nitrogen. After polymerization at 80 °C for 6 h, a transparent dynamic slip-ring supramolecular polymer network P5R-2 was obtained. The solvent was removed by vacuum drying, and the dynamic slip-ring supramolecular polymer network was hot-pressed into dumbbell-shaped strips using a polytetrafluoroethylene mold for mechanical property testing.

[0058] Example 3

[0059] Ethyl acrylate (4.0 g, 40.0 mmol), polywheel of polycaprolactone mono-acrylate modified pillar[5]arene prepared in Example 1 (180.0 mg, Mn=9000, 0.02 mmol), azobisisobutyronitrile (3.2 mg, 0.02 mmol) and diisopropyl xanthate disulfide (5.4 mg, 0.02 mmol) were mixed in a 100 mL reaction flask, and 8 mL of 1,4-dioxane was added. The oxygen in the reaction flask was removed by three cycles of freeze-pump-thaw and filled with nitrogen. After polymerization at 80 °C for 6 h, a transparent dynamic slip-ring supramolecular polymer network P5R-1 was obtained. The solvent was removed by vacuum drying, and the dynamic slip-ring supramolecular polymer network was hot-pressed into dumbbell-shaped strips using a polytetrafluoroethylene mold for mechanical property testing.

[0060] Example 4

[0061] ​Ethyl acrylate (1.0 g, 10.0 mmol), polyrotaxane modified with polycaprolactone monopropylene [5] aromatics prepared in Example 1 (180.0 mg, Mn = 9000, 0.02 mmol), azobisisobutyronitrile (1.6 mg, 0.01 mmol) and diisopropyl disulfide xanthate (2.7 mg, 0.01 mmol) were mixed in a 100 mL reaction flask, and 2 mL of 1,4-dioxane was added. After removing oxygen from the reaction flask by three cycles of freeze-drainage and filling it with nitrogen, it was polymerized at 80 °C for 6 hours to obtain a transparent dynamic slip ring supramolecular polymer network P5R-3. Finally, the solvent was removed by vacuum drying, and it was hot-pressed into dumbbell-shaped strips using a polytetrafluoroethylene mold for mechanical property testing.

[0062] Comparative Example 1

[0063] The only difference between the preparation method of the polymer network in this comparative example and that in Example 2 is that the polyrotaxane of the columnar aromatic hydrocarbon modified with polycaprolactone monopropylene[5] was replaced with 1,4-butanediol diacrylate (19.8 mg, 0.1 mmol) to prepare a covalent polymer network Control without slip rings.

[0064] Sample Analysis

[0065] The performance of the polymer networks prepared in Examples 2-4 and Comparative Example 1 was tested. Figure 2 Infrared spectra of the polymer networks obtained in Examples 2-4 and Comparative Example 1; Figure 3 Thermogravimetric diagrams of the polymer networks obtained in Examples 2-4 and Comparative Example 1 show that the addition of polycaprolactone monopropylene modified columnar aromatics [5] to polyrotaxane has no effect on the entire polymer backbone. Figure 4 The differential scanning calorimetry (DSC) curves of the polymer networks prepared in Examples 2-4 and Comparative Example 1 show that the T values ​​of the polymer networks after adding polycaprolactone monopropylene modified columnar aromatics [5] are significantly higher than those of the polyrotaxanes. g The increase in the molecular weight of polyrotaxane also indicates that the flexibility of the polymer network is increasing. Figure 5 The figure shows the stress-strain curves of different polymer networks. As can be seen from the figure, the tensile strength and elongation of the polymer network increase after the addition of polyrotaxane, indicating that the addition of polyrotaxane endows the entire epoxy polymer with dynamics and toughness. Figure 6 The graph shows the toughness variation of the polymer network with different concentrations of polyrotaxane. It can be seen from the graph that the toughness of the entire network increases with the increase of polyrotaxane concentration. However, adding excessive polyrotaxane will make the dynamics of the entire polymer network stronger, increasing its brittleness and reducing its toughening performance. Figure 7The cyclic tensile curves of the polymer network under different strains can be seen from the figure. With the increase of strain, the hysteresis loop of the polymer network is larger, which shows that the sliding of the sliding ring plays a dissipative role under the condition of large strain, thereby enhancing the toughness of the polymer network.

[0066] The above embodiments have described the technical solutions of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, supplement or similar replacement within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a dynamic slip ring supramolecular polymer network, characterized in that, In an organic solvent, polyrotaxane modified with acrylate monomers, initiators, accelerators and polycaprolactone monopropylene [5] propylene undergoes RAFT polymerization under an inert gas atmosphere to obtain the dynamic slip ring supramolecular polymer network described above. The structural formula of the polyrotaxane modified with polycaprolactone monopropylene [5] aromatic hydrocarbon is shown below: ； In the formula, n and m are independent positive integers, and R is an ethyl group; The acrylate monomer is ethyl acrylate.

2. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The polyrotaxane of the columnar aromatic hydrocarbon modified with polycaprolactone monopropylene [5] has a molecular weight of 1,000-200,000, n is a positive integer from 2 to 1,000, and m is a positive integer from 2 to 1,000.

3. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The initiator includes azobisisobutyronitrile; the accelerator includes diisopropyl disulfide xanthate.

4. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The molar ratio of the acrylate monomer, initiator, accelerator and polycaprolactone monopropylene modified columnar aromatics [5] rotaxane is 100-2000:1:1-10:0.1-200.

5. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The organic solvents mentioned include 1,4-dioxane, tetrahydrofuran, toluene, or ethanol.

6. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The ratio of the volume of organic solvent to the molar amount of acrylate monomer is 0.1-10 L:1 mol.

7. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The inert gas atmosphere is nitrogen.

8. The method for preparing the dynamic slip ring supramolecular polymer network according to claim 1, characterized in that, The conditions for the RAFT polymerization reaction are: temperature 0-120℃, time 2-72 hours.

9. The dynamic slip ring supramolecular polymer network prepared by the method according to any one of claims 1-8.

10. The application of the dynamic slip ring supramolecular polymer network according to claim 9 in the preparation of adhesives and / or toughening agents.

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