Method for preparing large cavity gamma-cyclodextrin polyrotaxane based on steric hindrance method and application

Abstract

The application discloses a method for preparing a large-cavity gamma-cyclodextrin polyrotaxane based on a steric hindrance method and application, and belongs to the field of high polymer materials. The polyrotaxane prepared by the method is assembled by polyethylene glycol with a steric hindrance group at an end and large-cavity gamma-cyclodextrin, and then terminated by a single amino cage silsesquioxane. By controlling the feeding ratio of the gamma-cyclodextrin and PEG, the gamma-polyrotaxane with different cyclodextrin ring numbers and single PEG nesting can be obtained. The single PEG nesting macrocyclic polyrotaxane material can provide a precursor for subsequent construction of a high-toughness and high-rebound gel material.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high polymer materials, and particularly relates to a method for preparing large-cavity gamma-cyclodextrin polyrotaxane based on a steric hindrance method and application. BACKGROUND

[0002] Polyrotaxane is a supramolecular polymer formed by the non-covalent interaction between cyclic molecules and linear molecules, and has unique physical and chemical properties, and can be used for preparing high-toughness elastomers and gel materials. The polymer molecular chains (guests) in the polyrotaxane are various, such as polyglycols (polyethylene glycol, polypropylene glycol), polyolefins (polypropylene), polyethers (polymethyl vinyl ether) and conjugated polymers (polyvinylbenzene, polyformaldehyde) and the like. The cyclic molecules as the host are commonly cyclodextrin (CD), crown ether and calixarene and the like. Cyclodextrin is a kind of macrocyclic compound formed by connecting D-glucopyranose units at the head and tail through alpha-1, 4 glycosidic bonds. The commonly used alpha-, beta- and gamma-cyclodextrins are composed of 6, 7 and 8 glucose units respectively. In recent years, cyclodextrin has become the most widely used host molecule of polyrotaxane due to its relatively large intramolecular cavity, relatively low price, non-toxicity and good biocompatibility. However, the preparation method of the polyrotaxane material is complex, and the number of the sheath rings is difficult to control, which affects the actual application. SUMMARY

[0003] The technical problem solved by the application is to provide a method for preparing large-cavity gamma-cyclodextrin polyrotaxane based on a steric hindrance method. The method controls the feeding ratio of gamma-cyclodextrin and PEG to obtain gamma-polyrotaxane with different numbers of cyclodextrin sheath rings and single PEG nesting. Another technical problem solved by the application is to provide the application of the polyrotaxane, in particular the application in high-toughness high-rebound ionic gel materials.

[0004] In order to solve the above technical problems, the technical scheme adopted by the application is as follows:

[0005] A method for preparing large-cavity gamma-cyclodextrin polyrotaxane based on a steric hindrance method, comprising the following steps:

[0006] (1) Synthesis of PEG-BuP containing steric hindrance end groups: polyethylene glycol is dissolved in an organic solvent, 4-tert-butyl phthalic anhydride is added, and the reaction is carried out under the action of a catalyst; after the reaction is completed, deionized water is added to the system, hydrochloric acid is used to adjust the pH, dichloromethane is used for extraction, and after rotary evaporation, ethyl ether is used for precipitation to obtain PEG-BuP;

[0007] (2) Assembly of PEG-BuP and gamma-cyclodextrin: gamma-cyclodextrin is dissolved in deionized water, and then PEG-BuP is dissolved in deionized water, mixed and stirred, and then placed in a refrigerator for assembly, and then freeze-dried to obtain gamma-PPR;

[0008] (3) end-capping: first, dissolving POSS-NH2, BOP and DIPEA in an organic solvent, then adding γ-PPR to the solution, stirring, centrifuging to obtain a precipitate; dissolving the precipitate in an organic solvent after washing with an organic solvent, stirring overnight, then water dialysis, freeze-drying to obtain the product γ-PR.

[0009] Further, the molecular weight M of the polyethylene glycol in the step (1) is 10000. n Further, the molecular weight M of the polyethylene glycol in the step (1) is 10000.

[0010] Further, the organic solvent in the step (1) is pyridine; and the catalyst is DMAP.

[0011] Further, the reaction temperature in the step (1) is 55 ℃, and the reaction time is 24 h.

[0012] Further, the molar ratio of PEG-BuP to γ-cyclodextrin in the step (2) is 1:10-20.

[0013] Further, the organic solvent in the step (3) is one or more of N, N-dimethylformamide, tetrahydrofuran and dimethyl sulfoxide.

[0014] Further, the stirring temperature in the step (3) is 35 ℃, and the stirring time is 48 h.

[0015] Further, the method for preparing the large-cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to any one of the above, the polyrotaxane is prepared.

[0016] Further, the polyrotaxane is applied to high-toughness high-rebound ion gel materials.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] The polyrotaxane preparation method provided by the present application is assembled by PEG with a steric hindrance group at the end group and large-cavity γ-cyclodextrin, and is capped by a single amino cage silsesquioxane (POSS-NH2); the steric hindrance group at the end group of PEG can effectively ensure the nesting of a single PEG in the assembly stage, and avoid the formation of two PEGs nested in the same γ-cyclodextrin, thereby causing the formation of cross-linked polyrotaxane. By controlling the feeding ratio of γ-cyclodextrin and PEG, γ-PR-single with different numbers of rings (9, 14 and 32) can be obtained, and the polyrotaxane material with a single PEG nested large ring provided by the present application can provide a precursor for subsequent construction of high-toughness high-rebound gel materials. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a synthesis route diagram for synthesizing polyrotaxane by polyethylene glycol and γ-cyclodextrin.

[0020] Figure 2 H NMR spectrum of the polymer polyethylene glycol PEG-BuP 1 H NMR spectrum;

[0021] Figure 3 H NMR spectrum of the polyrotaxane γ-PR with a feed ratio of 10:1 1 H NMR spectrum;

[0022] Figure 4 H NMR spectrum of the polyrotaxane γ-PR with a feed ratio of 15:1 1 H NMR spectrum;

[0023] Figure 5 H NMR spectrum of the polyrotaxane γ-PR with a feed ratio of 20:1 1 H NMR spectrum;

[0024] Figure 6 Stress-strain curve of the constructed high-toughness high-resilience ionic gel material

[0025] Figure 7 Cyclic tensile curve of the constructed high-toughness high-resilience ionic gel material DETAILED DESCRIPTION

[0026] The application will be further illustrated below in combination with specific examples, which are implemented on the premise of the technical solutions of the application and are intended to illustrate the application but not to limit the scope of the application.

[0027] In the following examples, the cavity size of the γ macrocycle of the large cavity γ-cyclodextrin is 7.4-9.5 A, PEG is polyethylene glycol, DMAP is 4-dimethylaminopyridine, POSS-NH2 is a monoamino cage silsesquioxane, BOP is benzotriazol-1-oxyl tris(dimethylamino) phosphorus hexafluorophosphate, and DIPEA is N, N-diisopropylethylamine.

[0028] Figure 1 The synthesis route map of the method for preparing the large cavity γ-cyclodextrin polyrotaxane is as follows:

[0029] (1) Synthesis of PEG-BuP containing a steric end group: polyethylene glycol is dissolved in an organic solvent, 4-tert-butyl phthalic anhydride is added, and the reaction is carried out under a catalyst; after the reaction is completed, deionized water is added to the system, hydrochloric acid is used to adjust the pH, the product is extracted with dichloromethane, and after rotary evaporation, a large amount of diethyl ether is used for precipitation; the precipitate is dried and subjected to the next step;

[0030] (2) Assembly of PEG-BuP and γ-cyclodextrin: γ-cyclodextrin was dissolved in deionized water, and PEG-BuP was dissolved in deionized water. After mixing and stirring, assembly was carried out in a refrigerator, and then freeze-drying was carried out to obtain white powder γ-PPR;

[0031] (3) End-capping: POSS-NH2, BOP and DIPEA were first dissolved in an organic solvent, and then dry γ-PPR was added to the solution. After stirring, the turbid solution was centrifuged to obtain a precipitate. The precipitate was washed with an organic solvent, and then centrifuged again to obtain a precipitate. The precipitate obtained by centrifugation was dissolved in an organic solvent, stirred overnight, and then subjected to water phase dialysis. After dialysis was completed, the solution was freeze-dried to obtain the product γ-PR.

[0032] Example 1

[0033] A method for preparing a large-cavity γ-cyclodextrin polyrotaxane based on a steric hindrance method, comprising the following steps:

[0034] The molar ratio of PEG-BuP to γ-cyclodextrin is 1:10

[0035] (1) Synthesis of PEG-BuP containing steric hindrance end groups: 20 g of PEG-10k was dissolved in 80 mL of anhydrous pyridine, 5 g of 4-tert-butyl phthalic anhydride and 0.2 g of DMAP catalyst were added, and the reaction was carried out at 55°C for 24 h. After the reaction was completed, 300 mL of deionized water was added to the reaction system, the pH was adjusted to 3 with hydrochloric acid, 200 mL of dichloromethane was used for extraction, and after rotary evaporation, 500 mL of diethyl ether was used for precipitation to obtain PEG-BuP.

[0036] (2) Assembly of PEG-BuP and γ-cyclodextrin: 8.3 g of γ-cyclodextrin was dissolved in 47 mL of deionized water, and 6.4 g of PEG-BuP was dissolved in 75 mL of deionized water. After mixing and stirring for 10 min, assembly was carried out in a 4°C refrigerator for 3 days, and then freeze-drying was carried out to obtain white powder γ-PPR about 14.7 g. The nuclear magnetic resonance spectrum is shown in Figure 2 ;

[0037] (3) End-capping: 7 g of POSS-NH2, 3.5 g of BOP and 1 g of DIPEA were first dissolved in a mixed solution of 100 mL of N, N-dimethylformamide and 100 mL of tetrahydrofuran, and then 14.7 g of dry γ-PPR was added to the solution. Stirring was carried out at 35°C for 48 h. The precipitate was obtained by centrifugation, the precipitate was washed with tetrahydrofuran, dissolved in 100 mL of dimethyl sulfoxide, stirred overnight, subjected to water phase dialysis for 3 days, and then freeze-dried to obtain polyrotaxane product γ-PR-single-10 with 9 rings. The nuclear magnetic resonance spectrum is shown in Figure 3as shown.

[0038] Example 2

[0039] A method for preparing large cavity γ-cyclodextrin polyrotaxane based on steric hindrance method, comprising the following steps:

[0040] The molar ratio of PEG-BuP to γ-cyclodextrin is 1:15

[0041] (1) Synthesis of PEG-BuP containing steric end groups: the same as the method of Example 1;

[0042] (2) Assembly of PEG-BuP and γ-cyclodextrin: 12.5 g of γ-cyclodextrin was dissolved in 72 mL of deionized water, and 6.4 g of PEG-BuP was dissolved in 75 mL of deionized water. After mixing and stirring for 10 min, it was placed in a 4 ℃ refrigerator for assembly for 3 days. After freeze-drying, white powder γ-PPR about 23 g was obtained;

[0043] (3) End-capping: 7 g of POSS-NH2, 3.5 g of BOP, and 1 g of DIPEA were dissolved in a mixed solution of 100 mL of N, N-dimethylformamide and 100 mL of tetrahydrofuran, and then 18.9 g of dry γ-PPR was added. Stirring at 35 ℃ for 48 h. First, the precipitate was separated by centrifugation, and then the precipitate was washed with tetrahydrofuran and dissolved in 100 mL of dimethyl sulfoxide and stirred overnight. Water phase dialysis was performed for 3 days, and after freeze-drying, polyrotaxane product γ-PR-single-15 with 14 rings was obtained. The nuclear magnetic resonance spectrum is as shown. Figure 4

[0044] Example 3

[0045] A method for preparing large cavity γ-cyclodextrin polyrotaxane based on steric hindrance method, comprising the following steps:

[0046] The molar ratio of PEG-BuP to γ-cyclodextrin is 1:20

[0047] (1) Synthesis of PEG-BuP containing steric end groups: the same as the method of Example 1;

[0048] (2) Assembly of PEG-BuP and γ-cyclodextrin: 16.6 g of γ-cyclodextrin was dissolved in 95 mL of deionized water, and 6.4 g of PEG-BuP was dissolved in 75 mL of deionized water. After mixing and stirring for 10 min, it was placed in a 4 ℃ refrigerator for assembly for 3 days. After freeze-drying, white powder γ-PPR about 23 g was obtained;

[0049] ​(3) End-capping: 7 g POSS-NH2, 3.5 g BOP, 1 g DIPEA were dissolved in 100 mL of a mixture of N, N-dimethylformamide and 100 mL of tetrahydrofuran, and then 23 g of dry γ-PPR was added to the solution. Stirring was carried out at 35 °C for 48 h. The precipitate was obtained by centrifugal separation, and the precipitate was washed with tetrahydrofuran, dissolved in 100 mL of dimethyl sulfoxide, stirred overnight, dialyzed in water for 3 days, and freeze-dried to obtain a polyrotaxane product γ-PR-single-20 with a number of 32 rings. The nuclear magnetic resonance spectrum is shown in FIG. 5. Figure 5

[0050] Example 4

[0051] Construction of high-toughness and high-resilience ionic gel

[0052] 2 g of acrylic acid, 3 g of 1-ethyl-3-methylimidazolium ethyl sulfonate, and 0.02 g of a photoinitiator 1-hydroxycyclohexyl phenyl ketone were mixed, 0.25 g of a double bond modified γ-PR-single-20 was added, and 0.2 mL of N, N-dimethylformamide (DMF) was added to fully dissolve. The above solution was poured into a fluorotetrafluoro dish and placed in a UV curing box under a nitrogen atmosphere, and UV cured for 60 minutes. The DMF was removed by drying in a forced air oven at 85 °C overnight. Finally, a transparent ionic gel film was obtained. Due to the introduction of γ-PR-single, the ionic gel showed high toughness and stretchability. As can be seen from the stress-strain curve of the high-toughness and high-resilience ionic gel material of Figure 6 , the tensile elongation at break can reach 840%. At the same time, as can be seen from the cyclic tensile curve of the high-toughness and high-resilience ionic gel material of Figure 7 , due to the large annular cavity of γ-PR-single, the friction between the ring and the shaft is small during sliding, so the energy dissipation during stretching is low, and therefore the material shows good resilience (the residual strain can be as low as 10%).

[0053] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.​

Claims

1. A method for preparing large cavity γ-cyclodextrin polyrotaxanes based on the steric hindrance method, characterized by: The method comprises the following steps: (1) synthesis of PEG-BuP containing steric end groups: polyethylene glycol is dissolved in an organic solvent, 4-tert-butyl phthalic anhydride is added, and reaction is carried out under a catalyst; after the reaction is completed, deionized water is added to the system, hydrochloric acid is used to adjust the pH, dichloromethane is used for extraction, and after rotary evaporation, ether is used for precipitation to obtain PEG-BuP; (2) assembly of PEG-BuP and γ-cyclodextrin: γ-cyclodextrin is dissolved in deionized water, PEG-BuP is dissolved in deionized water, and after mixing and stirring, assembly is carried out in a refrigerator, and freeze-drying is carried out to obtain γ-PPR; (3) Sealing the end: First, seal the end. γ-PPR was dissolved in an organic solvent, and then γ-PPR was added to the solution. After stirring and centrifugation, a precipitate was obtained. The precipitate was washed with an organic solvent and then dissolved in an organic solvent. The mixture was stirred overnight, then dialyzed in aqueous phase and lyophilized to obtain the product γ-PR. (4) double bond modified γ-PR.

2. The method for preparing large cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to claim 1, characterized by: In step (1), the molecular weight M of polyethylene glycol is... n It is 10000.

3. The method for preparing large cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to claim 1, characterized by: The organic solvent in the step (1) is pyridine; and the catalyst is 4-dimethylaminopyridine.

4. The method for preparing large cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to claim 1, characterized by: The reaction temperature in the step (1) is 55 ℃, and the reaction time is 24 h.

5. The method for preparing large cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to claim 1, characterized by: The feeding molar ratio of PEG-BuP and γ-cyclodextrin in the step (2) is 1:10-20.

6. The method for preparing large cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to claim 1, characterized by: The organic solvent in the step (3) is one or more of N, N-dimethylformamide, tetrahydrofuran and dimethyl sulfoxide.

7. The method for preparing large cavity γ-cyclodextrin polyrotaxane based on the steric hindrance method according to claim 1, characterized by: The stirring temperature in the step (3) is 35 ℃, and the stirring time is 48 h.

8. The polyrotaxane prepared by the method for preparing large-cavity γ-cyclodextrin polyrotaxane based on steric hindrance according to any one of claims 1-7.

9. Application of the polyrotaxane according to claim 8 in preparation of high-toughness and high-resilience ionic gel materials.

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