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

Abstract

The invention discloses a method for preparing 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 invention is prepared by assembling polyethylene glycol with a steric hindrance group at a terminal group and large-cavity gamma-cyclodextrin, and then terminating by using monoamino polyhedral oligomeric silsesquioxane. According to the preparation method disclosed by the invention, the feeding ratio of the gamma-cyclodextrin to the PEG is controlled, so that the gamma-polyrotaxane with different cyclodextrin lantern ring numbers and nested single PEG can be obtained, and the single PEG nested macrocyclic polyrotaxane material can provide a precursor for subsequently constructing a high-toughness and high-resilience gel type material.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials, and in particular relates to a method for preparing a large-cavity gamma-cyclodextrin polyrotaxane based on a steric hindrance method and an application thereof. Background Art

[0002] Polyrotaxane is a supramolecular polymer formed by the interaction of cyclic molecules and linear molecules through non-covalent bonds. It has unique physical and chemical properties and can be used to prepare high-toughness elastomers and gel materials. There are many kinds of polymer molecular chains (guests) in polyrotaxanes, such as polyglycols (polyethylene glycol, polypropylene glycol), polyolefins (polypropylene), polyethers (polymethyl vinyl ether) and conjugated polymers (polyvinylbenzene, polymethylene alkali). Common cyclic molecules as the main body include: cyclodextrin (CD), crown ethers and calixarene. Cyclodextrin is a class of macrocyclic compounds composed of D-pyranose glucose units connected head to tail through α-1,4 glycosidic bonds. Common α-, β- and γ-cyclodextrins are composed of 6, 7 and 8 glucose units, respectively. In recent years, cyclodextrin has become the most widely used polyrotaxane main molecule due to its relatively large molecular cavity, relatively cheap price, non-toxicity and good biocompatibility. However, the current preparation method of polyrotaxane materials is complicated, and it is difficult to control the number of rings, which affects its practical application. Summary of the invention

[0003] The technical problem solved by the present invention is to provide a method for preparing a large-cavity γ-cyclodextrin polyrotaxane based on a steric hindrance method, wherein the method controls the feed ratio of γ-cyclodextrin and PEG to obtain a γ-polyrotaxane with different numbers of cyclodextrin rings and a single PEG nested therein; another technical problem to be solved by the present invention is to provide an application of the polyrotaxane, and its application in high-toughness and high-resilience ion gel materials.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

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

[0006] (1) Synthesis of PEG-BuP containing sterically hindered end groups: polyethylene glycol is dissolved in an organic solvent, 4-tert-butylphthalic anhydride is added, and the mixture is reacted in the presence of a catalyst; after the reaction, deionized water is added to the system, the pH is adjusted with hydrochloric acid, the mixture is extracted with dichloromethane, and the mixture is rotary evaporated and precipitated with ether to obtain PEG-BuP;

[0007] (2) Assembly of PEG-BuP and γ-cyclodextrin: dissolve γ-cyclodextrin in deionized water, then dissolve PEG-BuP in deionized water, mix and stir, place in a refrigerator for assembly, and freeze-dry to obtain γ-PPR;

[0008] (3) Capping: first dissolve POSS-NH2, BOP, and DIPEA in an organic solvent, then add γ-PPR to the solution, stir, and centrifuge to obtain a precipitate; wash the precipitate with an organic solvent and then dissolve it in an organic solvent, stir overnight, then dialyze in water, and lyophilize to obtain the product γ-PR.

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

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

[0011] Furthermore, in step (1), the reaction temperature is 55°C and the reaction time is 24 h.

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

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

[0014] Furthermore, in step (3), the stirring temperature is 35° C. and the stirring time is 48 h.

[0015] Furthermore, any of the above methods for preparing large-cavity γ-cyclodextrin polyrotaxanes based on the steric hindrance method prepares polyrotaxanes.

[0016] Furthermore, the polyrotaxane is used in high-toughness and high-resilience ion gel materials.

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

[0018] The polyrotaxane preparation method provided by the present invention is to assemble PEG with a steric hindering group at the end group and a large cavity γ-cyclodextrin, and to end-cap with a monoamino cage-shaped silsesquioxane (POSS-NH2); the steric hindering group at the PEG end group can effectively ensure the nesting of a single PEG in the assembly stage, avoiding the formation of two PEGs nested in the same γ-cyclodextrin, thereby leading to the formation of a cross-linked polyrotaxane. By controlling the feed ratio of γ-cyclodextrin and PEG, γ-PR-single with different numbers of rings (9, 14 and 32) can be obtained. The polyrotaxane material with a single PEG nested in a large ring provided by the present invention can provide a precursor for the subsequent construction of high-toughness and high-resilience gel materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Synthetic route for the synthesis of polyrotaxanes from polyethylene glycol and γ-cyclodextrin;

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

[0021] Figure 3 The polyrotaxane feed ratio is 10:1 for γ-PR 1 H NMR spectrum;

[0022] Figure 4 The polyrotaxane feed ratio is 15:1 for γ-PR 1 H NMR spectrum;

[0023] Figure 5 The polyrotaxane feed ratio is 20:1 for γ-PR 1 H NMR spectrum;

[0024] Figure 6 The stress-strain curve of the constructed high-toughness and high-resilient ion gel material;

[0025] Figure 7 Cyclic tensile curve of the constructed high-toughness and high-resilient ion gel material. DETAILED DESCRIPTION

[0026] The present invention is further illustrated below in conjunction with specific examples. The examples are implemented based on the technical solutions of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

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

[0028] Figure 1 The synthetic route is a method for preparing a large cavity γ-cyclodextrin polyrotaxane, and the synthetic route is:

[0029] (1) Synthesis of PEG-BuP containing sterically hindered end groups: polyethylene glycol is dissolved in an organic solvent, 4-tert-butylphthalic anhydride is added, and the reaction is carried out in the presence of a catalyst; after the reaction is completed, deionized water is added to the system, the pH is adjusted with hydrochloric acid, the product is extracted with dichloromethane, and then precipitated with a large amount of ether after rotary evaporation. After the precipitate is dried, the next step is carried out;

[0030] (2) Assembly of PEG-BuP and γ-cyclodextrin: Dissolve γ-cyclodextrin in deionized water, then dissolve PEG-BuP in deionized water, mix and stir, place in a refrigerator for assembly, and then freeze-dry to obtain white powder γ-PPR;

[0031] (3) Capping: first dissolve POSS-NH2, BOP, and DIPEA in an organic solvent, then add dry γ-PPR to the solution, stir, and centrifuge the turbid solution to obtain a precipitate; wash the precipitate with an organic solvent, centrifuge again to obtain a precipitate, and then dissolve the precipitate obtained by centrifugation in an organic solvent, stir overnight, and then dialyze the aqueous phase. After the dialysis is completed, the solution is 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 comprises the following steps:

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

[0035] (1) Synthesis of PEG-BuP with steric end groups: 20 g of PEG-10k was dissolved in 80 mL of anhydrous pyridine, and 5 g of 4-tert-butylphthalic anhydride and 0.2 g of DMAP catalyst were added. The mixture was reacted at 55 °C for 24 h. After the reaction, 300 mL of deionized water was added to the reaction system, and the pH was adjusted to 3 with hydrochloric acid. The mixture was extracted with 200 mL of dichloromethane, and then precipitated with 500 mL of ether after rotary evaporation 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. The mixture was stirred for 10 min and placed in a refrigerator at 4 °C for 3 days. After freeze-drying, about 14.7 g of white powder γ-PPR was obtained. The NMR spectrum was as follows: Figure 2 As shown;

[0037] (3) Capping: First, 7 g POSS-NH2, 3.5 g BOP, and 1 g DIPEA were dissolved in a mixed solution of 100 mL N, N-dimethylformamide and 100 mL tetrahydrofuran, and then 14.7 g dried γ-PPR was added to the solution. Stir at 35 °C for 48 h. The precipitate was first obtained by centrifugation, washed with tetrahydrofuran, dissolved in 100 mL dimethyl sulfoxide, stirred overnight, and dialyzed in water for 3 days. After freeze-drying, the polyrotaxane product γ-PR-single-10 with a ring number of 9 was obtained. The NMR spectrum is shown in the figure. Figure 3shown.

[0038] Example 2

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

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

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

[0042] (2) Assembly of PEG-BuP and γ-cyclodextrin: Dissolve 12.5 g of γ-cyclodextrin in 72 mL of deionized water, and then dissolve 6.4 g of PEG-BuP in 75 mL of deionized water. Mix and stir for 10 min and place in a refrigerator at 4 °C for 3 days. After freeze-drying, obtain about 23 g of white powder γ-PPR.

[0043] (3) Capping: First, 7 g POSS-NH2, 3.5 g BOP, and 1 g DIPEA were dissolved in a mixed solution of 100 mL N, N-dimethylformamide and 100 mL tetrahydrofuran, and then 18.9 g dried γ-PPR was added to the solution. Stir at 35 °C for 48 h. The precipitate was first obtained by centrifugation, washed with tetrahydrofuran, dissolved in 100 mL dimethyl sulfoxide, stirred overnight, and dialyzed in water for 3 days. After freeze-drying, the polyrotaxane product γ-PR-single-15 with a ring number of 14 was obtained. The NMR spectrum is shown in the figure. Figure 4 shown.

[0044] Example 3

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

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

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

[0048] (2) Assembly of PEG-BuP and γ-cyclodextrin: Dissolve 16.6 g of γ-cyclodextrin in 95 mL of deionized water, and then dissolve 6.4 g of PEG-BuP in 75 mL of deionized water. Mix and stir for 10 min and place in a refrigerator at 4 °C for 3 days. After freeze-drying, about 23 g of white powder γ-PPR was obtained.

[0049] (3) Capping: First, dissolve 7g POSS-NH2, 3.5g BOP, and 1g DIPEA in a mixed solution of 100mL N, N-dimethylformamide and 100mL tetrahydrofuran, and then add 23g dried γ-PPR to the solution. Stir at 35°C for 48h. First, obtain the precipitate by centrifugation, wash the precipitate with tetrahydrofuran, dissolve it in 100mL dimethyl sulfoxide, stir it overnight, and perform aqueous dialysis for 3 days. After freeze-drying, the polyrotaxane product γ-PR-single-20 with a ring number of 32 is obtained. The NMR spectrum is shown in the figure. Figure 5 shown.

[0050] Example 4

[0051] Construction of high-toughness and high-resilient ion gel

[0052] Take 2 g of acrylic acid, 3 g of 1-ethyl-3-methylimidazolium ethyl sulfonate, and 0.02 g of 1-hydroxycyclohexyl phenyl ketone as a photoinitiator, mix them, add 0.25 g of double-bond-modified γ-PR-single-20, and then add 0.2 mL of N, N-dimethylformamide (DMF) to fully dissolve. The above solution was inverted in a PTFE dish and placed in a UV curing box under a nitrogen atmosphere. UV curing was performed for 60 minutes, and the DMF was removed by drying at 85 ° C in a forced air oven overnight to finally obtain a transparent ion gel film. Due to the introduction of γ-PR-single, the ion gel exhibited higher toughness and stretchability. Figure 6 From the stress-strain curve of the high-toughness and high-rebound ion gel material, it can be seen that its elongation at break can reach 840%. Figure 7 From the cyclic tensile curve of the high-toughness and high-rebound ion gel material, it can be seen that due to the larger annular cavity of γ-PR-single, the friction between the ring and the axis is smaller during sliding, so the energy dissipation during the stretching process is lower, so the material exhibits good resilience (the residual strain can be as low as 10%).

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a large cavity γ-cyclodextrin polyrotaxane based on a steric hindrance method, characterized in that: The following steps are involved: (1) Synthesis of PEG-BuP containing sterically hindered end groups: polyethylene glycol is dissolved in an organic solvent, 4-tert-butylphthalic anhydride is added, and the mixture is reacted in the presence of a catalyst; after the reaction, deionized water is added to the system, the pH is adjusted with hydrochloric acid, the mixture is extracted with dichloromethane, and the mixture is rotary evaporated and precipitated with ether to obtain PEG-BuP; (2) Assembly of PEG-BuP and γ-cyclodextrin: Dissolve γ-cyclodextrin in deionized water, then dissolve PEG-BuP in deionized water, mix and stir, place in a refrigerator for assembly, and freeze-dry to obtain γ-PPR; (3) Capping: first dissolve POSS-NH2, BOP, and DIPEA in an organic solvent, then add γ-PPR to the solution, stir, and centrifuge to obtain a precipitate; wash the precipitate with an organic solvent and then dissolve it in an organic solvent, stir overnight, then dialyze in water, and lyophilize to obtain the product γ-PR.

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

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

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

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

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

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

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

9. Use of the polyrotaxane according to claim 8 in high-toughness and high-resilience ion gel materials.

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