Curcumin functionalized montmorillonite modified polylactic acid and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses curcumin-functionalized montmorillonite-modified polylactic acid, curcumin has broad-spectrum antibacterial performance and anticoagulant performance, so that polylactic acid can be endowed with better antibacterial and anticoagulant performance, the curcumin-functionalized montmorillonite-modified polylactic acid can be better applied to the field of medical materials such as drug eluting stents and the like, and the curcumin-functionalized montmorillonite-modified polylactic acid has good application prospects. The introduction of the grafted macromolecular chitosan can well avoid the dissolution of curcumin micromolecules, so that the long-acting antibacterial and anticoagulant properties are maintained, the chitosan macromolecules are grafted on the surface of the montmorillonite in a curcumin bridging manner, the organically modified montmorillonite has larger interlayer spacing, and the antibacterial and anticoagulant properties of the montmorillonite are improved. Therefore, the polylactic acid has better interface bonding force and can absorb a large amount of energy, so that the polylactic acid has better mechanical properties, and properties such as thermal stability and the like can be improved, so that the composite polylactic acid material has more excellent comprehensive properties.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to curcumin functionalized montmorillonite modified polylactic acid and a preparation method thereof. Background Art

[0002] With the continuous development of modern medical technology and the continuous improvement of the pharmacology of traditional Chinese medicine, people have become more and more clear about the effective active ingredients and functions of traditional Chinese medicine. Among them, curcumin is a plant polyphenol extracted from the rhizome of turmeric, a traditional Chinese medicine of the ginger family. It is its main active ingredient and has antioxidant, anti-cancer, anticoagulant and antibacterial effects. Therefore, whether used in vivo or in vitro, curcumin has excellent physiological activity and performance. It is a natural plant extract ingredient with very high development prospects.

[0003] Since curcumin has multiple functions, there are many studies on the composite of curcumin and polymers. In the Chinese patent "CN107308137A A curcumin-loaded antibacterial fiber membrane and its preparation method", a fiber material with antibacterial effect is prepared by electrostatic spinning of curcumin and block copolymerized polylactic acid. However, the antibacterial effect of simple addition will be relatively dissolved and fall off, so the antibacterial effect is usually not durable enough. The occurrence of such phenomenon can be effectively avoided by grafting macromolecular chitosan with good compatibility, and the mechanical properties of polylactic acid can be effectively enhanced by compounding inorganic materials such as montmorillonite. The modified polylactic acid can also have very good anticoagulant properties and can be very well applied in the field of medical devices.

[0004] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a curcumin-functionalized montmorillonite-modified polylactic acid and a preparation method thereof, which solves the problems that the direct addition antibacterial effect is not long-lasting and the mechanical properties are relatively poor.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: A method for preparing curcumin functionalized montmorillonite modified polylactic acid comprises the following steps: (1) Add montmorillonite to anhydrous toluene solvent, stir and mix, then add hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 5-15 minutes, then heat to 70-90°C, react for 60-120 minutes, and after the reaction is completed, naturally cool, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) Add curcumin and isocyanate montmorillonite into a reaction vessel, then add acetone solvent, stir and mix, then dropwise add dibutyltin dilaurate as a catalyst, heat to 60-80° C., stir and react for 2-6 hours, after the reaction is completed, centrifuge, wash with acetone, and vacuum dry to obtain curcumin-modified montmorillonite; (3) Dissolve carboxymethyl chitosan in N,N-dimethylformamide solvent, add 4-dimethylaminopyridine and dicyclohexylcarbodiimide in sequence, stir and activate for 1-2 hours, then add curcumin-modified montmorillonite, heat to 45-65°C, stir and react for 24-36 hours in a dark environment, and after the reaction is completed, add anhydrous ethanol for precipitation, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan-grafted curcumin-modified montmorillonite; (4) Add polylactic acid, antioxidant 1010 and chitosan grafted curcumin modified montmorillonite into a torque rheometer, blend at 160-180°C for 3-10 min, rotate at 40-60 r / min, and discharge to obtain curcumin functionalized montmorillonite modified polylactic acid.

[0006] Preferably, the mass ratio of anhydrous toluene, montmorillonite and hexamethylene diisocyanate in step (1) is 40-130:5:1-3.

[0007] Preferably, in step (2), the mass ratio of acetone, isocyanate montmorillonite, curcumin and dibutyltin dilaurate is 700-1600:100:30-80:0.3-1.

[0008] Preferably, in step (3), the mass ratio of N,N-dimethylformamide, curcumin-modified montmorillonite, carboxymethyl chitosan, 4-dimethylaminopyridine and dicyclohexylcarbodiimide is 800-3600:100:120-480:20-60:80-160.

[0009] Preferably, in step (4), the mass ratio of polylactic acid, antioxidant 1010 and chitosan grafted curcumin modified montmorillonite is 100:0.3-0.8:1.5-5.

[0010] 3. Beneficial technical effects

[0011] Compared with the prior art, the present invention has the following experimental principles and beneficial technical effects: The curcumin functionalized montmorillonite modified polylactic acid comprises the following steps: firstly, isocyanate is reacted with active hydroxyl groups on the surface of montmorillonite to obtain isocyanate-based montmorillonite; secondly, isocyanate on the surface of montmorillonite is reacted with active hydroxyl groups on curcumin to obtain curcumin-modified montmorillonite; thirdly, the hydroxyl groups on the other end of curcumin are esterified with activated carboxyl groups on the surface of carboxymethyl chitosan under the catalytic system of 4-dimethylaminopyridine and dicyclohexylcarbodiimide to obtain chitosan grafted curcumin-modified montmorillonite; and finally, the curcumin-functionalized montmorillonite is mixed with polylactic acid by mixing to obtain curcumin-functionalized montmorillonite. Montmorillonite-modified polylactic acid can impart good antibacterial properties to polylactic acid due to the broad-spectrum antibacterial properties of curcumin, which are effective against common bacteria such as Escherichia coli, Staphylococcus aureus and Candida albicans. Curcumin has anticoagulant properties, which can impart anticoagulant properties to polylactic acid materials, thereby enabling them to be better applied in the field of medical materials such as drug-eluting stents. The introduction of curcumin by grafting macromolecular chitosan can better avoid the dissolution of small molecules of curcumin, thereby maintaining long-lasting antibacterial and anticoagulant properties, giving polylactic acid materials a broader application prospect.

[0012] The curcumin-functionalized montmorillonite-modified polylactic acid also grafts chitosan macromolecules onto the surface of montmorillonite by curcumin bridging. The organically modified montmorillonite has a larger interlayer spacing, and due to the good compatibility of chitosan and polylactic acid, the montmorillonite has better dispersibility in the polylactic acid matrix, and therefore has better interfacial bonding force, and can play a role in heterogeneous nucleation in the polylactic acid matrix. In addition, the montmorillonite can also induce silver streaks and block the silver streaks from developing into cracks, thereby absorbing a large amount of energy, so that the polylactic acid has better mechanical properties, and can also improve properties such as thermal stability, so that the composite polylactic acid material has more excellent comprehensive properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Reaction diagram for preparing curcumin-modified montmorillonite; Figure 2 Reaction diagram for preparing chitosan grafted curcumin modified montmorillonite. DETAILED DESCRIPTION

[0014] A method for preparing curcumin functionalized montmorillonite modified polylactic acid, characterized in that it comprises the following steps: Example 1

[0015] (1) Add 3 g of montmorillonite to 30 ml of anhydrous toluene solvent, stir and mix, then add 0.6 g of hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 5 min, then heat to 70 ° C, react for 60 min, wait for the reaction to be completed, cool naturally, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) 0.6 g of curcumin and 2 g of isocyanate montmorillonite were added to a reaction vessel, followed by the addition of 20 ml of acetone solvent, stirring and mixing, and then dropwise addition of 0.06 g of catalyst dibutyltin dilaurate. The mixture was heated to 60° C. and stirred for 2 h. After the reaction was completed, the mixture was centrifuged, washed with acetone, and dried in vacuo to obtain curcumin-modified montmorillonite. (3) Dissolve 1.2 g of carboxymethyl chitosan in 10 ml of N,N-dimethylformamide solvent, add 0.2 g of 4-dimethylaminopyridine and 0.8 g of dicyclohexylcarbodiimide in sequence, stir and activate for 1 h, then add 1 g of curcumin-modified montmorillonite, heat to 45 ° C, stir and react for 24 h in the dark, after the reaction is completed, add anhydrous ethanol to precipitate, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan grafted curcumin-modified montmorillonite; (4) 150 g of polylactic acid, 0.45 g of antioxidant 1010 and 2.2 g of chitosan grafted curcumin modified montmorillonite were added into a torque rheometer, blended at 160 °C for 3 min, with a rotation speed of 40 r / min, and discharged to obtain curcumin functionalized montmorillonite modified polylactic acid.

[0016] Example 2 (1) Add 3 g of montmorillonite to 40 ml of anhydrous toluene solvent, stir and mix, then add 1.1 g of hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 10 min, then heat to 80 ° C, react for 80 min, wait for the reaction to be completed, cool naturally, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) 0.8 g of curcumin and 2 g of isocyanate montmorillonite were added to a reaction vessel, followed by the addition of 25 ml of acetone solvent, stirring and mixing, and then dropwise addition of 0.12 g of catalyst dibutyltin dilaurate. The mixture was heated to 65° C. and stirred for 3 h. After the reaction was completed, the mixture was centrifuged, washed with acetone, and dried in vacuo to obtain curcumin-modified montmorillonite. (3) Dissolve 2.2 g of carboxymethyl chitosan in 15 ml of N,N-dimethylformamide solvent, add 0.3 g of 4-dimethylaminopyridine and 1.2 g of dicyclohexylcarbodiimide in sequence, stir and activate for 1 h, then add 1 g of curcumin-modified montmorillonite, heat to 45 ° C, stir and react for 28 h in the dark, after the reaction is completed, add anhydrous ethanol to precipitate, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan-grafted curcumin-modified montmorillonite; (4) Add 150 g of polylactic acid, 0.7 g of antioxidant 1010 and 4.5 g of chitosan grafted curcumin modified montmorillonite into a torque rheometer, blend at 170 °C for 8 min, rotate at 50 r / min, and discharge to obtain curcumin functionalized montmorillonite modified polylactic acid. Example 3

[0017] (1) Add 3 g of montmorillonite to 80 ml of anhydrous toluene solvent, stir and mix, then add 1.2 g of hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 10 min, then heat to 80 ° C, react for 80 min, wait for the reaction to be completed, cool naturally, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) 1.2 g of curcumin and 2 g of isocyanate montmorillonite were added to a reaction vessel, followed by the addition of 30 ml of acetone solvent, stirring and mixing, and then dropwise addition of 0.16 g of catalyst dibutyltin dilaurate. The mixture was heated to 70° C. and stirred for 4 h. After the reaction was completed, the mixture was centrifuged, washed with acetone, and dried in vacuo to obtain curcumin-modified montmorillonite. (3) Dissolve 2.8 g of carboxymethyl chitosan in 15 ml of N,N-dimethylformamide solvent, add 0.3 g of 4-dimethylaminopyridine and 1.2 g of dicyclohexylcarbodiimide in sequence, stir and activate for 1.5 h, then add 1 g of curcumin-modified montmorillonite, heat to 55 ° C, stir and react for 30 h in the dark, after the reaction is completed, add anhydrous ethanol to precipitate, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan grafted curcumin-modified montmorillonite; (4) 150 g of polylactic acid, 0.8 g of antioxidant 1010 and 5.2 g of chitosan grafted curcumin modified montmorillonite were added into a torque rheometer, blended at 170 °C for 6 min, with a rotation speed of 50 r / min, and discharged to obtain curcumin functionalized montmorillonite modified polylactic acid. Example 4

[0018] (1) Add 3 g of montmorillonite to 90 ml of anhydrous toluene solvent, stir and mix, then add 1.8 g of hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 15 min, then heat to 90 ° C, react for 120 min, wait for the reaction to be completed, cool naturally, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) 1.6 g of curcumin and 2 g of isocyanate montmorillonite were added to a reaction vessel, followed by the addition of 40 ml of acetone solvent, stirring and mixing, and then dropwise addition of 0.2 g of catalyst dibutyltin dilaurate. The mixture was heated to 80° C. and stirred for 6 h. After the reaction was completed, the mixture was centrifuged, washed with acetone, and dried in vacuo to obtain curcumin-modified montmorillonite. (3) Dissolve 4.8 g of carboxymethyl chitosan in 20 ml of N,N-dimethylformamide solvent, add 0.6 g of 4-dimethylaminopyridine and 1.6 g of dicyclohexylcarbodiimide in sequence, stir and activate for 2 h, then add 1 g of curcumin-modified montmorillonite, heat to 65 ° C, stir and react for 36 h in the dark, after the reaction is completed, add anhydrous ethanol to precipitate, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan grafted curcumin-modified montmorillonite; (4) 150 g of polylactic acid, 1.2 g of antioxidant 1010 and 7.5 g of chitosan grafted curcumin modified montmorillonite were added into a torque rheometer, blended at 180 °C for 10 min, with a rotation speed of 60 r / min, and discharged to obtain curcumin functionalized montmorillonite modified polylactic acid.

[0019] Comparative Example 1 (1) Dissolve 2.8 g of carboxymethyl chitosan in 15 ml of N,N-dimethylformamide solvent, add 0.4 g of 4-dimethylaminopyridine and 1.2 g of dicyclohexylcarbodiimide in sequence, stir and activate for 1 h, then add 0.5 g of curcumin, heat to 55 ° C, stir and react for 30 h in the dark, after the reaction is completed, add anhydrous ethanol to precipitate, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan grafted curcumin; (2) 150 g of polylactic acid, 0.8 g of antioxidant 1010 and 6 g of chitosan grafted curcumin-modified montmorillonite were added into a torque rheometer, blended at 170 °C for 8 min, with a rotation speed of 50 r / min, and discharged to obtain curcumin-modified polylactic acid.

[0020] Comparative Example 2 (1) Add 3 g of montmorillonite to 50 ml of anhydrous toluene solvent, stir and mix, then add 1.2 g of hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 10 min, then heat to 80 ° C, react for 100 min, wait for the reaction to be completed, cool naturally, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) Add 150 g of polylactic acid, 1 g of antioxidant 1010 and 6 g of isocyanate-based montmorillonite into a torque rheometer, blend at 170 °C for 8 min, rotate at 50 r / min, and discharge to obtain montmorillonite-modified polylactic acid.

[0021] The polylactic acid prepared in Example 1-4 and Comparative Example 1-2 are compared as follows: The polylactic acid materials prepared in the embodiment and the comparative example were respectively made into standard tensile specimens, and the tensile strength and elongation at break were tested using a DWS-9000B electronic universal testing machine, and the test standard was GB / T 8804.2-2003.

[0022] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Tensile strength (MPa) 54.3 56.8 64.7 62.8 51.2 56.9 Elongation at break (%) 8.4 10.7 14.3 11.8 3.6 10.2 0.75 g of the polylactic acid sample prepared in the examples and comparative examples was added to a flask, with no sample added as a blank control, and then 70 ml of 0.03 mol / L PBS buffer was added to the flask, and then 5 ml of Escherichia coli suspension (Staphylococcus aureus suspension) was added, and the mixture was fully shaken. Then 1 ml of the solution was taken, diluted 10 times, and cultured at 37°C for 24 h, and the colony count and antibacterial rate were calculated. The test standard was GB / T 20944.3-2008.

[0023] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Escherichia coli antibacterial rate (%) 85.7 89.6 92.5 91.3 92.7 24.8 Antibacterial rate of Staphylococcus aureus (%) 90.9 92.6 96.7 97.8 95.1 12.7

Claims

1. A curcumin functionalized montmorillonite modified polylactic acid, characterized in that: The method for preparing a curcumin-functionalized montmorillonite-modified polylactic acid comprises the following steps: (1) Add montmorillonite to anhydrous toluene solvent, stir and mix, then add hexamethylene diisocyanate under nitrogen atmosphere, ultrasonically disperse for 5-15 minutes, then heat to 70-90°C, react for 60-120 minutes, and after the reaction is completed, naturally cool, filter, wash, and vacuum dry to obtain isocyanate montmorillonite; (2) Add curcumin and isocyanate montmorillonite into a reaction vessel, then add acetone solvent, stir and mix, then dropwise add dibutyltin dilaurate as a catalyst, heat to 60-80° C., stir and react for 2-6 hours, after the reaction is completed, centrifuge, wash with acetone, and vacuum dry to obtain curcumin-modified montmorillonite; (3) Dissolve carboxymethyl chitosan in N,N-dimethylformamide solvent, add 4-dimethylaminopyridine and dicyclohexylcarbodiimide in sequence, stir and activate for 1-2 hours, then add curcumin-modified montmorillonite, heat to 45-65°C, stir and react for 24-36 hours in a dark environment, and after the reaction is completed, add anhydrous ethanol for precipitation, centrifuge, wash with anhydrous ethanol and deionized water, and vacuum dry to obtain chitosan-grafted curcumin-modified montmorillonite; (4) Add polylactic acid, antioxidant 1010 and chitosan grafted curcumin modified montmorillonite into a torque rheometer, blend at 160-180°C for 3-10 min, rotate at 40-60 r / min, and discharge to obtain curcumin functionalized montmorillonite modified polylactic acid.

2. The curcumin functionalized montmorillonite modified polylactic acid according to claim 1, characterized in that: The mass ratio of anhydrous toluene, montmorillonite and hexamethylene diisocyanate in step (1) is 40-130:5:1-3.

3. The curcumin functionalized montmorillonite modified polylactic acid according to claim 1, characterized in that: In the step (2), the mass ratio of acetone, isocyanate montmorillonite, curcumin and dibutyltin dilaurate is 700-1600:100:30-80:0.3-1.

4. The curcumin functionalized montmorillonite modified polylactic acid according to claim 1, characterized in that: In the step (3), the mass ratio of N,N-dimethylformamide, curcumin-modified montmorillonite, carboxymethyl chitosan, 4-dimethylaminopyridine and dicyclohexylcarbodiimide is 800-3600:100:120-480:20-60:80-160.

5. The curcumin functionalized montmorillonite modified polylactic acid according to claim 1, characterized in that: In the step (4), the mass ratio of polylactic acid, antioxidant 1010 and chitosan grafted curcumin modified montmorillonite is 100:0.3-0.8:1.5-5.

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