Preparation method and application of a polymer polylactic acid nanocomposite material based on copper lutetium metal organic framework

Abstract

The present invention discloses a preparation method and application of a polymer polylactic acid nanocomposite material based on a copper-lutetium metal organic framework (Cu-LU) metal organic framework (MOF), belonging to the technical field of polymer composite materials. The method comprises the following steps: first, adding polylactic acid to dioxane to prepare a uniform polylactic acid solution; second, dispersing copper-lutetium metal organic framework (MOF) nanoparticles in dioxane to prepare a uniform dispersion of the Cu-lutetium metal organic framework (MOF) nanoparticles; third, adding the Cu-lutetium metal organic framework (MOF) nanoparticle dispersion obtained in step two to the polylactic acid solution obtained in step one, stirring at 60°C for 1 hour, obtaining a uniform film-forming solution for later use; and fourth, pouring the film-forming solution obtained in step three into a flat-bottomed glass dish and drying it to obtain a polylactic acid nanocomposite film having both antibacterial and ammonia-responsive functions. The present invention utilizes the above preparation method to obtain a polymer polylactic acid nanocomposite material having excellent water vapor barrier, mechanical strength, UV shielding, blue light shielding, and ammonia-responsive color change properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, and in particular to a preparation method and application of a polymer polylactic acid nanocomposite material based on a copper lutetium metal organic framework. Background Art

[0002] Polylactic acid is a new type of biodegradable material made from starch raw materials derived from renewable plant resources (such as corn). The starch raw material is saccharified to obtain glucose, which is then fermented with glucose and certain strains of bacteria to produce high-purity lactic acid, and then polylactic acid of a certain molecular weight is synthesized by chemical synthesis. It has good biodegradability and can be completely degraded by microorganisms in nature after use, eventually generating carbon dioxide and water without polluting the environment. This is very beneficial to protecting the environment and is a recognized environmentally friendly material that has been widely used in food packaging materials. However, due to the lack of ammonia response, antibacterial, UV shielding, blue light shielding and other functions of polylactic acid materials, its actual application is subject to certain limitations. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method and application of a high-molecular-weight polylactic acid nanocomposite material based on a copper-lutetium metal-organic framework. The composite material has excellent water vapor barrier, mechanical strength, toughness, ultraviolet shielding, blue light shielding, antibacterial, ammonia response color change and other properties. It can be used as an intelligent indicator material to timely and effectively indicate the changes in the freshness of seafood and meat products during storage. The preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for scale-up production.

[0004] To achieve the above objectives, the present invention provides a preparation method and application of a polymer polylactic acid nanocomposite material based on a copper-lutetium metal organic framework. The polymer polylactic acid nanocomposite material is composed of the following components in parts by weight: 100 parts of polylactic acid, 1-5 parts of copper-lutetium MOF nanoparticles, and 3-8 parts of amino acids;

[0005] The specific steps of the preparation method of the polymer polylactic acid nanocomposite material are as follows:

[0006] Step 1: Add 80 parts of polylactic acid to 1000 parts of dioxane to prepare a uniform polylactic acid solution for later use;

[0007] Step 2: Dispersing 1-5 parts of copper-lutetium MOF nanoparticles in 500 parts of dioxane to prepare a uniform dispersion of copper-lutetium MOF nanoparticles for later use;

[0008] Step 3: Add the copper lutetium MOF nanoparticle dispersion obtained in step 2 to the polylactic acid solution obtained in step 1, and stir at 60° C. for 1 hour to obtain a uniform film-forming solution for standby use;

[0009] Step 4: pour the film-forming solution obtained in step 3 into a flat-bottomed glass dish and dry it to obtain a polylactic acid nanocomposite film having both antibacterial and ammonia-responsive functions.

[0010] Preferably, in the above method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material, the condition for obtaining a uniform polylactic acid solution in step 1 is stirring at 60° C. for 2 hours.

[0011] Preferably, in the above-mentioned method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material, the condition for preparing a uniform dispersion of copper-lutetium MOF nanoparticles in step 2 is ultrasonic stirring at room temperature for 30 minutes.

[0012] Preferably, in the above method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material, the drying condition in step 4 is drying in an oven at 60° C. for 24 hours.

[0013] Preferably, in the above-mentioned method for preparing a polymer polylactic acid nanocomposite material based on copper-lutetium metal, the method for preparing the copper-lutetium MOF nanoparticles comprises the following steps:

[0014] Step 1: dissolving copper nitrate and lutetium nitrate in deionized water, adding lauric acid thereto, and stirring and mixing to obtain a uniform blend solution;

[0015] Step 2: dissolving trimesic acid in N,N-dimethylformamide to obtain a trimesic acid solution;

[0016] Step 3: Add the trimesic acid solution obtained in step 2 to the mixed solution obtained in step 1, stir and react at room temperature for 5 minutes, and then centrifuge, wash and dry in sequence to obtain copper lutetium MOF nanoparticles.

[0017] Preferably, in the above-mentioned method for preparing a polymer polylactic acid nanocomposite material based on copper lutetium metal, the weight parts of the raw materials for preparing the blend solution in step 1 are as follows: 3 parts of copper nitrate, 2 parts of lutetium nitrate, 500 parts of deionized water, and 20 parts of lauric acid.

[0018] Preferably, in the above-mentioned method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material, the weight parts of the raw materials for preparing the trimesic acid solution in step 2 are as follows: 8 parts of trimesic acid and 500 parts of N,N-dimethylformamide.

[0019] Preferably, in the application of the above-mentioned copper-lutetium metal-based polymer polylactic acid nanocomposite material, the prepared polymer polylactic acid nanocomposite material is used in food packaging, smart materials, biomedicine, antibacterial materials, ammonia detection, environmental monitoring and safety fields.

[0020] Therefore, the present invention adopts a preparation method and application of a high-molecular-weight polylactic acid nanocomposite material based on a copper-lutetium metal-organic framework with the above-mentioned structure. The prepared polylactic acid nanocomposite material, on the one hand, utilizes the synergistic effect of the complexing properties of copper ions and the electronic transition properties of rare earth lutetium ions to enhance the color response performance of the composite material to ammonia; on the other hand, utilizes the antibacterial properties of amino acids and the enhanced and toughened polylactic acid material properties to obtain excellent water vapor barrier, mechanical strength, toughness, ultraviolet shielding, blue light shielding, antibacterial, ammonia response color change and other properties. It can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of seafood and meat products during storage. The preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for large-scale production. It has potential application value in food packaging, intelligent materials, biomedicine, antibacterial materials, ammonia detection, environmental monitoring and safety and other fields.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope image of copper-lutetium MOF nanoparticles involved in the preparation method and application of a polymer polylactic acid nanocomposite material based on a copper-lutetium metal organic framework of the present invention;

[0023] Figure 2 This is a scanning electron microscope image of the polylactic acid nanocomposite material prepared in Example 3 of the preparation method and application of a high-molecular polylactic acid nanocomposite material based on a copper lutetium metal organic framework of the present invention. DETAILED DESCRIPTION

[0024] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0026] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0027] The present invention uses polylactic acid as a matrix and utilizes copper lutetium metal organic framework nanoparticles and amino acids as functional fillers to improve the water vapor barrier, mechanical strength, toughness, ultraviolet shielding, blue light shielding, antibacterial, ammonia response color change and other properties of the polylactic acid material, creating a biodegradable polylactic acid nanocomposite material with both antibacterial and ammonia response functions, and broadening its application in food packaging, smart materials, biomedicine, antibacterial materials, ammonia detection, environmental monitoring and safety and other fields.

[0028] In the following specific embodiments and comparative example formulas and preparation methods, the preparation method of the copper lutetium MOF nanoparticles includes the following steps:

[0029] Step 1: dissolving 3 parts of copper nitrate and 2 parts of lutetium nitrate in 500 parts of deionized water, adding 20 parts of lauric acid thereto, and stirring and mixing to obtain a uniform blend;

[0030] Step 2: dissolving 8 parts of trimesic acid in 500 parts of N,N-dimethylformamide to obtain a trimesic acid solution;

[0031] Step 3: Add the trimesic acid solution obtained in step 2 to the mixed solution obtained in step 1, stir and react at room temperature for 5 minutes, then centrifuge, wash and dry in sequence to obtain copper lutetium MOF nanoparticles. (The scanning electron microscope image is shown in Figure 1 ).

[0032] Example 1

[0033] A polylactic acid nanocomposite material with both antibacterial and ammonia responsive functions is characterized by being composed of the following components in parts by weight: 80 parts of polylactic acid, 1 part of copper lutetium MOF nanoparticles and 4 parts of lysine.

[0034] The preparation method comprises the following steps:

[0035] (1) Add 80 parts of polylactic acid to 1000 parts of dioxane, stir at 60°C for 2 hours to obtain a uniform polylactic acid solution for later use;

[0036] (2) Dispersing 1 part of copper-lutetium MOF nanoparticles and 4 parts of lysine in 500 parts of dioxane, stirring ultrasonically at room temperature for 30 minutes, and obtaining a uniform dispersion of copper-lutetium MOF nanoparticles for later use;

[0037] (3) adding the copper lutetium MOF nanoparticle dispersion obtained in step (2) to the polylactic acid solution obtained in step (1), stirring at 60° C. for 1 h to obtain a uniform film-forming solution for standby use;

[0038] (4) The film-forming solution obtained in step (3) was poured into a flat-bottomed glass dish and dried in an oven at 60° C. for 24 h to obtain a polylactic acid nanocomposite film having both antibacterial and ammonia response functions.

[0039] Example 2

[0040] A polylactic acid nanocomposite material having both antibacterial and ammonia responsive functions, characterized in that it is composed of the following components in parts by weight: 80 parts of polylactic acid, 3 parts of copper lutetium MOF nanoparticles and 4 parts of lysine.

[0041] The preparation method comprises the following steps:

[0042] (1) Add 80 parts of polylactic acid to 1000 parts of dioxane, stir at 60°C for 2 hours to obtain a uniform polylactic acid solution for later use;

[0043] (2) Dispersing 3 parts of copper-lutetium MOF nanoparticles and 4 parts of lysine in 500 parts of dioxane, stirring ultrasonically at room temperature for 30 minutes, and obtaining a uniform dispersion of copper-lutetium MOF nanoparticles for later use;

[0044] (3) adding the copper lutetium MOF nanoparticle dispersion obtained in step (2) to the polylactic acid solution obtained in step (1), stirring at 60° C. for 1 h to obtain a uniform film-forming solution for standby use;

[0045] (4) The film-forming solution obtained in step (3) was poured into a flat-bottomed glass dish and dried in an oven at 60° C. for 24 h to obtain a polylactic acid nanocomposite film having both antibacterial and ammonia response functions.

[0046] Example 3

[0047] A polylactic acid nanocomposite material with both antibacterial and ammonia response functions is characterized by being composed of the following components in parts by weight: 100 parts of polylactic acid and 5 parts of copper lutetium MOF nanoparticles.

[0048] (1) Add 80 parts of polylactic acid to 1000 parts of dioxane, stir at 60°C for 2 hours to obtain a uniform polylactic acid solution for later use;

[0049] (2) Dispersing 5 parts of copper-lutetium MOF nanoparticles and 4 parts of lysine in 500 parts of dioxane, stirring ultrasonically at room temperature for 30 minutes, and obtaining a uniform dispersion of copper-lutetium MOF nanoparticles for later use;

[0050] (3) adding the copper lutetium MOF nanoparticle dispersion obtained in step (2) to the polylactic acid solution obtained in step (1), stirring at 60° C. for 1 h to obtain a uniform film-forming solution for standby use;

[0051] (4) The film-forming solution obtained in step (3) was poured into a flat-bottomed glass dish and dried in an oven at 60° C. for 24 h to obtain a polylactic acid nanocomposite film having both antibacterial and ammonia response functions.

[0052] Comparative Example 1

[0053] As a comparison standard for the above embodiment, the present invention provides a polylactic acid composite material prepared without copper lutetium MOF nanoparticles, comprising the following steps:

[0054] (1) Add 80 parts of polylactic acid to 1000 parts of dioxane, stir at 60°C for 2 hours, and add 4 parts of lysine to obtain a uniform polylactic acid solution for later use;

[0055] (2) adding 500 parts of dioxane to the polylactic acid and lysine solution obtained in step (1), stirring at 60° C. for 1 hour to obtain a uniform film-forming solution for standby use;

[0056] (3) The film-forming solution obtained in step (2) was poured into a flat-bottomed glass dish and dried in an oven at 60° C. for 24 h to obtain a polylactic acid composite material.

[0057] Comparative Example 2

[0058] As a comparison standard for the above embodiment, the present invention provides a polylactic acid composite material prepared without copper lutetium MOF nanoparticles, comprising the following steps:

[0059] (1) Add 80 parts of polylactic acid to 1000 parts of dioxane, stir at 60°C for 2 hours to obtain a uniform polylactic acid solution for later use;

[0060] (2) adding 500 parts of dioxane to the polylactic acid solution obtained in step (1), stirring at 90° C. for 1 hour to obtain a uniform film-forming solution for standby use;

[0061] (3) The film-forming solution obtained in step (2) was poured into a flat-bottomed glass dish and dried in an oven at 60° C. for 24 h to obtain a polylactic acid composite material.

[0062] Structure and performance test:

[0063] The polylactic acid material prepared in the above comparative example and the polylactic acid nanocomposite prepared in the embodiment were subjected to structure and performance tests, wherein the cross-sectional morphology of the polylactic acid nanocomposite was characterized by scanning electron microscopy; the ultraviolet-visible performance was tested by ultraviolet-visible spectrometer, and the average transmittance of ultraviolet rays (UVA, UVB, UVC) was calculated in accordance with GB / T18830-2009; the tensile properties were tested in accordance with GB / T1040-2006; the water vapor permeability coefficient was tested in accordance with ASTME96; the antibacterial properties of the material were tested in accordance with QBT2591-2003; the ammonia response test method was as follows: the sample material was exposed to an ammonia environment, and the color change of the sample material was observed.

[0064] Shrimp freshness monitoring experiment: Fresh shrimp were purchased from the market and placed in a Petri dish. The Petri dish was sealed with a Petri dish lid. The polylactic acid material prepared in the comparative example and the polylactic acid nanocomposite material prepared in the example (pre-cut into sample materials with a diameter of 1 cm) were attached to the bottom of the lid. The above shrimp samples were then placed in a 25°C oven for storage. The changes in the freshness of the shrimp and the color changes of the sample materials were observed and recorded. The volatile basic nitrogen (TVB-N) value released by the shrimp samples during storage was tested according to the GB5009.288-2016 method.

[0065] The above performance test data are shown in Table 1 and Table 2.

[0066] Table 1 Sample performance test data

[0067]

[0068]

[0069] Table 2 Shrimp freshness monitoring test results (where t is the storage time of fresh shrimp)

[0070]

[0071] The SEM results of the polylactic acid nanocomposite material showed that the copper-lutetium MOF nanoparticles can be evenly dispersed in the polylactic acid matrix, which means that the copper-lutetium MOF nanoparticles and the polylactic acid matrix have good compatibility, which is conducive to obtaining a polylactic acid nanocomposite material with excellent performance.

[0072] The results of the ammonia response test experiment show that the polylactic acid materials prepared in Comparative Examples 1 and 2 are colorless and transparent. After exposure to an ammonia environment, their color does not change, and they still exhibit colorless and transparent optical properties; the polylactic acid nanocomposite prepared in Example 1 is light blue, and after exposure to an ammonia environment, its color changes to dark blue; the polylactic acid nanocomposite prepared in Example 2 is light blue, and after exposure to an ammonia environment, its color changes to dark blue; the polylactic acid composite material prepared in Example 3 is blue, and after exposure to an ammonia environment, its color changes to blue-black; this indicates that the polylactic acid nanocomposite prepared in the present invention has excellent ammonia response color-changing properties.

[0073] In summary, the sample performance test data (see Tables 1 and 2) show that the polylactic acid nanocomposite prepared by the present invention has excellent water vapor barrier, mechanical strength, toughness, UV shielding, blue light shielding, antibacterial, ammonia response color change and other properties, and can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of meat foods such as shrimp during storage (see Table 2). The preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for scale-up production. It has potential application value in food packaging, intelligent materials, biomedicine, antibacterial materials, ammonia detection, environmental monitoring and safety and other fields.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a polymer polylactic acid nanocomposite material based on copper lutetium metal, characterized in that: The polymer polylactic acid nanocomposite material is composed of the following components in parts by weight: 100 parts of polylactic acid, 1-5 parts of copper lutetium MOF nanoparticles, and 3-8 parts of amino acids; The specific steps of the preparation method of the polymer polylactic acid nanocomposite material are as follows: Step 1: Add 80 parts of polylactic acid to 1000 parts of dioxane to prepare a uniform polylactic acid solution for later use; Step 2: Dispersing 1-5 parts of copper-lutetium MOF nanoparticles and 3-8 parts of amino acids in 500 parts of dioxane to prepare a uniform dispersion of copper-lutetium MOF nanoparticles for later use; Step 3: Add the copper-lutetium MOF nanoparticle dispersion obtained in step 2 to the polylactic acid solution obtained in step 1, and stir at 60° C. for 1 hour to obtain a uniform film-forming solution for later use; Step 4: pouring the film-forming solution obtained in step 3 into a flat-bottomed glass dish and drying it to obtain a polylactic acid nanocomposite film having both antibacterial and ammonia-responsive functions; The preparation method of the copper-lutetium MOF nanoparticles comprises the following steps: Step 1: dissolving copper nitrate and lutetium nitrate in deionized water, adding lauric acid thereto, and stirring and mixing to obtain a uniform blend solution; Step 2: dissolving trimesic acid in N,N-dimethylformamide to obtain a trimesic acid solution; Step 3: Add the trimesic acid solution obtained in step 2 to the mixed solution obtained in step 1, stir and react at room temperature for 5 minutes, and then centrifuge, wash and dry in sequence to obtain copper lutetium MOF nanoparticles.

2. The method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material according to claim 1, characterized in that: The condition for obtaining a uniform polylactic acid solution in step 1 of the preparation method of the polymer polylactic acid nanocomposite material is stirring at 60° C. for 2 hours.

3. The method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material according to claim 1, characterized in that: Preparation of Polymer Polylactic Acid Nanocomposite Material The conditions for preparing a uniform dispersion of copper lutetium MOF nanoparticles in step 2 are ultrasonic stirring at room temperature for 30 minutes.

4. The method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material according to claim 1, characterized in that: The drying condition in step 4 of the preparation method of the polymer polylactic acid nanocomposite material is drying in an oven at 60° C. for 24 hours.

5. The method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material according to claim 1, characterized in that: In the preparation method of the copper-lutetium MOF nanoparticles, the weight parts of the raw materials for preparing the blend solution in step 1 are as follows: 3 parts of copper nitrate, 2 parts of lutetium nitrate, 500 parts of deionized water, and 20 parts of lauric acid.

6. The method for preparing a copper-lutetium metal-based polymer polylactic acid nanocomposite material according to claim 1, characterized in that: The weight parts of the raw materials for preparing the trimesic acid solution in step 2 of the preparation method of the copper lutetium MOF nanoparticles are as follows: 8 parts of trimesic acid, 500 parts of N,N-dimethylformamide.

7. The use of a copper-lutetium metal-based polymer polylactic acid nanocomposite material according to any one of claims 1 to 6, characterized in that: The prepared polymer polylactic acid nanocomposites are used in food packaging, smart materials, biomedicine, antibacterial materials, ammonia detection, environmental monitoring and safety fields.

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