A tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions, and its preparation method and application

Abstract

The present invention belongs to the technical field of polymer composite materials, specifically relating to a strong and tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing properties, its preparation method, and applications. The strong and tough polyvinyl alcohol / starch composite film is prepared from the following raw materials: polyvinyl alcohol, potato starch, and a zinc-copper metal-organic framework. The present invention also provides a method for preparing the strong and tough polyvinyl alcohol / starch composite film. The prepared composite film material exhibits excellent compatibility, mechanical strength, toughness, oxygen barrier properties, UV barrier properties, high-energy blue light barrier properties, ammonia-responsive color change properties, and biodegradability. The preparation process is simple, and the film has broad application value in food packaging, smart materials, ammonia detection, environmental monitoring, and safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite films, and in particular relates to a strong and tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions, as well as a preparation method and application thereof. Background Art

[0002] Polyvinyl alcohol (PVA) and starch, as biodegradable materials, are environmentally friendly organic polymers with excellent film-forming properties and biocompatibility. They hold broad application prospects in areas such as food packaging, biomedicine, and smart gels. However, pure PVA has drawbacks such as high cost and slow degradation in soil. One approach to overcoming these drawbacks is to blend PVA with natural biopolymers. Potato starch is abundant and inexpensive, exhibiting high biocompatibility, rapid degradation, and complete degradability. It holds potential for application in various fields, including food packaging, agricultural production, papermaking, and electronic devices. Adding potato starch to PVA can increase the biodegradation rate, resulting in more economical and environmentally friendly PVA / potato starch composites. However, the compatibility between PVA and potato starch is limited, and PVA / potato starch composites exhibit poor mechanical and oxygen barrier properties. Furthermore, they lack ammonia response, UV protection, and antibacterial properties, limiting their practical applications. The present invention uses polyvinyl alcohol / potato starch as a matrix and a zinc-copper metal organic framework as a functional filler to improve the compatibility, mechanical strength, toughness, oxygen barrier, ultraviolet barrier, high-energy blue light barrier, ammonia-responsive color change and other properties of the polyvinyl alcohol / potato starch composite material. A strong and tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color change functions is developed, broadening its application in food packaging, smart materials, biomedicine, ammonia-responsive materials, ammonia detection, environmental monitoring and safety and other fields. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a strong and tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing properties, as well as its preparation method and application. This composite material exhibits excellent compatibility, mechanical strength, toughness, oxygen barrier properties, UV barrier properties, high-energy blue light barrier properties, and ammonia-responsive color change properties, while maintaining high visible light transparency. It can be used as an intelligent indicator material to effectively and timely indicate the freshness of meat products (such as shrimp) during storage. Furthermore, the composite material's preparation process is simple, environmentally friendly, low-cost, and suitable for scale-up production.

[0004] Technical solution of the present invention:

[0005] The present invention provides a strong and tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions, characterized in that it is composed of the following components in parts by weight: 80 parts of polyvinyl alcohol, 20 parts of potato starch, and 1 part of a zinc-copper metal-organic framework;

[0006] The microstructure of the zinc-copper metal-organic framework is a rod-like structure with a diameter of 20-60 nm and a length of 40-400 nm. The preparation method thereof comprises the following steps:

[0007] (1) Take 10 parts of copper acetate and 11 parts of zinc acetate dihydrate, dissolve them in 1000 parts of deionized water to obtain a uniform mixed solution, and set aside;

[0008] (2) Dissolve 21 parts of 1,3,5-trimethylbenzene tricarboxylic acid in 9000 parts of deionized water, and heat to 100°C in an oil bath to obtain a uniform 1,3,5-trimethylbenzene tricarboxylic acid solution for later use;

[0009] (3) The mixed solution obtained in step (1) is added to the 1,3,5-benzenetricarboxylic acid solution obtained in step (2), stirred at 100° C. for 10 min, cooled to room temperature, and then centrifuged, washed with deionized water, and dried to obtain a zinc-copper metal-organic framework.

[0010] The present invention also provides a method for preparing the above-mentioned tough polyvinyl alcohol / starch composite film having both antibacterial and ammonia-sensitive color-changing functions, which is characterized by comprising the following steps:

[0011] (1) Add 80 parts of polyvinyl alcohol and 20 parts of potato starch to 1500 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution, and set aside;

[0012] (2) Disperse 1 part of the zinc-copper metal-organic framework in 500 parts of anhydrous ethanol and stir at room temperature for 60 minutes to obtain a uniform dispersion for later use;

[0013] (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 60 minutes to obtain a uniform film-forming solution for standby use;

[0014] (4) The film-forming liquid obtained in step (3) is poured into a flat-bottomed plastic film mold and dried in an oven at 60°C for 12 hours to obtain a strong polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions.

[0015] The application of the tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions is characterized by being used in the fields of food packaging, smart materials, ammonia detection, environmental monitoring and safety.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The tough polyvinyl alcohol / starch composite film prepared by the present invention has excellent compatibility, mechanical strength, toughness, oxygen barrier, ultraviolet barrier, high-energy blue light barrier, ammonia response color change, biodegradability and other properties, while maintaining high visible light transparency. It can be used as an intelligent indicator material to timely and effectively indicate the changes in the freshness of meat foods (such as shrimp) during storage. The preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for large-scale production. It has wide application value in food packaging, intelligent materials, ammonia detection, environmental monitoring and safety and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope image of the zinc-copper metal-organic framework involved in the present invention;

[0019] Figure 2 This is a photo of the polyvinyl alcohol / starch composite film sample prepared in the comparative example;

[0020] Figure 3 This is a photo of the tough polyvinyl alcohol / starch composite film sample prepared in Example 1;

[0021] Figure 4 These are scanning electron microscope images of the polyvinyl alcohol / starch composite film prepared in the comparative example of the present invention and the tough polyvinyl alcohol / starch composite film prepared in Example 1. DETAILED DESCRIPTION

[0022] The present invention is described in detail below by way of examples. It is necessary to point out that the present examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. Those skilled in the art may make some non-essential improvements and adjustments based on the above-mentioned contents of the present invention. The parts of the raw materials are by weight unless otherwise specified.

[0023] In the following specific embodiments and comparative example formulas and preparation methods, the polyvinyl alcohol used is a product provided by Ruyi Biotechnology Co., Ltd.; the potato starch used is a product provided by Aladdin Reagent Co., Ltd.; 1,3,5-trimethylbenzenecarboxylic acid is an analytical grade reagent provided by Roen Reagent Co., Ltd.; zinc acetate dihydrate and copper acetate are analytical grade reagents provided by Xilong Chemical Co., Ltd.

[0024] In the following specific embodiment formula and preparation method, the microstructure of the zinc-copper metal organic framework is a rod-like structure with a diameter of 20-60 nm and a length of 40-400 nm. The preparation method includes the following steps:

[0025] (1) Take 10 parts of copper acetate and 11 parts of zinc acetate dihydrate, dissolve them in 1000 parts of deionized water to obtain a uniform mixed solution, and set aside;

[0026] (2) Dissolve 21 parts of 1,3,5-trimethylbenzene tricarboxylic acid in 9000 parts of deionized water, and heat to 100°C in an oil bath to obtain a uniform 1,3,5-trimethylbenzene tricarboxylic acid solution for later use;

[0027] (3) The mixed solution obtained in step (1) is added to the 1,3,5-benzenetricarboxylic acid solution obtained in step (2), stirred at 100° C. for 10 min, cooled to room temperature, and then centrifuged, washed with deionized water, and dried to obtain a zinc-copper metal-organic framework.

[0028] Example 1

[0029] A tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions is composed of the following components in parts by weight: 80 parts of polyvinyl alcohol, 20 parts of potato starch, and 1 part of a zinc-copper metal-organic framework.

[0030] The preparation method comprises the following steps:

[0031] (1) Add 80 parts of polyvinyl alcohol and 20 parts of potato starch to 1500 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution, and set aside;

[0032] (2) Disperse 1 part of the zinc-copper metal-organic framework in 500 parts of anhydrous ethanol and stir at room temperature for 60 minutes to obtain a uniform dispersion for later use;

[0033] (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 60 minutes to obtain a uniform film-forming solution for standby use;

[0034] (4) The film-forming liquid obtained in step (3) is poured into a flat-bottomed dish and dried in an oven at 60°C for 12 h to obtain a strong polyvinyl alcohol / starch composite film having both antibacterial and ammonia-sensitive color-changing functions.

[0035] Comparative Example

[0036] As a comparison standard for the above examples, the present invention provides a polyvinyl alcohol / starch composite film prepared without a zinc-copper metal organic framework, comprising the following steps:

[0037] (1) Add 80 parts of polyvinyl alcohol and 20 parts of potato starch to 1500 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution, and set aside;

[0038] (2) Add 500 parts of anhydrous ethanol to the blend solution obtained in step (1), and stir at 95°C for 60 minutes to obtain a uniform film-forming solution for standby use;

[0039] (3) The film-forming solution obtained in step (2) was poured into a flat-bottomed dish and dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch composite film.

[0040] Structure and performance test:

[0041] The structure and performance of the polyvinyl alcohol / starch composite film prepared in the comparative example and the tough polyvinyl alcohol / starch composite film prepared in Example 1 were tested. The cross-sectional morphology of the composite film was characterized by SEM (SU-5000, Japan Advanced Technology Corporation). Figure 4 UV-visible properties were tested using a UV-visible spectrometer (Lamdba365, PerkinElmer Instruments), and the average UV transmittance was calculated according to GB / T 18830-2009. Tensile properties were tested using an electronic tensile testing machine (LDW-2G). The oxygen permeability coefficient was tested as follows: a film sample (diameter: 1.8 cm) was sealed in a glass vial containing 3 g of deoxidizer (including 1.0 g of activated carbon, 1.5 g of sodium chloride, and 0.5 g of reduced iron powder). The vial was weighed (denoted as W1) and then placed in a sealed container at a relative humidity of 90% and a temperature of 25°C. After 48 h, the vial was reweighed (denoted as W2). The oxygen permeability coefficient (OP) = (W2–W1) / (S×t), where S and t represent the area and exposure time of the film sample. The ammonia response test was tested as follows: the sample material was exposed to an ammonia environment, and the color change of the sample material was observed.

[0042] The above performance test data is shown in Table 1.

[0043] Table 1 Sample performance test data

[0044] Group Example 1 Comparative Example Average transmittance of ultraviolet UVA (%) 51.1 81.6 Average transmittance of ultraviolet UVB (%) 12.2 75.8 Average transmittance of ultraviolet UVC (%) 0.6 60.2 Average transmittance of high-energy short-wave blue light (%) 70.3 84.8 Tensile strength (MPa) 48.94 47.28 Tensile elongation at break (%) 97.93 87.45 <![CDATA[Toughness (MJ / m 3 )]]> 41.24 35.28 <![CDATA[Oxygen permeability coefficient (10 -3 g / m 2 ·s)]]> 2.8 3.3

[0045] The brittle cross section of the polyvinyl alcohol / starch composite film prepared in the comparative example and the brittle cross section of the tough polyvinyl alcohol / starch composite film prepared in Example 1 were observed and analyzed using a scanning electron microscope. Figure 4For the polyvinyl alcohol / starch composite film prepared in the comparative example, it can be observed that its brittle cross-section exhibits a rough, uneven, and cracked morphology, with a large number of dispersed phase particles (starch particles) with larger particle sizes. This indicates that the compatibility between polyvinyl alcohol and starch is poor, and the interfacial bonding between the polyvinyl alcohol and starch phases is weak. For the strong and tough polyvinyl alcohol / starch composite film prepared in Example 1, it can be observed that its brittle cross-section exhibits a relatively uniform, smooth, and dense morphology, the dispersed phase particle size is significantly reduced, the phase morphology structure of the system is significantly improved, and the interfacial bonding between the polyvinyl alcohol and starch phases is also significantly improved, which is conducive to the improvement of mechanical properties. That is, after the zinc-copper metal organic framework is added to the polyvinyl alcohol / starch blend system, it can effectively improve the compatibility of the polyvinyl alcohol / starch blend system, significantly reduce the dispersed phase particle size, and improve the interfacial bonding between the polyvinyl alcohol and starch phases.

[0046] The results of the ammonia response test experiment show that the polyvinyl alcohol / starch composite film prepared in the comparative example is colorless and transparent. After exposure to an ammonia environment, its color does not change, and it still exhibits colorless and transparent optical properties; the tough polyvinyl alcohol / starch composite film prepared in Example 1 is light green, and after exposure to an ammonia environment, its color changes to light blue.

[0047] In summary, based on the sample structure and performance test data (see Figure 4 As shown in Table 1), the tough polyvinyl alcohol / starch composite film prepared by the present invention has excellent compatibility, mechanical strength, toughness, oxygen barrier, ultraviolet barrier, high-energy blue light barrier, ammonia response color change, biodegradability and other properties, while maintaining high visible light transparency. It can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of meat foods such as shrimp during storage. In addition, the preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for scale-up production. It has wide application value in food packaging, smart materials, biomedicine, ammonia detection, environmental monitoring and safety and other fields.

[0048] The content of the present invention is not limited to the embodiments listed. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the description of the present invention is covered by the claims of the present invention.

Claims

1. A tough polyvinyl alcohol / starch composite film with both antibacterial and ammonia-sensitive color-changing functions, characterized in that: The invention is composed of the following components in parts by weight: 80 parts of polyvinyl alcohol, 20 parts of potato starch, and 1 part of zinc-copper metal-organic framework; The microstructure of the zinc-copper metal-organic framework is a rod-like structure with a diameter of 20-60 nm and a length of 40-400 nm. The preparation method thereof comprises the following steps: (1) Take 10 parts of copper acetate and 11 parts of zinc acetate dihydrate, dissolve them in 1000 parts of deionized water to obtain a uniform mixed solution, and set aside; (2) Dissolve 21 parts of 1,3,5-trimethylbenzene tricarboxylic acid in 9000 parts of deionized water, and heat to 100°C in an oil bath to obtain a uniform 1,3,5-trimethylbenzene tricarboxylic acid solution for later use; (3) The mixed solution obtained in step (1) is added to the 1,3,5-benzenetricarboxylic acid solution obtained in step (2), stirred at 100° C. for 10 min, cooled to room temperature, and then centrifuged, washed with deionized water, and dried to obtain a zinc-copper metal-organic framework.

2. The method for preparing a tough polyvinyl alcohol / starch composite film having both antibacterial and ammonia-sensitive color-changing functions according to claim 1, characterized in that: The steps include: (1) Add 80 parts of polyvinyl alcohol and 20 parts of potato starch to 1500 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution, and set aside; (2) Disperse 1 part of the zinc-copper metal-organic framework in 500 parts of anhydrous ethanol and stir at room temperature for 60 minutes to obtain a uniform dispersion for later use; (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 60 minutes to obtain a uniform film-forming solution for standby use; (4) The film-forming liquid obtained in step (3) is poured into a flat-bottomed dish and dried in an oven at 60°C for 12 h to obtain a strong polyvinyl alcohol / starch composite film having both antibacterial and ammonia-sensitive color-changing functions.

3. The use of the tough polyvinyl alcohol / starch composite film having both antibacterial and ammonia-sensitive color-changing functions according to claim 1, characterized in that: Used in food packaging, smart materials, ammonia detection, environmental monitoring and safety fields.

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