Anti-photodegradation nanomaterial, preparation method and application thereof

Abstract

The application belongs to the technical field of polymer material additives, and particularly relates to an anti-photooxidation nano material, a preparation method and application thereof. The anti-photooxidation nano material provided by the application comprises a core, a mesoporous silica intermediate layer wrapping the core, and a long-alkyl-chain hydrophobic modified outer layer grafted on the outer surface of the silica intermediate layer. The core is a nanoparticle formed by self-assembly of biomass polyphenol. The biomass polyphenol in the anti-photooxidation nano material provided by the application is not prone to migration, can exist stably in a plastic matrix for a long time, and the core functional material is derived from natural and renewable biomass polyphenol, thereby avoiding the use of traditional petroleum-based chemicals, and being non-toxic and good in biocompatibility.

Description

Technical Field

[0001] This invention belongs to the field of polymer material additives technology, specifically relating to an anti-photooxidation nanomaterial, its preparation method, and its application. Background Technology

[0002] Ultraviolet rays (wavelength 270-400 nm) in sunlight have high energy and can trigger photo-oxidative degradation of plastic polymer molecular chains, leading to problems such as yellowing, embrittlement, surface powdering, and decreased mechanical properties, significantly shortening the service life of plastic products. To inhibit photo-oxidative aging, light stabilizers are usually added to plastics, among which ultraviolet absorbers are one of the most important types.

[0003] 2,4-Dihydroxybenzophenone (UV-O) is a widely used class of benzophenone-based ultraviolet absorbers with an effective absorption wavelength range of 270-380 nm. It effectively releases absorbed ultraviolet light energy as harmless heat, thus protecting the plastic matrix. However, this type of small-molecule ultraviolet absorber has a significant drawback: its small molecular weight, low melting point, and limited compatibility with the polymer matrix. During plastic processing and use, especially under high temperatures or prolonged outdoor environments, they easily migrate from the plastic interior to the surface, subsequently volatilizing or dissolving. This phenomenon not only causes a rapid decline in the plastic's UV protection function, resulting in a loss of long-term protective effect, but the migrated chemicals can also cause environmental pollution and potential health risks.

[0004] To overcome migration problems, existing technologies typically employ two strategies: one is to synthesize high-molecular-weight UV absorbers (such as by polymerizing small-molecule monomers), and the other is to chemically modify small molecules to increase their molecular weight and polarity. However, these methods often involve complex organic synthesis steps, requiring the use of various toxic and harmful chemical reagents and solvents, resulting in high production costs and the generation of large amounts of industrial waste, which contradicts the concept of environmentally friendly development. Therefore, developing a green, efficient, and long-lasting anti-photooxidative aging agent for plastics has become an urgent technical problem to be solved in this field.

[0005] Biomass polyphenols (such as tannic acid and gallic acid) are a class of natural compounds derived from plants, whose molecular structures contain abundant ortho- and olfactory hydroxyl groups. These hydroxyl groups not only give them excellent absorption in the ultraviolet region (especially the UV-A and UV-B regions), but also effectively capture free radicals (such as alkyl radicals and peroxide radicals) generated during photo-oxidation, interrupting the degradation chain reaction. They are ideal natural ultraviolet absorbers and free radical scavengers. However, directly adding biomass polyphenols to plastics also faces problems such as easy migration, easy oxidation, instability at processing temperatures, and poor compatibility with plastics. Summary of the Invention

[0006] The purpose of this invention is to provide an anti-photooxidation nanomaterial, its preparation method, and its application. The biomass polyphenols in the anti-photooxidation nanomaterial provided by this invention are not easily migrated and can exist stably in the plastic matrix for a long time. Moreover, the core functional material is derived from natural and renewable biomass polyphenols, avoiding the use of traditional petroleum-based chemicals. It is non-toxic and has good biocompatibility.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides an anti-photooxidation nanomaterial, comprising a core, a mesoporous silica intermediate layer encapsulating the core, and a hydrophobically modified outer layer with long alkyl chains grafted onto the outer surface of the silica intermediate layer; the core is a nanoparticle formed by the self-assembly of biomass polyphenols.

[0009] Preferably, the biomass polyphenols include one or more of tannic acid, gallic acid, and catechins.

[0010] Preferably, the material of the long alkyl chain hydrophobic modification layer includes a Cl2-C18 long-chain alkylsilane coupling agent.

[0011] Preferably, the mass ratio of the core, intermediate layer and outer layer is (0.1~0.2):(4~6):(2~4).

[0012] Preferably, the Cl2-C18 long-chain alkylsilane coupling agent includes one or more of dodecyltrimethoxysilane, dodecyltriethoxysilane, and hexadecyltrimethoxysilane.

[0013] This invention also provides a method for preparing the anti-photooxidation nanomaterials described in the above technical solution, comprising the following steps:

[0014] (1) Mix the solution of biomass polyphenols with a silicon source and carry out a hydrolysis-condensation reaction under alkaline conditions to allow the biomass polyphenols to self-assemble and be wrapped by a mesoporous silica layer formed in situ, thus obtaining a reaction solution.

[0015] (2) The reaction solution and the Cl2-C18 long-chain alkylsilane coupling agent are mixed to carry out a surface modification reaction, and alkyl chains are grafted onto the outside of the silica layer to obtain the anti-photooxidation nanomaterial.

[0016] Preferably, the mass-to-volume ratio of the biomass polyphenols to the silicon source is 100-500 mg: 10-20 mL.

[0017] Preferably, the hydrolysis-condensation reaction is carried out at a temperature of 25-50°C for 1-8 hours; the surface modification reaction is carried out at a temperature of 25-50°C for 1-8 hours.

[0018] The present invention also provides the application of the anti-photooxidation nanomaterials described in the above technical solutions or the anti-photooxidation nanomaterials prepared by the above preparation methods in plastic products.

[0019] The present invention also provides a polyolefin plastic matrix composite material, the raw materials of which include the anti-photooxidation nanomaterials described in the above technical solution or the anti-photooxidation nanomaterials prepared by the above preparation method and a polyolefin plastic matrix; the polyolefin plastic matrix includes polyethylene and / or polypropylene.

[0020] Compared with the prior art, the present invention has the following significant advantages:

[0021] (1) Dual anti-aging mechanism, high efficiency and long-lasting effect: The core biomass polyphenols have both ultraviolet absorption and free radical capture functions, providing a synergistic anti-photooxidation effect, which is more effective than single-mechanism additives. The silica shell firmly confines them, solving the problem of easy migration and loss of small molecule additives and natural polyphenols, and giving plastic products a long-lasting anti-aging life.

[0022] (2) Environmentally friendly and renewable source: The core functional material is derived from natural and renewable biomass polyphenols, avoiding the use of traditional petroleum-based chemicals, and is non-toxic and biocompatible.

[0023] (3) Good compatibility and uniform dispersion: The long alkyl chain structure of the outer layer is similar to the molecular chain structure of plastics such as polyolefins. According to the principle of "like dissolves like", it greatly improves the compatibility and dispersion of nanoparticles in hydrophobic plastic matrix, and avoids the impact of agglomeration on the transparency and mechanical properties of plastics.

[0024] This invention also provides a method for preparing the anti-photooxidation nanomaterials described in the above technical solution, which has the following advantages:

[0025] (1) Simple and green preparation process: This invention adopts a one-step (one-pot) synthesis method, in which silica coating and surface modification are completed sequentially in the same reaction system. The process is short and easy to operate. The reaction is mainly carried out in a water and ethanol system, avoiding the use of toxic organic solvents and complex organic synthesis. The post-processing is simple, the environmental pollution is small, and the production cost is low.

[0026] (2) High versatility: The core-shell structure design concept and preparation method can be applied to a variety of biomass polyphenols and alkyl chain modifiers. By adjusting the reaction conditions, the size of the nanoparticles and the shell thickness can be controlled. In addition, this additive can be widely used in a variety of plastic products (effectively and persistently integrating its natural UV resistance and free radical capture capabilities into the plastic), and has good adjustability and versatility. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 These are transmission electron microscope (TEM) images of the UV absorber obtained in Example 3 at different scales.

[0029] Figure 2 The image shows the elemental energy spectrum of the UV absorber obtained in Example 3 at a certain scale.

[0030] Figure 3 Thermogravimetric analysis of the UV absorber obtained in Example 3;

[0031] Figure 4 The UV / Vis / Near-Infrared diffuse reflectance spectrum of the UV absorber obtained in Example 3;

[0032] Figure 5 The UV / Vis / NIR diffuse reflectance spectra of the UV absorber doped in the PE film obtained in Application Example 1 are shown.

[0033] Figure 6 The contact angle diagrams are for films obtained by doping the ultraviolet absorbers obtained in Comparative Example 2 (A) and Example 1 (B) with PE films. Detailed Implementation

[0034] This invention provides an anti-photooxidation nanomaterial, comprising a core, a mesoporous silica intermediate layer encapsulating the core, and a hydrophobically modified outer layer with long alkyl chains grafted onto the outer surface of the silica intermediate layer; the core is a nanoparticle formed by the self-assembly of biomass polyphenols.

[0035] In this invention, the core of the core-shell structured anti-photooxidation nanomaterial is composed of nanoparticles formed by the self-assembly of biomass polyphenols through intermolecular forces, primarily serving the functions of ultraviolet absorption and free radical capture. This layer is formed in situ via a sol-gel method; its mesoporous structure allows small molecules (such as free radicals) to pass through and react with the core polyphenols, while simultaneously physically confining the polyphenol nanoparticles within, effectively preventing their migration and precipitation from the plastic during use. The outer layer is composed of long-chain alkylsilanes grafted onto the silica surface via chemical bonds, significantly improving the compatibility and dispersibility of the nanoparticles with non-polar plastic (such as PE, PP) substrates, avoiding performance degradation caused by agglomeration.

[0036] In one embodiment of the present invention, the biomass polyphenols include one or more of tannic acid, gallic acid and catechins.

[0037] In one embodiment of the present invention, the material of the long alkyl chain hydrophobic modification layer includes a Cl2-C18 long-chain alkyl silane coupling agent; the Cl2-C18 long-chain alkyl silane coupling agent may include one or more of dodecyltrimethoxysilane, dodecyltriethoxysilane and hexadecyltrimethoxysilane.

[0038] As one embodiment of the present invention, the mass ratio of the core, intermediate layer and outer layer can be (0.1~0.2):(4~6):(2~4).

[0039] This invention also provides a method for preparing the anti-photooxidation nanomaterials described in the above technical solution, comprising the following steps:

[0040] (1) Mix the solution of biomass polyphenols with a silicon source and carry out a hydrolysis-condensation reaction under alkaline conditions to allow the biomass polyphenols to self-assemble and be wrapped by a mesoporous silica layer formed in situ, thus obtaining a reaction solution.

[0041] (2) The reaction solution and the Cl2-C18 long-chain alkylsilane coupling agent are mixed to carry out a surface modification reaction, and alkyl chains are grafted onto the outside of the silica layer to obtain the anti-photooxidation nanomaterial.

[0042] This invention mixes a solution of biomass polyphenols with a silicon source and carries out a hydrolysis-condensation reaction under alkaline conditions, causing the biomass polyphenols to self-assemble and be encapsulated by an in-situ formed mesoporous silica layer, thus obtaining a reaction solution.

[0043] In one embodiment of the present invention, the biomass polyphenol solution is obtained by mixing biomass polyphenols, ethanol, water, and ammonia; the volume ratio of ethanol to water can be 5~50:1, specifically 5:1, 10:1, 15:1, 20:1, 30:1, 40:1, or 50:1, and the concentration of ammonia is 25~28 wt.%; the volume ratio of water to ammonia can be 1:1~5:1, specifically 1:1, 1:2, 1:3, 1:4, or 1:5; the mass ratio of biomass polyphenols to water can be 100~500:20, specifically 100:20, 200:20, 300:20, 400:20, or 500:20. In another embodiment of the present invention, the silicon source is tetraethyl silicate and / or tetramethyl silicate. In one embodiment of the present invention, the mass-to-volume ratio of the biomass polyphenols and the silicon source can be 100-500 mg: 10-20 mL, specifically 100 mg: 10 mL, 200 mg: 10 mL, 500 mg: 10 mL or 500 mg: 20 mL.

[0044] In one embodiment of the present invention, the temperature of the hydrolysis-condensation reaction can be 25~50℃, specifically 25℃, 30℃, 35℃, 40℃ or 50℃; the time can be 1-8 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours; in this process, using self-assembled polyphenol nanoparticles as templates, silicon source hydrolysis-condensation forms a mesoporous silica network, generating a polyphenol composite material encapsulated in mesoporous silica, thus obtaining a preliminary core-shell structure.

[0045] In one embodiment of the present invention, the temperature of the surface modification reaction can be 25~50℃, specifically 25℃, 30℃, 35℃, 40℃ or 50℃; the time can be 1~8 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours. During this process, the hydrolysis products of alkylsilanes undergo a condensation reaction with the silanol groups on the silica surface, thereby grafting long alkyl chains onto the nanoparticle surface in a covalent bond form, completing the hydrophobic modification.

[0046] In one embodiment of the present invention, after the surface modification reaction, the reaction solution is preferably further subjected to sequential filtration, ethanol / water washing, and drying. The ethanol / water washing involves first washing with water until neutral, and then washing once with ethanol.

[0047] This invention also provides the application of the aforementioned anti-photooxidation nanomaterials in plastic products.

[0048] The present invention also provides a polyolefin plastic matrix composite material, the raw materials of which include the photo-oxidation resistant nanomaterials and polyolefin plastic matrix as described in the above technical solution; the polyolefin plastic matrix includes polyethylene (PE) and / or polypropylene (PP); the mass ratio of the photo-oxidation resistant nanomaterials to the polyolefin plastic matrix can be 0.1~1:100, specifically 5:1000.

[0049] As an experimental method of the present invention, the anti-photooxidation nanomaterials described in the above technical solution can also be used in biodegradable biopolyesters (such as PBAT, PLA); the application method is to add the anti-photooxidation nanomaterials to the biodegradable biopolyester and mix them by conventional melt blending granulation or solution blending.

[0050] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0051] Comparative Example 1

[0052] To a 500 mL beaker, add 200 mL of ethanol, 20 mL of water, 100 mg of tannic acid, and 10 mL of ammonia (28 wt%) sequentially. Stir at room temperature for 30 min to obtain a homogeneous, transparent, brownish-yellow solution. Slowly add 10 mL of tetraethyl silicate to the above solution, and stir at 25 °C for 1 h after the addition is complete. Continue to add 5 mL of methyltrimethoxysilane to the above reaction solution, and continue stirring at 25 °C for 1 h. After the reaction is complete, filter, wash with water and ethanol, and vacuum dry to obtain the anti-photooxidation nanomaterial (denoted as UV absorber UV1).

[0053] Comparative Example 2

[0054] To a 500 mL beaker, add 200 mL of ethanol, 20 mL of water, 200 mg of tannic acid, and 10 mL of ammonia (28 wt%) sequentially. Stir at room temperature for 30 min to obtain a homogeneous, transparent, brownish-yellow solution. Slowly add 10 mL of tetraethyl silicate to the above solution, and stir at 25 °C for 1 h after the addition is complete. Continue to add 5 mL of methyltrimethoxysilane to the above reaction solution, and continue stirring at 25 °C for 1 h. After the reaction is complete, filter, wash with water and ethanol, and vacuum dry to obtain the anti-photooxidation nanomaterial (denoted as UV absorber UV2).

[0055] Example 1

[0056] To a 500 mL beaker, 200 mL of ethanol, 20 mL of water, 100 mg of tannic acid, and 10 mL of ammonia (28 wt%) were added sequentially. The mixture was stirred at room temperature for 30 min to obtain a homogeneous, transparent, brownish-yellow solution. 10 mL of tetraethyl silicate was then slowly added dropwise to this solution, and the mixture was stirred at 25 °C for 1 h after the addition was complete. Next, 5 mL of dodecyltrimethoxysilane was added dropwise to the reaction solution, and the mixture was stirred at 25 °C for another 1 h. After the reaction was complete, the mixture was filtered, washed with water and ethanol, and then vacuum dried to obtain the anti-photooxidation nanomaterial (denoted as UV absorber UV3).

[0057] Example 2

[0058] To a 500 mL beaker, 200 mL of ethanol, 20 mL of water, 500 mg of tannic acid, and 10 mL of ammonia (28 wt%) were added sequentially. The mixture was stirred at room temperature for 30 min to obtain a homogeneous, transparent, brownish-yellow solution. 10 mL of tetraethyl silicate was then slowly added dropwise to this solution, and the mixture was stirred at 25 °C for 1 h after the addition was complete. Next, 5 mL of dodecyltrimethoxysilane was added dropwise to the reaction solution, and the mixture was stirred at 25 °C for another 1 h. After the reaction was complete, the mixture was filtered, washed with water and ethanol, and then dried under vacuum to obtain the anti-photooxidation nanomaterial (denoted as UV absorber UV4).

[0059] Example 3

[0060] To a 500 mL beaker, add 200 mL of ethanol, 20 mL of water, 500 mg of tannic acid, and 10 mL of ammonia (28 wt%) sequentially. Stir at room temperature for 30 min to obtain a homogeneous, transparent, brownish-yellow solution. Slowly add 20 mL of tetraethyl silicate to the above solution, and stir at 25 °C for 1 h after the addition is complete. Continue to add 10 mL of dodecyltrimethoxysilane to the above reaction solution, and continue stirring at 25 °C for 1 h. After the reaction is complete, filter, wash with water and ethanol, and vacuum dry to obtain the anti-photooxidation nanomaterial (denoted as UV absorber UV5).

[0061] Figure 1 These are transmission electron microscopy (TEM) images of the UV absorber obtained in Example 3 at different scales. Figure 1 The three-layer structure of the nanoparticles can be clearly seen.

[0062] Figure 2 The image shows the elemental energy spectrum of the UV absorber obtained in Example 3 at a certain scale. Figure 2 The distribution of different elements in different regions can be clearly seen in the spectrum. Based on this energy spectrum, it can be determined that the core layer is tannic acid, the middle layer is mesoporous silica, and the outermost layer is a long-chain alkyl hydrophobic layer.

[0063] Figure 3 The thermogravimetric diagram of the ultraviolet absorber obtained in Example 3 is shown below. Figure 3 As can be seen, the obtained ultraviolet absorber UV5 exhibits high thermal stability, with a temperature of 300℃ at which a weight loss of 5 wt% occurs. It can be used for subsequent plastic granulation and blown film production.

[0064] Figure 4 The UV / Vis / Near-Infrared diffuse reflectance spectrum of the UV absorber obtained in Example 3 is shown below. Figure 4 As can be seen, the obtained ultraviolet absorber has good absorption capacity below 380 nm.

[0065] Application Example 1

[0066] One kilogram of purchased polyethylene (PE) premix was mixed with 5 g of UV absorber UV5, and then fed into a granulator for granulation at 180°C and a screw speed of 170 rpm to obtain PE masterbatch containing UV5. Subsequently, the obtained masterbatch was fed into a blown film machine to prepare PE / UV-5 film. During the blown film process, the temperature in zones one through five was controlled at approximately 160°C, and the film thickness was controlled at 10 ± 1 μm.

[0067] Figure 5To obtain the UV / Vis / NIR diffuse reflectance spectra of the UV absorber doped in the PE film obtained in Example 1, from... Figure 5 It can be seen that, compared with pure PE film and PE film with only SiO2 particles (that is, 5 g of UV absorber UV5 is replaced with 5 g of SiO2 particles), PE film doped with UV absorber UV5 has good absorption capacity for ultraviolet rays in the range of 274~360 nm.

[0068] Application Example 2

[0069] One kilogram of purchased polyethylene (PE) premix was mixed with 5 g of UV absorber UV3 or 5 g of UV absorber UV1, and then fed into a granulator for granulation at 180°C and 170 rpm to obtain PE masterbatch containing UV3 or UV1. Subsequently, the masterbatch was fed into a blown film machine to prepare films. During the blown film process, the temperature in zones one through five was controlled at approximately 160°C, and the film thickness was controlled at 10 ± 1 μm. Figure 6 The contact angle diagrams are shown for the films obtained by doping the ultraviolet absorbers in Comparative Example 2 (A) and Example 1 (B) with PE films. Figure 6 It can be seen that Example 1 has stronger hydrophobicity.

[0070] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A nanomaterial for resisting photo-oxidation, characterized in that, It includes a core, a mesoporous silica intermediate layer enclosing the core, and a hydrophobically modified outer layer with long alkyl chains grafted onto the outer surface of the silica intermediate layer; the core is a nanoparticle formed by the self-assembly of biomass polyphenols. The biomass polyphenols are one or more of tannic acid, gallic acid and catechins; The material of the long alkyl chain hydrophobically modified outer layer is a C12-C18 long-chain alkylsilane coupling agent; the mass ratio of the core, intermediate layer and outer layer is (0.1~0.2):(4~6):(2~4); The C12-C18 long-chain alkylsilane coupling agent is one or more of dodecyltrimethoxysilane, dodecyltriethoxysilane, and hexadecyltrimethoxysilane.

2. The preparation method of the anti-photooxidation nanomaterial according to claim 1, comprising the following steps: (1) Mix the solution of biomass polyphenols with a silicon source and carry out a hydrolysis-condensation reaction under alkaline conditions to allow the biomass polyphenols to self-assemble and be wrapped by a mesoporous silica layer formed in situ, thus obtaining a reaction solution. (2) The reaction solution and a C12-C18 long-chain alkylsilane coupling agent are mixed to carry out a surface modification reaction, and alkyl chains are grafted onto the outside of the silica layer to obtain the anti-photooxidation nanomaterial.

3. The preparation method according to claim 2, characterized in that, The mass-to-volume ratio of the biomass polyphenols and the silicon source is 100-500 mg: 10-20 mL.

4. The preparation method according to claim 2, characterized in that, The hydrolysis-condensation reaction is carried out at a temperature of 25-50°C for 1-8 hours; the surface modification reaction is carried out at a temperature of 25-50°C for 1-8 hours.

5. The application of the anti-photooxidation nanomaterial according to claim 1 or the anti-photooxidation nanomaterial prepared by the preparation method according to any one of claims 2 to 4 in plastic products.

6. A polyolefin plastic matrix composite material, the raw materials for preparation include the anti-photooxidation nanomaterial as described in claim 1 or the anti-photooxidation nanomaterial prepared by the preparation method according to any one of claims 2 to 4 and a polyolefin plastic matrix; wherein the polyolefin plastic matrix includes polyethylene and / or polypropylene.

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