Hydrophobic anti-ultraviolet degradable polymer material with bionic micro-nano structure and preparation method of hydrophobic anti-ultraviolet degradable polymer material

Abstract

The invention discloses a hydrophobic anti-ultraviolet degradable polymer material with a bionic micro-nano structure and a preparation method of the hydrophobic anti-ultraviolet degradable polymer material with the bionic micro-nano structure, a surface cross-linkable / inner-layer hydrophobic supported double-layer structure is constructed through double-layer co-extrusion, surface layer cross-linking is initiated through heat treatment, non-cross-linked parts on the surface are removed through selective etching of solvent vapor, and the hydrophobic anti-ultraviolet degradable polymer material with the bionic micro-nano structure is obtained. Finally, surface molecular chain micro-regions are rearranged and fixed through ultraviolet radiation, the chemical stability and durability of the structure are improved, a secondary nano-structure of the cross-linked bionic fruit epidermis wax with light stability is constructed on the surface of a degradable polymer, the structure ingeniously utilizes a physical scattering ultraviolet protection mechanism, and the mechanical property of the structure is improved. Meanwhile, the material is endowed with the super-hydrophobic characteristic, a long-acting and stable protective layer is constructed on the surface of the material, the ideal performance of durability in the early stage and rapid degradation in the later stage is achieved, and the material can be used for preparing high-end packaging materials, agricultural mulching films, outdoor protective coatings or photoelectric device protective layers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a hydrophobic anti-ultraviolet degradable polymer material with biomimetic micro-nano structure and a preparation method thereof. BACKGROUND

[0002] Biodegradable plastics such as polybutylene adipate terephthalate (PBAT), polylactic acid (PLA) and the like are increasingly widely used in packaging, agricultural mulching and other fields. However, these polymer materials are easily eroded by ultraviolet rays (UV) in sunlight when used outdoors, leading to molecular chain breakage (degradation) or crosslinking, causing deterioration of the physical and mechanical properties (such as strength and ductility) of the material, formation of water molecule channels through aging cracks, and further shortening of the service life. At present, the mainstream method to improve the ultraviolet aging resistance of polymers is to add small molecule ultraviolet absorbers or light stabilizers during processing. However, these additives have the problems of easy migration and precipitation, not only the effect is difficult to last, but also it may cause secondary pollution. In addition, the addition of external additives may affect the biodegradability and transparency of the material. Therefore, it is crucial to develop a green and long-acting anti-aging technology based on the modification of the material itself structure. SUMMARY

[0003] The purpose of the present application is to provide a hydrophobic anti-ultraviolet degradable polymer material with biomimetic micro-nano structure and a preparation method thereof, which solves the problem of insufficient green and long-acting anti-aging technology in the prior art.

[0004] The present application is realized by the following technical solutions:

[0005] A preparation method of a hydrophobic anti-ultraviolet degradable polymer material with biomimetic micro-nano structure, comprising the following steps:

[0006] (a) preparing a surface-crosslinkable double-layer degradable material: a surface layer degradable aromatic polyester containing a crosslinking agent and a bottom layer degradable aromatic polyester containing a hydrophobic agent are co-extruded through a multi-layer co-extrusion device (such as a twin-screw extruder) to form a surface-crosslinkable double-layer degradable material film or sheet; the co-extrusion temperature is controlled between 150-200℃ to ensure sufficient melting and mixing of the material;

[0007] (b) heat treatment: the double-layer degradable material film or sheet is placed in a hot air circulating oven or a heat treatment device and treated at 70-120℃ for 5-60 minutes; this process forms a micro-crosslinked network on the surface of the material through the crosslinking agent, thereby enhancing the surface stability; after heat treatment, the thickness of the crosslinked layer on the surface of the material is about 0.5-5 microns;

[0008] (c) surface etching treatment: exposing the double-layer degradable material film or sheet treated in step (b) to an organic solvent vapor atmosphere, etching to remove the uncrosslinked polymer portion on the surface of the material, thereby exposing the micro-nano secondary rough structure composed of crosslinked structure, and promoting the migration of the hydrophobic agent to the surface;

[0009] (d) secondary rearrangement by UV irradiation: placing the material etched in step (c) under UV light for irradiation, the wavelength of the UV light ranges from 250-400 nm, the irradiation intensity is 300-1200 mW / cm², and the irradiation time is 1-30 minutes, so that the micro-area rearrangement and fixation of the surface molecular chain occur, and the stability of the surface structure is further improved.

[0010] Preferably, the degradable aromatic polyester is a blend of one or more of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), and polybutylene succinate (PBS).

[0011] Preferably, the crosslinking agent is one or both of di-tert-butyl peroxide and triallyl isocyanurate.

[0012] Preferably, the hydrophobic agent is erucamide or ethylene bis-stearamide.

[0013] Preferably, in step (c), the organic solvent vapor is the vapor of dichloromethane, chloroform, or acetone; the etching temperature is 20-50°C, and the etching time is 10 seconds-30 minutes.

[0014] The present application also protects the high-stability degradable polymer material with a surface micro-nano secondary structure prepared by the preparation method. The surface of the material has a micro-nano scale rough structure, and the contact angle of the material surface with water is greater than 130°. The thickness of the crosslinked layer on the surface of the material is about 0.5-5 microns, and the shielding rate of ultraviolet light with a wavelength of 200-400 nm is not less than 80%.

[0015] Therefore, the present application also protects the application of the degradable polymer material in the preparation of high-end packaging materials, agricultural mulching films, outdoor protective coatings, or protective layers of optoelectronic devices.

[0016] Compared with the prior art, the present application has the following outstanding advantages:

[0017] (1) The present application does not need to rely on small molecule additives that are easy to migrate. By simulating the microstructure and function of fruit cuticle wax, a crosslinked biomimetic disordered secondary nanostructure with light stability is constructed on the surface of the degradable polymer. The nanostructure can physically reflect / scatter ultraviolet light through Rayleigh scattering, thereby achieving the effect of physically shielding ultraviolet light. At the same time, the hydrophobic agent introduced by the support layer further reduces the surface energy of the micro-nano structure, prolongs the service life, and improves the hydrophobicity and durability of the micro-nano structure.

[0018] (2) The present application can simultaneously improve the hydrophobicity (contact angle > 130°) and UV resistance of the material in one step. The surface hydrophobicity can play a self-cleaning role, further delaying pollution and aging, and significantly improving the service life of degradable polymers.

[0019] (3) The process is relatively simple, and a small amount of crosslinking agent is used, avoiding the migration and precipitation of small molecule additives. The method can be applied to PBAT, PLA and other degradable polyesters, providing a new method for developing high-end functional degradable materials.

[0020] In summary, the present application has a simple process. A double-layer structure with a surface cross-linkable layer and a hydrophobic support layer is constructed by double-layer co-extrusion. The surface layer is cross-linked by heat treatment to form a stable network. The non-cross-linked part of the surface is removed by solvent vapor selective etching to expose the micro-nano rough structure and promote the migration of the hydrophobic agent. Finally, the molecular chain micro-zone is rearranged and fixed by UV irradiation to further improve the chemical stability and durability of the structure. Without relying on easily migratory small molecule additives, a cross-linked type of biomimetic fruit skin wax secondary nano structure with light stability is constructed on the surface of degradable polymers. This structure cleverly uses the physical scattering UV protection mechanism, while giving the material super-hydrophobic properties. A long-acting, stable protective layer is constructed on the surface of the material, realizing the ideal performance of "early durability and later rapid degradation". It can be used to prepare high-end packaging materials, agricultural mulch, outdoor protective coatings or photovoltaic device protective layers. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the SEM photo of the surface microstructure of the material obtained in Example 1. DETAILED DESCRIPTION

[0022] The following is a further description of the present application, but not a limitation of the present application.

[0023] Example 1:

[0024] (a) Preparation of a double-layer degradable material with a surface cross-linkable layer:

[0025] Raw material preparation:

[0026] Surface layer material: 100 parts by weight of PBAT, 0.5 parts by weight of crosslinking agent di-tert-butyl peroxide (DTBP) and 0.5 parts by weight of triallyl isocyanurate (TAIC) are mixed uniformly in a high-speed mixer.

[0027] Bottom layer material: 100 parts by weight of PBAT and 3 parts by weight of hydrophobic agent erucamide are mixed uniformly in a high-speed mixer.

[0028] The above-mentioned surface layer and bottom layer materials are respectively added into different hoppers of a double-screw co-extrusion film blowing machine to prepare a double-layer film by co-extrusion. The processing temperature range is 150-165°C.

[0029] (b) Heat treatment: the obtained double-layer film is placed in a hot air circulating oven at 100°C for heat treatment for 40 minutes to form a micro-crosslinking network in the surface layer.

[0030] (c) Surface etching treatment: the film after heat treatment in step (b) is placed in a dichloromethane vapor atmosphere at 40°C for etching for 5 minutes.

[0031] (d) UV irradiation secondary rearrangement: the film after etching in step (c) is placed in a UV lamp box and irradiated for 10 minutes under the condition of wavelength 365 nm and intensity 800 mW / cm².

[0032] Example 2:

[0033] (a) Preparation of surface-crosslinkable double-layer degradable material:

[0034] Raw material preparation:

[0035] Surface layer material: 80 parts by weight of PBAT, 20 parts by weight of PLA and 0.8 parts by weight of DTBP and 0.8 parts by weight of TAIC (composite crosslinking agent) are uniformly mixed.

[0036] Bottom layer material: a blend of 70 parts by weight of PLA and 30 parts by weight of PBS and 4 parts by weight of hydrophobic agent ethylene bis-stearamide (EBS) are uniformly mixed.

[0037] The above-mentioned surface layer and bottom layer materials are respectively added into different hoppers of a double-screw co-extrusion film blowing machine to prepare a double-layer film by co-extrusion. The processing temperature range is 150-165°C.

[0038] (b) Heat treatment: the film is placed in a hot air circulating oven at 85°C for heat treatment for 60 minutes.

[0039] (c) Surface etching treatment: the film after heat treatment in step (b) is placed in a dichloromethane vapor atmosphere at 40°C for etching for 5 minutes.

[0040] (d) UV irradiation secondary rearrangement: the film after etching in step (c) is placed in a UV lamp box and irradiated for 10 minutes under the condition of wavelength 365 nm and intensity 800 mW / cm².

[0041] Example 3:

[0042] (a) Preparation of surface-crosslinkable double-layer degradable material:

[0043] Raw material preparation:

[0044] Surface layer material: 100 parts by weight of PLA was mixed with 0.8 parts by weight of DTBP and 0.8 parts by weight of TAIC (a complex crosslinking agent) uniformly.

[0045] Bottom layer material: 100 parts by weight of PLA was mixed with 2.5 parts by weight of erucamide uniformly.

[0046] The above-mentioned surface layer and bottom layer materials were respectively added to different hoppers of a double-screw co-extrusion film blowing machine to prepare a double-layer film by co-extrusion, and the processing temperature interval was 170-190°C.

[0047] (b) Heat treatment: the film was placed in a hot air circulating oven at 115°C for heat treatment for 30 minutes.

[0048] (c) Surface etching treatment: the film after heat treatment in step (b) was placed in a chloroform vapor atmosphere at 25°C for etching for 2 minutes.

[0049] (d) UV irradiation secondary rearrangement: the film after etching in step (c) was irradiated under the condition of wavelength 285 nm and intensity 1100 mW / cm² for 5 minutes.

[0050] Comparative Example 1:

[0051] Reference Example 1, except that the heat treatment step was omitted.

[0052] (a) Preparation of surface-crosslinkable double-layer degradable material:

[0053] Raw material preparation:

[0054] Surface layer material: 100 parts by weight of PBAT was mixed with 0.5 parts by weight of crosslinking agent di-tert-butyl peroxide (DTBP) and 0.5 parts by weight of triallyl isocyanurate (TAIC) in a high-speed mixer uniformly.

[0055] Bottom layer material: 100 parts by weight of PBAT was mixed with 3 parts by weight of hydrophobic agent erucamide in a high-speed mixer uniformly.

[0056] The above-mentioned surface layer and bottom layer materials were respectively added to different hoppers of a double-screw co-extrusion film blowing machine to prepare a double-layer film by co-extrusion. The processing temperature interval was 150-165°C.

[0057] (b) Surface etching treatment:

[0058] The film processed in step (a) was placed in a dichloromethane vapor atmosphere at 40°C for etching for 5 minutes.

[0059] (c) UV irradiation secondary rearrangement: the film after etching in step (b) was placed in a UV light box and irradiated under the condition of wavelength 365 nm and intensity 800 mW / cm² for 10 minutes.

[0060] Result: The surface forms a certain rough structure, and the initial contact angle can reach 100°, but the crosslinking structure is very fragile and is destroyed by slight wiping. After irradiation in the ultraviolet aging box for 24 hours, the surface structure is basically collapsed, and the hydrophobicity decreases. Comparative Example 1 proves that the micro / nano structure without sufficient crosslinking structure support is unstable.

[0061] Comparative Example 2:

[0062] Reference Example 1, except that the etching step is omitted.

[0063] (a) Preparation of a biodegradable material with a crosslinkable surface:

[0064] Raw material preparation:

[0065] Surface layer material: 100 parts by weight of PBAT was mixed with 0.5 parts by weight of crosslinking agent di-tert-butyl peroxide (DTBP) and 0.5 parts by weight of triallyl isocyanurate (TAIC) in a high-speed mixer.

[0066] Bottom layer material: 100 parts by weight of PBAT was mixed with 3 parts by weight of hydrophobic agent erucamide in a high-speed mixer.

[0067] The above-mentioned surface and bottom layer materials were respectively added to different hoppers of a double-screw co-extrusion film blowing machine to prepare a double-layer film by co-extrusion. The processing temperature range was 150-165°C.

[0068] (b) Heat treatment: The obtained double-layer film was placed in a hot air circulating oven at 100°C for heat treatment for 40 minutes to form a micro-crosslinking network on the surface layer.

[0069] (c) Ultraviolet irradiation secondary rearrangement: The film heat-treated in step (b) was placed in an ultraviolet lamp box and irradiated for 10 minutes under the condition of wavelength 365 nm and intensity 800 mW / cm².

[0070] Result: The material surface is smooth, and the water contact angle is only 85° (hydrophilic). The hydrophobic function decreases compared with Example 1, and due to the lack of light scattering structure, its ultraviolet shielding rate is only about 30%, and its bulk anti-aging performance is much lower than that of Example 1.

[0071] Comparative Example 3:

[0072] Reference Example 1, except that in step (a) the surface layer material does not add a crosslinking agent, and the bottom layer material adds an ultraviolet absorber.

[0073] (a) Preparation of a biodegradable material with a small molecule ultraviolet absorber added to the surface:

[0074] Raw material preparation:

[0075] Surface layer material: 100 parts by weight of PBAT was used directly.

[0076] Bottom layer material: 100 parts by weight of PBAT was mixed with 3 parts by weight of hydrophobic agent erucic amide, 0.1 part of UV absorber UV531 in a high-speed mixer.

[0077] The above-mentioned surface layer and bottom layer materials were respectively added to different hoppers of a double-screw co-extrusion film blowing machine to prepare a double-layer film by co-extrusion. The processing temperature range was 150-165°C.

[0078] (b) Heat treatment: the obtained double-layer film was placed in a hot air circulating oven at 100°C for heat treatment for 40 minutes.

[0079] (c) Surface etching treatment: the film after heat treatment in step (b) was placed in a dichloromethane vapor atmosphere at 40°C for etching for 5 minutes.

[0080] (d) UV irradiation secondary rearrangement: the film after etching in step (c) was placed in a UV lamp box and irradiated for 10 minutes under the condition of wavelength 365 nm and intensity 800 mW / cm².

[0081] Comparative Example 3 had good initial hydrophobicity, indicating that the microstructure was successfully constructed by etching. However, its contact angle was lower than that of Example 1, indicating that the addition of no crosslinking agent and only relying on short-time UV irradiation was insufficient to form micro-nano structures on the surface. The addition of UV531 avoided the structural damage to the substrate by absorbing UV, but its effect of enhancing surface hydrophobicity and maintaining mechanical properties was still lower than that of Example 1, indicating that the durability of the micro-nano structure was more advantageous.

[0082] Table 1 Comparison of expected effects of different performance indicators of examples and comparative examples

[0083]

[0084] Through the comparison of the above Example 1 and Comparative Examples 1-3, it is fully proved that the "crosslinking-etching-UV irradiation" provided by the present application is an organic whole, which can successfully construct stable micro-nano secondary structures on the surface of degradable polymers. This structure realizes the integration of improving hydrophobicity and high-efficiency anti-UV aging, and the effect is durable, which is significantly superior to single treatment or traditional addition method, and has outstanding innovation and application value.

Claims

1. A method for preparing a hydrophobic ultraviolet-degradable polymeric material with biomimetic micro-nano structures, characterized in that, The method comprises the following steps: (a) preparing a surface-crosslinkable double-layer degradable material: co-extruding a surface layer degradable aromatic polyester containing a crosslinking agent and a bottom layer degradable aromatic polyester containing a hydrophobic agent through a multi-layer co-extrusion device to form a surface-crosslinkable double-layer degradable material film or sheet; the co-extrusion temperature is controlled between 150-200℃; (b) heat treatment: placing the double-layer degradable material film or sheet in a hot air circulating oven or heat treatment device for treatment at 70-120℃ for 5-60 minutes; (c) surface etching treatment: exposing the double-layer degradable material film or sheet treated in step (b) to an organic solvent vapor atmosphere to etch and remove the uncrosslinked polymer portion on the surface of the material; (d) secondary rearrangement by ultraviolet irradiation: placing the material etched in step (c) under ultraviolet light for irradiation, the ultraviolet light wavelength range is 250-400 nm, the irradiation intensity is 300-1200 mW / cm², and the irradiation time is 1-30 minutes.

2. The production method according to claim 1, characterized by, The degradable aromatic polyester is a blend of one or more of polybutylene adipate terephthalate, polylactic acid, and polybutylene succinate.

3. The preparation method according to claim 1, characterized in that, The crosslinking agent is one or both of di-t-butyl peroxide and triallyl isocyanurate.

4. The method of claim 1, wherein, The hydrophobic agent is erucic acid amide or ethylene bis-stearamide.

5. The preparation method according to claim 1, characterized in that, In step (c), the organic solvent vapor is dichloromethane, chloroform, or acetone vapor; the etching temperature is 20-50℃, and the etching time is 10 seconds-30 minutes.

6. The high-stability degradable polymer material with surface micro-nano secondary structure prepared by the preparation method of claim 1, characterized in that, The surface of the material has a micro- and nano-scale rough structure, the contact angle of the material surface with water is greater than 130°, the thickness of the crosslinked layer on the surface of the material is 0.5-5 microns, and the shielding rate of ultraviolet light with a wavelength of 200-400 nm is not less than 80%.

7. Use of the degradable polymer material of claim 1 in the preparation of high-end packaging materials, agricultural mulching films, outdoor protective coatings, or photovoltaic device protective layers.

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