Single-layer MoS2 nanosheet modified polyethylene functional film as well as preparation method and application thereof

Abstract

The invention provides a single-layer MoS2 nanosheet modified polyethylene functional film as well as a preparation method and application thereof, and belongs to the technical field of advanced materials. The preparation method of the polyethylene functional film comprises the following steps: reacting a single-layer MoS2 nanosheet with a surface polarity regulating agent to obtain gelatinous H-MoS2; carrying out extrusion granulation on the MoS2 and polyethylene to obtain MoS2-based polyethylene master batches; and extruding and granulating with polyethylene, and processing to form a film. According to the method disclosed by the invention, agglomeration and stacking of a two-dimensional material in polyethylene are prevented by virtue of long-chain fatty alcohol modification, and uniform dispersion of a single-layer MoS2 nanosheet in a polyethylene matrix is realized; under the condition that the addition amount of the two-dimensional material is extremely low, the polyethylene functional film shows an extremely strong photo-thermal heating effect, and meanwhile, the original mechanical property of the polyethylene functional film is not lost. The method disclosed by the invention is adaptive to a current industrial processing mode, large-scale processing can be quickly carried out, and the method has a relatively strong application prospect in thermal insulation agricultural films.

Description

Technical Field

[0001] This invention belongs to the field of advanced materials technology, specifically relating to a single-layer MoS2 nanosheet modified polyethylene functional film, its preparation method, and its application. Background Technology

[0002] Polyethylene (PE) materials are lightweight, easy to process, and corrosion-resistant, and are widely used in agriculture, electronics, biomedicine, aerospace, and other fields. Currently, PE materials are rapidly developing towards functionalization and greener processing. Introducing functional fillers into the PE matrix is ​​an important means to improve PE performance and endow it with new functions. However, traditional inorganic fillers currently lack strong functionality, and excessive addition can affect the mechanical properties of PE. For example, in the method for preparing a heat-insulating film disclosed in patent document CN118240347A, zeolite-type imidazole framework-8 functional filler is composited with PBAT at a mass ratio of 1:5. The large amount of filler added significantly reduces the mechanical properties of the composite film. In a method for preparing a graphene-alumina silicate composite material disclosed in patent CN118206803A, the amount of graphene-alumina silicate composite material added is as high as 10-20%, resulting in an extremely large amount of inorganic filler, which adversely affects the original mechanical properties of the composite film. Therefore, traditional functional fillers need to be added in large quantities due to insufficient functionality, which leads to damage to the mechanical properties of composite materials; if the amount added is reduced to maintain mechanical properties, the functionality is difficult to meet the requirements, and it is difficult to achieve both.

[0003] Two-dimensional monolayer MoS2 nanosheets are nanomaterials only 1.0 nm thick, possessing ultra-high specific surface area and unique optical, electrical, and magnetic properties. They exhibit extremely strong light absorption and high photothermal conversion efficiency in the ultraviolet-visible-near-infrared region, making them ideal photothermal conversion materials with great potential as functional fillers. However, ultrathin MoS2 nanomaterials have poor compatibility with polyethylene films, and achieving uniform dispersion of two-dimensional materials in a polyethylene matrix presents a significant challenge.

[0004] Therefore, how to uniformly disperse two-dimensional monolayer MoS2 nanosheets in a polyethylene matrix while endowing the material with excellent mechanical properties and functionality is of great research significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a polyethylene functional film modified with monolayer MoS2 nanosheets, its preparation method, and its applications. The method utilizes long-chain fatty alcohol modification to prevent the aggregation and stacking of two-dimensional materials in polyethylene, achieving uniform dispersion of ultrathin monolayer MoS2 nanosheets within the polyethylene matrix. Under conditions of extremely low addition of two-dimensional materials, the polyethylene functional film exhibits a strong photothermal heating effect, while maintaining its original mechanical properties. This invention employs an industrial twin-screw extruder for polyethylene functional modification, adapting to current industrial processing methods and enabling rapid large-scale processing, showing strong application prospects in heat-insulating agricultural films.

[0006] To achieve the above effects, the technical solution provided by the present invention is as follows:

[0007] This invention provides a polyethylene functional film modified with monolayer MoS2 nanosheets, wherein the monolayer MoS2 nanosheets are uniformly dispersed in a polyethylene matrix. The polyethylene functional film of this invention exhibits excellent photothermal heating performance. When the amount of monolayer MoS2 nanosheets added is 0.001–5%, after 5 minutes of illumination under one solar intensity, the functional film can achieve an adjustable surface temperature within the range of room temperature to 76°C through self-heating.

[0008] According to a preferred embodiment of the present invention, the average thickness of the monolayer MoS2 nanosheet is 1.0 nm, and the lateral dimension is 50 nm to 100 nm.

[0009] According to a preferred embodiment of the present invention, the mass content of monolayer MoS2 nanosheets in the polyethylene functional film is 0.001–5%, preferably 0.05–1%. The mass content of monolayer MoS2 nanosheets refers to the percentage of the mass of monolayer MoS2 nanosheets in the total mass of the polyethylene functional film.

[0010] According to the present invention, the polyethylene matrix is ​​preferably one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) or high-density polyethylene (HDPE), with low-density polyethylene (LDPE) being preferred.

[0011] According to a preferred embodiment of the present invention, the thickness of the polyethylene functional film is 5–200 μm.

[0012] This invention also provides a method for preparing the above-mentioned monolayer MoS2 nanosheet modified polyethylene functional film, comprising the steps of:

[0013] (1) The monolayer MoS2 nanosheets were thoroughly mixed with the surface polarity modifier and reacted to obtain gel-like H-MoS2, in which the H-MoS2 nanosheets existed in monolayer form.

[0014] (2) Gel-like H-MoS2 is thoroughly mixed with polyethylene and then extruded and granulated to obtain MoS2-based polyethylene masterbatch.

[0015] (3) MoS2-based polyethylene masterbatch is fully mixed with polyethylene and extruded to obtain functional polyethylene masterbatch, which is then processed into a film to obtain a single-layer MoS2 nanosheet modified polyethylene functional film.

[0016] According to a preferred embodiment of the present invention, in step (1), the monolayer MoS2 nanosheets are prepared by a spatial confinement method. Preferably, the method for preparing monolayer MoS2 nanosheets includes the following steps: (i) dehydrating layered double hydroxide (LDH) by heating at 300-500°C for 1-3 hours to obtain LDO; (ii) mixing (NH4)2MoS4, LDO, and deionized water at a mass ratio of 1:1:8-12, stirring for 8-12 hours, followed by filtration and drying to obtain MoS4. 2- -LDH, calcined to obtain LDO-MoS2. (iii) LDO-MoS2 is mixed with hydrochloric acid, and after acid dissolution, filtration, washing, and drying, MoS2 powder is obtained. The nanosheets contain a large number of defects on their surface, with an average thickness of 1 nm and a lateral size of 50 nm to 100 nm.

[0017] According to a preferred embodiment of the present invention, in step (1), the surface polarity modifier is an organic compound with terminal hydroxyl groups or capable of hydrolyzing to produce terminal hydroxyl groups; preferably, the surface polarity modifier includes long-chain fatty alcohols such as lauryl ether-4, lauryl alcohol, stearyl alcohol, myristyl alcohol, and cetyl alcohol; more preferably, the surface polarity modifier is lauryl ether-4.

[0018] According to a preferred embodiment of the present invention, in step (1), the mass ratio of monolayer MoS2 nanosheets to surface polarity modifier is 1:3 to 5.

[0019] According to a preferred embodiment of the present invention, in step (1), the reaction temperature is 60-100°C, the reaction time is 2-8 hours, and the reaction is carried out under stirring conditions.

[0020] According to a preferred embodiment of the present invention, in step (2), the polyethylene is one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) or high-density polyethylene (HDPE), preferably low-density polyethylene (LDPE).

[0021] According to the present invention, in step (2), extrusion granulation is carried out using conventional granulation methods. Preferably, the extrusion granulation process is as follows: gel-like H-MoS2 and polyethylene masterbatch are premixed in a mixer, then melt-extruded by a twin-screw extruder and granulated to obtain MoS2-based polyethylene masterbatch. The melt temperature is 160–220°C, the screw speed is 30–80 rpm, and the screw residence time is 1–3 min.

[0022] According to a preferred embodiment of the present invention, in step (2), the mass content of monolayer MoS2 nanosheets in the MoS2-based polyethylene masterbatch is 1-20%, preferably 1-5%. The mass content of monolayer MoS2 nanosheets refers to the percentage of the mass of monolayer MoS2 nanosheets to the mass of the MoS2-based polyethylene masterbatch.

[0023] According to the present invention, in step (3), extrusion granulation is carried out in accordance with conventional granulation methods. Preferably, the extrusion granulation process is as follows: MoS2-based polyethylene masterbatch and polyethylene are premixed in a mixer, and then melt-extruded by a twin-screw extruder to granulate, thereby obtaining functional polyethylene masterbatch. The melt temperature is 160-220°C, the screw speed is 30-80 rpm, and the screw residence time is 1-3 min.

[0024] According to a preferred embodiment of the present invention, in step (3), the method of processing into a film is: extrusion, blow molding, calendering, casting, or stretching.

[0025] Application of the above-mentioned monolayer MoS2 nanosheet modified polyethylene functional film in photothermal heating materials and / or heat-insulating agricultural films.

[0026] The technical features and beneficial effects of this invention are as follows:

[0027] (1) The present invention uses hydroxyl-mediated controllable dispersion technology to prevent the aggregation of monolayer MoS2 nanosheets. It achieves efficient heterogeneous composite of polyethylene and ultrathin MoS2 nanosheets through a simple twin-screw process. The monolayer MoS2 nanosheets are dispersed in the polymer in the form of monolayer sheets. The technology used in the present invention can be directly integrated with existing processes.

[0028] (2) The present invention can achieve uniform dispersion of monolayer MoS2 nanosheets in polyethylene matrix at the molecular scale. The addition of a small amount of monolayer MoS2 nanosheets can realize the photothermal function of polyethylene film, ensuring the efficient transformation of the excellent performance of monolayer MoS2 nanosheets from micro to macro, giving the composite film excellent photothermal response characteristics, and maintaining the excellent mechanical properties of the composite film.

[0029] (3) Thanks to the uniform dispersion of two-dimensional monolayer MoS2 nanosheets in the polymer, the polyethylene functional film prepared by the present invention can exhibit excellent photothermal self-heating and heat preservation performance with extremely low monolayer MoS2 nanosheet addition, making it very promising for agricultural production, especially heat preservation agricultural film. Attached Figure Description

[0030] Figure 1 These are physical images of the polyethylene functional films prepared in Example 3 (left) and Comparative Example 4 (right).

[0031] Figure 2The Raman spectra of the MoS2-based LDPE masterbatch and polyethylene functional film prepared in Example 4 are shown.

[0032] Figure 3 The images show the SEM and EDS images of the polyethylene functional film prepared in Example 4.

[0033] Figure 4 The images show fluorescence confocal imaging of the films prepared in Examples 2, 4, and Comparative Example 1.

[0034] Figure 5 The images show the XRD patterns of the films prepared in Examples 1, 4, and Comparative Example 1.

[0035] Figure 6 The images show the photothermal response of the polyethylene functional films prepared in Examples 1-4 and Example 6, the MoS2-based LDPE masterbatch, and the LDPE film prepared in Comparative Example 1.

[0036] Figure 7 The graphs show the photothermal heating curves of the thin films prepared in Example 3 and Comparative Example 4.

[0037] Figure 8 The tensile strength and elongation at break of the polyethylene functional films prepared in Examples 1-6 and the LDPE film prepared in Comparative Example 1 are shown in the figure. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0039] Unless otherwise specified, all materials, reagents and equipment used in the embodiments are commercially available products; and all methods used are prior art unless otherwise specified.

[0040] In this embodiment, monolayer MoS2 nanosheets were synthesized via a spatial confinement method. The specific preparation steps included: (ii) dehydrating commercially available layered bimetallic hydroxides (Mg-Al-CO3 LDHs) by heating in air at 400°C for 2 hours to obtain LDO; (ii) mixing (NH4)2MoS4 with LDO and deionized water at a mass ratio of 1:1:10, stirring for 10 hours, then filtering and drying to obtain MoS2-intercalated LDH, which was then calcined at 500°C in a nitrogen atmosphere for 2 hours to obtain LDO-MoS2; and (iii) mixing a fixed amount of LDO-MoS2 with a 0.5 mol / L hydrochloric acid aqueous solution (the mass ratio of LDO-MoS2 to the volume of the hydrochloric acid aqueous solution was 0.04 g / ml), followed by acid dissolution, filtration, washing, and drying to obtain MoS2 powder. The nanosheets contained numerous defects on their surface, with an average thickness of 1 nm and a lateral dimension of 50 nm to 100 nm.

[0041] Example 1

[0042] A method for preparing a polyethylene functional membrane modified with monolayer MoS2 nanosheets includes the following steps:

[0043] (1) In Example 1, lauryl ether-4 was selected as the surface polarity regulator. 100g of monolayer MoS2 nanosheet powder (the average thickness of the nanosheets is 1.0nm and the lateral size is 50nm~100nm) was fully mixed with 300g of lauryl ether-4 at room temperature, and then the temperature was raised to 80℃ and stirred for 4h to obtain disordered stacked gel-like H-MoS2.

[0044] (2) In Example 1, the polymer used is LDPE (low-density polyethylene, BASF, 2426H). Specifically, the gel-like H-MoS2 prepared in step (1) is premixed with LDPE in a mixer and then melt-blended in a twin-screw melt extruder. The melt blending temperature is 160°C, the screw speed is 60 rpm, the screw residence time is 2 min, and the product is extruded and granulated to obtain a uniformly dispersed MoS2-based LDPE masterbatch with a nanosheet mass fraction of 5%.

[0045] (3) In Example 1, the polymer used is LDPE (low-density polyethylene, Yangzi BASF, 2426H). Specifically, 100g of MoS2-based LDPE masterbatch and 9.9kg of pure LDPE are mixed by a mixer. The mixture is then melt-blended in a twin-screw extruder at a blending temperature of 160℃. The screw residence time is 2min and the speed is 60rpm. The resulting MoS2 / LDPE functional polyethylene masterbatch is obtained by granulation.

[0046] (4) The MoS2 / LDPE functional polyethylene masterbatch from step (3) is used to prepare a functional film by blow molding. Specific steps: 8 kg of MoS2 / LDPE functional polyethylene masterbatch is taken for blow molding. The screw processing temperature is 180℃, the die temperature is controlled at approximately 170℃, the blow-up ratio is controlled at approximately 2-3, and the film thickness is controlled at approximately 100 μm. The resulting polyethylene functional film is yellowish-green, with a single-layer MoS2 nanosheet content of 0.05%.

[0047] Example 2

[0048] A method for preparing a single-layer MoS2 nanosheet modified polyethylene functional film is as described in Example 1, except that in step (3), the amount of MoS2-based LDPE masterbatch is 200g and the amount of LDPE is 9.8kg; other steps and conditions are the same as in Example 1. The mass content of the single-layer MoS2 nanosheets in the obtained polyethylene functional film is 0.1%.

[0049] Example 3

[0050] A method for preparing a single-layer MoS2 nanosheet modified polyethylene functional film is as described in Example 1, except that in step (3), the amount of MoS2-based LDPE masterbatch is 600g and the amount of LDPE is 9.4kg; other steps and conditions are the same as in Example 1. The mass content of the single-layer MoS2 nanosheets in the obtained polyethylene functional film is 0.3%.

[0051] like Figure 1 As shown on the left, due to the different band gaps, ordinary commercial block MoS2 appears black, while monolayer MoS2 nanosheets are a unique yellow-green. The polyethylene functional film prepared in this embodiment exhibits the unique yellow-green color of monolayer MoS2 nanosheets, indicating that the nanosheets are uniformly dispersed in the polymer matrix in the form of monolayer sheets.

[0052] Example 4

[0053] A method for preparing a single-layer MoS2 nanosheet modified polyethylene functional film is as described in Example 1, except that in step (3), the amount of MoS2-based LDPE masterbatch is 1 kg and the amount of LDPE is 9 kg; other steps and conditions are the same as in Example 1. The mass content of the single-layer MoS2 nanosheets in the obtained polyethylene functional film is 0.5%.

[0054] from Figure 2 The Raman spectroscopy results show that the E0 of the MoS2-based LDPE masterbatch (5 wt.% MoS2 / LDPE) and the polyethylene functional film (0.5 wt.% MoS2 / LDPE) prepared in this example are similar. 2g With A 1g The distance between the two peaks is 24.1 cm. -1 This indicates that the monolayer MoS2 nanosheets exist in the LDPE matrix as monolayer sheets without significant stacking.

[0055] To further investigate the dispersion morphology of monolayer MoS2 nanosheets in the LDPE matrix, the microstructure of the polyethylene functional film prepared in this example was characterized using scanning electron microscopy (SEM), and the elemental distribution uniformity was verified by energy-dispersive X-ray spectroscopy (EDS). Figure 3 As shown, monolayer MoS2 nanosheets are uniformly dispersed in the LDPE matrix in the form of monolayer sheets.

[0056] Meanwhile, since monolayer MoS2 nanosheets exhibit a significant fluorescence effect, a characteristic not found in ordinary commercially available bulk multilayer MoS2 or pure LDPE films, the films prepared in this example (0.5%), Example 2 (0.1%), and Comparative Example 1 (0%) were characterized using laser confocal microscopy to further verify the dispersion state of MoS2 nanosheets in the LDPE matrix. Figure 4As shown, no fluorescence signal was observed in the pure LDPE film, while the polyethylene functional film prepared in Example 2 and this example showed obvious fluorescence effect. Moreover, the fluorescence intensity increased with the increase of MoS2 nanosheet content, which effectively proved that MoS2 was uniformly dispersed in the LDPE functional film in the form of monolayer sheets.

[0057] like Figure 5 As shown, X-ray diffraction (XRD) analysis was performed on the films prepared by pure LDPE, Example 1 (0.05 wt.% MoS2 / LDPE), and this example (0.5 wt.% MoS2 / LDPE). No obvious characteristic peaks of MoS2 nanosheets were detected in the results, indicating that the MoS2 nanosheets did not agglomerate in the matrix, which further confirms its good dispersibility in LDPE from the structural level.

[0058] Example 5

[0059] A method for preparing a single-layer MoS2 nanosheet modified polyethylene functional film is as described in Example 1, except that in step (3), the amount of MoS2-based LDPE masterbatch is 1.4 kg and the amount of LDPE is 8.6 kg; other steps and conditions are the same as in Example 1. The mass content of the single-layer MoS2 nanosheets in the obtained polyethylene functional film is 0.7%.

[0060] Example 6

[0061] A method for preparing a single-layer MoS2 nanosheet modified polyethylene functional film is as described in Example 1, except that in step (3), the amount of MoS2-based LDPE masterbatch is 2 kg and the amount of LDPE is 8 kg; other steps and conditions are the same as in Example 1. The mass content of the single-layer MoS2 nanosheets in the obtained polyethylene functional film is 1%.

[0062] Example 7

[0063] A method for preparing a polyethylene functional film modified with monolayer MoS2 nanosheets is described in Example 4, except that: in step (1), stearic acid is used as the surface polarity modifier. 100g of monolayer MoS2 nanosheet powder (the average thickness of the nanosheets is 1nm, and the lateral size is 50nm~100nm) is thoroughly mixed and stirred with 300g of pre-melted stearic acid, and then heated to 80℃ and stirred for 4h to obtain disordered stacked gel-like H-MoS2. Other steps and conditions are the same as in Example 4. In the obtained polyethylene functional film, the mass content of monolayer MoS2 nanosheets is 0.5%.

[0064] Example 8

[0065] A method for preparing a polyethylene functional membrane modified with monolayer MoS2 nanosheets includes the following steps:

[0066] (1) In Example 8, lauryl ether-4 was selected as the surface polarity regulator. 100g of monolayer MoS2 nanosheet powder (the average thickness of the nanosheets is 1nm and the lateral size is 50nm~100nm) was thoroughly mixed with 300g of lauryl ether-4 at room temperature. Then the temperature was raised to 80℃ and stirred for 4h to obtain disordered stacked gel-like H-MoS2.

[0067] (2) In Example 8, the polymer used is LLDPE (linear low-density polyethylene, Lanzhou Petrochemical, DFDA-7042). Specifically, the gel-like H-MoS2 prepared in step (1) is premixed with LLDPE in a mixer and then melt-blended in a twin-screw melt extruder. The melt blending temperature is 170°C, the screw speed is 60 rpm, the screw residence time is 2 min, and the product is extruded and granulated to obtain a uniformly dispersed MoS2-based LLDPE masterbatch with a nanosheet mass fraction of 5%.

[0068] (3) In Example 8, the polymer used is LLDPE (linear low-density polyethylene, Lanzhou Petrochemical, DFDA-7042). Specifically, 1 kg of MoS2-based LLDPE masterbatch and 9 kg of pure LLDPE are mixed by a mixer. The mixture is then melt-blended in a twin-screw extruder at a blending temperature of 190°C. The screw residence time is 2 min and the speed is 60 rpm. After granulation, a single-layer MoS2 / LLDPE functional polyethylene masterbatch is obtained.

[0069] (4) The MoS2 / LLDPE functional polyethylene masterbatch from step (3) is used to prepare a functional film by blow molding. Specific steps: 8 kg of MoS2 / LLDPE functional polyethylene masterbatch is taken for blow molding. The screw processing temperature is 190℃, the die temperature is controlled at approximately 180℃, the blow-up ratio is controlled at approximately 2-3, and the film thickness is controlled at approximately 100 μm. The resulting polyethylene functional film is yellowish-green, with a single-layer MoS2 nanosheet content of 0.5%.

[0070] Example 9

[0071] A method for preparing a polyethylene functional membrane modified with monolayer MoS2 nanosheets includes the following steps:

[0072] (1) In Example 9, lauryl ether-4 was selected as the surface polarity regulator. 100g of monolayer MoS2 nanosheet powder (the average thickness of the nanosheets is 1.0nm and the lateral size is 50nm~100nm) was thoroughly mixed with 300g of lauryl ether-4 at room temperature. Then the temperature was raised to 80℃ and stirred for 4h to obtain disordered stacked gel-like H-MoS2.

[0073] (2) In Example 9, the polymer used is HDPE (high-density polyethylene, Chevron Phillips, 9650). Specifically, the gel-like H-MoS2 prepared in step (1) is premixed with HDPE in a mixer and then melt-blended in a twin-screw melt extruder. The melt blending temperature is 190°C, the speed is 30 rpm, the screw residence time is 3 min, and the product is extruded and granulated to obtain a uniformly dispersed MoS2-based HDPE masterbatch with a nanosheet mass fraction of 5%.

[0074] (3) In Example 9, the polymer used is HDPE (high-density polyethylene, Chevron Phillips, 9650). Specifically, 1 kg of MoS2-based HDPE masterbatch and 9 kg of pure HDPE are mixed by a mixer. The mixture is then melt-blended in a twin-screw extruder at a blending temperature of 190°C. The screw residence time is 3 min and the speed is 30 rpm. After granulation, a single-layer MoS2 / HDPE functional polyethylene masterbatch is obtained.

[0075] (4) The MoS2 / HDPE functional polyethylene masterbatch from step (3) is used to prepare a functional film by blown film method. Specific steps: 8 kg of MoS2 / HDPE functional polyethylene masterbatch is taken for blown film processing. The screw processing temperature is 210℃, the die temperature is controlled at around 200℃, the blow-up ratio is controlled at around 3-5, and the film thickness is controlled at around 100 μm. The resulting polyethylene functional film is yellow-green, with a single-layer MoS2 nanosheet content of 0.5%.

[0076] Comparative Example 1

[0077] A method for preparing a common LDPE film material includes the following steps: LDPE (low-density polyethylene, BASF, 2426H) is blown at 180°C to obtain a pure LDPE film material with a film thickness of 100 μm.

[0078] Comparative Example 2

[0079] A method for preparing a common LLDPE film material includes the following steps: LLDPE (linear low-density polyethylene, Lanzhou Petrochemical, DFDA-7042) is blown at 190°C to obtain a pure LLDPE film material with a film thickness of 100 μm.

[0080] Comparative Example 3

[0081] A method for preparing a common HDPE film material includes the following steps: HDPE (high-density polyethylene, Chevron Phillips, 9650) is blown at 210°C to obtain a pure HDPE film material with a film thickness of 100 μm.

[0082] Comparative Example 4

[0083] A method for preparing a polyethylene functional film modified with common commercially available bulk MoS2 nanosheets, comprising the following steps:

[0084] (1) 100g of ordinary commercial MoS2 (B-MoS2) powder with a blocky microstructure (referring to molybdenum disulfide material with a multilayer stacked structure that has not been peeled or thinned) was thoroughly mixed with 300g of lauryl ether-4 at room temperature and stirred. Then the temperature was raised to 80℃ and stirred for 4h to obtain B-MoS2 gel.

[0085] (2) In Comparative Example 4, the polymer used was LDPE (low-density polyethylene, BASF Yangzi, 2426H). Specifically, the B-MoS2 gel prepared in step (1) was premixed with LDPE in a mixer and then melt-blended in a twin-screw melt extruder. The melt blending temperature was 160℃, the screw speed was 60rpm, the screw residence time was 2min, and the mixture was extruded and granulated to obtain B-MoS2-based LDPE masterbatch with a B-MoS2 mass fraction of 5%.

[0086] (3) In Comparative Example 4, the polymer used was LDPE (low-density polyethylene, Yangzi BASF, 2426H). Specifically, 600g of B-MoS2-based LDPE masterbatch and 9.4kg of pure LDPE were mixed in a mixer. The mixture was then melt-blended in a twin-screw extruder at a blending temperature of 160℃. The screw residence time was 2min and the speed was 60rpm. The resulting B-MoS2 / LDPE functional polyethylene masterbatch was obtained by granulation.

[0087] (4) The B-MoS2 / LDPE functional polyethylene masterbatch from step (3) is used to prepare a functional film by blow molding. Specific steps: 8 kg of B-MoS2 / LDPE functional polyethylene masterbatch is taken for blow molding. The screw processing temperature is 180℃, the die temperature is controlled at approximately 170℃, the blow-up ratio is controlled at approximately 2-3, and the film thickness is controlled at approximately 100 μm. Unlike the functional polyethylene film (yellow-green) modified with single-layer MoS2 nanosheets, the B-MoS2 / LDPE composite film obtained above is light gray. Figure 1 (Right), of which the mass content of commercial B-MoS2 is 0.3%.

[0088] Experimental Example 1

[0089] Photothermal conversion performance test: At room temperature, a xenon lamp was used to simulate sunlight. The functional films prepared in Examples 1-4 and Examples 6-9, the B-MoS2 / LDPE film prepared in Comparative Example 4, the MoS2-based LDPE masterbatch in Example 1, and the pure LDPE, pure LLDPE, and pure HDPE films prepared in Comparative Examples 1-3 were irradiated at a solar intensity for 5 minutes. The real-time temperature was recorded using a thermal imager to obtain the photothermal heating curve.

[0090] like Figure 6 As shown, the data points from left to right correspond to the film of Example 1, the films of Examples 1-4, the film of Example 6, and the MoS2-based LDPE masterbatch in Example 1, respectively. The addition of monolayer MoS2 nanosheets endows the monolayer MoS2 / LDPE composite film with excellent photothermal response characteristics. When the amount of MoS2 nanosheets added is 0-5 wt%, the surface temperature of the functional film can be adjusted within the range of room temperature to 76°C after 5 minutes of illumination. It is evident that monolayer MoS2 nanosheets, thanks to their ultra-large specific surface area and extremely strong photothermal conversion characteristics, can impart excellent photothermal heating performance to the LDPE film even with very low addition amounts.

[0091] like Figure 7 As shown, under the same filler addition amount, the photothermal heating effect of the functional film based on commercially available MoS2 modification (0.3% B-MoS2 / LDPE) in Comparative Example 4 is far inferior to that of the functional film based on monolayer MoS2 nanosheet modification (0.3% MoS2 / LDPE) in Example 3. This indicates that compared with ordinary functional fillers, monolayer MoS2 nanosheets benefit from their direct band gap of 1.8 eV, which has super strong light absorption and photothermal conversion performance, and has significant functionality. It can endow the composite material with excellent functionality with extremely low filler addition amount.

[0092] The polyethylene functional films prepared in Examples 7 and 4 were heated to 57°C and 59.6°C respectively after being irradiated with simulated sunlight, showing photothermal temperature rise effects of 19.8°C and 22.4°C respectively compared to pure LDPE. The above experimental results indicate that stearyl alcohol (Example 7) and lauryl ether-4 (Example 4), as surface polarity modifiers for nanosheets, can both achieve surface regulation of the nanosheets, ensuring their uniform dispersion in the LDPE matrix and imparting excellent photothermal conversion properties to the film. However, lauryl ether-4 exhibits superior regulation effect.

[0093] The polyethylene functional film prepared in Example 8 heated to 51.3°C after being irradiated with simulated sunlight, exhibiting a photothermal temperature rise of 24.5°C compared to pure LLDPE (26.8°C). This demonstrates that by controlling the surface polarity of monolayer MoS2 nanosheets, they can be uniformly dispersed in the LLDPE matrix, imparting excellent photothermal temperature rise to the functional film with low filler content.

[0094] The polyethylene functional film prepared in Example 9 heated to 49.8°C after being irradiated with simulated sunlight, exhibiting a photothermal temperature rise of 23.3°C compared to pure HDPE (26.5°C). The addition of a single layer of MoS2 imparts excellent photothermal temperature rise to the HDPE functional film. Therefore, this invention enables the preparation of various polyethylene functional films, and the process is universal and easily promoted.

[0095] Experimental Example 2

[0096] Mechanical property testing: The mechanical properties of the polyethylene functional films prepared in Examples 1-9 and the films prepared in Comparative Examples 1-4 were tested using a Zwick / Roell Z020 universal testing machine, and the methods were in accordance with GB / T1040.1-2018.

[0097] like Figure 8 As shown, the data points from left to right correspond to the films prepared in Example 1 and Examples 1-6, respectively. Thanks to the uniform dispersion of nanosheets in the polyethylene matrix and the strong interfacial interaction with the matrix, the mechanical properties of the film are effectively guaranteed even with low nanosheet addition.

[0098] The mechanical property test data of the films prepared in the examples and comparative examples are shown in the table below.

[0099] Table 1 Mechanical property test data

[0100]

[0101]

[0102] As shown in Table 1, since the thickness of a single-layer MoS2 nanosheet is about 1.0 nm and it has a very large aspect ratio, after surface control, it can achieve near-molecular-level composite with the polymer matrix. It has strong interfacial interaction with the polymer matrix, which effectively ensures the mechanical properties of the material. In contrast, ordinary inorganic fillers, such as commercial MoS2 powder, have large microparticle sizes and poor compatibility with the polymer matrix. They agglomerate in the polymer to form stress points, which has an adverse effect on the mechanical properties of the composite film.

[0103] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only.

[0104] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A single-layer MoS2 nanosheet modified polyethylene functional membrane, characterized in that, The polyethylene functional film is composited through a melt blending strategy, with a single layer of MoS2 nanosheets uniformly dispersed in the polyethylene matrix. The functional film has excellent photothermal heating performance.

2. The polyethylene functional membrane modified with monolayer MoS2 nanosheets according to claim 1, characterized in that, The average thickness of the monolayer MoS2 nanosheets is 1.0 nm, and the lateral dimensions are 50 nm to 100 nm.

3. The polyethylene functional membrane modified with monolayer MoS2 nanosheets according to claim 1, characterized in that, In the polyethylene functional film, the mass content of monolayer MoS2 nanosheets is 0.001–5%, preferably 0.05–1%.

4. The polyethylene functional membrane modified with monolayer MoS2 nanosheets according to claim 1, characterized in that, The polyethylene matrix is ​​one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE), preferably low-density polyethylene (LDPE).

5. The polyethylene functional membrane modified with monolayer MoS2 nanosheets according to claim 1, characterized in that, The thickness of the polyethylene functional film is 5–200 μm.

6. The method for preparing a monolayer MoS2 nanosheet-modified polyethylene functional membrane according to any one of claims 1-5, characterized in that, Including the following steps: (1) The monolayer MoS2 nanosheets were thoroughly mixed with a surface polarity modifier, and a gel-like H-MoS2 was obtained by reaction. (2) Gel-like H-MoS2 is thoroughly mixed with polyethylene and then extruded and granulated to obtain MoS2-based polyethylene masterbatch. (3) MoS2-based polyethylene masterbatch is fully mixed with polyethylene and then extruded and granulated to obtain functional polyethylene masterbatch, which is then processed into a film to obtain a single-layer MoS2 nanosheet modified polyethylene functional film.

7. The method for preparing a monolayer MoS2 nanosheet-modified polyethylene functional membrane according to claim 6, characterized in that, In step (1), the monolayer MoS2 nanosheets are prepared by spatial confinement method; preferably, the preparation method of monolayer MoS2 nanosheets includes the following steps: (i) layered bimetallic hydroxide (LDH) is dehydrated by heating at 300-500℃ for 1-3h to obtain LDO; (ii) (NH4)2MoS4, LDO and deionized water are mixed in a mass ratio of 1:1:8-12, stirred for 8-12h, and then filtered and dried to obtain MoS4. 2- -LDH, calcined to obtain LDO-MoS2; (iii) LDO-MoS2 is mixed with hydrochloric acid, and then dissolved in acid, filtered, washed and dried to obtain MoS2 powder.

8. The method for preparing a monolayer MoS2 nanosheet-modified polyethylene functional membrane according to claim 6, characterized in that, In step (1), the surface polarity modifier is an organic compound with terminal hydroxyl groups or capable of hydrolyzing to produce terminal hydroxyl groups; preferably, the surface polarity modifier includes lauryl ether-4, lauryl alcohol, stearyl alcohol, myristyl alcohol or cetyl alcohol; more preferably, the surface polarity modifier is lauryl ether-4; preferably, the mass ratio of monolayer MoS2 nanosheets to surface polarity modifier is 1:3 to 5.

9. The method for preparing a monolayer MoS2 nanosheet-modified polyethylene functional membrane according to claim 6, characterized in that, Includes one or more of the following conditions: i. In step (1), the reaction temperature is 60-100℃, the reaction time is 2-8h, and the reaction is carried out under stirring conditions; ii. In step (2), the mass content of monolayer MoS2 nanosheets in the MoS2-based polyethylene masterbatch is 1-20%, preferably 1-5%.

10. The application of the monolayer MoS2 nanosheet modified polyethylene functional film as described in any one of claims 1-5 in photothermal heating materials and / or heat-insulating agricultural films.

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