Preparation method of a biomass-based durable super-hydrophobic material

Abstract

The application belongs to the technical field of functional materials, and relates to a preparation method of a biomass-based durable super-hydrophobic material, which comprises the following steps: (1) preparing silane-modified biological nanomaterial; (2) adding biological wax powder into heated ethanol under low-speed stirring, then adding hydrophobic nanomaterial, and then rapidly cooling in a water bath and gently stirring to form a stable homogeneous suspension system of a wax outer layer coated on the nanometer hydrophobic material; (3) adding biological polyester material to uniformly stir and mix, so as to obtain hydrophobic paint; (4) coating the hydrophobic paint on the surface of a substrate through a coating process, and then standing at room temperature to volatilize ethanol, deposit and dry the resin; and (5) curing the coated material through two-step curing to obtain a durable super-hydrophobic coating. The application provides a preparation method of a biomass-based durable super-hydrophobic material by using green and safe materials, and has the advantages of high durability, high barrier, high moisture and oxygen permeability, high mechanical strength and the like. The application is suitable for paper-based packaging material surfaces, has anti-adhesion and safety to various liquid fluids, and has a wide application prospect in the fields of biological medicine, food packaging, cosmetic packaging and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional materials, and particularly relates to a preparation method of a biomass-based durable super-hydrophobic material. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of providing an understanding of the overall background of the application, and does not necessarily constitute an admission of prior art by the inventor or any representative of the inventor, and is not specifically admitted to be prior art by this disclosure.

[0003] Designing a biomass-based durable super-hydrophobic coating capable of repelling multiple liquids and at the same time imparting multifunctionality is of great importance in the fields of biomedical, food packaging, cosmetic packaging, etc. However, it is difficult to achieve these characteristic functions simultaneously through a single structural design. First, the introduction of a rough microstructure on the coating is the first choice to achieve liquid repellency, but the durability of the structure is difficult to improve; second, it is difficult to simultaneously improve its local air and moisture permeability, anti-curling and folding, mechanical strength, etc.

[0004] In the past decade, there have been a large number of studies to alleviate these challenges. However, most of them use full petroleum-based raw materials or fluorinated materials with superstructure, and are fine in the selection of substrates to achieve super-hydrophobic durable coatings. Nevertheless, durability cannot be translated into the entire coating, or the construction of microstructure requires complex high preparation condition process. So far, it is still challenging to design and manufacture a universal, biomass-based, durable super-hydrophobic coating. SUMMARY

[0005] In order to solve the above problems, the present application provides a preparation method of a biomass-based durable super-hydrophobic material using green and safe materials, which has the advantages of high durability, high barrier moisture and oxygen permeability, high mechanical strength, etc. It is suitable for paper-based packaging material surface to have anti-adhesion and safety to multiple liquid fluids.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a biomass-based durable super-hydrophobic material, comprising:

[0008] using a reactive silane to modify a biological nanomaterial to obtain a hydrophobic biological nanomaterial;

[0009] After heating ethanol to a predetermined temperature, adding biological wax and the hydrophobic biological nanomaterial in sequence, mixing uniformly, and cooling to obtain a homogeneous suspension system of a biological wax core coated with hydrophobic nanocellulose;

[0010] dissolving a biological polyester material in a solution to obtain a biological polyester material solution;

[0011] adding the solution of the biopolymer material into the homogeneous suspension system of the hydrophobic nanocellulose coated hydrophobic wax core outer layer, mixing uniformly to obtain a hydrophobic coating;

[0012] loading the hydrophobic coating on the surface of the substrate, standing until the ethanol is evaporated and the biopolymer material is settled, and then two-step curing, to obtain the product.

[0013] In some embodiments, the reactive silane is selected from at least one of n-octyltrichlorosilane, hexadecyltrimethoxysilane, octyltriethoxysilane, and tetraethyl orthosilicate.

[0014] In some embodiments, the biologic nanomaterial is selected from at least one of nanocellulose, nanolignin, and nanodiatomite.

[0015] In some embodiments, the biologic nanomaterial has a particle size of 3-20 nm.

[0016] In some embodiments, the biologic wax is selected from at least one of rice bran wax, soybean wax, carnauba wax, candelilla wax, and beeswax.

[0017] In some embodiments, the biologic wax has a particle size of 10-50 μm.

[0018] In some embodiments, the predetermined temperature is 3-10 °C higher than the melting point of the biologic wax.

[0019] In some embodiments, the biologic wax is added in an amount of 8%-16% of the ethanol.

[0020] In some embodiments, the hydrophobic nanomaterial is added in an amount of 20%-30% of the biologic wax powder.

[0021] In some embodiments, the biopolymer material is selected from at least one of polyvinyl alcohol, poly-3-hydroxyalkanoate, polyhydroxybutyrate, polycaprolactone, and polybutylene succinate.

[0022] In some embodiments, the biopolymer material is added in an amount of 15%-20% of the biologic wax.

[0023] In some embodiments, the loading method includes, but is not limited to, dip coating, rod coating, spray coating, and shower coating.

[0024] In some embodiments, the specific steps of the two-step curing include curing at a temperature higher than the curing temperature of the biopolymer for 5-15 min, and then curing at a temperature higher than the melting temperature of the biologic wax for 10-15 min.

[0025] More specifically, the method includes the following steps:

[0026] Add 50 ml of deionized water to 500 ml of ethanol, adjust the pH of the solution to 8-9 with ammonia, add 18-25 g of nanocellulose and stir at room temperature for 5-10 min; then add 2-5 mL of octadecyltrichlorosilane and stir the reaction in a closed environment at 50-60 °C for 12-24 h, wash with ethanol and dry under vacuum.

[0027] Heat 50ml of ethanol to 85-95℃, control the stirring speed at 300-500r / min, add 4-8g of candelilla wax powder, add 0.8-2.4g of hydrophobic nanocellulose after 30s, and then quickly cool and stir in a 15-20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0028] Take 7.5-20g of 6wt% diluted biopolyester solution and add it to the above homogeneous suspension system. Stir at a low speed of 500-800r / min until uniformly mixed to obtain a hydrophobic coating.

[0029] In a second aspect, the present invention provides a biomass-based durable superhydrophobic material prepared by the above-described method.

[0030] A third aspect of the present invention provides the application of the above-mentioned biomass-based durable superhydrophobic material in the fields of biomedicine, food packaging, and cosmetic packaging.

[0031] Beneficial effects of the present invention

[0032] (1) This invention enables bio-based composite materials to utilize non-polar homogeneous protection and a hierarchical solidification strategy to construct biosafe, durable, and superhydrophobic materials.

[0033] (2) This invention employs a bio-wax-coated hydrophobic bio-nanomaterial method to effectively avoid the problem of strong encapsulation of nano-silane modified materials by bio-polyester. The hydrophobic coating applied to the substrate surface requires room temperature settling of the bio-polyester, resulting in a thinner resin thickness at the wax particle protrusions. With thermal curing of the bio-polyester, a primary microstructure with the bio-polyester as a supporting framework is formed. Secondary high-temperature curing effectively releases the hydrophobic properties of the nano-silane material. Simultaneously, the small amount of bio-wax remaining in the hydrophobic nanomaterial compensates for minor defects in silane modification and the exposed water-absorbing hydroxyl groups on the bio-polyester surface. The paper-based impregnation and curing of the bio-wax and bio-polyester interweaves and complements each other to effectively avoid local defects, jointly achieving high barrier properties against moisture and oxygen permeability. The released hydrophobic nanomaterial can still be adsorbed onto the bio-polyester surface. Utilizing the mechanical strength of the bio-polyester, the bio-polyester framework structure left by the melting of the bio-wax particles effectively protects the hydrophobic nanomaterial from wear, thereby effectively improving the material's durability and superhydrophobicity.

[0034] (3) The hydrophobic coating of the present invention uses biomass-based materials as raw materials, which is biosafe and reliable, has a simple preparation method, is highly practical, and is easy to promote. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 This is a schematic diagram of the process flow for preparing the biomass-based durable superhydrophobic material of the present invention. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0039] In the following examples, the hydrophobic nanomaterial is nanocellulose modified with octadecyltrichlorosilane, with a particle size of 7-15 nanometers; the biowax is candelilla wax powder with a melting point of 73°C and a particle size of 25-40 μm; and the biopolyester is thermosetting polyvinyl alcohol with a curing temperature of 55°C.

[0040] Example 1

[0041] (1) Add 50ml of deionized water to 500ml of ethanol, adjust the pH of the solution to 8 with ammonia, add 20g of nanocellulose and stir at room temperature for 5min; then add 3mL of octadecyltrichlorosilane and stir the reaction in a closed environment at 50℃ for 12h, and freeze dry at 20℃ for 12h to obtain hydrophobic nanocellulose.

[0042] (2) Heat 50ml of ethanol to 90℃, control the stirring speed at 500r / min and add 4g of candelilla wax powder. After 30s, add 2.4g of hydrophobic nanocellulose prepared in step (1), and then quickly cool and stir in a 20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0043] (3) Add 10g of biopolyester to 100ml of deionized water and heat to dissolve to prepare a 10wt% biopolyester dilute solution. Then take 10g and add it to the above homogeneous suspension system and stir at a low speed of 500r / min to mix evenly to obtain a hydrophobic coating.

[0044] (4) Apply the hydrophobic coating containing biopolyester to the surface of 70g A4 paper, and then let it stand at room temperature to allow the ethanol to evaporate and the biopolyester to settle. First, cure at a low temperature (60℃) slightly higher than the curing temperature of polyester for 10 minutes, and then cure at a high temperature (105℃) higher than the melting temperature of candelilla wax for 10 minutes to obtain a durable superhydrophobic material.

[0045] Example 2

[0046] (1) Same as Example 1.

[0047] (2) Heat 50ml of ethanol to 90℃, control the stirring speed at 500r / min and add 5g of candelilla wax powder. After 30s, add 2.1g of hydrophobic nanocellulose prepared in step (1), and then quickly cool and stir in a 20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0048] (3) Add 10g of biopolyester to 100ml of deionized water and heat to dissolve to prepare a 10wt% dilute biopolyester solution. Then take 11.5g and add it to the above homogeneous suspension system and stir at a low speed of 500r / min to mix evenly to obtain a hydrophobic coating.

[0049] (4) Same as Example 1.

[0050] Example 3

[0051] (1) Same as Example 1.

[0052] (2) Heat 50ml of ethanol to 90℃, control the stirring speed at 500r / min and add 6g of candelilla wax powder. After 30s, add 1.9g of hydrophobic nanocellulose prepared in step (1), and then quickly cool and stir in a 20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0053] (3) Add 10g of biopolyester to 100ml of deionized water and heat to dissolve to prepare a 10wt% biopolyester dilute solution. Then take 13g and add it to the above homogeneous suspension system and stir at a low speed of 500r / min to mix evenly to obtain a hydrophobic coating.

[0054] (4) Same as Example 1.

[0055] Example 4

[0056] (1) Same as Example 1.

[0057] (2) Heat 50ml of ethanol to 90℃, control the stirring speed at 500r / min and add 7g of candelilla wax powder. After 30s, add 1.7g of hydrophobic nanocellulose prepared in step (1), and then quickly cool and stir in a 20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0058] (3) Add 10g of biopolyester to 100ml of deionized water and heat to dissolve to prepare a 10wt% dilute biopolyester solution. Then take 14.5g and add it to the above homogeneous suspension system and stir at a low speed of 500r / min to mix evenly to obtain a hydrophobic coating.

[0059] (4) Same as Example 1.

[0060] Example 5

[0061] (1) Same as Example 1.

[0062] (2) Heat 50ml of ethanol to 90℃, control the stirring speed at 500r / min and add 8g of candelilla wax powder. After 30s, add 1.5g of hydrophobic nanocellulose prepared in step (1), and then quickly cool and stir in a 20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0063] (3) Add 10g of biopolyester to 100ml of deionized water and heat to dissolve to prepare a 10wt% biopolyester dilute solution. Then take 16g and add it to the above homogeneous suspension system and stir at a low speed of 500r / min to mix evenly to obtain a hydrophobic coating.

[0064] (4) Same as Example 1.

[0065] Comparative Example 1: No water-based polyester added

[0066] (1) Same as Example 1.

[0067] (2) Heat 50ml of ethanol to 90℃, control the stirring speed at 500r / min and add 6g of candelilla wax powder. After 30s, add 1.9g of hydrophobic nanocellulose prepared in step (1), and then quickly cool and stir in a 20℃ water bath to form a homogeneous suspension system with a stable biological wax core and an outer layer of hydrophobic nanocellulose.

[0068] (3) The homogeneous suspension system is coated onto the surface of the substrate, first cured at a low temperature of 60°C for 10 min, and then cured at a high temperature of 105°C, which is higher than the melting temperature of the candelilla wax, for 10 min to obtain the candelilla wax nanocellulose composite superhydrophobic material.

[0069] Comparative Example 2: Candelilla wax powder not added

[0070] (1) Same as Example 1.

[0071] (2) Heat 50ml of ethanol to 90℃, add 1.9g of the hydrophobic nanocellulose prepared in step (1), and mix evenly while controlling the stirring speed at 500r / min;

[0072] (3) Add 10g of biopolyester to 100ml of deionized water and heat to dissolve to prepare a 10wt% dilute biopolyester solution. Then take 13g and add it to the above homogeneous suspension system and stir at a low speed of 500r / min to mix evenly to obtain a hydrophobic coating.

[0073] (4) Apply the hydrophobic coating containing biopolyester to the surface of 70g A4 paper, and then let it stand at room temperature to allow the ethanol to evaporate and the biopolyester to settle. First, cure at a low temperature of 60℃ for 10min, and then cure at a high temperature of 100℃ for 10min to obtain a durable superhydrophobic material.

[0074] Performance testing

[0075] The relevant performance of the biomass-based durable superhydrophobic materials prepared by Examples 1-5 and Comparative Examples 1-2 of this invention was tested.

[0076] Contact angle test: The contact angle measurement method for nanofilms is adopted according to GB / T 30447-2013; Abrasion resistance and hydrophobicity test: The contact angle is measured after 20 and 50 cycles of cyclic abrasion using a 500g weight; Water flow impact hydrophobicity test: Water flow at a speed of 40ms... -1 After spraying at speed for 30s and 60s, the contact angle was measured again; Bending resistance hydrophobicity test: the durable superhydrophobic A4 paper was folded completely 180° to create a crease, then unfolded and the contact angle was measured; Water vapor transmission rate test: the gravimetric (permeability cup) method was used for the determination of moisture permeability of thin sheet materials according to GB / T 2679.2-2015; Oxygen transmission rate test: the coulometric method was used for the oxygen permeability test of plastic films and sheets for packaging materials according to GB / T 19789-2021.

[0077] Table 1 Performance of durable superhydrophobic material examples

[0078]

[0079]

[0080] As shown in Examples 1-5, with the increase of the proportion of bio-wax in the system, the proportion of hydrophobic SiO2 decreases, and the proportion of polyvinyl alcohol increases, the initial coating contact angle gradually decreases from a maximum of 162.4°. However, both the wear-resistant contact angle and the water flow impact-resistant contact angle show a trend of first increasing and then decreasing, with the water flow impact resistance being more sensitive. All the coatings in the examples exhibit bending resistance, and the contact angle does not change much after being completely folded at 180°, which is beneficial for secondary processing on flexible substrate surfaces. Similarly, with the increase of the amount of bio-wax and polyvinyl alcohol, the oxygen permeability of the material is more excellent, but for long-term moisture permeability, polyvinyl alcohol still exhibits moisture absorption and permeability properties.

[0081] In Comparative Example 1, without the addition of polyvinyl alcohol, the initial coating exhibited excellent hydrophobic properties, reaching 163.4°. However, due to the lack of a framework curing structure provided by polyvinyl alcohol, the contact angle rapidly decreased after exposure to wear and water impact. Nevertheless, thanks to the protective effect of the wax on the matrix, its oxygen permeability and water vapor permeability remained excellent. In Comparative Example 2, the hydrophobic nanocellulose added without wax protection only achieved an initial contact angle exceeding 76.9°. The functional role of the hydrophobic nanocellulose was almost completely covered, while many hydrophilic hydroxyl groups of polyvinyl alcohol were exposed, resulting in poor moisture permeability.

[0082] A suitable dosage ratio, as in Example 3, allows the wax powder to provide better initial protection for the hydrophobic nanocellulose, and polyvinyl alcohol to provide a more robust framework structure. This results in enhanced abrasion resistance with a contact angle of 153.9° even after 50 abrasion cycles, and water flow impact resistance with a contact angle of 153.0° even after 60 seconds of water flow impact. Simultaneously, it effectively prevents the migration of the coating matrix, ensuring safety in contact with the solution. The base paper has virtually no moisture and oxygen permeability; the synergistic effect of the bio-polyester and bio-wax interwoven filling significantly improves the moisture permeability of the paper base (12.1 g / m³). 2 / 24h) and oxygen permeability (9.3cm) 3 / m 2 The effect of 24h (0.1Mpa) is also very obvious.

[0083] As can be seen from the comparison between Example 3 and Comparative Examples 1 and 2, the base layer formed by the interweaving and complementary curing of bio-wax and bio-polyester can better improve the wear resistance, water flow impact resistance, and moisture and oxygen permeability of superhydrophobic materials.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a biomass-based durable superhydrophobic material, characterized in that, include: Hydrophobic cellulose nanoparticles were obtained by modifying cellulose nanoparticles with reactive silanes. After heating ethanol to a predetermined temperature, biowax and the hydrophobic nanocellulose were added sequentially, mixed evenly, and cooled to obtain a homogeneous suspension system with a biowax core coated with hydrophobic nanocellulose. The biopolyester material is dissolved in a solution to obtain a biopolyester material solution; The biopolyester material solution is added to the homogeneous suspension system of the biowax core coated with hydrophobic nanocellulose, and mixed evenly to obtain a hydrophobic coating. The hydrophobic coating is loaded onto the surface of a substrate, left to stand, and cured in two steps to obtain the final product. The specific steps of the two-step curing process include: curing at a temperature higher than the curing temperature of biopolyester for 5-15 minutes, and then curing at a temperature higher than the melting temperature of biowax for 10-15 minutes. The biopolyester material is selected from at least one of polyvinyl alcohol, poly(3-hydroxyalkanoate), polyhydroxybutyrate, polycaprolactone, and polybutylene succinate.

2. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The reactive silane is selected from at least one of n-octyltrichlorosilane, hexadecyltrimethoxysilane, octadecyltrichlorosilane, and octyltriethoxysilane.

3. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The nanocellulose has a particle size of 3-20 nm.

4. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The biowax is selected from at least one of rice bran wax, soybean wax, carnauba wax, candelilla wax, and beeswax; Alternatively, the particle size of the biowax is 10-50 μm.

5. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The predetermined temperature is 3-10°C higher than the melting point of the biowax.

6. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The amount of biowax added is 8%-16% of ethanol; Alternatively, the amount of hydrophobic nanomaterials added can be 20%-30% of the bio-wax powder.

7. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The amount of biopolyester material added is 15%-20% of the biomass wax.

8. The method for preparing the biomass-based durable superhydrophobic material as described in claim 1, characterized in that, The loading methods are: dip coating, bar coating, spray coating, and curtain coating.

9. The biomass-based durable superhydrophobic material prepared by the method according to any one of claims 1-8.

10. The application of the biomass-based durable superhydrophobic material according to claim 9 in the fields of biomedicine, food packaging, and cosmetic packaging.

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