Cellulose-silicon oxide composite superhydrophobic material and preparation method thereof

Abstract

A cellulose-silicon oxide composite superhydrophobic material and a preparation method thereof are disclosed. In the method, cellulose substrates with different surface topographies are pretreated by a low-temperature plasma, and then a first silicon oxide layer is deposited on the cellulose substrate by a low-temperature plasma-enhanced chemical vapor deposition method, then modified by a low-temperature plasma, and finally a second silicon oxide layer is deposited thereon, thereby preparing a micro-nano structured superhydrophobic surface on the cellulose substrate, to obtain a cellulose-silicon oxide composite superhydrophobic material, which is an environmentally friendly bio-based hydrophobic material.

Claims

1. A method for preparing a cellulose-silicon oxide composite superhydrophobic material, comprising: preparing a cellulose substrate in the form of paper, paperboard or a film; pretreating the cellulose substrate with a low-temperature plasma; depositing a first silicon oxide layer with a thickness of 200-1200 nm on the pretreated cellulose substrate by a low-temperature plasma-enhanced chemical vapor deposition method; after removing residual reactants in the depositing, modifying the first silicon oxide layer initially deposited with a low-temperature plasma; and depositing a second silicon oxide layer with a thickness of 40-160 nm on the modified first silicon oxide layer by a low-temperature plasma-enhanced chemical vapor deposition method, to finally obtain a micro-nano structured superhydrophobic surface, wherein in the pretreating, a mixed gas of argon and oxygen, argon and carbon dioxide, or argon and air is used as a carrier gas, wherein the argon accounts for 1/11-½ of the total gas volume, the total pressure in the deposition vacuum chamber is 15-30 Pa absolute, the power is 50-150 W, and the frequency is 40 kHz; the pretreatment is performed for 30-180 s.

2. The method for preparing a cellulose-silicon oxide composite superhydrophobic material as claimed in claim 1, wherein in the preparing, the cellulose substrate has a surface topography in the form of the smooth plane, or with corrugated, checkered or dot-matrix patterns.

3. The method for preparing a cellulose-silicon oxide composite superhydrophobic material as claimed in claim 1, wherein in the preparing, the cellulose substrate has a grammage of 60-500 g/m.sup.2 for the form of paper and paperboard, and a grammage of 38-68 g/m.sup.2 for the form of film.

4. The method for preparing a cellulose-silicon oxide composite superhydrophobic material as claimed in claim 1, wherein in the pretreating, the distance between the electrode plates is 2-6 cm during the process of pretreating the cellulose substrate by a low-temperature plasma.

5. A method for preparing a cellulose-silicon oxide composite superhydrophobic material, comprising: preparing a cellulose substrate in the form of paper, paperboard or a film; pretreating the cellulose substrate with a low-temperature plasma; depositing a first silicon oxide layer with a thickness of 200-1200 nm on the pretreated cellulose substrate by a low-temperature plasma-enhanced chemical vapor deposition method; after removing residual reactants in the depositing, modifying the first silicon oxide layer initially deposited with a low-temperature plasma; and depositing a second silicon oxide layer with a thickness of 40-160 nm on the modified first silicon oxide layer by a low-temperature plasma-enhanced chemical vapor deposition method, to finally obtain a micro-nano structured superhydrophobic surface, wherein in the depositing of the first silicon oxide layer and the depositing of the second silicon oxide layer, in the low-temperature plasma-enhanced chemical vapor deposition method, a precursor used is selected from the group consisting of tetramethyldisiloxane, hexamethyldisiloxane, tetramethyldivinyl disiloxane, bis(tert-butylamino)silane, trimethyl(dimethylamino)silane, tetraethyl ortho silicate, diisopropylamino silane, bis(diethylamino)silane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane, and the oxidant used is oxygen; under the condition that the vacuum degree in the deposition vacuum chamber is 3 Pa absolute, the precursor is introduced first, and then oxygen is introduced, with a volume ratio of oxygen to the precursor of 1:1 to 1:8; the total pressure in the deposition vacuum chamber is 20-50 Pa absolute, the power is 50-150 W, and the frequency is 40 kHz; the deposition is performed for 1-20 min.

6. A method for preparing a cellulose-silicon oxide composite superhydrophobic material, comprising: preparing a cellulose substrate in the form of paper, paperboard or a film; pretreating the cellulose substrate with a low-temperature plasma; depositing a first silicon oxide layer with a thickness of 200-1200 nm on the pretreated cellulose substrate by a low-temperature plasma-enhanced chemical vapor deposition method; after removing residual reactants in the depositing, modifying the first silicon oxide layer initially deposited with a low-temperature plasma; and depositing a second silicon oxide layer with a thickness of 40-160 nm on the modified first silicon oxide layer by a low-temperature plasma-enhanced chemical vapor deposition method, to finally obtain a micro-nano structured superhydrophobic surface, wherein a precursor used in the low-temperature plasma in the modifying is selected from the group consisting of tetrafluoromethane, a fluorosilane and a fluorosiloxane, and argon is used as an auxiliary gas; under the condition that the vacuum degree in the deposition vacuum chamber is 3 Pa absolute, argon is first introduced until that the total pressure in the deposition vacuum chamber reaches 10 Pa absolute, and then the precursor is introduced; the total pressure in the deposition vacuum chamber is 20-50 Pa absolute, the power is 50-150 W, and the frequency is 40 kHz; the modification is performed for 30-150 s.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to illustrate the embodiments of the present disclosure or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For those ordinary skilled in the art, without creative labor, other drawings may be obtained from these drawings.

(2) FIG. 1 shows substrates with different surface topographies; in which (a) shows the paper substrate with a checkered patterned surface in Example 1, (b) shows the paper substrate with a corrugated patterned surface in Example 2, (c) shows the paperboard substrate with a smooth surface in Example 3, (d) shows the nanocellulose film substrate with a smooth surface in Example 4, and (e) shows the nanocellulose film substrate with a dot-matrix patterned surface in Example 5.

(3) FIG. 2 shows an AFM image of the first silicon oxide layer deposited initially during the preparation process of the composite material in Example 1, and a static water contact angle diagram and a water sliding angle diagram of the prepared superhydrophobic composite material in water at 4° C.

(4) FIG. 3 shows an AFM image of the first silicon oxide layer deposited initially during the preparation process of the composite material in Example 2, and a static water contact angle diagram and a water sliding angle diagram of the prepared superhydrophobic composite material in water at 80° C.

(5) FIG. 4 shows an AFM image of the first silicon oxide layer deposited initially during the preparation process of the composite material in Example 3, and a static water contact angle diagram and a water sliding angle diagram of the prepared superhydrophobic composite material in water at 60° C.

(6) FIG. 5 shows an AFM image of the first silicon oxide layer deposited initially during the preparation process of the composite material in Example 4, and a static water contact angle diagram and a water sliding angle diagram of the prepared superhydrophobic composite material in water at 40° C.

(7) FIG. 6 shows an AFM image of the first silicon oxide layer deposited initially during the preparation process of the composite material in Example 5, and a static water contact angle diagram and a water sliding angle diagram of the prepared superhydrophobic composite material in water at 20° C.

DETAILED DESCRIPTION

(8) Various embodiments of the present disclosure are described in detail. The detailed description should not be considered as a limitation to the present disclosure, but should be understood as a more detailed description of certain aspects, characteristics, and embodiments of the present disclosure.

(9) It should be understood that the terms described in the present disclosure are only used to describe specific embodiments and are not used to limit the scope of the present disclosure. In addition, for the numerical range in the present disclosure, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the stated range and any other stated value or intermediate value within the stated range is also covered in the present disclosure. The upper and lower limits of these smaller ranges can be independently included within the range or eliminated out of the range.

(10) Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those ordinary skilled in the art. Although the present disclosure only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure. All references mentioned in this specification are incorporated by reference to disclose and describe methods and/or materials related to the references. In the event of conflicting with any incorporated references, the content of this text shall prevail.

(11) Without departing from the scope or spirit of the present disclosure, various improvements and changes can be made to the specific embodiments of the present specification, which is obvious to those skilled in the art. Other embodiments derived from the specification of the present disclosure will be obvious to the skilled person. The specification and examples of this disclosure are only exemplary.

(12) As used herein, “comprising”, “including”, “having”, “containing”, etc., are all open terms, which means including but not limited to.

Example 1

(13) (1) Preparation of a paper substrate with a checkered patterned surface topography: the bleached spruce pulp was fully moistened, then disconnected to prepare into a pulp with a concentration of 10%, and the pulp was beaten by a PFI beater; then the obtained wet pulp after beating was weighed, to make paper by a Kaiser rapid prototyping equipment; after squeezing to dehydrate, finally a single piece of wet paper sheet was sandwiched between a smooth carrier paperboard and a cloth with 300-mesh textures to dry, obtaining paper with a single checkered patterned surface and a grammage of 60 g/m.sup.2, as shown in (a) in FIG. 1.

(14) (2) Under the condition that the distance between the electrode plates was 2 cm, the paper substrate was pretreated with a low-temperature plasma, in which a mixed gas of argon and oxygen with an argon/oxygen volume ratio of 1:3 was used as the carrier gas, under the conditions that the total pressure in the deposition vacuum chamber was maintained at 15 Pa absolute, the power was 50 W, and the frequency was 40 kHz, the pretreatment was performed for 180 s.

(15) (3) The deposition of a first silicon oxide layer on the pretreated paper substrate by a low-temperature plasma-enhanced chemical vapor deposition method: tetramethyldivinyldisiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:1; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 20 Pa absolute, the power was 50 W and the frequency was 40 kHz, the deposition was performed for 5 min.

(16) (4) After removing residual reactants in the previous step, the modification of the first silicon oxide layer deposited above by a low-temperature plasma: difluorodimethylsilane was used as the precursor and argon was used as the auxiliary gas; under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, argon was introduced first until that the total pressure in the deposition vacuum chamber reached 10 Pa absolute, then the precursor was introduced; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 30 Pa absolute, the power was 100 W, and the frequency was 40 kHz, the modification was performed for 90 s.

(17) (5) The deposition of a second silicon oxide layer on the modified silicon oxide layer above by a low-temperature plasma-enhanced chemical vapor deposition method: tetramethyldivinyldisiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:3; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 20 Pa absolute, the power was 50 W and the frequency was 40 kHz, the deposition was performed for 3 min.

(18) As a result, for the paper substrate, after pretreatment, the surface roughness decreased by 9%, the carbon element content decreased, oxygen element content increased, the oxygen/carbon ratio increased, the static water contact angle was 98.5°, and the water sliding angle was >45°. The first silicon oxide layer initially deposited had a thickness of 200 nm, a surface roughness of 23.31 nm, a static water contact angle of 131.4°, and a water sliding angle of 19.26°; the second silicon oxide layer deposited again had a thickness of 114 nm, and a surface roughness of 46.64 nm. The finally prepared paper-silicon oxide composite superhydrophobic material was superhydrophobic in water at 4° C., with a static water contact angle of 154.8° and a water sliding angle of 3.12°, as shown in FIG. 2.

Example 2

(19) (1) Preparation of a paper substrate with a corrugated patterned surface topography: the bleached poplar pulp was fully moistened and disconnected to prepare into a pulp with a concentration of 10%, and the obtained pulp was beaten by PFI beater; the obtained wet pulp after beating was weighed, to make paper by a Kaiser rapid prototyping equipment; after squeezing to dehydrate, finally a single piece of wet paper sheet was sandwiched between a smooth carrier paperboard and a cloth with 180-mesh textures to dry, obtaining paper with a single corrugated patterned surface and a grammage of 160 g/m.sup.2, as shown in (b) in FIG. 1.

(20) (2) Under the condition that the distance between the electrode plates was 4 cm, the paper substrate was pretreated with a low-temperature plasma, in which a mixed gas of argon and oxygen with an argon/oxygen volume ratio of 1:1 was used as the carrier gas; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 20 Pa absolute, the power was 100 W, and the frequency was 40 kHz, the pretreatment was performed for 30 s.

(21) (3) The deposition of a first silicon oxide layer on the pretreated paper substrate by a low-temperature plasma-enhanced chemical vapor deposition method: bis(tert-butylamino)silane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:2; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 35 Pa absolute, the power was 100 W, and the frequency was 40 kHz, the deposition was performed for 10 min.

(22) (4) After removing residual reactants in the previous step, the modification of the first silicon oxide layer deposited above by a low-temperature plasma: tetrafluoromethane was used as the precursor and argon was used as the auxiliary gas; under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, argon was first introduced until that the total pressure in the deposition vacuum chamber reached 10 Pa absolute, and then the precursor was introduced; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 20 Pa absolute, the power was 50 W, and the frequency was 40 kHz, the modification was performed for 120 s.

(23) (5) The deposition of a second silicon oxide layer on the modified first silicon oxide layer above by a low-temperature plasma-enhanced chemical vapor deposition method: bis(tert-butylamino)silane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:8; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 50 Pa absolute, the power was 150 W and the frequency was 40 kHz, the deposition was performed for 4 min.

(24) As a result, for the paper substrate, after pretreatment, the surface roughness decreased by 3%, the carbon element content decreased, the oxygen element content increased, the oxygen/carbon ratio increased, the static water contact angle was 87.8°, and the water sliding angle was >45°. The first silicon oxide layer initially deposited had a thickness of 520 nm, a surface roughness of 41.87 nm, a static water contact angle of 121.3°, and a water sliding angle of 30.45°; the second silicon oxide layer deposited again has a thickness of 160 nm, and a surface roughness of 60.65 nm. The finally prepared paper-silicon oxide composite superhydrophobic material was superhydrophobic in water at 80° C., with a static water contact angle of 150.1° and a water sliding angle of 5.03°, as shown in FIG. 3.

Example 3

(25) A method for preparing a superhydrophobic material from cellulose and silicon oxide, comprising the following steps:

(26) (1) preparation of a paper substrate with a smooth surface: the bleached eucalyptus pulp was fully moistened and disconnected, to prepare into a pulp with a concentration of 10%, and the obtained pulp was beaten by a PFI beater; then the obtained wet pulp after beating was weighed, to make paper by a Kaiser rapid prototyping equipment; finally, each piece of wet paper sheet was stacked together in the order as required, and a carrier paperboard and a blanket were put respectively on the two sides to sandwich the stacking of the wet paper sheet, then fully squeezed to dehydrate, dried and calendered, obtaining a paperboard with a smooth surface and a grammage of 500 g/m.sup.2, as shown in (c) in FIG. 1;

(27) (2) under the condition that the distance between the electrode plates was 6 cm, the paperboard substrate was pretreated with a low-temperature plasma, in which a mixed gas of argon and air with an argon/air volume ratio of 1:2 was used as the carrier gas; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 15 Pa absolute, the power was 50 W, and the frequency was 40 kHz, the pretreatment was performed for 90 s;

(28) (3) the deposition of a first silicon oxide layer on the pretreated paperboard by a low-temperature plasma-enhanced chemical vapor deposition method: decamethylcyclopentasiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:2; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 25 Pa absolute, the power was 80 W, and the frequency was 40 kHz, the deposition was performed for 20 min;

(29) (4) after removing the residual reactants in the previous step, the modification of the first silicon oxide layer deposited above by a low-temperature plasma: (trifluoromethyl)trimethylsilane was used as the precursor and argon was used as the auxiliary gas; under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, argon was introduced first until that the total pressure in the deposition vacuum chamber reached 10 Pa absolute, and then the precursor was introduced; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 40 Pa absolute, the power was 120 W, and the frequency was 40 kHz, the modification was performed for 150 s;

(30) (5) the deposition of a second silicon oxide layer on the modified first silicon oxide layer above by a low-temperature plasma-enhanced chemical vapor deposition method: decamethylcyclopentasiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:4; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 35 Pa absolute, the power was 120 W, and the frequency was 40 kHz, the deposition was performed for 4 min.

(31) As a result, for the paperboard substrate, after pretreatment, the surface roughness decreased by 10%, the carbon element content decreased, the oxygen element content increased, the oxygen/carbon ratio increased, the static water contact angle was 106.2°, and the water sliding angle was >45°. The first silicon oxide layer initially deposited had a thickness of 1200 nm, a surface roughness of 103.5 nm, a static water contact angle of 139.6°, and a water sliding angle of 17.53°; the second silicon oxide layer deposited again had a thickness of 140 nm, and a surface roughness of 132.03 nm. The finally prepared paperboard-silicon oxide composite superhydrophobic material was superhydrophobic in water at 60° C., with a static water contact angle of 155.7°, and a water sliding angle of 2.36°, as shown in FIG. 4.

Example 4

(32) A method for preparing a superhydrophobic material from cellulose and silicon oxide, comprising the following steps:

(33) (1) preparation of a film substrate with a smooth surface: the bleached bagasse pulp was fully moistened and disconnected to prepare into a pulp with a concentration of 3%, and then ground for 10 times by an ultrafine pulverizer; then the ground pulp was diluted with water to a concentration of 0.8%, and treated by a high-pressure homogenizer at a pressure of 2000 bar absolute for 20 times, obtaining a cellulose nanofibers (CNFs) suspension; finally, according to the papermaking principle, the CNFs suspension was suction filtered to form a film by using a sand core filter and a filter membrane, and the film obtained was sandwiched between the smooth paperboard to dehydrate and dry, obtaining a nanocellulose film with a smooth surface and a grammage of 38 g/m.sup.2, as shown in (d) in FIG. 1;

(34) (2) under the condition that the distance between the electrode plates was 3 cm, the nanocellulose film substrate was pretreated by a low-temperature plasma, in which the mixed gas of argon and carbon dioxide with an argon/carbon dioxide volume ratio of 1:4 was used as the carrier gas; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 25 Pa absolute, the power was 100 W, and the frequency was 40 kHz, the pretreatment was performed for 90 s;

(35) (3) the deposition of a first silicon oxide layer on the pretreated nanocellulose film by a low-temperature plasma-enhanced chemical vapor deposition method: octamethylcyclotetrasiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:3; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 30 Pa absolute, the power was 100 W, and the frequency was 40 kHz, the deposition was performed for 9 min;

(36) (4) after removing residual reactants in the previous step, the modification of the first silicon oxide layer deposited above by a low-temperature plasma: trifluoropropylmethylcyclotrisiloxane was used as the precursor and argon was used as the auxiliary gas; under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, argon was introduced first until that the total pressure in the deposition vacuum chamber reached 10 Pa absolute, and then the precursor was introduced; under the condition that the total pressure in the deposition vacuum chamber was maintained at 35 Pa absolute, the power was 110 W, and the frequency was 40 kHz, the modification was performed for 120 s;

(37) (5) the deposition of a second silicon oxide layer on the modified first silicon oxide layer above by a low-temperature plasma-enhanced chemical vapor deposition method: octamethylcyclotetrasiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:6; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 45 Pa absolute, the power was 120 W, and the frequency was 40 kHz, the deposition was performed for 1 min.

(38) As a result, for the nanocellulose film substrate, after the pretreatment, the surface roughness decreased by 7%, the carbon element content decreased, the oxygen element content increased, the oxygen/carbon ratio increased, the static water contact angle was 74.3°, and the water sliding angle was >45°. The first silicon oxide layer initially deposited had a thickness of 460 nm, a surface roughness of 36.06 nm, a static water contact angle of 130.3°, and a water sliding angle of 22.61°; the second silicon oxide layer deposited again had a thickness of 40 nm, and a surface roughness of 48.87 nm. The finally prepared nanocellulose film-silicon oxide composite superhydrophobic material was superhydrophobic in water at 40° C., with a static water contact angle of 154.1° and a water sliding angle of 3.47°, as shown in FIG. 5.

Example 5

(39) A method for preparing a superhydrophobic material from cellulose and silicon oxide, comprising the following steps:

(40) (1) preparation of a film substrate with a dot-matrix patterned surface topography: the bleached bagasse pulp was fully moistened and disconnected to prepare into a pulp with a concentration of 2%, then ground by an ultrafine pulverizer for 6 times; then ground pulp was diluted with water to a concentration of 0.5%, and then treated by a high-pressure homogenizer at a pressure of 1000 bar for 10 times, obtaining a cellulose nanofibers (CNFs) suspension; finally, according to the papermaking principle, the CNFs suspension was suction filtered to form a film by using a sand core filter and a filter membrane, and the film obtained was sandwiched between the smooth paperboard and the cloth to dehydrate and dry, obtaining a nanocellulose film with a single dot-matrix patterned surface and a grammage of 68 g/m.sup.2, as shown in (e) in FIG. 1;

(41) (2) under the condition that the distance between the electrode plates was 5 cm, the nanocellulose film substrate was pretreated by a low-temperature plasma, in which the mixed gas of argon and air with an argon/air volume ratio of 1:10 was used as the carrier gas; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 30 Pa absolute, the power was 150 W, and the frequency was 40 kHz, the modification was performed for 60 s;

(42) (3) the deposition of a first silicon oxide layer on the pretreated nanocellulose film by a low-temperature plasma-enhanced chemical vapor deposition method: hexamethyldisiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 5 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:6; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 45 Pa absolute, the power was 150 W, and the frequency was 40 kHz, the deposition was performed for 7 min;

(43) (4) after removing residual reactants in the previous step, the modification of the first silicon oxide layer deposited above by a low-temperature plasma: tridecafluorooctyltriethoxysilane was used as the precursor and argon was used as the auxiliary gas; under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, argon was introduced first until that the total pressure in the deposition vacuum chamber reached 10 Pa absolute, and then the precursor was introduced; under the conditions that the total pressure in the deposition vacuum chamber was maintained at 50 Pa absolute, the power was 150 W, and the frequency was 40 kHz, the modification was performed for 30 s;

(44) (5) the deposition of a second silicon oxide layer on the modified first silicon oxide layer above by a low-temperature plasma-enhanced chemical vapor deposition method: hexamethyldisiloxane was used as the precursor and oxygen was used as the oxidant; after removing residues in the pretreatment, under the condition that the vacuum degree in the deposition vacuum chamber was 3 Pa absolute, the precursor was introduced first, and then oxygen was introduced, with a volume ratio of oxygen to the precursor of 1:8. Under the conditions that the total pressure in the deposition vacuum chamber was maintained at 50 Pa absolute, the power was 150 W, and the frequency was 40 kHz, the deposition was performed for 2 min.

(45) As a result, for the nanocellulose film substrate, after pretreatment, the surface roughness decreased by 6%, the carbon content decreased, the oxygen content increased, the oxygen/carbon ratio increased, the static water contact angle was 68.7°, and the water sliding angle was >45°. The first silicon oxide layer deposited initially had a thickness of 350 nm, a surface roughness of 33.95 nm, a static water contact angle of 127.4°, and a water sliding angle of 27.04°; the second silicon oxide layer deposited again had a thickness of 86 nm, and a surface roughness of 52.56 nm. The finally prepared nanocellulose film-silicon oxide composite superhydrophobic material was superhydrophobic in water at 20° C., with a static water contact angle of 151.6° and a water sliding angle of 4.45°, as shown in FIG. 6.

(46) The low-temperature plasma method of the present disclosure was a method that uses a low-temperature plasma equipment to perform the vapor-phase chemical deposition, pretreatment or modification, and its specific operation steps are the prior art known in the art, and will not be repeated here.

(47) The above-mentioned embodiments only describe the preferred mode of the present disclosure, and do not limit the scope of the present disclosure. Without departing from the spirits of the present disclosure, variations and improvements to the technical solutions of the present disclosure made by those ordinary skilled in the art shall fall within the scope defined in the claims of the present disclosure.