Polymer aerogel and preparation method for preparing polymer aerogel by using waste plastics

Abstract

The invention relates to the technical field of solid waste plastic recycling, in particular to polymer aerogel and a preparation method for preparing the polymer aerogel from waste plastic. The method comprises the following steps: (1) dissolving waste plastics in an organic solvent to obtain a homogeneous solution; (2) adding the homogeneous solution into cellulose aerogel for aging treatment to obtain an aged product; (3) carrying out pre-freezing and drying treatment on the aging product to obtain composite aerogel; and (4) immersing the composite aerogel into water to obtain a leachate and polymer aerogel. According to the preparation method for preparing the polymer aerogel by using the waste plastics, the cellulose aerogel is used as a framework to prepare the polymer aerogel, so that the specific surface area of the polymer aerogel can be remarkably increased.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste plastic resource recovery, and in particular to a polymer aerogel and a method for preparing the polymer aerogel by utilizing waste plastic. Background Art

[0002] Aerogel has a three-dimensional porous network structure, which gives it high porosity, low density, high specific surface area and low thermal conductivity. Inorganic silica aerogel is a relatively mature aerogel, which has a wide range of applications in aerospace, chemical catalysis, building energy conservation, life sciences, electricity and other fields. It is often used to make thermal insulation materials, catalyst carrier materials, drug delivery materials, adsorption and filtration materials, supercapacitors, etc. Compared with inorganic silica aerogel, polymer aerogel usually has better mechanical properties, solvent tolerance and environmental stability.

[0003] Polymer aerogels are usually prepared from monomers through a series of chemical reactions such as hydrolysis and polycondensation, and can also be prepared directly using macromolecular polymers. Plastics are macromolecular polymers that are widely used in various industries such as packaging, construction, and manufacturing due to their excellent durability, corrosion resistance, plasticity, and stability. In 2018, global plastic production reached 359 million tons, with an annual growth rate of about 3.2%. In contrast to its high production, the service life of plastic products is generally short. The average service life of about half of the plastics is only 1-2 years, and the service life of packaging plastics is less than 1 month. In addition, the natural degradation of plastics is extremely difficult, resulting in an increasing amount of waste plastics produced worldwide, with an annual output of nearly 300 million tons. According to statistics, only 9% of the plastics used in the world are recycled, and a large amount of waste plastics that have not been properly disposed of have accumulated year by year, causing many environmental problems such as marine plastic particles and white pollution, which seriously threaten human health. The use of waste plastics to prepare polymer aerogels not only turns waste into treasure and realizes the high-value resource utilization of waste plastics, but also effectively solves the ecological and environmental pollution problems caused by them, but the resulting polymer aerogels have the defect of a small specific surface area.

[0004] CN109721760A reports a method for preparing a polymer aerogel, first dissolving a polymer powder such as polyvinylidene fluoride, polyvinyl chloride or polyurethane in an organic solvent and letting it stand, then scraping a liquid film of the polymer solution on the surface of a substrate, then immersing the substrate in a coagulation bath for gelation, and finally drying the gel to obtain a polymer aerogel. The aerogel prepared by this method has a small specific surface area (25-202m 2 / g), still needs to be further improved.

[0005] Therefore, there is an urgent need to provide a method for preparing high specific surface area polymer aerogels using waste plastics. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems in the prior art that waste plastics are difficult to recycle and the specific surface area of ​​polymer aerogels is small, and to provide a polymer aerogel and a method for preparing the polymer aerogel using waste plastics.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing polymer aerogel using waste plastics, wherein the method comprises the following steps:

[0008] (1) dissolving waste plastic in an organic solvent to obtain a homogeneous solution;

[0009] (2) adding the homogeneous solution into cellulose aerogel for aging treatment to obtain an aged product;

[0010] (3) pre-freezing and drying the aged product to obtain a composite aerogel;

[0011] (4) Immersing the composite aerogel in water to obtain an leaching liquid and a polymer aerogel.

[0012] The second aspect of the present invention provides a polymer aerogel prepared by the method described in the first aspect of the present invention.

[0013] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0014] 1) The method for preparing polymer aerogel using waste plastics provided in the present invention uses cellulose aerogel as a skeleton to prepare polymer aerogel, which can significantly increase the specific surface area of ​​the polymer aerogel;

[0015] 2) The preparation method of polymer aerogel using waste plastics provided in the present invention and the preparation of polymer aerogel using waste plastics provide a new way for the high-value resource utilization of waste plastics, which is of great significance for promoting the development of aerogel materials, alleviating the white crisis, improving the natural environment, and helping to achieve the "dual carbon" goals, and has good environmental benefits, social benefits and economic benefits;

[0016] 3) The method for preparing polymer aerogel using waste plastics provided in the present invention has a wide source of waste plastics and cellulose raw materials, low cost, simple process, low operation difficulty, and is suitable for industrial promotion;

[0017] 4) The polymer aerogel provided in the present invention has a large specific surface area, excellent performance, and broad application prospects. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] It should be noted that the method for preparing polymer aerogel using waste plastics provided in the present invention can not only prepare waste plastics into polymer aerogels with high specific surface area, but can also be used to process new plastics. In order to reduce the production cost of polymer aerogels and realize the resource utilization of waste plastics, it is preferred to prepare polymer aerogels using waste plastics. However, the preparation of polymer aerogels using new plastics should also be regarded as the content disclosed by the present invention and belongs to the protection scope of the present invention.

[0020] A first aspect of the present invention provides a method for preparing polymer aerogel using waste plastics, wherein the method comprises the following steps:

[0021] (1) dissolving waste plastic in an organic solvent to obtain a homogeneous solution;

[0022] (2) adding the homogeneous solution into cellulose aerogel for aging treatment to obtain an aged product;

[0023] (3) pre-freezing and drying the aged product to obtain a composite aerogel;

[0024] (4) Immersing the composite aerogel in water to obtain an leaching liquid and a polymer aerogel.

[0025] Among them, in the present invention, the inventor of the present invention has found through research that when a homogeneous solution containing waste plastics is added to cellulose aerogel, the cellulose aerogel can serve as a skeleton to support the polymer, thereby obtaining a cellulose / polymer composite aerogel in which the cellulose aerogel and the polymer aerogel are interlaced. By utilizing the property of cellulose aerogel being soluble in water, the cellulose / polymer composite aerogel can be immersed in water to remove the cellulose aerogel in the cellulose / polymer composite aerogel, thereby increasing the pores in the polymer aerogel and obtaining a polymer aerogel with a high specific surface area.

[0026] In step (1):

[0027] In one embodiment of the present invention, the waste plastic is selected from one or more of waste polyethylene (PE), waste polypropylene (PP), waste polystyrene (PS), and waste polyvinyl chloride (PVC).

[0028] In the present invention, before dissolving the waste plastics with the organic solvent, the waste plastics may be cleaned, dried and crushed to remove mechanical impurities in the waste plastics.

[0029] In one embodiment of the present invention, the organic solvent is selected from one or more of xylene, tetralin, decalin, hexadecane, cyclohexanone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0030] In one embodiment of the present invention, the waste plastic is waste polyethylene and / or waste polypropylene, and the organic solvent is one or more of xylene, tetralin, decalin, and hexadecane, preferably hexadecane.

[0031] In one embodiment of the present invention, the waste plastic is waste polystyrene, and the organic solvent is one or more of cyclohexanone, xylene, tetralin, and decalin, preferably cyclohexanone.

[0032] In one embodiment of the present invention, the waste plastic is waste polyvinyl chloride, and the organic solvent is one or more of dimethyl sulfoxide, cyclohexanone, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, preferably dimethyl sulfoxide.

[0033] In one embodiment of the present invention, the mass ratio of the waste plastic to the organic solvent is 1:10-200, preferably 1:20-100.

[0034] Among them, in the present invention, limiting the masses of waste plastics and organic solvents to the above ranges can ensure that the waste plastics can be fully dissolved in the organic solvent to obtain a homogeneous solution.

[0035] In one embodiment of the present invention, the dissolution operating conditions include: a dissolution temperature of 40-140°C, preferably 50-70°C; and a dissolution time of 15-120 min, preferably 30-60 min.

[0036] In step (2):

[0037] In one embodiment of the present invention, the cellulose aerogel is selected from one or more of carboxymethyl cellulose aerogel, carboxylated cellulose nanofiber aerogel, hydroxypropyl methyl cellulose aerogel, and methyl cellulose aerogel, and is preferably carboxymethyl cellulose aerogel.

[0038] In one embodiment of the present invention, the cellulose aerogel is prepared by a sol-gel method.

[0039] In one embodiment of the present invention, the sol-gel method comprises: firstly adding a crosslinking agent into an aqueous solution containing cellulose, stirring and ultrasonically treating the solution, and then pre-freezing I and drying I to obtain a cellulose aerogel.

[0040] In one embodiment of the present invention, the cross-linking agent is selected from one or more of polyethylene glycol diglycidyl ether, citric acid, 1,4-butanediol diglycidyl ether, and polyvinyl alcohol, preferably polyethylene glycol diglycidyl ether.

[0041] In one embodiment of the present invention, the cellulose is selected from one or more of carboxymethyl cellulose, carboxylated cellulose nanofibers, hydroxypropyl methyl cellulose, and methyl cellulose, preferably carboxymethyl cellulose.

[0042] In one embodiment of the present invention, the mass ratio of the cross-linking agent to the cellulose is 1:5-15, preferably 1:8-12.

[0043] In one embodiment of the present invention, the cellulose content in the aqueous solution containing cellulose is 0.5-2 wt%, preferably 1-1.5 wt%.

[0044] In one embodiment of the present invention, the stirring operating conditions include: a stirring speed of 500-1500 rpm, preferably 800-1200 rpm; a stirring time of 5-35 min, preferably 15-25 min; a stirring temperature of 30-80°C, preferably 40-60°C.

[0045] In one embodiment of the present invention, the ultrasonic operating conditions include: ultrasonic power of 200-1000w, preferably 500-700w; ultrasonic time of 10-50min, preferably 20-40min.

[0046] Among them, in the present invention, stirring is performed first and then ultrasonic treatment is performed, so that bubbles in the solution can be removed and the discontinuity of the three-dimensional network structure in the polymer aerogel, that is, the presence of discontinuous places, can be avoided.

[0047] In one embodiment of the present invention, the freezing temperature of the pre-freezing I is -80°C to -10°C, preferably -60°C to -30°C; the pre-freezing time of the pre-freezing I is 12-48h, preferably 24-36h.

[0048] In one embodiment of the present invention, the drying I is selected from one or more of freeze drying, supercritical carbon dioxide drying, and vacuum freeze drying.

[0049] In a preferred embodiment of the present invention, the adding method is dropwise addition; wherein the dropwise addition speed is 30-200 d(drops) / min, preferably 60-100 d(drops) / min.

[0050] Among them, in the present invention, the homogeneous solution can be evenly dispersed in the cellulose aerogel by dripping, which helps to improve the stability of the three-dimensional network structure in the polymer aerogel and improve the mechanical properties of the polymer aerogel.

[0051] In a preferred embodiment of the present invention, the dropping temperature of the homogeneous solution is 25-50°C, preferably 30-40°C.

[0052] Among them, in the present invention, when the dropping temperature is low, the viscosity of the homogeneous solution is large, which easily leads to uneven distribution of the homogeneous solution in the cellulose aerogel; when the dropping temperature is low or high, the cellulose aerogel skeleton will be deformed, which easily leads to poor stability of the polymer aerogel. When the homogeneous solution is dropped at the above-defined temperature, the prepared polymer aerogel can have a continuous and stable three-dimensional network structure with uniform pore distribution without deformation or collapse.

[0053] In one embodiment of the present invention, the homogeneous solution is added until the homogeneous solution remains on the surface of the cellulose aerogel and no longer penetrates into the cellulose aerogel.

[0054] In the present invention, after the homogeneous solution contacts the cellulose aerogel, the homogeneous solution will penetrate into the cellulose aerogel and be absorbed by the cellulose aerogel. When the cellulose aerogel reaches saturation, it can be observed with the naked eye that the homogeneous solution stays on the surface of the cellulose aerogel and no longer continues to penetrate downward. At this time, the addition of the homogeneous solution can be stopped.

[0055] In one embodiment of the present invention, the operating conditions of the aging treatment include: an aging temperature of 25-50°C, preferably 30-40°C; an aging time of 4-48h, preferably 24-36h.

[0056] Among them, in the present invention, the formation of the three-dimensional network structure of the polymer aerogel can be promoted through aging, and the stability of the three-dimensional network structure of the polymer aerogel can be improved.

[0057] In step (3):

[0058] In one embodiment of the present invention, the freezing temperature of the pre-freezing is -80°C to -10°C, preferably -60°C to -30°C; the pre-freezing time of the pre-freezing is 6-48h, preferably 12-24h.

[0059] In one embodiment of the present invention, the drying is selected from one or more of freeze drying, supercritical carbon dioxide drying, and vacuum freeze drying.

[0060] Among them, in the present invention, the organic solvent in the aged product can be removed by drying, thereby obtaining a high-purity composite aerogel.

[0061] In step (4):

[0062] In one embodiment of the present invention, the temperature of the water is 20-50°C, preferably 40-50°C; the immersion time is 0.5-6h, preferably 2-4h.

[0063] In the present invention, in order to increase the dissolution rate of the cellulose aerogel in the composite aerogel in water, the composite aerogel may be immersed in water and then stirred.

[0064] In a preferred embodiment of the present invention, the method further comprises step (5), subjecting the extract to pre-freezing II and drying II treatments to recover the cellulose aerogel.

[0065] In the present invention, the impregnation liquid is an aqueous solution containing dissolved cellulose aerogel, and the impregnation liquid is subjected to pre-freezing II and drying II treatments to separate water therefrom to obtain recovered cellulose aerogel. The recovered cellulose aerogel can be returned to step (1) for recycling.

[0066] In a preferred embodiment of the present invention, in step (4), the mass ratio of the composite aerogel to water is 1:20-100, preferably 1:40-60.

[0067] Among them, in the present invention, since the cellulose aerogel is recovered by freezing II and drying II treatment, the volume of the impregnation liquid itself will affect the stability of the skeleton structure of the recovered cellulose aerogel. When the amount of water used is too much, the volume of the impregnation liquid is large, and the three-dimensional network structure of the cellulose aerogel obtained after freezing II and drying II treatment is easy to collapse. In order to stabilize the skeleton structure of the recovered cellulose aerogel, it is preferred to control the mass ratio of the composite aerogel to water to be between 1:20-100.

[0068] In one embodiment of the present invention, the freezing temperature of the pre-freezing II is -80°C to -10°C, preferably -60°C to -30°C; the pre-freezing time of the pre-freezing II is 6-48h, preferably 12-24h.

[0069] In one embodiment of the present invention, the drying II is selected from one or more of freeze drying, supercritical carbon dioxide drying, and vacuum freeze drying.

[0070] Among them, in the present invention, unless otherwise specified, pre-freezing, pre-freezing I, pre-freezing II, drying, drying I, drying II may be the same or different, and the present invention does not make any special limitation on this.

[0071] The second aspect of the present invention provides a polymer aerogel prepared by the method described in the first aspect of the present invention.

[0072] In one embodiment of the present invention, the specific surface area of ​​the polymer aerogel is 150-400m 2 / g, preferably 250-325m 2 / g.

[0073] The present invention will be described in detail below through examples: Polyethylene glycol diglycidyl ether was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product model P134831; carboxymethyl cellulose was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product model C104985.

[0074] Example 1

[0075] (1) adding waste polyvinyl chloride to dimethyl sulfoxide, stirring at 60° C. for 40 minutes, so that the waste polyvinyl chloride is fully dissolved in the dimethyl sulfoxide to obtain a homogeneous solution; wherein the mass ratio of the waste polyvinyl chloride to the dimethyl sulfoxide is 1:50;

[0076] (2) adding 1 g of carboxymethyl cellulose to 99 g of deionized water, stirring at 50° C. until completely dissolved, to obtain a homogeneous cellulose solution; adding 0.1 g of polyethylene glycol diglycidyl ether to the homogeneous cellulose solution, stirring at 1000 rpm for 20 min, using ultrasonic sonication with a power of 600 W for 30 min to remove bubbles, and then pre-freezing at -30° C. for 24 h, and then vacuum freeze-drying at -196° C. for 48 h to obtain a carboxymethyl cellulose aerogel;

[0077] The homogeneous solution was cooled to 30°C and dripped onto the carboxymethyl cellulose aerogel at a speed of 80 d / min until the dripped droplets stayed on the surface of the carboxymethyl cellulose aerogel and no longer penetrated downward; then aged at 30°C for 24 hours to obtain an aged product;

[0078] (3) pre-freezing the aged product at -60°C for 12 hours, and then freeze-drying it in a vacuum at -196°C for 48 hours to obtain a composite aerogel;

[0079] (4) immersing the composite aerogel in water, slowly stirring at 40° C. for 3 h, and then filtering to obtain an extract and a solid, and drying the solid at 40° C. to obtain a polymer aerogel; wherein the mass ratio of the composite aerogel to water is 1:50;

[0080] (5) The extract was pre-frozen at -30°C for 12 h, and then vacuum freeze-dried at -196°C for 48 h to obtain the recovered carboxymethyl cellulose aerogel.

[0081] Example 2

[0082] (1) adding waste polyethylene to hexadecane and stirring at 130° C. for 40 min to fully dissolve the waste polyethylene in the hexadecane to obtain a homogeneous solution; wherein the mass ratio of the waste polyethylene to the hexadecane is 1:100;

[0083] (2) adding 1 g of carboxymethyl cellulose to 99 g of deionized water, stirring at 50° C. until completely dissolved, to obtain a homogeneous cellulose solution; adding 0.1 g of polyethylene glycol diglycidyl ether to the homogeneous cellulose solution, stirring at 1000 rpm for 20 min, using ultrasonic sonication with a power of 600 W for 30 min to remove bubbles, and then pre-freezing at -30° C. for 24 h, and then vacuum freeze-drying at -196° C. for 48 h to obtain a carboxymethyl cellulose aerogel;

[0084] The homogeneous solution was cooled to 40°C and dripped onto the carboxymethyl cellulose aerogel at a speed of 60 d / min until the dripped droplets stayed on the surface of the carboxymethyl cellulose aerogel and no longer penetrated downward; then aged at 30°C for 24 hours to obtain an aged product;

[0085] (3) pre-freezing the aged product at -60°C for 12 hours, and then freeze-drying it in a vacuum at -196°C for 48 hours to obtain a composite aerogel;

[0086] (4) immersing the composite aerogel in water, slowly stirring at 40° C. for 3 h, and then filtering to obtain an extract and a solid, and drying the solid at 40° C. to obtain a polymer aerogel; wherein the mass ratio of the composite aerogel to water is 1:50;

[0087] (5) The extract was pre-frozen at -30°C for 12 h and then vacuum freeze-dried at -196°C for 48 h to obtain the recovered cellulose aerogel.

[0088] Example 3

[0089] (1) adding waste polystyrene to cyclohexanone and stirring at 60° C. for 40 minutes to fully dissolve the waste polystyrene in the cyclohexanone to obtain a homogeneous solution; wherein the mass ratio of the waste polystyrene to the cyclohexanone is 1:70;

[0090] (2) adding 1 g of carboxymethyl cellulose to 99 g of deionized water, stirring at 50° C. until completely dissolved, to obtain a homogeneous cellulose solution; adding 0.1 g of polyethylene glycol diglycidyl ether to the homogeneous cellulose solution, stirring at 1000 rpm for 20 min, using ultrasonic sonication with a power of 600 W for 30 min to remove bubbles, and then pre-freezing at -30° C. for 24 h, and then vacuum freeze-drying at -196° C. for 48 h to obtain a carboxymethyl cellulose aerogel;

[0091] The homogeneous solution was cooled to 35°C and dripped onto the carboxymethyl cellulose aerogel at a rate of 100 d / min until the dripped droplets stayed on the surface of the carboxymethyl cellulose aerogel and no longer penetrated downward; then aged at 30°C for 24 hours to obtain an aged product;

[0092] (3) pre-freezing the aged product at -60°C for 12 hours, and then freeze-drying it in a vacuum at -196°C for 48 hours to obtain a composite aerogel;

[0093] (4) immersing the composite aerogel in water, slowly stirring at 40° C. for 3 h, and then filtering to obtain an extract and a solid, and drying the solid at 40° C. to obtain a polymer aerogel; wherein the mass ratio of the composite aerogel to water is 1:50;

[0094] (5) The extract was pre-frozen at -30°C for 12 h and then vacuum freeze-dried at -196°C for 48 h to obtain the recovered cellulose aerogel.

[0095] Example 4

[0096] The same as Example 1, except that dimethyl sulfoxide is replaced by N,N-dimethylacetamide in an equal amount.

[0097] Example 5

[0098] The same as Example 1, except that the mass ratio of waste polyvinyl chloride plastic to dimethyl sulfoxide is 1:10.

[0099] Example 6

[0100] The same as Example 1, except that the cellulose aerogel in step (2) is the recovered carboxymethyl cellulose aerogel in Example 1.

[0101] Example 7

[0102] The same as Example 1, except that the mass ratio of the composite aerogel to water is 1:120.

[0103] Comparative Example 1

[0104] (1) adding waste polyvinyl chloride plastic into dimethyl sulfoxide, stirring at 60° C. until the waste polyvinyl chloride plastic is fully dissolved in the dimethyl sulfoxide to obtain a homogeneous solution; wherein the mass ratio of the waste polyvinyl chloride plastic to the dimethyl sulfoxide is 1:50;

[0105] (2) aging the homogeneous solution at 30° C. for 24 h to obtain an aged product;

[0106] (3) The aged product was frozen at -60°C for 12 h, and then vacuum freeze-dried at -196°C for 48 h to obtain a polymer aerogel.

[0107] Comparative Example 2

[0108] The same as Example 7, except that the cellulose aerogel in step (2) is the cellulose aerogel recovered in Example 7.

[0109] Test Case

[0110] The specific surface areas of the polymer aerogels prepared in the examples and comparative examples were tested by N2 adsorption and desorption. The test results are shown in Table 1.

[0111] Table 1

[0112] <![CDATA[Specific surface area m 2 / g]]> Example 1 311 Example 2 258 Example 3 274 Example 4 287 Example 5 198 Example 6 307 Example 7 304 Comparative Example 1 52 Comparative Example 2 95

[0113] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including combining various technical features in any other suitable manner, and these simple modifications and combinations are the same.

Claims

1. A method for preparing polymer aerogel using waste plastics, characterized in that: The method comprises the following steps: (1) dissolving waste plastics in an organic solvent to obtain a homogeneous solution; (2) adding the homogeneous solution into cellulose aerogel for aging treatment to obtain an aged product; (3) pre-freezing and drying the aged product to obtain a composite aerogel; (4) Immersing the composite aerogel in water to obtain an leaching liquid and a polymer aerogel.

2. The preparation method according to claim 1, wherein The waste plastic is selected from one or more of waste polyethylene, waste polypropylene, waste polystyrene and waste polyvinyl chloride; Preferably, the organic solvent is selected from one or more of xylene, tetralin, decalin, hexadecane, dimethyl sulfoxide, cyclohexanone, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

3. The preparation method according to claim 2, wherein The waste plastic is waste polyethylene and / or waste polypropylene, and the organic solvent is one or more of xylene, tetralin, decalin, and hexadecane, preferably hexadecane; Preferably, the waste plastic is waste polystyrene, and the organic solvent is one or more of cyclohexanone, xylene, tetralin, and decalin, preferably cyclohexanone; Preferably, the waste plastic is waste polyvinyl chloride, and the organic solvent is dimethyl sulfoxide, cyclohexanone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, preferably dimethyl sulfoxide.

4. The preparation method according to any one of claims 1 to 3, wherein The mass ratio of the waste plastic to the organic solvent is 1:10-200, preferably 1:20-100; Preferably, the dissolution operating conditions include: dissolution temperature of 40-140°C, preferably 50-70°C; dissolution time of 15-120 min, preferably 30-60 min.

5. The preparation method according to any one of claims 1 to 4, wherein: The cellulose aerogel is selected from one or more of carboxymethyl cellulose aerogel, carboxylated cellulose nanofiber aerogel, hydroxypropyl methyl cellulose aerogel, and methyl cellulose aerogel, preferably carboxymethyl cellulose aerogel; Preferably, the cellulose aerogel is prepared by a sol-gel method; Preferably, the sol-gel method comprises: firstly adding a crosslinking agent into an aqueous solution containing cellulose, stirring and ultrasonically treating the solution, and then pre-freezing I and drying I to obtain a cellulose aerogel; Preferably, the cross-linking agent is selected from one or more of polyethylene glycol diglycidyl ether, citric acid, 1,4-butanediol diglycidyl ether, and polyvinyl alcohol, preferably polyethylene glycol diglycidyl ether; Preferably, the cellulose is selected from one or more of carboxymethyl cellulose, carboxylated cellulose nanofibers, hydroxypropyl methyl cellulose, and methyl cellulose, preferably carboxymethyl cellulose; Preferably, the mass ratio of the crosslinking agent to cellulose is 1:5-15, preferably 1:8-12; Preferably, the cellulose content in the aqueous solution containing cellulose is 0.5-2wt%, preferably 1-1.5wt%; Preferably, the stirring operating conditions include: stirring speed of 500-1500rpm, preferably 800-1200rpm; stirring time of 5-35min, preferably 15-25min; stirring temperature of 30-80°C, preferably 40-60°C; Preferably, the ultrasonic operation conditions include: ultrasonic power of 200-1000w, preferably 500-700w; ultrasonic time of 10-50min, preferably 20-40min; Preferably, the freezing temperature of the pre-freezing I is -80°C to -10°C, preferably -60°C to -30°C; Preferably, the drying I is selected from one or more of freeze drying, supercritical carbon dioxide drying, and vacuum freeze drying.

6. The preparation method according to any one of claims 1 to 5, wherein: The adding method is dropwise addition; Preferably, the dropping speed is 30-200 d / min, preferably 60-100 d / min; Preferably, the dropping temperature of the homogeneous solution is 25-50°C, preferably 30-40°C; Preferably, the homogeneous solution is added until the homogeneous solution remains on the surface of the cellulose aerogel and no longer penetrates into the cellulose aerogel; Preferably, the operating conditions of the aging treatment include: an aging temperature of 25-50°C, preferably 30-40°C; an aging time of 4-48h, preferably 24-36h.

7. The preparation method according to any one of claims 1 to 6, wherein: The pre-freezing temperature is -80°C to -10°C, preferably -60°C to -30°C; Preferably, the drying is selected from one or more of freeze drying, supercritical carbon dioxide drying, and vacuum freeze drying.

8. The preparation method according to any one of claims 1 to 7, wherein: The temperature of the water is 20-50° C., preferably 40-50° C.; the immersion time is 0.5-6 h, preferably 2-4 h.

9. The preparation method according to any one of claims 1 to 8, wherein: The method further comprises step (5), wherein the leaching solution is subjected to pre-freezing II and drying II treatments to recover the cellulose aerogel; Preferably, in step (4), the mass ratio of the composite aerogel to water is 1:20-100, preferably 1:40-60; Preferably, the freezing temperature of the pre-freezing II is -80°C to -10°C, preferably -60°C to -30°C; Preferably, the drying II is selected from one or more of freeze drying, supercritical carbon dioxide drying, and vacuum freeze drying.

10. A polymer aerogel prepared by the method according to any one of claims 1 to 9.