Super-hydrophilic and oleophylic polymethacrylimide foam and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of polymethacrylimide foam, and particularly relates to super-hydrophilic and oleophylic polymethacrylimide foam and a preparation method thereof. The preparation method comprises the following steps: firstly, preparing polyvinyl alcohol coated metal oxide powder, namely filler, by taking polyvinyl alcohol and metal oxide powder as raw materials, then applying the filler as a raw material to preparation of polymethacrylimide foam, soaking the polymethacrylimide foam in a weak acid solution to dissolve polyvinyl alcohol on the surface of the filler, and finally, preparing the polymethacrylimide foam. A weak acid solution and metal oxide powder are used for carrying out surface etching reaction, and a micro-nano coarse structure is constructed on the surface of the polymethacrylimide foam, so that the polymethacrylimide foam has very good affinity with polar and non-polar macromolecules, and the super-hydrophilic and oleophylic characteristics are realized; the problems that the impregnation property of the polymethacrylimide foam surface and resin is insufficient, and the bonding strength between a bonding agent and a foam interface is insufficient are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polymethacrylimide foam preparation, and particularly relates to super-hydrophilic and super-oleophilic polymethacrylimide foam and a preparation method thereof. BACKGROUND

[0002] Polymethacrylimide (PMI) foam is a 100% rigid structure foam with closed pores, uniform pore size distribution and isotropy, and has excellent structural stability, high mechanical strength and high temperature resistance, etc. It is the polymer rigid foam material with the highest specific strength and specific stiffness at present, commonly known as 'foam king', and is widely used in the fields of aerospace, weapon equipment, etc. As one of the main core materials of foam sandwich structure composites, like other closed-cell rigid foams, in the process of preparing the composite material, due to the insufficient impregnation of the foam surface and the resin, the bonding strength between the skin of the foam sandwich structure composite and the foam core layer is weak, especially the bonding strength between the adhesive and the foam interface is insufficient, which is one of the main reasons for the skin peeling and bulging of the foam sandwich structure composite. The traditional solution is to adjust the components or viscosity of the adhesive or spend a lot of effort to clean the foam surface, but the bonding effect is difficult to guarantee. SUMMARY

[0003] In view of the above problems in the prior art, the application provides super-hydrophilic and super-oleophilic polymethacrylimide foam and a preparation method thereof. The application first prepares polyvinyl alcohol-coated metal oxide powder, i.e. filler, using polyvinyl alcohol and metal oxide powder as raw materials, then uses the filler as raw material and applies it to the preparation of PMI foam, and then soaks the PMI foam in a weak acid solution, uses the weak acid aqueous solution to dissolve the polyvinyl alcohol on the surface of the filler, and then performs etching reaction with the metal oxide powder to construct a micro-nano rough structure on the surface of the PMI foam. The PMI foam with the micro-nano rough structure has good affinity with polar and non-polar polymers, realizes the super-hydrophilic and super-oleophilic properties of the PMI foam, and then obtains super-hydrophilic and super-oleophilic PMI foam, which overcomes the problems of insufficient impregnation of the foam surface and the resin and insufficient bonding strength between the adhesive and the foam interface.

[0004] Based on the above technical purposes, the application adopts the following technical solutions: The application protects a preparation method of a filler, which comprises the following steps: Dissolve polyvinyl alcohol macromolecular particles in hot water to prepare a polyvinyl alcohol aqueous solution, then mix the metal oxide powder with the polyvinyl alcohol aqueous solution and perform ball milling, and then sequentially filter and dry to obtain the filler, which is the polyvinyl alcohol-coated metal oxide powder; wherein the metal oxide powder is a metal oxide powder capable of reacting with a weak acid, facilitating reaction with the weak acid after the PMI foam is prepared to construct a micro-nano rough structure on the surface of the PMI foam. In this step, the purpose of polyvinyl alcohol is to uniformly coat the metal oxide powder, so the amount of polyvinyl alcohol used in the preparation process is higher than that of the metal oxide powder.

[0005] Preferably, the metal oxide is selected from MgO, ZnO, Al2O3, and CaO.

[0006] Preferably, the particle size of the metal oxide powder is less than 300 mesh. If it is higher than 300 mesh, a micro-nano structure cannot be formed; based on the micro-nano structure and the contact angle being less than 90°, the PMI foam achieves super-hydrophilic and super-oleophilic properties.

[0007] Preferably, the molecular weight of the polyvinyl alcohol macromolecular particles is greater than 2000. A molecular weight higher than 2000 is more likely to form a film and facilitates coating of the metal oxide powder.

[0008] Preferably, the metal oxide powder is a metal oxide capable of reacting with a weak acid, and the weak acid is selected from glacial acetic acid, formic acid, or benzoic acid.

[0009] The application also protects a filler prepared by the above preparation method.

[0010] The application also protects a super-hydrophilic and super-oleophilic polymethacrylimide foam prepared using the above filler.

[0011] Preferably, the super-hydrophilic and super-oleophilic polymethacrylimide foam is prepared from the following raw materials by weight: 100 parts of base resin monomer, 5-10 parts of thickening agent, 20-50 parts of filler, 0.01-0.05 parts of retarder, 0.1-0.5 parts of initiator, 0.7-5 parts of crosslinking agent, 3-12 parts of foaming agent, and 0.2-5 parts of nucleating agent. Too much filler will affect foaming and foam density, and too little filler will not be conducive to the micro-nano rough structure of the super-hydrophilic and super-oleophilic polymethacrylimide foam.

[0012] Preferably, the base resin monomer is composed of acrylonitrile monomer and acrylic monomer, the mass ratio of the acrylonitrile monomer to the acrylic monomer is 1:0.95-1.05, the thickening agent is polyacrylonitrile with a molecular weight of >80000, the retarder is an allyl monomer, the initiator is a peroxo compound or a peroxide compound, the foaming agent is at least one selected from isopropyl alcohol, formamide, and tert-butyl methacrylate, the crosslinking agent is at least one selected from allyl methacrylate, allyl acrylate, and magnesium methacrylate, and the nucleating agent is at least one selected from tert-butyl methacrylate, isobutyl methacrylate, and N-methyl formamide.

[0013] The application also protects a preparation method of the super-hydrophilic and oleophilic PMI foam, comprising the following steps: The raw materials are weighed according to the following proportions: 100 parts of base resin monomer, 5-10 parts of thickening agent, 20-50 parts of filler, 0.01-0.05 parts of retarder, 0.1-0.5 parts of initiator, 0.7-5 parts of crosslinking agent, 3-12 parts of foaming agent, and 0.2-5 parts of nucleating agent.

[0014] After the base resin monomer is dissolved, the retarder, the initiator, the crosslinking agent, the foaming agent, and the nucleating agent are mixed to obtain a mixed solution.

[0015] The filler is mixed in the mixed solution to obtain a mixed reaction slurry.

[0016] The thickening agent is mixed in the mixed reaction slurry to obtain a viscous mixed reaction slurry.

[0017] The viscous mixed reaction slurry is polymerized at 30-60℃ for 24-48h to obtain a PMI foaming precursor polymer.

[0018] The PMI foaming precursor polymer is heat-treated to obtain a PMI foam.

[0019] The PMI foam is soaked in a weak acid solution, and the weak acid solution and the metal oxide powder on the surface of the PMI foam are etched to form a micro-nano rough structure on the surface of the PMI foam, thereby obtaining a super-hydrophilic and oleophilic PMI foam.

[0020] Preferably, the heat treatment conditions are as follows: first, the PMI foaming precursor polymer is treated at 105℃ for 3-5h to remove the water in the PMI foaming precursor polymer; then, the PMI foaming precursor polymer is treated at 150℃ for 10-12h to ensure that the PMI foaming precursor polymer is uniformly heated inside and outside; then, the PMI foaming precursor polymer is foamed at 180-240℃ for 0.5-3h; finally, the PMI foam is treated at 160℃ for 4-5h and at 100℃ for 5-6h to gradually reduce the temperature inside and outside the PMI foam, thereby avoiding deformation or cracking of the PMI foam due to a large temperature difference between the inside and the outside of the PMI foam; and finally, the PMI foam is naturally cooled to room temperature.

[0021] Compared with the prior art, the present application has the beneficial effects that: 1、The present application is based on the preparation of traditional PMI foam, one is to modify the matrix of PMI foam by adding fillers, the fillers are polyvinyl alcohol coated metal oxide powder, and the other is to construct a micro-nano rough structure on the surface of PMI foam by surface weak acid etching for surface structure modification, that is, to modify the intrinsic properties of PMI foam to improve the impregnation and bonding effect of PMI foam and adhesive. Compared with traditional external modification, it has the significant advantages of strong foam adaptability and low process cost.

[0022] 2、The technical difficulties of the present application are the selection and pretreatment of fillers, which not only prevent the fillers from reacting with the methyl methacrylate in the PMI reaction components, but also facilitate the subsequent etching reaction with weak acid, and the construction of micro-nano rough structure on the surface of the foam. For the first one, polyvinyl alcohol is selected by the present application, which can be dissolved in water and not in PMI reaction monomers. During the polymerization process of viscous mixed reaction slurry, the polyvinyl alcohol coating prevents the methyl methacrylate in the matrix resin monomer from reacting with the metal oxide. For the second one, the PMI foam is placed in a weak acid aqueous solution, the polyvinyl alcohol of the fillers on the surface layer of the PMI foam will dissolve in water, allowing the metal oxide particles on the surface layer of the PMI foam to react with the acid and be removed, thereby forming a micro-nano rough structure on the surface of the PMI foam.

[0023] 3、The super-hydrophilic and super-oleophilic PMI foam prepared by the method of the present application has super-hydrophilic and super-oleophilic properties, which generally refer to two types of functional groups, the super-oleophilic is generally non-polar, and the super-hydrophilic is generally polar, the super-hydrophilic and super-oleophilic properties indicate that the surface has good affinity with polar and non-polar polymers; the super-hydrophilic and super-oleophilic PMI foam has a contact angle close to 0 degrees with water, commonly used epoxy resin and unsaturated polyester resin, and the interfacial adhesion strength between the skin and the foam is greater than 5 N / cm; in the process of preparing sandwich structure composites using super-hydrophilic and super-oleophilic PMI foam, the selection space of the matrix resin material can be effectively expanded, the surface treatment process of super-hydrophilic and super-oleophilic PMI foam can be greatly simplified, thereby greatly reducing the process and material cost of preparing sandwich structure composites, and having significant economic and social effects. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A physical diagram of a foam sandwich structure composite prepared using the super-hydrophilic and super-oleophilic PMI foam of Example 1. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application. The experimental methods described in the embodiments of the present application are conventional methods unless otherwise specified.

[0026] In view of the problems of insufficient impregnation of the foam surface of the prior art PMI foam in the preparation of the composite material and insufficient bonding strength between the adhesive and the foam interface, the present application first provides a filler, which is a polyvinyl alcohol coated metal oxide powder, then the filler is applied to the conventional PMI foam, and then the polyvinyl alcohol is dissolved in a weak acid solution and completely reacts with the metal oxide powder to build a micro-nano rough structure on the surface of the PMI foam. This surface has good affinity with polar and non-polar polymers, thereby realizing the super-hydrophilic and oleophilic properties of the PMI foam. Compared with the prior art, the present application starts from the structure of the PMI foam and overcomes the technical defects of the traditional solutions in the prior art by preparing a super-hydrophilic and oleophilic PMI foam.

[0027] The technical solutions of the present application are further studied by using the following examples, as shown below: Example 1 A preparation method of a super-hydrophilic and oleophilic PMI foam, comprising the following steps: S1, dissolve polyvinyl alcohol particles in hot water to prepare a 5wt% polyvinyl alcohol aqueous solution, then mix MgO powder with the polyvinyl alcohol aqueous solution, the mass ratio of the two is 20:100, ball mill for 30min, then filter, dry and disperse in sequence to obtain polyvinyl alcohol coated MgO powder, i.e. the filler.

[0028] S2, the raw materials are weighed as follows: 100 parts of base resin monomer (mass ratio of 1:1 of methacrylonitrile and acrylic acid), 5 parts of thickening agent (polyacrylonitrile polymer), 20 parts of filler (polyvinyl alcohol coated MgO powder), 0.01 parts of retarder (allyl alcohol), 0.1 parts of initiator (methyl ethyl ketone peroxide), 0.7 parts of crosslinking agent (allyl methacrylate), 5 parts of foaming agent (formamide), and 0.2 parts of nucleating agent (tert-butyl methacrylate).

[0029] S3, take 100 parts of base resin monomer, then add the retarder, initiator, crosslinking agent, foaming agent and nucleating agent in sequence, and mechanically stir and disperse for 30min to obtain a mixed solution.

[0030] S4, add the filler to the mixed solution while stirring, and stir for another 30min after the addition is completed to obtain a mixed reaction slurry.

[0031] S5, the thickening agent is added to the mixed reaction slurry in batches and stirred and dissolved to obtain a viscous mixed reaction slurry.

[0032] S6, the viscous mixed reaction slurry is injected into a sealed mold and polymerized in a water bath at 50°C for 24h, until the mixed reaction slurry is completely cured, to obtain a PMI foaming precursor polymer, and the PMI foaming precursor polymer is demolded.

[0033] S7, the PMI foaming precursor polymer is placed in a hot air oven, first treated at 105°C for 3h, then treated at 150°C for 12h, foamed at 240°C for 0.5h, finally treated at 160°C for 4h, and finally treated at 100°C for 6h, and then naturally cooled to room temperature, to obtain a PMI foam.

[0034] S8, the PMI foam is skinned and cut to the desired size, and then soaked in 50% glacial acetic acid for 30min, to obtain a super-hydrophilic and oleophilic PMI foam.

[0035] Example 2 The preparation steps are the same as those of Example 1, except that the mass of the filler is replaced by 30 parts instead of 20 parts, and the mass of the foaming agent is replaced by 8 parts instead of 5 parts.

[0036] Example 3 A method for preparing a super-hydrophilic and oleophilic PMI foam, comprising the following steps: S1, polyvinyl alcohol macromolecular particles are dissolved in hot water to prepare a 5wt% polyvinyl alcohol aqueous solution, then ZnO powder is mixed with the polyvinyl alcohol aqueous solution, the mass ratio of the two being 30:100, ball-milled for 30min, and then filtered, dried and dispersed in sequence to obtain polyvinyl alcohol-coated ZnO powder, i.e. a filler.

[0037] S2, the raw materials are weighed according to the following proportions: 100 parts of base resin monomer (mass ratio of methacrylonitrile and acrylic acid 1:0.95), 8 parts of thickening agent (polyacrylonitrile macromolecule), 40 parts of filler (polyvinyl alcohol-coated ZnO powder), 0.03 parts of retarder (allyl alcohol), 0.2 parts of initiator (methyl ethyl ketone peroxide), 3 parts of crosslinking agent (allyl methacrylate), 3 parts of foaming agent (formamide), and 3 parts of nucleating agent (tert-butyl methacrylate).

[0038] S3, 100 parts of base resin monomer are taken, and then the retarder, initiator, crosslinking agent, foaming agent and nucleating agent are added in sequence, and mechanically stirred and dispersed for 30min to obtain a mixed liquid.

[0039] S4, the filler is added to the mixed liquid while stirring, and after the addition is completed, stirring is continued for 30min to obtain a mixed reaction slurry.

[0040] S5, the thickening agent is added to the mixed reaction slurry in batches and stirred and dissolved to obtain a viscous mixed reaction slurry.

[0041] S6, the viscous mixed reaction slurry is injected into a sealed mold and polymerized in a water bath at 30°C for 48h, and the mixed reaction slurry is completely cured to obtain a PMI foaming precursor polymer. The PMI foaming precursor polymer is demolded.

[0042] S7, the PMI foaming precursor polymer is placed in a hot air oven, first treated at 105°C for 4h, then treated at 150°C for 11h, foamed at 200°C for 1h, finally treated at 160°C for 4.5h, and finally treated at 100°C for 5h, and then naturally cooled to room temperature to obtain a PMI foam.

[0043] S8, the PMI foam is peeled and cut into the required size, and then soaked in 50% formic acid for 10min to obtain a super-hydrophilic and oleophilic PMI foam.

[0044] Example 4 A method for preparing a super-hydrophilic and oleophilic PMI foam, comprising the following steps: S1, polyvinyl alcohol macromolecular particles are dissolved in hot water to prepare a 5wt% polyvinyl alcohol aqueous solution, then CaO powder is mixed with the polyvinyl alcohol aqueous solution, the mass ratio of the two is 10:100, ball milling for 30min, and then filtering, drying and dispersing in sequence to obtain polyvinyl alcohol coated CaO powder, i.e. filler.

[0045] S2, the raw materials are weighed according to the following proportions: 100 parts of base resin monomer (mass ratio of methacrylonitrile and acrylic acid 1:1), 10 parts of thickening agent (polyacrylonitrile macromolecule), 50 parts of filler (polyvinyl alcohol coated CaO powder), 0.05 parts of retarder (allyl alcohol), 0.5 parts of initiator (methyl ethyl ketone peroxide), 5 parts of crosslinking agent (allyl methacrylate), 12 parts of foaming agent (formamide), and 5 parts of nucleating agent (tert-butyl methacrylate).

[0046] S3, 100 parts of base resin monomer are taken, and then the retarder, initiator, crosslinking agent, foaming agent and nucleating agent are added in sequence, and mechanically stirred and dispersed for 30min to obtain a mixed liquid.

[0047] S4, the filler is added to the mixed liquid while stirring, and after the addition is completed, the stirring is continued for 30min to obtain a mixed reaction slurry.

[0048] S5, the thickening agent is added to the mixed reaction slurry in batches and stirred and dissolved to obtain a viscous mixed reaction slurry.

[0049] S6, inject the viscous mixed reaction slurry into a closed mold, and polymerize in a water bath at 60°C for 30h, until the mixed reaction slurry is completely cured, to obtain a PMI foaming precursor polymer, and demold the PMI foaming precursor polymer.

[0050] S7, place the PMI foaming precursor polymer in a hot air oven, first treat at 105°C for 5h, then treat at 150°C for 10h, again treat at 180°C for 3h, finally treat at 160°C for 5h, and finally treat at 100°C for 5.5h, and then naturally cool to room temperature, to obtain a PMI foam.

[0051] S8, skin the PMI foam and cut it to the desired size, and then soak it in 50% benzoic acid for 5min, to obtain a super-hydrophilic and oleophilic PMI foam.

[0052] Comparative Example 1 A method for preparing a PMI foam, which is the same as the preparation steps of Example 1, except that no filler is used to prepare the PMI foam, comprising the following steps: S1, take the following raw materials according to the weight ratio: 100 parts of base resin monomer (mass ratio of 1:1 of methacrylonitrile and acrylic acid), 5 parts of thickening agent (polyacrylonitrile polymer), 0.01 parts of retarder (allyl alcohol), 0.1 parts of initiator (methyl ethyl ketone peroxide), 0.7 parts of crosslinking agent (allyl methacrylate), 5 parts of foaming agent (formamide), and 0.2 parts of nucleating agent (tert-butyl methacrylate), for standby use.

[0053] S2, take 100 parts of base resin monomer, and then add the retarder, initiator, crosslinking agent, foaming agent, and nucleating agent into it in sequence, and mechanically stir and disperse for 30min, to obtain a mixed liquid.

[0054] S3, add the thickening agent into the mixed liquid in batches, and stir and dissolve, to obtain a viscous mixed reaction slurry.

[0055] S4, inject the viscous mixed reaction slurry into a closed mold, and polymerize in a water bath at 50°C for 24h, until the mixed reaction slurry is completely cured, to obtain a PMI foaming precursor polymer, and demold the PMI foaming precursor polymer.

[0056] S5, place the PMI foaming precursor polymer in a hot air oven, first treat at 105°C for 3h, then treat at 150°C for 12h, again treat at 240°C for 0.5h, finally treat at 160°C for 4h, and finally treat at 100°C for 6h, and then naturally cool to room temperature, to obtain a PMI foam.

[0057] The super-hydrophilic and super-oleophilic PMI foams prepared in Embodiment 1 to Embodiment 4 all have excellent performance, and the super-hydrophilic and super-oleophilic PMI foam prepared in Embodiment 1 is taken as an example for research, and the specific research method and results are shown as follows. Table 1: Summary of experimental data of preparation method of super-hydrophilic and super-oleophilic PMI foam The results in Table 1 show that the super-hydrophilic and super-oleophilic PMI foam prepared by the method of the present application has super-oleophilic and super-hydrophilic properties, and the contact angles with water, epoxy resin and unsaturated polyester resin are all less than 5 degrees; the addition of fillers has little effect on the mechanical properties of the PMI foam; compared with the conventional PMI foam sandwich structure composite (i.e., the sandwich structure composite prepared by using the PMI foam of Comparative Example 1), the skin glass strength of the sandwich structure composite prepared by using the super-hydrophilic and super-oleophilic PMI foam is increased by 52.6%.

[0058] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing a super-hydrophilic and oleophilic polymethacrylimide foam, characterized in that, The method comprises the following steps: The raw materials are weighed according to the following proportions: 100 parts of base resin monomer, 5-10 parts of thickening agent, 20-50 parts of filler, 0.01-0.05 parts of retarder, 0.1-0.5 parts of initiator, 0.7-5 parts of crosslinking agent, 3-12 parts of foaming agent, and 0.2-5 parts of nucleating agent; The filler is prepared by the following steps: dissolving polyvinyl alcohol macromolecular particles in hot water to prepare a polyvinyl alcohol aqueous solution, then mixing the metal oxide powder with the polyvinyl alcohol aqueous solution and performing ball milling, and then sequentially filtering and drying to obtain the filler; After the base resin monomer is dissolved, the retarder, initiator, crosslinking agent, foaming agent, nucleating agent, filler and thickening agent are uniformly mixed to obtain a viscous mixed reaction slurry; The viscous mixed reaction slurry is subjected to polymerization reaction to obtain a PMI foaming precursor polymer; The PMI foaming precursor polymer is subjected to heat treatment to obtain a PMI foam; The PMI foam is soaked in a weak acid solution, the polyvinyl alcohol on the surface of the filler is dissolved by the weak acid solution, and then an etching reaction is performed with the metal oxide powder to construct a micro-nano rough structure on the surface of the PMI foam, thereby obtaining a super-hydrophilic and oleophilic polymethacrylimide foam.

2. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The metal oxide is selected from MgO, ZnO, Al2O3 or CaO.

3. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The particle size of the metal oxide powder is less than 300 mesh.

4. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The molecular weight of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is greater than 2000.

5. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The weak acid is selected from glacial acetic acid, formic acid or benzoic acid.

6. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The base resin monomer is composed of acrylonitrile monomers and acrylic monomers, the mass ratio of which is 1:0.95-1.05, the thickening agent is polyacrylonitrile with a molecular weight of >80000, the retarder is an allyl monomer, the initiator is a per-azo compound or a peroxide compound, the foaming agent is selected from at least one of isopropyl alcohol, formamide and tert-butyl methacrylate, the crosslinking agent is selected from at least one of allyl methacrylate, allyl acrylate and magnesium methacrylate, and the nucleating agent is selected from at least one of tert-butyl methacrylate, isobutyl methacrylate and N-methyl formamide.

7. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The polymerization reaction is performed at 30-60℃ for 24-48h.

8. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The heat treatment is performed at 105℃ for 3-5h, then at 150℃ for 10-12h, followed by foaming at 180-240℃ for 0.5-3h, then at 160℃ for 4-5h, and finally at 100℃ for 5-6h, and then naturally cooled to room temperature.

9. The method of making a superhydrophilic oleophilic polymethacrylimide foam according to claim 1, wherein, The etching reaction is performed at room temperature for 5-30min.

10. A super-hydrophilic and oleophilic polymethacrylimide foam, characterized in that, The method is prepared by any one of claims 1-9.

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