Furfural acetal-maleic anhydride copolymer and preparation method thereof

Abstract

The invention relates to a furfural acetal-maleic anhydride copolymer and a preparation method thereof. The furfural acetal-maleic anhydride copolymer comprises a structural unit I as shown in a formula (1) and a structural unit II as shown in a formula (2), in formula (II), the bond having the number * represents a linking bond to another structural unit, n represents an integer of 1-2, R1 and R2 each independently represent a hydrogen atom, a hydroxyl group, an alkyl group, or a hydroxyalkyl group, where the alkyl group and the hydroxyalkyl group each independently have 1-3 carbon atoms, and when n is 2, each R2 may be the same or different. The furfural acetal-maleic anhydride copolymer disclosed by the invention can be prepared by taking biomass as an initial raw material, so that the consumption of fossil resources is reduced, the total cost is reduced, and the requirement of constructing a zero-carbon society is better met. The preparation method is simple in process, low in cost, high in efficiency, easy in product separation and suitable for industrial production. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of polymer chemistry, and particularly relates to a furfural acetal-maleic anhydride copolymer and a preparation method thereof. Background Art

[0002] The shortage and non-renewability of fossil resources have made renewable and sustainable biomass materials the key to future sustainable material innovation. Among them, synthesizing bio-based polymers from biomass monomers is one of the main approaches. Among numerous biomass platform chemicals, furfural is one of the few products that have achieved industrial-scale biorefining. The industrial production of furfural mainly originates from lignocellulosic wastes (such as corncobs, wheat bran, and sawdust). Due to its mature technology and low price (7000-9000 yuan / ton), and it exhibits excellent derivatization versatility, and can synthesize a series of furan derivatives through mature chemical routes. Its high-value utilization has great potential in both industry and scientific research.

[0003] Currently, more than 60% of the global furfural is used for catalytic hydrogenation to prepare furfuryl alcohol (FA). Furfuryl alcohol is one of the main precursors of foundry-grade furfuryl alcohol resin (accounting for 90% of the FA market). Furfuryl alcohol and itself or other products (including formaldehyde, phenols, urea, etc.) polymerize through cationic active centers under acid catalysis. Generally speaking, there are various bonding modes between furfuryl alcohol molecules, including methylene bridges (-CH2-), ether bonds, etc. Although furfural can be hydrogenated to furfuryl alcohol and used for synthesizing bio-based polymers, it is worth noting that there is no literature reporting the preparation of polymer materials by directly using furfural as a monomer through radical polymerization.

[0004] It is pointed out in Non-Patent Document 1 that furfural itself cannot directly participate in radical polymerization, whether it is homopolymerization of furfural or copolymerization with other monomers, because the conjugated electron structure of its furan ring will capture free radicals and initiate chain termination reactions. These inherent limitations make furfural an unconventional polymerization inhibitor / polymerization retarder in radical polymerization systems. Moreover, the present inventors also found in previous experiments that after heating furfural monomers or a mixture of furfural and radical initiators, only a small amount of black insoluble substances can be observed.

[0005] The radical copolymerization reaction of 2-furan-5,5-dimethyl-1,3-dioxane and maleic anhydride is disclosed in Non-Patent Document 2. This radical copolymerization reaction is carried out in dioxane or benzene in the presence of AIBN to obtain a soluble copolymer.

[0006] Existing technical literature:

[0007] Non-Patent Documents:

[0008] Non - Patent Document 1: Gandini A, M. Lacerda T. Furan polymers: state of the art and perspectives[J]. Macromolecular Materials and Engineering, 2022, 307(6): 2100902;

[0009] Non - Patent Document 2: - Solich J. Studies on the copolymerization of unsaturated 1,3 - dioxane derivatives - IV. Radical copolymerization of 2 - furyl - 5,5 - dimethyl - 1,3 - dioxane with maleic anhydride[J]. European Polymer Journal, 1975, 11(1): 43 - 46. Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] The radical polymerization method in Non - Patent Document 2 is solution polymerization. The process of product separation and purification is complex, and the yield is at most 11.4%, so the production efficiency is very low.

[0012] Therefore, from the perspective of expanding the high - value utilization of furfural resources, it is urgent to develop a new strategy that can simply, efficiently and economically prepare radical polymers using furfural as the starting material.

[0013] The purpose of the present invention is to provide a furfural acetal - maleic anhydride copolymer, which can be simply, efficiently and economically prepared using furfural as the starting material. The present invention also correspondingly provides a method for preparing the copolymer of the present invention.

[0014] Solutions for Solving the Problems

[0015] In view of the above problems, the inventors of the present invention found in the research that: the acetal of furfural and a specific aliphatic polyol can undergo a radical copolymerization reaction with maleic anhydride through a self - stabilizing precipitation polymerization method, thus completing the present invention.

[0016] Specifically, the present invention solves the problems of the present invention through the following solutions.

[0017] [1] A furfural acetal - maleic anhydride copolymer, which comprises a structural unit I represented by the following formula (1) and a structural unit II represented by the following formula (2):

[0018]

[0019] In formula (2), the bond with an asterisk represents a connecting bond with other structural units, n represents 1 or 2, R1 and R2 independently of each other represent a hydrogen atom, a hydroxyl group, an alkyl group or a hydroxyalkyl group, wherein the alkyl group and the hydroxyalkyl group each independently have 1 to 3 carbon atoms, and when n is 2, each R2 may be the same or different.

[0020] [2] The furfural acetal-maleic anhydride copolymer according to [1], wherein in formula (2), R1 and R2 independently of each other represent a hydrogen atom, a hydroxyl group, a methyl group or a hydroxymethyl group, and at most one of R1 and each R2 is not a hydrogen atom.

[0021] [3] The furfural acetal-maleic anhydride copolymer according to [1] or [2], wherein the structural unit II is at least one selected from the following formulas (3) to (7),

[0022]

[0023]

[0024] [4] The method for preparing a furfural acetal-maleic anhydride copolymer according to any one of [1] to [3], which comprises the following steps:

[0025] Carry out self-stabilized precipitation polymerization of a furfural acetal compound, maleic anhydride and a radical polymerization initiator in a solvent to obtain a furfural acetal-maleic anhydride copolymer.

[0026] [5] The preparation method according to [4], wherein the radical polymerization initiator is at least one selected from azo radical initiators or peroxy radical initiators; preferably, the radical initiator is one or more selected from azodiisobutyronitrile (AIBN), azodiisoheptonitrile, benzoyl peroxide (BPO), tert-butyl hydroperoxide, dicumyl peroxide, lauroyl peroxide, bis(hexadecyl) peroxydicarbonate, cumyl peroxyneodecanoate; based on the total weight of the furfural acetal compound and maleic anhydride being 100%, the amount of the radical polymerization initiator used is 0.05 to 10 wt%, preferably 3 to 8 wt%.

[0027] [6] The preparation method according to [4] or [5], wherein the solvent is one or more selected from organic alkanoate esters, alkyl ethers, organic ketones, aromatic hydrocarbon solvents.

[0028] [7] The preparation method according to [4] or [5], wherein, based on the total weight of the furfural acetal compound, maleic anhydride and the solvent being 100%, the total concentration of the furfural acetal compound and maleic anhydride is 5-60 wt%, preferably 10-50 wt%; the molar ratio of the furfural acetal compound to maleic anhydride is 1:(0.1-10), preferably 1:(0.2-5).

[0029] [8] The preparation method according to [4] or [5], wherein the reaction temperature of the self-stabilizing precipitation polymerization is 40-120 °C, preferably 65-110 °C; the reaction time is 0.1-24 hours, preferably 2-24 hours.

[0030] [9] The preparation method according to [4] or [5] further comprises the following steps:

[0031] After the self-stabilizing precipitation polymerization reaction is completed, solid-liquid separation is carried out on the polymerization system.

[0032]

[10] A copolymer microsphere, which is obtained by the preparation method according to any one of [4] to [8], and the average particle size of the copolymer microsphere is 300-3000 nm.

[0033] Effects of the invention

[0034] The furfural acetal-maleic anhydride copolymer of the present invention can be prepared using biomass as the initial raw material, reducing the consumption of fossil resources, lowering the overall cost, and being more in line with the requirements of building a zero-carbon society.

[0035] The furfural acetal-maleic anhydride copolymer of the present invention contains a large number of highly active anhydride groups, has the possibility of subsequent modification, and thus has broad application prospects.

[0036] The preparation method of the present invention has simple process, low cost, high efficiency, and easy product separation, and is suitable for industrial production. Description of the drawings

[0037] Figure 1 : Photograph of the copolymer microspheres obtained in Example 1 dispersed in a solvent.

[0038] Figure 2 : 1H NMR spectrum of the copolymer microspheres obtained in Example 1.

[0039] Figure 3 : SEM photograph of the copolymer microspheres obtained in Example 1.

[0040] Figure 4 : SEM photograph of the copolymer microspheres obtained in Example 2.

[0041] Figure 5: SEM photograph of the copolymer microspheres obtained in Example 11.

[0042] Figure 6 : Thermogravimetric (TGA) curve of the copolymer microspheres obtained in Example 1. Detailed implementation manners

[0043] Hereinafter, the content of the present invention will be described in detail. The description of the technical features recorded below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples.

[0044] <Terms and definitions>

[0045] In this specification, unless otherwise clearly stated, "alkyl" means straight-chain, branched-chain or cyclic alkyl.

[0046] In this specification, the numerical range expressed as "numerical value A to numerical value B" means a range including the endpoint numerical values A and B.

[0047] In this specification, the numerical range expressed as "above" or "below" means a numerical range including this number.

[0048] In this specification, the meaning expressed by "can" includes both the meaning of performing a certain treatment and not performing a certain treatment.

[0049] In this specification, the use of "optionally" or "optional" means that certain substances, components, execution steps, applied conditions and other factors are used or not used.

[0050] In this specification, the unit names used are all international standard unit names, and unless otherwise specified, the "%" used represents weight or mass percentage content.

[0051] In this specification, the "preferred embodiments", "embodiments", etc. mentioned refer to the specific elements (for example, features, structures, properties and / or characteristics) related to the embodiments described, which are included in at least one of the embodiments described here, and may or may not exist in other embodiments. In addition, it should be understood that the elements can be combined in various embodiments in any suitable manner.

[0052] <Furfural acetal-maleic anhydride copolymer>

[0053] One object of the present invention is to provide a furfural acetal-maleic anhydride copolymer, which is characterized in that it includes a structural unit I represented by the following formula (1) and a structural unit II represented by the following formula (2):

[0054]

[0055] In formula (2), the key with an asterisk represents a connecting key to other structural units, n represents 1 or 2, R1 and R2 independently represent a hydrogen atom, a hydroxyl group, an alkyl group or a hydroxyalkyl group, wherein the alkyl group and the hydroxyalkyl group each independently have 1 to 3 carbon atoms, and when n is 2, each R2 may be the same or different.

[0056] Structural unit I is a structural unit derived from maleic anhydride. Structural unit I imparts active anhydride groups to the copolymer of the present invention. Therefore, the copolymer of the present invention can be modified by methods such as ammoniation and imidation, and thus has a broader application prospect.

[0057] Structural unit II is a structural unit derived from a furfural acetal compound. The furfural acetal compound forms structural unit II shown in formula (II) by 1,4 polymerization of furfural.

[0058] In one embodiment, R1 and R2 independently represent a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, a hydroxyethyl group or a hydroxypropyl group, and when n is 2, each R2 may be the same or different.

[0059] Preferably, R1 and R2 independently represent a hydrogen atom, a hydroxyl group, a methyl group or a hydroxymethyl group, and at most one of R1 and each R2 is not a hydrogen atom.

[0060] Preferably, structural unit II is at least one selected from the following formulas (3) to (7),

[0061]

[0062]

[0063] In the furfural acetal-maleic anhydride copolymer of the present invention, the molar ratio of structural unit I to structural unit II is 1:(0.8 - 1.2), preferably 1:(0.9 - 1.1), more preferably 1:(0.95 - 1.05). Preferably, the furfural acetal-maleic anhydride copolymer of the present invention is an alternating copolymer of structural unit I and structural unit II.

[0064] In some embodiments, the number-average relative molecular weight M of the furfural acetal-maleic anhydride copolymer of the present invention n is 3000 - 20000 g / mol

[0065] <Preparation method>

[0066] An object of the present invention is to provide a preparation method of the furfural acetal-maleic anhydride copolymer of the present invention, which comprises the following steps:

[0067] A furfural acetal compound, maleic anhydride, and a free radical polymerization initiator are subjected to self-stabilized precipitation polymerization in a solvent to obtain a furfural acetal-maleic anhydride copolymer.

[0068] In this article, "self-stabilized precipitation polymerization" refers to a polymerization method in which no emulsifier is used in the polymerization system and the polymerization product is suspended in the reaction medium.

[0069] In this article, the "furfural acetal compound" refers to a product obtained by the acetal reaction of furfural with a polyol, and also encompasses compounds that, although not obtained by the acetal reaction, have the same structure.

[0070] In some embodiments, the preparation method of the present invention further includes the step of preparing a furfural acetal compound. Specifically, a furfural acetal compound is obtained by subjecting furfural to an acetal reaction with a polyol. For the specific conditions of the acetal reaction, those skilled in the art can select according to needs.

[0071] In the step of preparing the furfural acetal compound, it is preferred to use furfural of biological origin. In this article, "biological origin" means obtained using biomass as a raw material.

[0072] The polyol has the structure shown in the following formula (8):

[0073]

[0074] In formula (8), n, R1, and R2 have one of the meanings described above.

[0075] Preferred polyols are one or more of ethylene glycol, 1,2-propanediol, 1,3-propanediol, and glycerol (glycerin).

[0076] Preferably, the furfural acetal compound used in the present invention is one or more selected from the following:

[0077]

[0078]

[0079] In some embodiments, the free radical polymerization initiator is at least one selected from azo free radical initiators or peroxide free radical initiators; preferably, the free radical initiator is one or more selected from azobisisobutyronitrile (AIBN), azobisisoheptonitrile, benzoyl peroxide (BPO), tert-butyl hydroperoxide, dicumyl peroxide, lauroyl peroxide, bis(hexadecyl) peroxydicarbonate, and cumyl peroxyneodecanoate.

[0080] In some embodiments, based on the total weight of the furfural acetal compound and maleic anhydride being 100%, the amount of the radical initiator is 0.05 to 10 wt%, preferably 3 to 8 wt%, more preferably 1 to 5 wt%.

[0081] In some embodiments, the solvent is one or more selected from organic alkanoate esters, alkyl ethers, organic ketones, and aromatic hydrocarbon solvents.

[0082] Preferably, the organic alkanoate ester is one or more selected from ethyl formate, propyl formate, isobutyl formate, pentyl formate, ethyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, pentyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isoamyl butyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, or ethyl phenylacetate.

[0083] Preferably, the alkyl ether solvent is one or more selected from tetrahydrofuran, dioxane, dimethyl ether, methyl ethyl ether, diethyl ether, ethyl propyl ether, dipropyl ether, dibutyl ether, methyl propyl ether, methyl butyl ether, methyl isobutyl ether, methyl tert-butyl ether, methyl isoamyl ether, methyl tert-amyl ether, methyl cyclopentyl ether, ethylene glycol dimethyl ether, or ethylene glycol diethyl ether.

[0084] Preferably, the organic ketone solvent is one or more selected from acetone, butanone, cyclohexanone, methyl isobutyl ketone, or methyl isopropyl ketone.

[0085] Preferably, the aromatic hydrocarbon solvent is one or more selected from benzene, toluene, ethylbenzene, or xylene.

[0086] Preferably, by selecting the solvent, the solubility parameter of the copolymer as the polymerization product is 1 to 7 MPa greater than the solubility parameter of the organic solvent 1 / 2 , preferably 2 to 5 MPa greater 1 / 2 .

[0087] The solubility parameter of the polymer has the usual meaning in the art and can be calculated by an indirect method, that is, using the contribution values of each group in the molecular structure, from the following formula:

[0088] δ = ρ∑F i / M

[0089] where δ is the solubility parameter of the polymer; F i is the molar attraction constant of each group component in the polymer molecule; ρ is the density of the polymer; M is the chain segment molecular weight of the polymer.

[0090] For the solubility parameter of the solvent, those skilled in the art can obtain it by referring to technical manuals or public literatures in the field. For example, the solubility parameters of various solvents are recorded in "Polymer Physics" (Hua Youqing, Jin Riguang, Chemical Industry Press, 2013, page 83).

[0091] In some embodiments, based on the total weight of the furfural acetal compound, maleic anhydride and the solvent being 100%, the total concentration of the furfural acetal compound and maleic anhydride is 5 to 60 wt%, preferably 10 to 50 wt%.

[0092] In some embodiments, the molar ratio of the furfural acetal compound to maleic anhydride is 1:(0.1 to 10), preferably 1:(0.2 to 5).

[0093] In some embodiments, the reaction temperature of the self-stabilized precipitation polymerization is 40 to 120 °C, preferably 65 to 110 °C.

[0094] In some embodiments, the reaction time of the self-stabilized precipitation polymerization is 0.1 to 24 hours, preferably 1 to 24 h, more preferably 2 to 16 hours, still more preferably 3 to 12 h, and further preferably 4 to 8 h.

[0095] In some embodiments, the preparation method of the present invention further comprises the following steps:

[0096] After the self-stabilized precipitation polymerization reaction is completed, solid-liquid separation is performed on the polymerization system.

[0097] In the preparation method of the present invention, by using the self-stabilized precipitation polymerization method for the polymerization reaction, complex post-treatment is not required after polymerization, and the copolymer can be separated by directly performing solid-liquid separation on the polymerization system. For the specific method of solid-liquid separation, the present invention is not particularly limited, and centrifugation followed by filtration is preferred.

[0098] The preparation method of the present invention can obtain furfural acetal-maleic anhydride copolymer microspheres in high yield.

[0099] <Copolymer microspheres>

[0100] The present invention also correspondingly relates to a copolymer microsphere obtained by the preparation method of the furfural acetal-maleic anhydride copolymer of the present invention.

[0101] Preferably, the average particle size of the copolymer microspheres is 300 to 3000 nm.

[0102] Examples

[0103] The embodiments of the present invention will be described in detail below in conjunction with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0104] Example 1

[0105] Take 14 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 96 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids to obtain a clear and transparent reaction solution, and bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction is completed, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min, and dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 14.3 g and the yield rate is 60%.

[0106] Example 2

[0107] Take 14 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 36 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids to obtain a clear and transparent reaction solution, and bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction is completed, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min, and dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 15.9 g and the yield rate is 67%.

[0108] Example 3

[0109] Take 14 g of furfural ethylene acetal, 9.8 g of maleic anhydride, 0.24 g of AIBN, and 215 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction is completed, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene acetal-maleic anhydride copolymer. The yield is 4.0 g and the yield rate is 17%.

[0110] Example 4

[0111] Take 14 g of furfural ethylene acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 215 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction is completed, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene acetal-maleic anhydride copolymer. The yield is 9.0 g and the yield rate is 38%.

[0112] Example 5

[0113] Take 14 g of furfural ethylene acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 96 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 1 h without stirring. After the reaction is completed, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene acetal-maleic anhydride copolymer. The yield is 5.0 g and the yield rate is 21%.

[0114] Example 6

[0115] Take 14 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 96 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 24 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 18.1 g and the yield rate is 76%.

[0116] Example 7

[0117] Take 14 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 96 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 60 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 4.1 g and the yield rate is 17%.

[0118] Example 8

[0119] Take 14 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 70 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 80 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 10 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 19.3 g and the yield rate is 81%.

[0120] Example 9

[0121] Take 14 g of furfural ethylene acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 96 g of methyl tert-butyl ether in a 300 mL single-necked pressure-resistant reaction flask. Ultrasonically oscillate for 5 min to dissolve the solid, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization reaction. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene acetal-maleic anhydride copolymer. The yield is 14.5 g and the yield rate is 61%.

[0122] Example 10

[0123] Take 14 g of furfural ethylene acetal, 9.8 g of maleic anhydride, 1.19 g of AIBN, and 96 g of xylene in a 500 mL single-necked flask. Ultrasonically oscillate for 5 min to dissolve the solid, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization reaction. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene acetal-maleic anhydride copolymer. The yield is 14.3 g and the yield rate is 60%.

[0124] Example 11

[0125] Take 17 g of furfural glycerol acetal, 9.8 g of maleic anhydride, 1.34 g of AIBN, and 108 g of methyl tert-butyl ether in a 300 mL single-necked pressure-resistant reaction flask. Ultrasonically oscillate for 5 min to dissolve the solid, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 75 °C and heat it to carry out self-stabilized precipitation polymerization reaction. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural glycerol acetal-maleic anhydride copolymer. The yield is 19.6 g and the yield rate is 73%.

[0126] Example 12

[0127] Take 17 g of furfural glycerol acetal, 9.8 g of maleic anhydride, 1.34 g of benzoyl peroxide, and 108 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically oscillate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 100 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural glycerol acetal-maleic anhydride copolymer. The yield is 17.2 g and the yield rate is 64%.

[0128] Example 13

[0129] Take 15.4 g of furfural 1,3-propanediol acetal, 9.8 g of maleic anhydride, 1.26 g of benzoyl peroxide, and 101 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically oscillate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 85 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 8 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural 1,3-propanediol acetal-maleic anhydride copolymer. The yield is 16.6 g and the yield rate is 66%.

[0130] Example 14

[0131] Take 42 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 2.59 g of AIBN, and 207 g of isoamyl acetate in a 500 mL single-necked flask. Ultrasonically oscillate for 5 min to dissolve the solids, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 16.1 g and the yield rate is 31%.

[0132] Example 15

[0133] Take 14 g of furfural ethylene glycol acetal, 29.4 g of maleic anhydride, 2.17 g of AIBN, and 174 g of isopentyl acetate in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solid, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 70 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 15.2 g and the yield rate is 35%.

[0134] Example 16

[0135] Take 14 g of furfural ethylene glycol acetal, 9.8 g of maleic anhydride, 2.38 g of AIBN, and 453 g of isopentyl acetate in a 1000 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solid, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 75 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 6 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural ethylene glycol acetal-maleic anhydride copolymer. The yield is 5.7 g and the yield rate is 24%.

[0136] Example 17

[0137] Take 15.4 g of furfural 1,2-propanediol acetal, 9.8 g of maleic anhydride, 1.26 g of AIBN, and 101 g of isopentyl acetate / butanone mixed solvent (isopentyl acetate: butanone = 19:1, w / w) in a 500 mL single-necked flask. Ultrasonically vibrate for 5 min to dissolve the solid, obtaining a clear and transparent reaction solution. Then, bubble nitrogen into it for 15 min to remove the oxygen in the system. Immerse the flask in an oil bath at 75 °C and heat it to carry out self-stabilized precipitation polymerization. Let the system react for 8 h without stirring. After the reaction, a mixed solution containing polymer microspheres is obtained. After cooling, centrifuge at a speed of 6000 r / min for 5 min. Dry the centrifuged polymer in a vacuum oven at 70 °C for more than 24 h to obtain pure furfural 1,2-propanediol acetal-maleic anhydride copolymer. The yield is 17.7 g and the yield rate is 70%.

[0138] <Testing and Evaluation>

[0139] 1. 1H Nuclear Magnetic Resonance

[0140] The copolymer obtained in Example 1 was characterized by liquid nuclear magnetic resonance (JNM-ECA600). The sample to be tested was dissolved in deuterated acetone (acetone-d6, containing TMS as an internal standard) at a concentration of 5 - 20 mg / mL. The scanning range was -2 to 16 ppm, and 16 scans were performed. The obtained spectrum is as Figure 2 shown.

[0141] It can be seen from Figure 2 that the peaks located at 5.85 - 6.65 ppm are the two double-bond hydrogens in the furfural ethylene acetal unit (FEA). The peaks located at 4.70 - 5.70 ppm correspond to the hydrogens on the acetal carbon in the FEA structure and the secondary methyl hydrogens on the FEA main chain. The broad peak located at 3.30 - 4.45 ppm corresponds to the four methylene hydrogens (-O-CH2-CH2-O-) on the acetal ring and the two secondary methyl hydrogens (-CH-) on the main chain of the maleic anhydride group. The integral area ratio of the three groups of peaks is close to 2:2:6. This indicates that the furfural ethylene acetal-maleic anhydride copolymer was successfully prepared.

[0142] 2. Morphology Observation

[0143] To observe the morphological characteristics of the polymer microspheres, a Zeiss Gemini 300 field emission scanning electron microscope was used for microstructural characterization. Before the test, the polymer microspheres were evenly dispersed on the surface of the conductive adhesive, and a platinum layer was sputtered (current 20 mA, sputtering time 150 s) by an ion sputtering instrument (JFC-1600, JEOL, Japan) to eliminate the charging effect. Secondary electron images were obtained under the conditions of an acceleration voltage of 3 - 5 kV and a working distance of 8 - 10 mm. The SEM photos of the copolymers obtained in Examples 1, 2, and 11 are respectively as Figure 3 , Figure 4 and Figure 5 shown.

[0144] It can be seen from the SEM photos of Figure 3 , Figure 4 and Figure 5 that the prepared copolymers are all microspheres with uniform particle size and regular morphology.

[0145] 3. Microsphere Particle Size Analysis

[0146] The Image J software was used to perform particle size statistical analysis on at least 100 microspheres. The average particle size of the polymer microspheres was calculated according to the following formula:

[0147]

[0148] In the formula, D n is the number-average diameter.

[0149] The average particle diameters of the copolymer microspheres obtained in Examples 1 to 17 are shown in Table 1. As can be seen from Table 1, by adjusting parameters such as the reaction medium, monomer concentration, initiator concentration, monomer ratio, and reaction temperature, the particle diameter of the copolymer microspheres can be adjusted, and the particle diameter range is 300 - 3000 nm.

[0150] Table 1

[0151]

[0152] 4. Thermogravimetric analysis

[0153] Thermogravimetric tests were carried out using a thermogravimetric analyzer (TG 209 type) from Netzsch, Germany, under N2 with a flow rate of 20 mL / min. Approximately 3 - 5 mg of the polymer sample was accurately weighed and placed in an Al2O3 crucible. The test temperature range was 35 - 800 °C, and the heating rate was 10 °C / min.

[0154] The thermogravimetric (TGA) curve of the copolymer obtained in Example 1 is as Figure 6 shown. As Figure 6 can be seen, the initial decomposition temperature T 5％ (temperature at 5% weight loss) of the copolymer is 258 °C, and the temperature corresponding to the maximum decomposition rate is 390 °C, showing good thermal stability.

[0155] Industrial availability

[0156] The furfural acetal - maleic anhydride copolymer of the present invention can be widely used in many fields such as biomedicine, agriculture, textile industry, construction industry, etc., especially for paper sizing materials or wood adhesives.

Claims

1. A furfural acetal - maleic anhydride copolymer, characterized in that, It includes structural unit I represented by the following formula (1) and structural unit II represented by the following formula (2): In formula (2), the bond with an asterisk represents the bonding key to other structural units, n represents 1 or 2, R1 and R2 independently represent a hydrogen atom, a hydroxyl group, an alkyl group or a hydroxyalkyl group, wherein the alkyl group and the hydroxyalkyl group each independently have 1 to 3 carbon atoms, and when n is 2, each R2 may be the same or different.

2. The furfural acetal-maleic anhydride copolymer according to claim 1, wherein In formula (2), R1 and R2 independently represent a hydrogen atom, a hydroxyl group, a methyl group or a hydroxymethyl group, and at most one of R1 and each R2 is not a hydrogen atom.

3. The furfural acetal-maleic anhydride copolymer according to claim 1 or 2, characterized in that, The structural unit II is at least one selected from the following formulas (3) to (7), 4. The preparation method of the furfural acetal-maleic anhydride copolymer according to any one of claims 1 to 3, characterized in that, It includes the following steps: Subjecting a furfural acetal compound, maleic anhydride, and a radical polymerization initiator to self-stabilized precipitation polymerization in a solvent to obtain a furfural acetal-maleic anhydride copolymer.

5. The preparation method according to claim 4, characterized in that, The radical polymerization initiator is at least one selected from azo radical initiators or peroxide radical initiators; preferably, the radical initiator is one or more selected from azobisisobutyronitrile (AIBN), azobisisoheptonitrile, benzoyl peroxide (BPO), tert-butyl hydroperoxide, dicumyl peroxide, lauroyl peroxide, bis(hexadecyl) peroxydicarbonate, and cumyl peroxyneodecanoate; based on the total weight of the furfural acetal compound and maleic anhydride being 100%, the amount of the radical polymerization initiator used is 0.05 to 10 wt%, preferably 3 to 8 wt%.

6. The preparation method according to claim 4 or 5, characterized in that, The solvent is one or more selected from organic alkanoate esters, alkyl ethers, organic ketones, and aromatic hydrocarbon solvents.

7. The preparation method according to claim 4 or 5, characterized in that Based on the total weight of the furfural acetal compound, maleic anhydride, and the solvent being 100%, the total concentration of the furfural acetal compound and maleic anhydride is 5 to 60 wt%, preferably 10 to 50 wt%; the molar ratio of the furfural acetal compound to maleic anhydride is 1:(0.1 to 10), preferably 1:(0.2 to 5).

8. The preparation method according to claim 4 or 5, characterized in that, The reaction temperature of the self-stabilized precipitation polymerization is 40 to 120°C, preferably 65 to 110°C; the reaction time is 0.1 to 24 hours, preferably 2 to 24 hours.

9. The preparation method according to claim 4 or 5, characterized in that, It further includes the following steps: After the self-stabilized precipitation polymerization reaction ends, solid-liquid separation is performed on the polymerization system.

10. A copolymer microsphere, characterized in that, Obtained by the preparation method according to any one of claims 4 to 8, the average particle size of the copolymer microspheres is 300 to 3000 nm.

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