Alcohol-soluble bio-based citronella polymer as well as preparation method and application thereof

Abstract

The invention belongs to the field of bio-based macromolecules, and particularly relates to an alcohol-soluble bio-based citronella polymer as well as a preparation method and application thereof. In order to solve the problem that trisubstituted olefinic bonds of citronellol cannot directly participate in a polymerization reaction, trisubstituted olefinic bonds of citronellol are converted into alkene monomers by utilizing a photooxidation reaction through a one-step method strategy. And then, based on a photo-induced electron transfer-reversible addition / fragmentation chain transfer polymerization technology at room temperature, obtaining a polymer with controllable molecular weight, narrower dispersity and rich polar groups in side chains. Finally, the alcohol-soluble resin-based environment-friendly coating is developed, and the functional application of a paint film is expanded by doping inorganic filler. According to the invention, not only is a brand new green conversion way opened up for high-value utilization of citronellol containing trisubstituted olefinic bonds realized, but also a high-performance full-bio-based environment-friendly functional coating is created based on the alcohol-soluble resin.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of bio-based polymers, and more particularly relates to an alcohol-soluble bio-based citronella polymer, a preparation method and application thereof. BACKGROUND

[0002] Citronellol is the main component of more than 70 plant essential oils of Rosaceae family, has a sweet and sweet smell similar to rose, and its structural formula is shown in Figure 1 Although the compound has achieved industrial production, its downstream industry has been limited to basic perfumes and essential oils in the daily chemical / food industry for a long time, and has always failed to break through the technical bottleneck of high-value utilization. SUMMARY

[0003] In view of the defects of the prior art, the purpose of the present application is to provide an alcohol-soluble bio-based citronella polymer, a preparation method and application thereof, which aims to open up a new technical path for high-value utilization of citronellol.

[0004] To achieve the above-mentioned purpose, in a first aspect, the present application provides an alcohol-soluble bio-based citronella polymer, which has a general structural formula as shown in formula (I):

[0005] Formula (I) Wherein, n is an integer of 81-203.

[0006] In a second aspect, a preparation method of the alcohol-soluble bio-based citronella polymer is provided, which comprises the following steps: (1) taking citronellol as raw material, and performing photo-oxidation reaction under the action of singlet oxygen by photo-irradiation in the presence of a photosensitizer and a solvent to convert the citronellol into isopropenyl ketone monomer; (2) mixing the isopropenyl ketone monomer, the photosensitizer, the RAFT reagent and the solvent, and preparing the alcohol-soluble bio-based citronella polymer by PET-RAFT polymerization reaction under photo-irradiation.

[0007] In a third aspect, an alcohol-soluble resin-based environmentally friendly coating based on the bio-based citronella polymer is provided.

[0008] Preferably, the coating comprises an alcohol-soluble resin solution of the bio-based citronella polymer, and further comprises an inorganic filler; the alcohol-soluble resin solution is obtained by dissolving the bio-based citronella polymer in an alcohol solvent.

[0009] Further preferably, the inorganic filler is selected from one or more of oil-soluble toner, Fe3O4 nanoparticles, rare earth particles and Ag powder.

[0010] To establish a new method for biomass conversion and enrich the use scenarios of bio-based materials, the present application adopts a "one-step" strategy to convert citronellol into isopropenyl ketone monomer, and then obtains alcohol-soluble resin through photo-induced electron transfer-reversible addition / fragmentation chain transfer (PET-RAFT) polymerization, and displays its potential application in the field of coatings. Overall, compared with the prior art, the above technical scheme conceived by the present application has the following beneficial effects: (1) The present application uses singlet oxygen to convert the chemically inert tri-substituted alkene bond in citronellol molecules into an unsaturated ketone group in one step, thereby opening up the technical route for the conversion of natural product citronellol into olefin monomers. Further, through PET-RAFT polymerization, alcohol-soluble bio-based citronella polymers with controllable molecular weight and narrow dispersity are obtained, and the potential application of alcohol-soluble resin / inorganic filler composite in the field of functional coatings is developed.

[0011] (2) The environmental protection characteristics of the alcohol-soluble resin prepared by the present application not only lie in the fact that the resin and ethanol can be mutually soluble in an infinite ratio, but also in the fact that it is a truly 100% full-bio-based polymer material.

[0012] (3) The preparation method of the functional and environmentally friendly coating described in the present application is almost applicable to micro-nano particles of any material, showing good universality. The side chains of bio-based citronella polymers are rich in polar functional groups such as carbonyl and hydroxyl groups, so they can be mutually soluble with ethanol in any ratio at room temperature, significantly enhancing the environmental properties of the coating. Moreover, the above-mentioned groups help to enhance the interaction between the paint film and the substrate, thereby improving the adhesion and durability of the paint film. In addition, there are a large number of interaction sites between the resin and the inorganic filler, so uniform dispersion of the inorganic filler in the resin matrix can be achieved by simple high-speed vortex technology. It should be pointed out that the micro-nano particles of different materials endow the functional paint film with flexible and adjustable physicochemical properties, which undoubtedly lays a solid foundation for customizing bio-based environmentally friendly coatings on demand. The present application has cleared the technical obstacles for the development of high-performance environmentally friendly functional coatings, and the preparation method has the advantages of simple process, low cost, safety and health, and is expected to have broad practical prospects in the printing, construction, home furnishing and other industries. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is the molecular structure of citronellol.

[0014] Figure 2 is the route schematic diagram of the present application for synthesizing alcohol-soluble resin from citronellol.

[0015] Figure 3 is the molecular structure of isopropenyl ketone monomer. 1 H NMR spectrum (solvent: deuterated chloroform).

[0016] Figure 4GPC curves, molecular weight information and flight mass spectra of polymers P1-P3 prepared for Examples 4-6.

[0017] Figure 5 Photos of luminescence of phosphorescent coating prepared for Example 7 under natural light and ultraviolet light.

[0018] Figure 6 Photos of magnetic coating prepared for Example 8 and its being attracted by a magnet.

[0019] Figure 7 Photo of electrically conductive coating prepared for Example 9 replacing a wire to connect a circuit.

[0020] Figure 8 Route map of alcohol-soluble bio-based polyisopropenyl ketone prepared for Comparative Example 1. DETAILED DESCRIPTION In order to make the purposes, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0021] The present application aims to open up a brand-new technical path for high-value utilization of citronellol. Citronellol contains a trisubstituted olefinic bond (as shown in Figure 1 which is subject to reactivity and steric hindrance, and the compound cannot directly participate in polymerization as a monomer. The present application innovatively uses singlet oxygen to convert citronellol into an isopropenyl ketone monomer (as shown in Figure 2 ) in one step, and then obtains a polymer with controllable molecular weight and narrow dispersity through PET-RAFT polymerization, and develops potential applications of alcohol-soluble resin / inorganic filler composites in the field of functional coatings.

[0022] Specifically, the present application provides an alcohol-soluble bio-based citronella polymer, which has a general structure as shown in formula (I):

[0023] Formula (I) wherein n is an integer of 81-203.

[0024] The present application also provides a preparation method of the alcohol-soluble bio-based citronella polymer, comprising the following steps: (1) using citronellol as a raw material, performing light irradiation in the presence of a photosensitizer and a solvent, and converting the citronellol into an isopropenyl ketone monomer through photooxidation under the action of singlet oxygen; (2) mixing isopropenyl ketone monomer, photosensitizer, RAFT agent and solvent, and preparing the alcohol-soluble bio-based citronella polymer by PET-RAFT (photo-induced electron transfer-reversible addition / fragmentation chain transfer) polymerization reaction under light irradiation.

[0025] In some embodiments, the photosensitizer in step (1) and step (2) is independently one or more of hematoporphyrin, phenothiazine, benzoin ether, benzil ketals, dialkoxyacetophenone, acetophenone oxide, acyl phosphine oxide, benzophenone, 4,4'-dimethylaminobenzophenone, thia xanthone, thioxanthone, camphor phenol, bisimidazole, thiophenone, aryl diazonium salt, diaryl iodide, triaryl sulfide, eosin, phthalocyanine, and curcumin.

[0026] In some embodiments, the molar ratio of citronellol to photosensitizer in step (1) is 50 / 1-200 / 1; the molar ratio of isopropenyl ketone monomer to photosensitizer in step (2) is 2000 / 1-10000 / 1, and the molar ratio of isopropenyl ketone monomer to RAFT agent is 50 / 1-200 / 1.

[0027] In some embodiments, the solvent in step (1) and step (2) is independently one or more of water, acetic acid, acetone, acetonitrile, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl-p-cresol, chloroform, cyclohexane, dichloroethane, dichloromethane, diethyl ether, diglyme, glycol dimethyl ether, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, dioxane, ethanol, ethyl acetate, methyl ethyl ketone, ethylene glycol, n-hexane, hexamethylphosphoramide, nitromethane, n-heptane, pyridine, tetrahydrofuran, toluene, and triethylamine.

[0028] In preferred embodiments, the light irradiation in step (1) and step (2) is independently performed at a wavelength of 360-530 nm and an irradiation distance of 0.5-2.0 cm; wherein the time for the photo-oxidation reaction in step (1) is 12-48 h; and the time for the PET-RAFT polymerization in step (2) is 12-48 h.

[0029] In some embodiments, the light irradiation reaction can be performed in a dark environment and under a protective atmosphere using an LED lamp in the above wavelength range.

[0030] The RAFT agent in step (2) can be 2-[ (ethylthio) carbonylthio]thio]-2-methylpropionic acid, bis(carboxymethyl)trithiocarbonic acid, 2-[[ (butylthio) thioxomethyl]thio]propanoic acid, 2,2'-[thiocarbonylbis(sulfanediyl)]dipropanoic acid, 2-[[ (2-carboxyethyl) sulfanylthiocarbonyl]-sulfanyl]propanoic acid, 4-cyano-4-(( (ethylthio) thiocarbonyl) sulfanyl)pentanoic acid, 3-benzylsulfanylthiocarbonylsulfanylpropanoic acid, 2,2'-[methylthiobis(thio)]bis[2-methylpropanoic acid], cyanomethyl dodecylcarbonyl carbon trithioformate, 2-cyano-2-propyldodecyltrithiocarbonic acid ester, 3,3'-[(dithia-1,2-dithiocarbonyl) bis(sulfanediyl)]dipropionic acid, 2-[dodecylthio(thiocarbonyl) sulfanyl]-2-methylpropanoic acid, benzyl dodecyl trithiocarbonic acid ester, 2-[[ (dodecylmercapto) thiomethyl]thio]-2-methylbenzoic acid methyl ester, 4-cyano-4-[[ (dodecylthio) thionomethyl] sulfanyl]pentanoic acid, 2-dodecylthiocarbonylthio-2-methylpropanoic acid N -hydroxysuccinimidyl ester, bis(dodecylsulfanylthiocarbonyl) disulfide, (2-hydroxyethyl) benzyl trithiocarbonic acid ester, 2-mercapto-S-thiobenzoyl acetic acid, 2-cyano-2-propyl benzene dithio, benzyl dithiobenzoate, thio-benzoic acid-2-phenylpropane thioester, 4-cyano-4-(thiobenzoyl sulfanyl) pentanoic acid, bis(thiobenzoyl) disulfide, 4-cyano-4-(phenylthiocarbonyl sulfanyl) pentanoic acid N -succinimidyl ester, rhodanine, 3-ethyl-2-thioxothiazolidin-4-one, 3-carboxymethyl rhodanine, 3-(4-oxo-2-thioxothiazolidin-3-yl)propanoic acid, methyl(phenyl) aminodithiocarbonic acid cyanomethyl ester, 3-benzyl rhodanine, benzyl diethyl dithioaminocarboxylate, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetraisopropyl thiuram disulfide, p-xylylene bis N , N -dithio, tetrabutyl thiuram disulfide, tetrabenzyl thiuram disulfide, and the like.

[0031] In some embodiments, the crude product obtained after the photo-oxidation reaction of step (1) is separated by silica gel column chromatography (eluent is petroleum ether and ethyl acetate) to obtain a colorless transparent oily liquid. Nuclear magnetic resonance is used to characterize the structure and purity of the obtained isopropenyl ketone monomer. In preferred embodiments, the volume ratio of the eluent petroleum ether and ethyl acetate is 20 / 1 to 1 / 1. The yield of isopropenyl ketone monomer is 70%-90%.

[0032] In some embodiments, the crude product obtained from the PET-RAFT polymerization reaction of step (2) is precipitated in cold methanol for multiple times, centrifuged and vacuum dried to obtain a colorless transparent high-viscosity liquid. The structure and molecular weight of the polymerization product are characterized by time-of-flight mass spectrometry (MALDI-TOF-MS) and gel permeation chromatography (GPC), respectively. In preferred embodiments, the yield of the bio-based citronella polymer is 70-90%. At the beginning of the experiment, the inventors also tried to synthesize alcohol-soluble bio-based polyisopropenyl ketone using the synthetic route shown in Figure 8 The synthetic route shown in has as many as six preparation steps, is complicated to operate and has a very low actual yield of only 18-26%.

[0033] The present application also provides an alcohol-soluble resin-based environmentally friendly coating based on the bio-based citronella polymer.

[0034] The alcohol-soluble resin environmentally friendly coating provided by the present application comprises an alcohol-soluble resin solution of the bio-based citronella polymer, and further comprises an inorganic filler. The alcohol-soluble resin solution is obtained by dissolving the bio-based citronella polymer in an alcohol solvent, and the alcohol solvent includes but is not limited to anhydrous ethanol and the like.

[0035] In some embodiments, the mass fraction of the alcohol-soluble resin solution is 5-25%, and the alcohol solvent is ethanol. The inorganic filler is selected from one or more of oil-soluble toner, Fe3O4 nanoparticles, rare earth particles and Ag powder.

[0036] In some embodiments, the preparation method of the environmentally friendly coating comprises the following steps: dissolving the bio-based citronella polymer in an alcohol solvent, stirring uniformly at room temperature to obtain a homogeneous solution. Subsequently, the inorganic filler is added to the aforementioned solution, and the environmentally friendly coating is obtained after mixing.

[0037] In some embodiments, the environmentally friendly coating is obtained after mixing using a vortex mixer. The functional coating is obtained after brushing on a substrate and drying at room temperature for 24-36 h. The optional range of the substrate material includes plastic, glass, metal, wood, ceramic and the like. The thickness of the paint film is 40-60 μm.

[0038] In some embodiments, the mass ratio of the inorganic filler to the alcohol-soluble resin is 1 / 10 to 1 / 2.

[0039] The model of the LED lamp used in the embodiments of the present application is GCH-4, and the manufacturer is Wuhan Jushang Technology Co., Ltd.

[0040] The model of the vortex mixer used in the embodiments of the present application is XWY-2, and the manufacturer is Ningbo Kemai Instrument Co., Ltd.

[0041] The preparation method of the functional environment-friendly coating in the application is almost applicable to micro-nano particles of any material, showing good universality. The side chain of the bio-based citronella polymer is rich in polar functional groups such as carbonyl and hydroxyl groups, and thus can be mutually soluble with ethanol at room temperature, significantly enhancing the environmental protection property of the coating. Moreover, the above-mentioned groups help to enhance the interaction between the paint film and the substrate, thereby improving the adhesion and durability of the paint film. In addition, there are a large number of interaction sites between the resin and the inorganic filler, so that the inorganic filler can be uniformly dispersed in the resin matrix by simple high-speed vortex technology. It should be pointed out that the micro-nano particles of different materials endow the functional paint film with flexible and adjustable physicochemical properties, which undoubtedly lays a solid foundation for customizing bio-based environment-friendly coatings on demand. The application has cleared the technical obstacles for the development of high-performance environment-friendly functional coatings, and the preparation method has the advantages of simple process, low cost, safety and health, and is expected to have broad practical prospects in the printing, building, home furnishing and other industries.

[0042] The bio-based citronella polymer provided by the application has the following technical advantages over commercial products: 1) 100% pure bio-based material, while most commercial products are petrochemical-based polymer coatings, the raw material source of the bio-based citronella polymer of the application is more green and environmentally friendly; 2) The bio-based citronella polymer involved in the application is alcohol-soluble, so ethanol can be used as a solvent, and it has good environmental properties. The reason why the commercial product has an odor is that it contains organic solvents, which are harmful to the human body and the environment; 3) The bio-based citronella polymer involved in the application contains a large number of ketone carbonyl and alcohol hydroxyl groups, and the interaction between these polar groups and the substrate material is very strong, which helps to improve the stability of the coating.

[0043] The application solves the problem that the trisubstituted olefinic bond of citronellol cannot directly participate in the polymerization reaction by using a one-step strategy to convert it into an olefinic monomer through photooxidation reaction. Secondly, based on the photo-induced electron transfer-reversible addition / fragmentation chain transfer (PET-RAFT) polymerization technology at room temperature, a polymer with controllable molecular weight, narrow dispersity and rich in polar groups in the side chain is obtained. Finally, alcohol-soluble resin-based environment-friendly coatings are developed, and inorganic fillers are doped to expand the functional applications of the paint film. The application not only opens up a new green transformation route for the high-value utilization of many terpenoids containing trisubstituted olefinic bonds, but also creates high-performance all-bio-based environment-friendly functional coatings based on alcohol-soluble resins.

[0044] The embodiments of the application are implemented on the premise of the technical solutions of the application, and detailed implementation methods and processes are given, but the protection scope of the application is not limited to the following embodiments. The process parameters not specified in the following examples are usually according to conventional conditions.

[0045] The endpoints of the ranges and any values described in this disclosure are not limited to the precise values stated. The ranges and values should be construed to be approximations that allow for significant error and variations. The endpoints of the ranges and values of described values are not exclusive; the values of each range of values can be combined with values from other aspects of the disclosure. Numerous values have been presented for the parameter being described. Each of the numerical values and ranges have at least one significant digit. Unless otherwise indicated each and every significant digit is significant to at least one more digit than is expressed by the desired number of significant figures. No statement on a preferred group for a substituent is intended to be limiting.

[0046] Process parameters not specifically indicated in the following examples were generally conducted under conventional conditions.

[0047] Analytical test methods involved in the embodiments of the present application are as follows: (1) Nuclear magnetic resonance hydrogen spectrum (1H NMR) 1 H NMR) Isopropenyl ketone monomer was dissolved in deuterated chloroform (CDCl3), and tetramethylsilane (TMS) was used as a chemical shift internal standard. The 1 H NMR (400 MHz) spectrum of the sample was determined by a Bruker Avance 400 nuclear magnetic resonance spectrometer.

[0048] (2) Time-of-flight mass spectrometry (MALDI-TOF-MS) The base-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of the polymer was determined by a Bruker Ultraflextreme mass spectrometer. The mass spectrometer was equipped with a 355 nm Nd:YAG laser operating in positive ion linear mode. The analyzer was used under an acceleration voltage of +20 kV. The laser was focused on the sample by an 8.02 kV lens. The pulse ion extraction was optimized to 170 ns. The THF solution of the sample (concentration of 10 mg mL -1 ), trans The THF solution of 2-[3-(4-tert-butylphenyl)-2-methyl-2-propenyl]propanedinitrile (DCTB) (concentration of 50 mg mL -1 ) and the aqueous solution of sodium trifluoroacetate (concentration of 5 mg mL -1 ) were mixed in a volume ratio of 4 / 4 / 1, and then 1 μL of the sample was deposited on the target plate and tested after drying. MALDI-TOF-MS ensured detection at 10 different sample deposition areas, providing a total of 500 shots. FlexControl3.4 software was used for data acquisition and processing.

[0049] (3) Gel permeation chromatography (GPC) The number average molecular weight (Mn) of the polymer was measured using a Polymer Laboratories Gel Permeation Chromatograph (PL GPC50) equipped with three PL Gel Mixed-C columns. Mn ) and dispersity ( Ð ). Each injection of polymer solution (volume of 100 μL, concentration of 1 mg mL -1 ) in THF (flow rate: 1 mL min -1 ) at 35 o C using a Waters 1525 binary HPLC pump equipped with a Waters 2414 refractive index detector. Several narrow-dispersity polystyrenes (PSS) with known molecular weights (Mw) were used as internal standards and the Breeze 3.30 SPA software was employed to calculate M n = 1.3-900.0 kDa; Ð = 1.06-1.10) as internal standards and the Breeze 3.30 SPA software was employed to calculate M n and Ð values.

[0050] The embodiments of the present application will be described below with reference to the accompanying drawings of the embodiments of the present application.

[0051] Examples 1 to 3 are the synthesis and characterization of isopropenyl ketone monomers.

[0052] Example 1 Precisely weigh 156.3 mg (1 mmol) of citronellol and 5.1 mg (10 μmol) of phthalocyanine into a 25 mL straight Schlenk flask, respectively. Add 1 mL of anhydrous acetonitrile into it, and obtain a homogeneous reaction solution after stirring. Place the Schlenk flask in a photoreactor, and open the LED lamp (λ Lambda = 365 nm, illumination distance about 1 cm) in the dark environment, and stir at room temperature for 24 h. Dry the solvent, and separate the crude product by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10 / 1) to obtain a colorless transparent oily liquid. Yield: 86%. The 1 H NMR spectrum of the isopropenyl ketone monomer prepared in Example 1 is shown in Figure 3 .

[0053] 1 H NMR (400 MHz, CDCl3) Delta = 5.93 (s, 1H), 5.72 (s, 1H), 3.59-3.67 (m,2H), 2.66 (t, J = 10 Hz, 2H), 2.54 (s, 1H), 1.80 (s, 3H), 1.50-1.65 (m, 3H),1.31-1.40 (m, 2H), 0.85 (d, J = 8.8 Hz, 3H). Example 2 Weigh 156.3 mg (1 mmol) of citronellol and 15.3 mg (10 μmol) of 5,10,15,20-tetra(4-trimethylamino)phenylporphyrin tetratoluenesulfonate separately using a precision balance, and transfer them sequentially to 25 mL straight-sided Schlenk flasks. Add 1 mL of anhydrous acetonitrile to each flask, and stir to obtain a homogeneous reaction solution. Place the Schlenk flask in a photoreactor, and in the dark, turn on the LED light (…). Lambda = 365 nm (irradiation distance approximately 1 cm), stirred at room temperature for 24 h. The solvent was evaporated, and the crude product was separated by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10 / 1) to obtain a colorless, transparent oily liquid. Yield: 75%.

[0054] Example 3 Weigh 156.3 mg (1 mmol) of citronellol and 3.7 mg (10 μmol) of curcumin using a precision balance, and transfer them sequentially to 25 mL Schlenk flasks. Add 1 mL of anhydrous acetonitrile and stir to obtain a homogeneous reaction solution. Place the Schlenk flask in a photoreactor, and in the dark, turn on the LED light (…). Lambda = 365 nm (irradiation distance approximately 1 cm), stirred at room temperature for 24 h. The solvent was evaporated, and the crude product was separated by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10 / 1) to obtain a colorless, transparent oily liquid. Yield: 81%.

[0055] Examples 4 to 6 are examples of the preparation and characterization of bio-based lemongrass polymers.

[0056] Example 4 85.1 mg (0.5 mmol) of isopropenyl ketone monomer and 0.1 mg (0.2 μmol) of eosin Y were weighed separately using a precision balance and transferred to 25 mL straight-sided Schlenk flasks. Under argon protection, 3.7 mg (10 μmol) of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and 0.5 mL of anhydrous dimethyl sulfoxide were added sequentially. After three cycles of freezing-vacuuming-thawing, the polymerization system was sealed. The Schlenk flask was placed in a photoreactor, and in the dark, the LED light was turned on. Lambda = 465nm (irradiation distance approximately 1 cm), stirred at room temperature for 24 h. After polymerization, the crude product was diluted with a small amount of dichloromethane and eosin Y was removed by passing it through an alkaline alumina column. After rotary evaporation and concentration, the resulting viscous solution was precipitated three times in cold methanol, and after centrifugation and drying, a colorless, transparent, highly viscous liquid P1 was obtained. Yield: 90%.

[0057] Example 5 170.3 mg (1 mmol) of isopropenyl ketone monomer and 0.1 mg (0.2 μmol) of eosin Y were weighed using a precision balance and transferred sequentially to 25 mL straight-sided Schlenk flasks. Under argon protection, 3.7 mg (10 μmol) of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and 0.5 mL of anhydrous dimethyl sulfoxide were added sequentially. After three cycles of freezing-vacuuming-thawing, the polymerization system was sealed. The Schlenk flask was placed in a photoreactor, and in the dark, the LED light was turned on. Lambda = 465nm (irradiation distance approximately 1 cm), stirred at room temperature for 24 h. After polymerization, the crude product was diluted with a small amount of dichloromethane and eosin Y was removed by passing it through an alkaline alumina column. After rotary evaporation and concentration, the resulting viscous solution was precipitated three times in cold methanol, and after centrifugation and drying, a colorless, transparent, highly viscous liquid P2 was obtained. Yield: 84%.

[0058] Example 6 340.5 mg (2 mmol) of isopropenyl ketone monomer and 0.1 mg (0.2 μmol) of eosin Y were weighed using a precision balance and transferred sequentially to 25 mL straight-sided Schlenk flasks. Under argon protection, 3.7 mg (10 μmol) of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and 0.5 mL of anhydrous dimethyl sulfoxide were added sequentially. After three cycles of freezing-vacuuming-thawing, the polymerization system was sealed. The Schlenk flask was placed in a photoreactor, and in the dark, the LED light was turned on. Figure 4 = 465nm (irradiation distance approximately 1 cm), stirred at room temperature for 24 h. After polymerization, the crude product was diluted with a small amount of dichloromethane and eosin Y was removed by passing it through an alkaline alumina column. After rotary evaporation and concentration, the resulting viscous solution was precipitated three times in cold methanol, and after centrifugation and drying, a colorless, transparent, highly viscous liquid P3 was obtained. Yield: 78%.

[0059] The GPC curves, molecular weight information, and flight mass spectra of polymers P1-P3 are shown below. Figure 4 As shown.

[0060] Depend on Figure 5 It is known that isopropyl ketone monomers can be polymerized via PET-RAFT to produce bio-based citronellol polymers with high molecular weight and narrow dispersion. The theoretical degree of polymerization of the product can be easily adjusted by controlling the ratio of monomer to chain transfer agent. Verification has shown that resin samples of different molecular weights are miscible with ethanol in any proportion at room temperature.

[0061] Examples 7 to 9 are examples of the preparation of alcohol-soluble resin-based environmentally friendly coatings.

[0062] Example 7 A solution of 0.8 g of the bio-based citronella polymer P3 was prepared by dissolving it in 5 mL of anhydrous ethanol and stirring for 5 min at room temperature. Subsequently, 0.4 g of micron-sized particles containing terbium / europium elements were added to the aforementioned solution, and an environmentally friendly coating was obtained after treatment with a vortex mixer for 10 min. This was brushed onto the surface of a polypropylene plate, and after drying in air at room temperature for 24 h, a phosphorescent coating was obtained. As shown in Lambda , after excitation by ultraviolet light (λ = 365 nm), the coating emitted a strong phosphorescence in the dark. After the ultraviolet light source was removed, the phosphorescence intensity gradually decayed within 3 s. Content (A) is a photograph of the phosphorescent coating under natural light, and content (B) is a photograph of the phosphorescent coating under ultraviolet light. Figure 6

[0063] Example 8 A solution of 0.8 g of the bio-based citronella polymer P3 was prepared by dissolving it in 5 mL of anhydrous ethanol and stirring for 5 min at room temperature. Subsequently, 0.16 g of Fe3O4 nanoparticles were added to the aforementioned solution, and an environmentally friendly coating was obtained after treatment with a vortex mixer for 10 min. This was brushed onto the surface of a polypropylene plate, and after drying in air at room temperature for 24 h, a magnetic coating was obtained. As shown in Figure 7 , a magnet could easily pick up the coated polymer plate, and content (A) is a photograph of the magnetic coating; content (B) is a photograph of the magnet picking up the polymer plate.

[0064] Example 9 A solution of 0.8 g of the bio-based citronella polymer P3 was prepared by dissolving it in 5 mL of anhydrous ethanol and stirring for 5 min at room temperature. Subsequently, 0.24 g of Ag powder was added to the aforementioned solution, and an environmentally friendly coating was obtained after treatment with a vortex mixer for 10 min. This was brushed onto the surface of a polypropylene plate, and after drying in air at room temperature for 24 h, a conductive coating was obtained. As shown in Figure 8 , after cutting the lead wire of an LED lamp and connecting the wire ends to the two ends of the conductive coating, the LED lamp could be normally illuminated after the power was turned on.

[0065] Comparative Example 1 This comparative example provides another method for synthesizing an alcohol-soluble bio-based polyisopropenyl ketone. The synthetic route diagram is shown in Figure 8 , and includes the following steps: ​ In step a, the reaction conditions are as follows: 1.1 equivalents of tert-butyldiphenylsilyl chloride and 1.5 equivalents of imidazole, the solvent is N , N dimethylformamide, the reaction is carried out at room temperature for 1 h, and the yield is 99%.

[0066] In step b, the reaction conditions are as follows: 1.05 equivalents of meta-chloroperoxybenzoic acid, the reaction is carried out at 0°C for 0.5 h, and the yield is 93%.​

[0067] Step c reaction conditions: 1.05 equivalent of isopropyl aluminum, solvent is toluene, 115 °C for 8 h; adjust pH to 1-2 with 1 mol / L hydrochloric acid solution, reaction yield is 89%.

[0068] Step d reaction conditions: 1.1 equivalent of o-iodoxybenzoic acid, solvent is dimethyl sulfoxide and tetrahydrofuran, room temperature for 2 h, yield is 87%.

[0069] Step e reaction conditions: 0.01 equivalent of 2-[dodecylsulfanyl (thiocarbonyl) sulfanyl]-2-methylpropanoic acid, 0.0002 equivalent of eosin Y, solvent is dimethyl sulfoxide, LED light source with wavelength of 465 nm, room temperature, 24 h, yield is 89%.

[0070] Step f reaction conditions: 1.5 equivalent of tetrabutylammonium fluoride, solvent is tetrahydrofuran, room temperature, 24 h, yield is 35%.

[0071] The total yield of step a to step f is 22%. It can be seen that the conventional idea of preparing alcohol-soluble bio-based polyisopropenyl ketone is complicated and has a very low yield.

[0072] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An alcohol-soluble bio-based citronella polymer, characterized in that, has a structural general formula as shown in formula (I): Formula (I) wherein n is an integer of 81-203.

2. The method of making an alcohol-soluble bio-based citronella polymer according to claim 1, wherein, Comprising the following steps: (1) taking citronellol as raw material, performing light irradiation in the presence of a photosensitizer and a solvent, and converting the citronellol into an isopropenyl ketone monomer through photooxidation under the action of singlet oxygen; (2) mixing the isopropenyl ketone monomer, a photosensitizer, a RAFT reagent and a solvent, and preparing the alcohol-soluble bio-based citronellal polymer through a PET-RAFT polymerization reaction under light irradiation.

3. The production method according to claim 2, wherein The photosensitizer in steps (1) and (2) is one or more of hematin, phenothiazine, benzoin ether, benzil ketals, dialkoxyacetophenone, acetophenone oxide, acyl phosphine oxide, benzophenone, 4,4'-dimethylaminobenzophenone, thiacronone, thioxanthone, camphor phenol, bisimidazole, thiophenone, aryl diazonium salt, diaryl iodide, triaryl sulfide, eosin, phthalocyanine, and curcumin.

4. The production method according to claim 2, wherein The molar ratio of citronellol to photosensitizer in step (1) is 50 / 1-200 / 1; the molar ratio of isopropenyl ketone monomer to photosensitizer in step (2) is 2000 / 1-10000 / 1, and the molar ratio of isopropenyl ketone monomer to RAFT reagent is 50 / 1-200 / 1.

5. The production method according to claim 2, wherein The solvent in steps (1) and (2) is one or more of water, acetic acid, acetone, acetonitrile, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl-p-cresol, chloroform, cyclohexane, dichloroethane, dichloromethane, diethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, dioxane, ethanol, ethyl acetate, methyl ethyl ketone, ethylene glycol, n-hexane, hexamethylphosphoramide, nitromethane, n-heptane, pyridine, tetrahydrofuran, toluene, and triethylamine.

6. The production method according to claim 2, characterized by, The light irradiation in steps (1) and (2) is performed under the following conditions: wavelength of 360-530 nm, and irradiation distance of 0.5-2.0 cm. The time of the photooxidation reaction in step (1) is 12-48 h, and the time of the PET-RAFT polymerization in step (2) is 12-48 h.

7. The production method according to claim 2, characterized by, The RAFT agent of step (2) is one or more of 2-[ (ethylthio) carbonylthio]propanoic acid, bis(carboxymethyl)trithiocarbonic acid, 2-[[ (butylthio) thioxomethyl]thio]propanoic acid, 2,2'-[thiocarbonylbis(sulfanediyl)]dipropionic acid, 2-[[ (2-carboxyethyl)sulfanylthiocarbonyl]- sulfanyl]propanoic acid, 4-cyano-4-(( (ethylthio)thiocarbonyl)thio)pentanoic acid, 3- benzylsulfanylthiocarbonylsulfanylpropanoic acid, 2,2'-[methylthiobis(thio)]bis[2- methylpropanoic acid], cyanomethyl dodecylcarbonyl carbon trithioformate, 2-cyano-2- propyldodecyltrithiocarbonic acid ester, 3,3'-[(dithia-1,2-dithiocarbonyl)bis(sulfanediyl)]dipropionic acid, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, benzyl dodecyl trithiocarbonic acid ester, 2-[[ (dodecylmercapto)thiomethyl]thio]-2- methylbenzoic acid methyl ester, 4-cyano-4-[[ (dodecylthio)thioxomethyl]thio]pentanoic acid, 2-dodecylthiocarbonylthio-2-methylpropanoic acid N - hydroxysuccinimidyl ester, bis(dodecylsulfanylthiocarbonyl)disulfide, (2-hydroxyethyl) benzyl trithiocarbonic acid ester, 2-mercapto-S-thiobenzoyl acetic acid, 2-cyano-2-propyl benzodithiole, benzyl dithiobenzoic acid ester, thio-benzoic acid-2-phenylpropane thioester, 4-cyano-4-(thiobenzoylthio)pentanoic acid, bis(thiobenzoyl) disulfide, 4-cyano-4-(phenylthiocarbonylthio)pentanoic acid N - succinimidyl ester, rhodanine, 3-ethyl-2-thioxothiazolidin-4-one, 3-carboxymethyl rhodanine, 3-(4-oxo-2-thioxothiazolidin-3-yl)propanoic acid, methyl(phenyl)amino dithioformic acid cyanomethyl ester, 3-benzylrhodanine, benzyl diethyl dithioaminocarboxylate, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetraisopropylthiuram disulfide, p-xylylene bis N , N - diethyl dithioaminocarboxylate), tetrabutylthiuram disulfide, tetrabenzylthiuram disulfide.

8. An alcohol-soluble resin-based environmentally friendly coating based on the bio-based citronellal polymer of claim 1.

9. The coating of claim 8, wherein, An alcohol-soluble resin solution containing the bio-based citronellal polymer of claim 1, further comprising an inorganic filler; the alcohol-soluble resin solution is obtained by dissolving the bio-based citronellal polymer in an alcohol solvent.

10. The coating of claim 9, wherein, The inorganic filler is selected from one or more of oil-soluble toner, Fe3O4 nanoparticles, rare earth particles, and Ag powder.

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