Preparation method and application of novel amphiphilic cellulose carboxymethyl cellulose palmitate

Abstract

The invention belongs to the technical field of preparation of modified cellulose carboxymethyl cellulose and nano-emulsion, and particularly relates to a preparation method of novel amphiphilic cellulose carboxymethyl cellulose palmitate, which comprises the following steps: S1, preparing palmitoleic acid from palm oil as a raw material, and further preparing palmitoleic acid into palmitoleic anhydride; and S2, reacting palmitoleic anhydride obtained in the step S1 with carboxymethyl cellulose, and purifying after the reaction is finished to obtain the carboxymethyl cellulose palmitate. According to the preparation method, ester bonds on palmitoleic acid anhydride and hydroxyl groups on carboxymethyl cellulose are replaced by utilizing the prepared novel palmitoleic acid anhydride derivative through ester exchange reaction, so that the amphipathic carboxymethyl cellulose palmitate is obtained. The novel amphiphilic cellulose carboxymethyl cellulose palmitate synthesized by the invention is green in reaction process and high in reaction activity of palmitic anhydride, and provides a basis for subsequent application in the aspect of self-assembly entrapment.

Description

Technical Field

[0001] The invention belongs to the technical field of modified cellulose carboxymethyl cellulose and nanoemulsion preparation, and more specifically, relates to a preparation method of a novel amphiphilic cellulose carboxymethyl cellulose palmitate and application thereof. Background Art

[0002] Compared with synthetic polymers, natural high molecular weight amphiphilic polymer materials have good biocompatibility and biodegradability. Cellulose is the most extensive biomass resource, and carboxymethyl cellulose is the product of cellulose etherification. Self-assembly requires that the polymer has good amphiphilicity. Carboxymethyl cellulose has good water solubility, but due to its insufficient hydrophobicity, it cannot self-assemble.

[0003] At present, the hydrophobic modification methods of carboxymethyl cellulose include esterification reaction, etherification reaction, atom transfer radical polymerization (ATRP), ring-opening polymerization (ROP), click chemistry, etc. Among the current methods for hydrophobic modification of carboxymethyl cellulose, Srokovd and Liu Zhanyong's research group used long carbon chains as hydrophobic groups. These two reactions used acyl chloride as the reaction raw material, which has a pungent smell and is toxic, and does not conform to the concept of green chemistry; Movaghamezhad et al. used hexamethylenediamine as the hydrophobic reagent, which required several hours of reaction under the protection of nitrogen, and the reaction time was relatively long; Cao Ya et al. used ultrasonic radiation to react carboxymethyl cellulose with the surfactant monomer dodecyl alcohol polyoxyethylene ether acrylate, but the reaction controllability was not high; Shao Bo et al. and Yang Fang et al. used methyl methacrylate and monomer acrylamide as the reaction raw materials to graft carboxymethyl cellulose, and finally applied them in concrete and conductive materials.

[0004] Polymers with special molecular structures can self-assemble under certain conditions to form aggregates of different forms, such as micelles and vesicles. The self-assembly process can usually be completed in aqueous solution through hydrophobic or electrostatic interactions between molecules, without the need for harsh reaction conditions and other organic solvents. This self-assembly has unique structural properties, such as unique rheology, nanoscale hydrodynamic radius and thermodynamic stability, and can be used to encapsulate hydrophobic substances, such as hydrophobic drugs, fluorescent probes, biomolecules, etc.

[0005] Therefore, there is an urgent need for a hydrophobic modification of carboxymethyl cellulose with a simple and green preparation process and easily controllable reaction conditions to obtain an amphiphilic carboxymethyl cellulose modification that can undergo self-emulsification in order to expand the needs of practical applications. Summary of the invention

[0006] This application intends to use a long carbon chain as a hydrophobic group, and obtain carboxymethyl cellulose palmitate by modifying palm oil into palmitoleic anhydride and then reacting it with carboxymethyl cellulose. This route has high reactivity and is expected to obtain amphiphilic carboxymethyl cellulose palmitate within 3 hours, thereby providing a basis for subsequent applications in self-assembly packaging.

[0007] Compared with other derivatization reactions, the preparation method provided in this application complies with the principles of green chemistry and successfully prepares nanoemulsions.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] A novel method for preparing carboxymethyl cellulose palmitate comprises the following steps:

[0010] S1, using palm oil as a raw material to prepare palmitoleic acid, and then further preparing palmitoleic acid into palmitoleic anhydride;

[0011] S2: reacting the palmitoleic anhydride obtained in step S1 with carboxymethyl cellulose, and obtaining carboxymethyl cellulose palmitate after purification.

[0012] Preferably, in step S1, palm oil is used as a raw material, ethanol, water and sodium hydroxide are added and mixed, and the mixture is reacted at 65 to 75° C. for 1 to 2 hours. After the reaction, the pH is adjusted to 3 with phosphoric acid, and the mixture is washed with deionized water for 3 to 4 times, then separated and the water is removed to obtain palmitoleic acid.

[0013] Preferably, in step S1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added twice and reacted with palmitoleic acid, and both reactions are carried out at 65-75° C. for 30 min, and then the solid precipitate is removed by centrifugation, leaving the upper liquid to obtain palmitoleic anhydride.

[0014] Preferably, in step S1, 50 wt% of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added for the first time, and 33.3 wt% of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added for the second time.

[0015] Preferably, the molar ratio of carboxymethyl cellulose to palmitoleic anhydride in step S2 is 1:3-6.

[0016] Preferably, in step S2, p-toluenesulfonic acid is used as a catalyst and dimethyl sulfoxide is used as a co-solvent for dissolution; wherein the mass ratio of palmitoleic anhydride to p-toluenesulfonic acid is 12:1, and the mass ratio of carboxymethyl cellulose to dimethyl sulfoxide is 1:10.

[0017] Preferably, dichloromethane is used for purification in step S2, and the mixture is washed three to four times, and the waste liquid is removed by centrifugation.

[0018] Furthermore, the novel carboxymethyl cellulose palmitate obtained by the above preparation method is also within the scope of protection claimed in the present application.

[0019] Furthermore, the novel carboxymethyl cellulose palmitate of the present application can be used to prepare nanoemulsions. In particular, the novel carboxymethyl cellulose palmitate itself acts as a surfactant to self-emulsify, and no other surfactant needs to be added to the nanoemulsion system.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The long carbon chain used in the present invention comes from palm oil, a biomass resource. The reaction raw materials are renewable and have no pollution to the environment. The waste liquid treatment and recycling in the preparation process is simple and convenient, which is conducive to industrial production.

[0022] The palm oleic anhydride synthesized by the present invention has the characteristics of high reactivity compared with palm oil itself. Unmodified palm oil cannot react with carboxymethyl cellulose, and the reaction process conditions are friendly. Compared with the hydrophobic modification of other carboxymethyl celluloses, it is greener chemistry.

[0023] The carboxymethyl cellulose palmitate synthesized by the invention can be self-emulsified without adding an additional surfactant and has the ability to load hydrophobic drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The infrared spectrum and nuclear magnetic resonance spectrum of palm oleic anhydride prepared in Example 1 and Comparative Example 1.

[0025] Figure 2 The infrared spectra and nuclear magnetic resonance spectra of carboxymethyl cellulose palmitate prepared in Example 1 and Comparative Example 1 are shown.

[0026] Figure 3 is the degree of substitution of carboxymethyl cellulose palmitate prepared in Examples 1-4.

[0027] Figure 4 Particle size and Zata potential of the carboxymethyl cellulose palmitate emulsion prepared in Experimental Example 5.

[0028] Figure 5 This is the transmission electron microscopy of carboxymethyl cellulose palmitate prepared in Experimental Example 5.

[0029] Figure 6 This is the encapsulation effect of carboxymethyl cellulose palmitate@curcumin prepared in Experimental Example 6. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the figures. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are prepared according to the conditions recommended by the normal conditions or the manufacturers. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] Example 1

[0032] Weigh 60g of palm oil, 50ml of anhydrous ethanol, and 11g of NaOH dissolved in 50ml of deionized water, mix well, react at 70°C for 1.5h, adjust the pH to 3 with phosphoric acid to terminate the reaction, split with 80°C deionized water 4 times, and remove water by rotary evaporation for 2h to obtain palmitoleic acid; weigh palmitoleic acid, add 50wt% 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDI) salt, react at 70°C for 20min, centrifuge at 8000rpm for 5min while hot, and The method comprises the following steps: adding 33.3 wt % 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDI) salt, centrifuging at 8000 rpm for 5 min while hot to obtain palmitoleic anhydride; weighing 3 g carboxymethyl cellulose, 1.5 g p-toluenesulfonic acid, and 90 ml dimethyl sulfoxide, and adding 18 g palmitoleic anhydride after the carboxymethyl cellulose is completely dissolved, reacting at 110° C. for 2.5 h, washing with dichloromethane, and purifying the product by centrifugation to finally obtain a purified carboxymethyl cellulose palmitate sample.

[0033] Example 2

[0034] Weigh 60g of palm oil, 50ml of anhydrous ethanol, and 11g of NaOH dissolved in 50ml of deionized water, mix well, react at 70°C for 1.5h, adjust the pH to 3 with phosphoric acid to terminate the reaction, split with 80°C deionized water 4 times, and remove water by rotary evaporation for 2h to obtain palmitoleic acid; weigh palmitoleic acid, add 50wt% 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDI) salt, react at 70°C for 20min, centrifuge at 8000rpm for 5min while hot, and Add 33.3 wt% 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDI) salt for the second time, centrifuge at 8000 rpm for 5 min while hot to obtain palmitoleic anhydride; weigh 3 g of carboxymethyl cellulose, 2 g of p-toluenesulfonic acid, and 90 ml of dimethyl sulfoxide, wait until the carboxymethyl cellulose is completely dissolved, add 24 g of palmitoleic anhydride, react at 110°C for 2.5 h, wash with dichloromethane, and purify the product by centrifugation to finally obtain a purified carboxymethyl cellulose palmitate sample.

[0035] Example 3

[0036] Weigh 60g of palm oil, 50ml of anhydrous ethanol, and 11g of NaOH dissolved in 50ml of deionized water, mix well, react at 70°C for 1.5h, adjust the pH to 3 with phosphoric acid to terminate the reaction, split with 80°C deionized water 4 times, and remove water by rotary evaporation for 2h to obtain palmitoleic acid; weigh palmitoleic acid, add 50wt% 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDI) salt, react at 70°C for 20min, centrifuge at 8000rpm for 5min while hot, and Add 33.3wt% 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDI) salt, centrifuge at 8000rpm for 5min while hot to obtain palmitoleic anhydride; weigh 3g carboxymethyl cellulose, 2.4g p-toluenesulfonic acid, and 90ml dimethyl sulfoxide, wait until the carboxymethyl cellulose is completely dissolved, add 29g palmitoleic anhydride, react at 110℃ for 2.5h, wash with dichloromethane, and purify the product by centrifugation to finally obtain a purified carboxymethyl cellulose palmitate sample.

[0037] Example 4

[0038] Weigh 60g of palm oil, 50ml of anhydrous ethanol, and 11g of NaOH dissolved in 50ml of deionized water, mix well, react at 70°C for 1.5h, adjust the pH to 3 with phosphoric acid to terminate the reaction, split with 80°C deionized water 4 times, and remove water by rotary evaporation for 2h to obtain palmitoleic acid; weigh palmitoleic acid, add 50wt% 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDI) salt, react at 70°C for 20min, centrifuge at 8000rpm for 5min while hot, and The method comprises the following steps: adding 33.3 wt % 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDI) salt, centrifuging at 8000 rpm for 5 min while hot to obtain palmitoleic anhydride; weighing 3 g carboxymethyl cellulose, 2.8 g p-toluenesulfonic acid, and 90 ml dimethyl sulfoxide, and adding 34 g palmitoleic anhydride after the carboxymethyl cellulose is completely dissolved, reacting at 110° C. for 2.5 h, washing with dichloromethane, and purifying the product by centrifugation to finally obtain a purified carboxymethyl cellulose palmitate sample.

[0039] Test Example 5:

[0040] The carboxymethyl cellulose palmitate (0.002 w / v%) prepared in Example 4 was dissolved in deionized water and homogenized for 7 min to obtain a CMCPOA emulsion.

[0041] Test Example 6:

[0042] 20 mg of carboxymethyl cellulose palmitate prepared in Example 4 was dissolved in deionized water, and 2 mg of curcumin was dissolved in dichloromethane. The mixture was homogenized for 7 min, and dichloromethane was removed by rotary evaporation. The precipitate was removed by 1 um nylon filter to obtain CMCPOA@curcumin emulsion.

[0043] Test Example 7:

[0044] 20 mg of carboxymethyl cellulose palmitate prepared in Example 4 was dissolved in deionized water, and 4 mg of curcumin was dissolved in dichloromethane. The mixture was homogenized for 7 min, and dichloromethane was removed by rotary evaporation. The precipitate was removed by 1 um nylon filter to obtain CMCPOA@curcumin emulsion.

[0045] Comparative Example 1

[0046] Weigh 3 g of carboxymethyl cellulose, 1.5 g of p-toluenesulfonic acid, and 90 ml of dimethyl sulfoxide. After the carboxymethyl cellulose is completely dissolved, add 18 g of palm oil, react at 110° C. for 2.5 h, wash with dichloromethane, and purify the product by centrifugation to finally obtain a purified carboxymethyl cellulose palmitate sample.

[0047] Performance testing and analysis

[0048] Test methods and conditions:

[0049] The infrared absorption spectra of palm oil and palm oleic anhydride were measured using a Nicolet IS10 spectrometer (Thermo Fisher, USA). Each group of samples was tested three times, and the most representative results are shown;

[0050] The NMR spectra of palm oil and palmitoleic anhydride were measured on a superconducting NMR spectrometer (Burker / AVANCE NEO600, Burker Biospin AG). Each group of samples was tested 3 times, and the most representative results are shown;

[0051] The infrared absorption spectra of carboxymethyl cellulose raw material and carboxymethyl cellulose palmitate were measured using a Nicolet IS10 spectrometer (Thermo Fisher, USA). Each group of samples was tested 3 times, and the most representative results are shown.

[0052] The NMR spectra of carboxymethyl cellulose raw material and carboxymethyl cellulose palmitate were measured on a superconducting NMR spectrometer (Burker / AVANCE NEO 600, Burker Biospin AG). Each group of samples was tested 3 times, and the most representative results are shown;

[0053] The substitution degree of carboxymethyl cellulose palmitate is determined by back titration. Take 0.5g carboxymethyl cellulose and carboxymethyl cellulose palmitate and dissolve them in 20ml 0.1N NaOH solution respectively. Stir the saponification reaction at 60℃ for 48h. After the reaction is completed, add two to three drops of phenolphthalein solution to the reaction solution, and then titrate the unreacted NaOH solution with 0.1N HCl solution until the color of the reaction solution changes from red to colorless. Record the volume of HCl solution consumed and substitute it into the following formula to calculate the substitution degree (DS):

[0054] DS=MAGU×W / [M POA ×(1-W)]

[0055] W=MAGU×(V1-V2)×C HCl / (m×1000)

[0056] Wherein, MAGU is the molar mass of carboxymethyl cellulose (242 g mol -1 );M POA is the net increase in mass per mole of AGU after successful grafting of palmitic anhydride (256 g mol -1 );C HCl is the concentration of hydrochloric acid solution (0.1 mol L -1 ), V1 and V2 (ml) are the volumes of hydrochloric acid consumed by the unesterified and unesterified samples, respectively, m (g) is the mass of the sample CMCPOA; W is the molar ratio of palmitoleic anhydride to AGU involved in the reaction, which is calculated according to the above formula.

[0057] The carboxymethylcellulose palmitate emulsion was stained with uranyl acetate under a microwave tissue processor (EM AWM, Leica, Germany); the TEM images were taken under a field emission transmission electron microscope (Talos F200S, FEI).

[0058] The particle size and Zata of carboxymethyl cellulose palmitate emulsion were measured using a laser particle size analyzer (Zatasizer Nano ZSE).

[0059] The encapsulation effect of carboxymethylcellulose palmitate@curcumin was determined by liquid chromatography (Waters 2695).

[0060] Analysis of measurement results

[0061] The infrared absorption spectra and nuclear magnetic resonance spectra of palm oil (PO) and palm oleic anhydride (POA) are shown in Figure 1 As shown. From the FTIR images of PO and POA, the 1743 cm -1 The stretching vibration peak of the ester bond C=O in triglycerides is 1820cm -1and 1730cm -1 They are the stretching vibration peaks of the ester bond C=O in O=COC=O; 1036cm -1 is the stretching vibration peak of CO; the appearance of these characteristic peaks preliminarily indicates the successful preparation of POA; from the 1 In the H-NMP spectrum, the signal peak a near 0.8ppm in PO is the methyl -CH3 of the three carbon chains on the triglyceride, with a hydrogen integral fraction of 9. The signal peak f near 0.8ppm in POA is the palmitoleic acid obtained by alcoholysis of triglyceride, which is obtained by dehydration to obtain POA, and its methyl -CH3 on the two long carbon chains has a hydrogen integral fraction of 6. The signal peaks b and c appearing at 4.1-4.4ppm on PO are the methylene -CH2 on the triglyceride, with a hydrogen integral fraction of 2 respectively. The signal peak h appearing at 2.3-2.5ppm on POA is the methylene next to the ester bond C=O in O=COC=O. The signal peak d appearing at 5.1-5.25ppm is the methyl group on the triglyceride, with a hydrogen integral fraction of 1, and this signal peak does not appear on POA; the signal peak e appearing at 5.25-5.5ppm on PO is that two long carbon chains on the triglyceride each contain a carbon-carbon double bond, and the hydrogen integral fraction is 4, and the signal peak i appearing at 5.25-5.5ppm on POA is that one of the long carbon chains contains a double bond, and the hydrogen integral fraction is 2; the results of the 1H-NMP spectra of PO and POA combined with the characteristic peaks appearing in FTIR indicate that palmitoleic anhydride was successfully prepared.

[0062] The infrared absorption spectra and nuclear magnetic spectra of carboxymethyl cellulose (CMC) raw materials and carboxymethyl cellulose palmitate (CMCPOA) are as follows: Figure 2 As shown in the figure. From the FTIR spectrum analysis, CMCPOA at 1750cm -1 A new peak appears at , which is the ester bond formed by the grafting of palmitic acid chain onto CMC, which preliminarily indicates that carboxymethyl cellulose palmitate was successfully synthesized; 12 C-NMR spectrum analysis shows that there are some additional peaks between 10-40ppm in the spectrum, which are the peaks of the carbon on the long carbon chain of palmitic acid. At 170-180ppm, the peak of the carbonyl carbon in the carboxylic acid on carboxymethyl cellulose shifts to a low chemical shift, and the peak area becomes wider. This is because the peak of the ester carbonyl carbon in carboxymethyl cellulose palmitate overlaps with the peak of the carbonyl carbon of the carboxylic acid on carboxymethyl cellulose. Combined with the analysis of infrared and nuclear magnetic spectra, it is shown that the long carbon chain of palmitic acid is successfully grafted onto carboxymethyl cellulose.

[0063] The degree of substitution of carboxymethyl cellulose palmitate is as follows Figure 3 As shown. Figure 3It can be seen that with the increase of n(POA):n(CMC), the degree of substitution of the synthesized carboxymethyl cellulose palmitate also increases. When the degree of substitution reaches a certain value, the rate of increase decreases. Since the transesterification reaction is a reversible reaction, under the condition of unchanged reaction conditions, increasing the amount of reactants is conducive to the reaction in the positive direction. Therefore, with the increase of n(POA):n(CMC), the degree of substitution of carboxymethyl cellulose palmitate also increases; however, when the degree of substitution increases to a certain extent, the degree of substitution tends to be saturated, and the long carbon chain of palmitic acid that has been grafted increases the steric hindrance of the reaction system, which is not conducive to the transesterification reaction. Therefore, when n(POA):n(CMC) reaches a certain value, the increasing trend of the degree of substitution slows down.

[0064] Particle size and Zata conductivity of carboxymethyl cellulose palmitate emulsions Figure 4 As shown. Because there are a large number of carboxylic acids on carboxymethyl cellulose, it has strong hydrophilicity, and the grafted palmitic acid long carbon chain is hydrophobic, so the synthesized carboxymethyl cellulose palmitate is amphiphilic. Driven by the intramolecular and intermolecular hydrophobic interaction forces, the carboxymethyl cellulose palmitate molecules gradually aggregate to form spherical micelles. When the length of the grafted alkyl chain is consistent, as the grafting degree increases, the particle size of the aggregates formed by the obtained carboxymethyl cellulose lauryl ester in the aqueous solution increases, and the particle size increases between 150nm-300nm. This is because the greater the grafting degree of carboxymethyl cellulose palmitate, the more hydrophobic chains there are on its molecular chain, and the larger the hydrophobic micro-regions formed when the molecules aggregate to form micelles, making the volume of the micelles larger, and thus the micelle particle size larger. The Zata potential is negative because the hydrophilic carboxylic acid groups on the carboxymethyl cellulose are distributed outside, and the hydrophobicity of the palmitic acid long carbon chain is inside. The size of the Zata potential is above 30, indicating that the nanoemulsion has a certain stability.

[0065] TEM image of carboxymethyl cellulose palmitate emulsion Figure 5 As shown in the figure, it can be seen that the amphiphilic carboxymethyl cellulose palmitate forms nanospheres with a particle size of about 150nm, which is smaller than the result measured by the particle size analyzer. This is because the particle size test condition of the particle size analyzer is in an aqueous solution, and the hydrophilic chain segments of the aggregates are in a stretched state in the aqueous solution, so the measured micelle particle size is larger; while the characterization by transmission electron microscopy is observed in the state of micelle drying, and the high molecular polymer is a flexible molecule, which is in a contracted state after drying, and the measured micelle particle size is smaller at this time.

[0066] The standard curve of carboxymethylcellulose palmitate@curcumin was prepared by Figure 6 As shown, 25ug / ml, 50ug / ml, 100ug / ml, 200ug / ml, and 400ug / ml curcumin solutions were prepared to prepare a standard curve, and the result was R 2=1, which meets the test conditions. The results are shown in Table 1.

[0067] Table 1

[0068]

[0069] As shown in Table 1, when the carboxymethylcellulose palmitate is 20 mg and the curcumin is 2 mg, the drug loading is 6.3% and the encapsulation efficiency is 70%; when the carboxymethylcellulose palmitate is 20 mg and the curcumin is 4 mg, the drug loading is 9.5% and the encapsulation efficiency is 57.6%. It can be concluded from the loading of curcumin with carboxymethylcellulose palmitate that carboxymethylcellulose palmitate has the ability to encapsulate hydrophobic drugs.

[0070] The above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a novel carboxymethyl cellulose palmitate, characterized in that: The steps include: S1, using palm oil as a raw material, first preparing palmitoleic acid, and then further preparing palmitoleic acid into palmitoleic anhydride; S2: reacting the palmitoleic anhydride obtained in step S1 with carboxymethyl cellulose, and obtaining carboxymethyl cellulose palmitate after purification.

2. The preparation method according to claim 1, characterized in that: In step S1, palm oil is used as a raw material, ethanol, water and sodium hydroxide are added and mixed, and the mixture is reacted at 65-75° C. for 1-2 hours. After the reaction, the pH is adjusted to 3 with phosphoric acid, and the mixture is washed with deionized water for 3-4 times, and then the liquid is separated and the water is removed to obtain palmitoleic acid.

3. The preparation method according to claim 1, characterized in that: In step S1, palmitoleic acid is further prepared into palmitoleic anhydride by reacting palmitoleic acid with 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added twice, and both reactions are reacted at 65-75° C. for 30 minutes. After the reaction is completed, the solid precipitate is removed by centrifugation, leaving the upper liquid to obtain palmitoleic anhydride.

4. The preparation method according to claim 3, characterized in that: In step S1, 50 wt% of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added for the first time, and 33.3 wt% of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added for the second time.

5. The preparation method according to claim 1, characterized in that: The molar ratio of carboxymethyl cellulose to palmitoleic anhydride in step S2 is 1:3-6.

6. The preparation method according to claim 1, characterized in that: In step S2, p-toluenesulfonic acid is used as a catalyst and dimethyl sulfoxide is used as a co-solvent for dissolution; wherein the mass ratio of palm oleic anhydride to p-toluenesulfonic acid is 12:1, and the mass ratio of carboxymethyl cellulose to dimethyl sulfoxide is 1:

10.

7. The preparation method according to claim 1, characterized in that: In step S2, dichloromethane is used for purification, and the mixture is washed three to four times, and the waste liquid is removed by centrifugation.

8. The novel carboxymethyl cellulose palmitate obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the novel carboxymethyl cellulose palmitate according to claim 8 in preparing nanoemulsion.

10. The use according to claim 9, characterized in that: The novel carboxymethyl cellulose palmitate itself acts as a surfactant to self-emulsify, and no other surfactant needs to be added to the nanoemulsion system.

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