Thermo-sensitive cellulose derivative as well as preparation method and application thereof

Abstract

The invention belongs to the field of functional polymer materials, and particularly relates to a thermo-sensitive cellulose derivative as well as a preparation method and application thereof. The cellulose derivative is cellulose with hydroxyl substituted by alkoxy glycidyl ether; and the low critical solution temperature can change in the range of 18-65 DEG C. The temperature-sensitive cellulose derivative integrates the advantages of cellulose and temperature-sensitive macromolecules, and has the characteristics of low cost, good biocompatibility, low toxicity, degradability, temperature response performance and the like. The method can be widely applied to the fields of drug carriers, sensors, biotechnology, surfactants, intelligent catalysis, separation engineering and the like.

Description

Technical Field

[0001] The present invention belongs to the field of functional polymer materials, and particularly relates to a temperature-sensitive cellulose derivative, a preparation method thereof, and an application thereof. Background Art

[0002] Intelligent polymers, also known as stimulus-responsive polymers, are a class of polymers whose molecular structure will suddenly undergo physical or chemical changes under the stimulus of small changes in the external environment. These polymer systems use the stimulus as a signal and change their molecular structure according to the strength of the signal. Among intelligent polymers, the most studied are temperature-sensitive polymers. Because temperature is the most widely applied stimulus, temperature changes are not only easy to control but also easily applicable in vivo and in vitro, and temperature-sensitive polymers are a type of intelligent polymer material that can respond to changes in the external temperature. Temperature-sensitive homopolymers will produce a large response to temperature changes within a certain range. Generally, there are two situations: when the solution temperature increases to the upper critical solution temperature, the solubility of some polymers will increase greatly; when the solution temperature increases to the lower critical solution temperature, the solubility of some polymers will decrease greatly. The solution temperature when the particle shape changes from coil-like to spherical is the LCST value. Different polymers and solvents have different LCST values. Temperature-sensitive homopolymers attract the interest of more and more researchers because of their potential application values in rheology-controllable food additives, thermally attractive separation methods, controlled drug release, gene therapy, etc. Most of the polymers developed for the above uses are copolymers, and there are also responsive microgels. A temperature-sensitive homopolymer has a repeating unit composed of a hydrophilic part and a hydrophobic part. A most famous example of an artificial temperature-sensitive polymer is poly(N-isopropylacrylamide) (PNIPAm), whose repeating unit is composed of a hydrophilic amide group and a hydrophobic isopropyl group, and it is in the form of solid powder and is extremely soluble in water. The LCST value of PNIPAm is about 32 °C, which is a good temperature for biomedical applications because it is lower than the human body temperature. However, synthetic polymers have poor biocompatibility, are not easily degradable, poly(N-isopropylacrylamide) is expensive, its monomer is a suspected carcinogen and neurotoxin, and it has a strong pungent smell. This limits its application in biomedical fields such as cell or protein separation, drug controlled release / sustained release, etc. Therefore, it is particularly important to find green synthesis technologies to prepare temperature-sensitive materials that are cheap, non-toxic, low-toxic, have good biocompatibility, and can precisely adjust the LCST.

[0003] Cellulose is the oldest and most abundant natural polymer on Earth and is an inexhaustible and invaluable natural renewable resource for humanity. More than 8 million tons of cellulose are used in textile and paper production worldwide every year. Cellulose has the advantages of being renewable, biodegradable, biocompatible, and non-toxic. The chemical structure of cellulose is a linear polymer formed by D-glucopyranose rings linked to each other by β-1,4-glycosidic bonds in the chair conformation of carbon 1. Each glucose unit ring in the cellulose molecule has three hydroxyl groups, located on the 2nd, 3rd, and 6th carbon atoms respectively. Among them, the hydroxyl group on carbon 6 is a primary alcohol hydroxyl group, while the hydroxyl groups on carbon 2 and carbon 3 are secondary alcohol hydroxyl groups. These three hydroxyl groups have different characteristics in heterogeneous chemical reactions and can undergo oxidation, esterification, etherification, grafting, copolymerization and other reactions. These three hydroxyl groups can all participate in the reaction, or only one of them can react. Therefore, under certain conditions, the types and positions of chemical functional groups on the glucose unit ring can be designed; and the degree of substitution and the distribution of the degree of substitution of chemical functional groups can be controlled separately on these three hydroxyl groups, so that the chemical structure of cellulose can be designed from the chemical structure on the glucose unit ring to prepare a variety of fine chemical products with special functions. Therefore, using cellulose as a raw material and making improvements can further expand the application fields of cellulose derivatives. Summary of the Invention

[0004] The purpose of the present invention is to provide a thermosensitive cellulose derivative, its preparation method and application.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A thermosensitive cellulose derivative, the cellulose derivative is cellulose in which the hydroxyl groups are replaced by alkoxy glycidyl ethers; its lower critical solution temperature can vary in the range of 18-65 °C.

[0007] The alkoxy glycidyl ether is one or more of ethyl glycidyl ether, isopropyl glycidyl ether, propyl glycidyl ether, n-butyl glycidyl ether, isobutyl glycidyl ether, butyl glycidyl ether, pentyl glycidyl ether or 2-[(2-(2-butoxyethoxy)propyl)methyl]glycidyl ether; among them,

[0008] The structural formula of 2-[(2-(2-butoxyethoxy)propyl)methyl]glycidyl ether is

[0009]

[0010] When the alkoxy glycidyl ether replacing the hydroxyl group is isopropyl glycidyl ether, its degree of substitution on cellulose is 2.00 - 2.90;

[0011] When it is propyl glycidyl ether, its degree of substitution on cellulose is 2.15 - 2.95;

[0012] When it is n-butyl glycidyl ether, its degree of substitution on cellulose is 0.80 - 2.99;

[0013] When it is isobutyl glycidyl ether, its degree of substitution on cellulose is 0.50 - 2.95;

[0014] When it is butyl glycidyl ether, its degree of substitution on cellulose is 0.20 - 2.89;

[0015] When it is pentyl glycidyl ether, its degree of substitution on cellulose is 0.05 - 2.22;

[0016] For 2-[(2-(2-butoxyethoxy)ethoxy)methyl] glycidyl ether, when n = 1, its degree of substitution on cellulose is 1.41 - 1.99; when n = 2, its degree of substitution on cellulose is 1.63 - 2.44; when n = 3, its degree of substitution on cellulose is 1.91 - 2.79.

[0017] A preparation method of the thermosensitive cellulose derivative described above. Add alkali to cellulose pulp with different molecular weights at a mass concentration of 10% - 60%, conduct alkalization treatment, and then add alkoxy glycidyl ether to the system and stir and react at 60 - 80 °C for 5 - 9 h. After the reaction, neutralize the pH of the system to 7, and then obtain cellulose substituted by alkoxy glycidyl ether in the form of powder or block solid through dialysis and drying.

[0018] Furthermore, add 2% - 25% of sodium hydroxide based on the mass of cellulose to cellulose pulp with different molecular weights at a mass concentration of 10% - 60% and stir. After alkalization at 70 °C for 1 h; then slowly drop alkoxy glycidyl ether into the system and stir and react at 60 - 80 °C for 5 - 9 h; after adding water for dilution and cooling, neutralize with hydrochloric acid to pH = 7, place it in a dialysis bag with a molecular weight of 7000 - 14000 for dialysis, and dialysis is completed when the conductivity is less than 10 μs / cm. Remove most of the water with a rotary evaporator, and then dry with a freeze dryer to obtain cellulose substituted by alkoxy glycidyl ether in the form of powder or block solid.

[0019] Put the dialysis bag filled with the reaction solution into deionized water with a conductivity of 1.3 μs / cm, and change the water continuously every day until the conductivity is less than 10 μs / cm.

[0020] The mass ratio of the alkoxy glycidyl ether to cellulose is 1 - 4:1,

[0021] The alkoxy glycidyl ether is one or several of ethyl glycidyl ether, isopropyl glycidyl ether, propyl glycidyl ether, n-butyl glycidyl ether, isobutyl glycidyl ether, butyl glycidyl ether, pentyl glycidyl ether or 2-[(2-(2-butoxyethoxy)propyl)methyl] glycidyl ether.

[0022] The mass ratio of the ethyl glycidyl ether to the cellulose is 3.2 - 4:1; the mass ratio of the isopropyl glycidyl ether to the cellulose is 2.6 - 3.8:1; the mass ratio of the propyl glycidyl ether to the cellulose is 2.8 - 3.9:1; the mass ratio of the n-butyl glycidyl ether to the cellulose is 1.9 - 3:1; the mass ratio of the isobutyl glycidyl ether to the cellulose is 2.1 - 3.2:1; the mass ratio of the butyl glycidyl ether to the cellulose is 1.9 - 3.5:1; the mass ratio of the amyl glycidyl ether to the cellulose is 0.5 - 3:1; or 2-[(2-(2-butoxy(ethoxy) n For 2-[(2-(2-propoxy)propyl)methyl]glycidyl ether, when n = 1, the mass ratio to the cellulose is 2 - 3:1; when n = 2, the mass ratio to the cellulose is 2.5 - 3.5:1; when n = 3, the mass ratio to the cellulose is 3 - 4:1.

[0023] The molecular weights of the cellulose are 90,000, 250,000 or 720,000 respectively.

[0024] The biggest feature of the thermosensitive cellulose derivative prepared by the above method is its temperature-responsive performance. By adjusting the substitution degree of different glycidyl ethers, thermosensitive cellulose derivatives with LCST varying in the range of 18 - 65 °C can be prepared. Besides the thermosensitive performance, this type of novel thermosensitive cellulose derivative also has good surface activity and rheological properties due to the presence of both hydrophilic and hydrophobic groups on the cellulose chain.

[0025] An application of the thermosensitive cellulose derivative as described above, which is used in smart windows or drug delivery.

[0026] The beneficial effects of the present invention are as follows:

[0027] The thermosensitive cellulose derivative of the present invention combines the advantages of cellulose and thermosensitive polymers, with excellent performance. Compared with petroleum-based thermosensitive polymers, it is cheap, has good biocompatibility, low toxicity, and is biodegradable. It provides a safer thermosensitive polymer for fields such as drug controlled release / sustained release and biological separation. Its LCST can be adjusted by changing the dosage of the etherifying agent, thereby changing the substitution degrees of the hydrophilic and hydrophobic groups on the cellulose chain, and thus achieving convenient regulation. The thermosensitive cellulose derivative prepared by this method can be applied in the pharmaceutical field, can be used as a drug carrier, has a thermosensitive controlled release function, and can also be used in other biomedical fields. It can be used for the separation of hydrophobic guest molecules in the field of separation engineering. In the field of chemical reactions, it can be used as a temperature-controlled phase transfer reaction carrier. Due to its good surface activity and rheological properties, this thermosensitive cellulose also has the functions of thickening, emulsifying, and dispersing, and can be widely applied in the daily chemical industry. Description of the Drawings

[0028] Figure 1For the embodiment of the present invention to obtain 3-ethoxy-2-hydroxybutyl cellulose product 1 1H-NMR spectrum.

[0029] Figure 2 For the embodiment of the present invention to obtain the release curve of Nile Red of cellulose derivatives at different temperatures. Specific embodiments

[0030] The following further illustrates the specific embodiments of the present invention in conjunction with examples. It should be noted that the specific embodiments described herein are only for explaining and illustrating the present invention and are not limited to the present invention.

[0031] The present invention modifies cellulose to prepare amphiphilic cellulose derivatives, and prepares temperature-sensitive cellulose derivatives by adjusting the hydrophobic / hydrophilic balance of cellulose. In order to adjust the hydrophobic / hydrophilic balance of cellulose, the present invention selects alkoxy glycidyl ether as the hydrophobizing reagent. One of the main reasons is that alkoxy glycidyl ether has high reactivity, which is conducive to the preparation of various hydrophobically modified celluloses with different high degrees of substitution; the second is that the hydrophobizing reagent and cellulose are connected by ether bonds, so it has high chemical stability; the third is that by changing the carbon chain length of the alkyl group, the hydrophilic / hydrophobic balance of the prepared amphiphilic cellulose can be conveniently adjusted. It lays a good theoretical foundation for preparing highly functional cellulose derivatives from cellulose with resource and performance advantages and broadening its application in high-tech fields such as biomedicine.

[0032] The determination method for the degree of substitution of the hydrophobic group, i.e., alkoxy glycidyl ether, of the derivative obtained in the following examples:

[0033] 1H-NMR was measured by a nuclear magnetic resonance instrument. The measurement method is: dissolve the product in deuterated water (D2O) and deuterated hydrochloric acid (DCl), acidify at 90 °C for 2 h, where V(D2O):V(DCl) = 1:1, and the concentration is 20 mg / 0.5 mL, and measure at room temperature (25 °C). The degree of substitution can be calculated by the following formula:

[0034]

[0035] In the formula is the integral area of the absorption peak at 0.6 - 0.9 ppm in the 1H-NMR spectrum, which is the absorption peak of the terminal methyl of the substituent, The value represents the number of moles of the substituent. is the integral area of the absorption peak at 4.5 - 5.5 ppm in the 1H-NMR spectrum, which is the absorption peak of the proton on the anomeric carbon of the cellulose glucose unit (AGU), The value represents the number of moles of AGU. The degree of substitution of the modified cellulose can be calculated by the ratio of the two. In the formula, n depends on the structure of the alkyl group. When the alkyl group is n-propyl, n-butyl, or n-pentyl, n = 3; when the alkyl group is isopropyl or isobutyl, n = 6; when the alkyl group is tert-butyl, n = 9.

[0036] For the determination of the lower critical solution temperature (LCST) value of the thermosensitive cellulose derivative, first prepare a 10% concentration sample solution, using deionized water as the reference sample. Then heat the solution at a heating rate of 1 °C / min, and use a UV-visible spectrophotometer to measure the transmittance of the sample at different temperatures. Take the first derivative of the transmittance with respect to temperature, and the temperature corresponding to the inflection point is the lower critical solution temperature.

[0037] The present invention will be further described below in conjunction with examples.

[0038] Example 1: Using cellulose with a molecular weight of 250,000 as the raw material to prepare 3-ethoxy-2-hydroxybutyl cellulose.

[0039] Add 5 g of cellulose to a 100 mL three-necked flask, add 25 mL of water for dispersion, and stir and heat to 70 °C. Drop 1.44 g of 40% sodium hydroxide into the three-necked flask and alkalize at 70 °C for 1 h. Then drop 14 g of n-butoxy glycidyl ether, raise the reaction temperature to 80 °C, and react for 8 h. After the reaction is completed, dilute with 100 mL of water, cool to room temperature, neutralize with hydrochloric acid to a pH value of 7, and then place it in a dialysis bag with a molecular weight of 7,000 - 14,000 for dialysis. Dialysis is completed when the conductivity is less than 10 μs / cm. Remove most of the water with a rotary evaporator, and then dry with a freeze dryer to obtain a block solid of 3-ethoxy-2-hydroxybutyl cellulose (see Figure 1 ), and its degree of substitution is measured to be DS = 1.88.

[0040] Prepare an aqueous solution of the above product with a concentration of 10%, heat it at a heating rate of 1 °C per minute, and use a UV-visible spectrophotometer to measure its LCST = 34 °C.

[0041] Using cellulose with a molecular weight of 90,000 or 720,000 as the raw material respectively, prepare cellulose ethers according to the above-described method; the basic reaction conditions and the measured degrees of substitution and LCST values are listed in Table 1. The specific experimental operation steps are the same as those in Example 1.

[0042] Table 1 Basic reaction conditions and measured degrees of substitution and LCST values using cellulose with different molecular weights as raw materials

[0043]

[0044] As described above, when the butyl substitution degree is less than 0.2, the cellulose product has weak hydrophobicity and cannot maintain the hydrophilic-lipophilic balance in the molecular structure. Therefore, it has no temperature-sensitive property and no LCST. When the butyl substitution degree is greater than 2.89, the cellulose product has extremely strong hydrophobicity and cannot dissolve in water. Therefore, it also has no temperature-sensitive property and no LCST; only when the product is obtained at a specific substitution degree can the hydrophobic / hydrophilic balance be achieved.

[0045] Example 2: 3-Ethoxy-2-hydroxypentyl cellulose was prepared using cellulose with a molecular weight of 250,000 as the raw material.

[0046] 5 g of cellulose was added to a 100 mL three-necked flask, dispersed with 42 mL of water, and stirred and heated to 70 °C. 2.19 g of sodium hydroxide with a concentration of 40% was added dropwise to the three-necked flask, and alkalized at 70 °C for 1 h. Then 7.1 g of n-butoxy glycidyl ether was added dropwise, and the reaction temperature was maintained at 80 °C for 8 h. After the reaction was completed, it was diluted with 100 mL of water, cooled to room temperature, neutralized with hydrochloric acid to a pH value of 7, placed in a dialysis bag with a molecular weight of 7000 - 14000 for dialysis, and dialysis was completed when the conductivity was less than 10 μs / cm. Most of the water was removed using a rotary evaporator, and then dried with a freeze dryer to obtain a blocky solid of 3-ethoxy-2-hydroxy-n-butyl cellulose. After measurement, its substitution degree was DS = 0.32.

[0047] An aqueous solution of the above product with a concentration of 10% was prepared, heated at a heating rate of 1 °C per minute, and its LCST = 15 °C was measured using a UV-visible spectrophotometer.

[0048] Cellulose ethers were prepared using cellulose with a molecular weight of 90,000 or 720,000 as the raw material according to the above-described method; the basic reaction conditions and the measured substitution degrees and LCST values are listed in Table 2. The specific experimental operation steps are the same as those in Example 2.

[0049] Table 2 Basic reaction conditions and measured substitution degrees and LCST values using cellulose with different molecular weights as raw materials

[0050]

[0051] Example 3: 2-Hydroxy-3-(2-butoxyethoxy)propyl cellulose ether was prepared using cellulose with a molecular weight of 250,000 as the raw material.

[0052] Add 5 g of cellulose into a 100 mL three-necked flask, add 42 mL of water for dispersion, stir and heat to 70 °C. Dropwise add 1.89 g of sodium hydroxide with a concentration of 40% into the three-necked flask, and alkalize at 70 °C for 1 h. Then dropwise add 13.4 g of 2-[(2-(2-butoxyethoxy)propyl)methyl]glycidyl ether, keep the reaction temperature at 90 °C, and react for 8 h. After the reaction is completed, dilute with 100 mL of water, cool to room temperature, neutralize with hydrochloric acid to a pH value of 7, then place it in a dialysis bag with a molecular weight of 7000 - 14000 for dialysis, and dialysis is completed when the conductivity is less than 10 μs / cm. Remove most of the water with a rotary evaporator, and then dry with a freeze dryer to obtain 3-ethoxy-2-hydroxy-n-butyl cellulose in the form of powder or bulk solid. After measurement, its degree of substitution is DS = 1.39.

[0053] Prepare an aqueous solution of the above product with a concentration of 10%, heat it at a heating rate of 1 °C per minute, and measure its LCST = 32 °C using an ultraviolet-visible spectrophotometer.

[0054] Use cellulose with a molecular weight of 900,000 or 720,000 as raw materials respectively to prepare cellulose ethers according to the method described above; the basic reaction conditions, measured degree of substitution, and LCST values are listed in Table 3. The specific experimental operation steps are the same as those in Example 3.

[0055] Table 3 Basic reaction conditions, measured degree of substitution, and LCST values using cellulose with different molecular weights as raw materials

[0056]

[0057] Application Example

[0058] Take the product using 720,000 cellulose in Example 1 as the research object, and conduct research on the drug delivery performance at different temperatures. As can be seen from the appendix Figure 2 When the temperature is 20 °C, the fluorescence intensity of Nile Red (simulated drug) in the cellulose product does not change significantly with the increase of time. This shows that at this temperature, Nile Red solubilized in the cellulose product is not significantly released within 150 h; when the temperature is 38 °C, the fluorescence intensity of Nile Red gradually decreases with the increase of time. This indicates that when the temperature is higher than the LCST, due to the deformation of the aggregate structure, Nile Red is released from the cellulose product into the aqueous solution, resulting in the fluorescence quenching of Nile Red and thus the decrease in fluorescence intensity.

Claims

1. A thermosensitive cellulose derivative, characterized in that: The cellulose derivative is cellulose in which the hydroxyl groups are replaced by alkoxy glycidyl ethers; its lower critical solution temperature can vary in the range of 18 to 65 °C.

2. The thermosensitive cellulose derivative according to claim 1, wherein: The alkoxy glycidyl ether is one or more of ethyl glycidyl ether, isopropyl glycidyl ether, propyl glycidyl ether, n-butyl glycidyl ether, isobutyl glycidyl ether, butyl glycidyl ether, pentyl glycidyl ether or 2-[(2-(2-butoxyethoxy)propyl)methyl]glycidyl ether; among them, the structural formula of 2-[(2-(2-butoxyethoxy)propyl)methyl]glycidyl ether is 3. The thermosensitive cellulose derivative according to claim 2, characterized in that: When the hydroxyl group is replaced by isopropyl glycidyl ether, its degree of substitution on cellulose is 2.00 - 2.90; When it is propyl glycidyl ether, its degree of substitution on cellulose is 2.15 - 2.95; When it is n-butyl glycidyl ether, its degree of substitution on cellulose is 0.80 - 2.99; When it is isobutyl glycidyl ether, its degree of substitution on cellulose is 0.50 - 2.95; When it is butyl glycidyl ether, its degree of substitution on cellulose is 0.20 - 2.89; When it is pentyl glycidyl, its degree of substitution on cellulose is 0.05 - 2.22; 2-[(2-(2-butoxyethoxy)ethoxy)methyl]glycidyl ether, when n = 1, its degree of substitution on cellulose is 1.41 - 1.99; when n = 2, its degree of substitution on cellulose is 1.63 - 2.44; when n = 3, its degree of substitution on cellulose is 1.91 - 2.

79.

4. A method for preparing the thermosensitive cellulose derivative according to claim 1, characterized in that: Alkali is added to cellulose pulp with different molecular weights at a mass concentration of 10% - 60% for alkalization treatment, and then alkoxy glycidyl ether is added to the system and stirred at 60 - 80 °C for 5 - 9 h. After the reaction, the pH of the system is neutralized to 7, and then dialysis and drying are carried out to obtain cellulose substituted by alkoxy glycidyl ether in the form of powder or block solid.

5. The preparation method of the thermosensitive cellulose derivative according to claim 4, characterized in that: Sodium hydroxide with 2% - 25% of the cellulose mass is added to cellulose pulp with different molecular weights at a mass concentration of 10% - 60% and stirred. After alkalization at 70 °C for 1 h; then alkoxy glycidyl ether is slowly added dropwise to the system, and after stirring at 60 - 80 °C for 5 - 9 h; it is diluted with water and cooled, then neutralized with hydrochloric acid to pH 7, placed in a dialysis bag with a molecular weight of 7000 - 14000 for dialysis, and dialysis is completed when the conductivity is less than 10 μs / cm. Most of the water is removed with a rotary evaporator, and then it is dried with a freeze dryer to obtain cellulose substituted by alkoxy glycidyl ether in the form of powder or block solid.

6. The preparation method of the thermosensitive cellulose derivative according to claim 4 or 5, characterized in that: The mass ratio of the alkoxy glycidyl ether to cellulose is 1 - 4:

1.

7. The preparation method of the thermosensitive cellulose derivative according to claim 6, characterized in that: The alkoxy glycidyl ether is one or more of ethyl glycidyl ether, isopropyl glycidyl ether, propyl glycidyl ether, n-butyl glycidyl ether, isobutyl glycidyl ether, butyl glycidyl ether, pentyl glycidyl ether or 2-[(2-(2-butoxyethoxy)propyl)methyl]glycidyl ether.

8. The preparation method of the thermosensitive cellulose derivative according to claim 6, characterized in that: The mass ratio of the ethyl glycidyl ether to the cellulose is 3.2 to 4:1; the mass ratio of the isopropyl glycidyl ether to the cellulose is 2.6 to 3.8:1; the mass ratio of the propyl glycidyl ether to the cellulose is 2.8 to 3.9:1; the mass ratio of the n-butyl glycidyl ether to the cellulose is 1.9 to 3:1; the mass ratio of the isobutyl glycidyl ether to the cellulose is 2.1 to 3.2:1; the mass ratio of the butyl glycidyl ether to the cellulose is 1.9 to 3.5:1; the mass ratio of the pentyl glycidyl ether to the cellulose is 0.5 to 3:1; or 2-[(2-(2-butoxy(ethoxy) n propyl)methyl]glycidyl ether, when n = 1, the mass ratio to the cellulose is 2 to 3:1, when n = 2, the mass ratio to the cellulose is 2.5 to 3.5:1, and when n = 3, the mass ratio to the cellulose is 3 to 4:

1.

9. The preparation method of the thermosensitive cellulose derivative according to claim 4 or 5, characterized in that: The molecular weights of the cellulose are 90,000, 250,000 or 720,000 respectively.

10. Use of the thermosensitive cellulose derivative according to claim 1, characterized in that: The application of the thermosensitive cellulose derivative in smart windows or drug delivery.

Images