Hydrophilic thermosensitive resin as well as preparation method and application thereof

Abstract

The invention relates to the field of hydrophilic thermosensitive resin, in particular to hydrophilic thermosensitive resin as well as a preparation method and application thereof, and aims to solve the problems that an existing thermosensitive material is insufficient in hydrophilicity, an existing hydrophilic material is insufficient in thermosensitive performance, and a resin material cannot give consideration to both the hydrophilic material and the hydrophilic material at the same time. According to the resin, an imidazole structure is introduced into polyacrylamide and grafted into PNIPAM to form an amido bond, the hydrophilic performance of the PNIPAM is improved, ethyl cellulose is grafted onto amino-treated silicon dioxide to form an amido bond, and the hydrophilic performance of the resin is improved together with modified polyacrylamide blended PNIPAM; when the resin is applied to a specific medium or environment, the resin can show a corresponding response behavior on absorption or release of moisture according to the change of environment temperature, realizes effective regulation and control and induction on temperature and humidity, and can be applied to temperature-sensitive medical treatment, electronic packaging and other emerging technical fields.

Description

Technical Field

[0001] The present invention relates to the field of hydrophilic thermosensitive resins, and in particular to a hydrophilic thermosensitive resin and a preparation method and application thereof. Background Art

[0002] Nowadays, polymers have attracted much attention due to their wide range of applications, especially polymer materials with special functions. Traditional polymer materials are mostly hydrophobic, but in many application scenarios, such as water treatment and drug delivery, materials are required to have excellent hydrophilicity. Therefore, hydrophilic resins have become a hot topic of research. In addition, the demand for thermosensitive materials is also increasing. Thermosensitive resin materials can undergo changes in physical or chemical properties at a specific temperature and are suitable for temperature-sensitive medical, electronic packaging and other emerging technology fields. Existing thermosensitive materials are not hydrophilic enough and have insufficient thermosensitive properties. Therefore, the present invention provides a hydrophilic thermosensitive resin that not only meets the high demand for hydrophilicity, but also can undergo significant thermosensitive changes at a specific temperature, meeting the dual needs of new materials in functionality and controllability. Summary of the Invention

[0003] In order to overcome the above technical problems, the purpose of the present invention is to provide: a hydrophilic thermosensitive resin and a preparation method thereof, which solves the problems of low hydrophilicity and poor thermosensitive performance of existing hydrophilic thermosensitive resins.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A hydrophilic thermosensitive resin comprises the following components in parts by weight: 50-100 parts of modified polyacrylamide blended with PNIPAM, 10-20 parts of ethyl cellulose grafted with amino-modified silica, and 5-10 parts of starch. The components are added into a twin-screw mixer, melt-blended, extruded, and granulated to obtain the hydrophilic thermosensitive resin.

[0006] Wherein, the modified polyacrylamide blended PNIPAM is prepared by the following steps:

[0007] Step A1: 2-hydroxybenzaldehyde, 2-aminophenol, benzil, ammonium acetate, and acetonitrile are added to a three-necked flask equipped with a reflux condenser and a thermometer, and the mixture is reacted at 110-120° C. for 22-24 hours. After completion of the reaction, the mixture is filtered under reduced pressure to obtain a solid, which is recrystallized from a mixed solution of ethanol and N,N-dimethylformamide, and the product is vacuum dried to obtain tetraphenylimidazole diphenol;

[0008] Step A2: Tetraphenylimidazole diphenol, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide are added to a three-necked flask equipped with a stirrer and a thermometer, and nitrogen is introduced. The mixture is reacted at a temperature of 24-26° C. and a stirring rate of 100-200 r / min for 30-40 minutes. Chloroacetic acid is added, the temperature is raised to 60-80° C., and the mixture is reacted at a stirring rate of 100-200 r / min for 6-8 hours. After the reaction is completed, the mixture is cooled and the reaction solution is added to ice water with a stirring rate of 50-100 r / min. Hydrochloric acid is added dropwise to adjust the pH to 3. The precipitate is extracted with ethyl acetate three times, washed with deionized water four times, dried with anhydrous sodium sulfate for 2 hours, filtered, and rotary evaporated to remove the ethyl acetate to obtain carboxylated tetraphenyl-substituted imidazole diphenol;

[0009] Step A3: Add polyacrylamide and deionized water to a three-necked flask equipped with a stirrer, and stir at a stirring rate of 200-300 r / min for 10-20 min to obtain a polyacrylamide aqueous solution;

[0010] Step A4: Carboxylated tetraphenyl substituted imidazole diphenol and N,N-dimethylformamide are added to a three-necked flask equipped with a stirrer and a thermometer, stirred until dissolved, N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide are added, MES buffer is added to adjust the pH to 5.5, nitrogen protection is introduced, and the reaction is carried out at a stirring rate of 50-100 r / min for 20-30 minutes. After the reaction is completed, a polyacrylamide aqueous solution is added dropwise, and the reaction is carried out at a temperature of 28-30°C for 12-24 hours. After the reaction is completed, hydrochloric acid is added and stirred for 8-10 minutes. The reaction solution is added to anhydrous ethanol and stirred at a stirring rate of 50-100 r / min for 20-30 minutes. The reaction is allowed to settle, filtered, and washed three times with an ethanol aqueous solution. The solid is added to deionized water, transferred to a 10 kDa dialysis bag, dialyzed for 48 hours, and the dialyzed solution is freeze-dried to obtain tetraphenyl imidazole diphenol grafted polyacrylamide;

[0011] Step A5: Add PNIPAM and deionized water to a three-necked flask equipped with a stirrer, and stir for 1-2 hours at a stirring rate of 100-200 rpm to obtain a PNIPAM aqueous solution;

[0012] Step A6: Tetraphenylimidazole diphenol grafted polyacrylamide and N,N-dimethylformamide are added to a single-necked flask, ultrasonically dispersed at a power of 300 W for 10 minutes, a magnetic rotor is added, and the PNIPAM aqueous solution is added dropwise at a stirring rate of 200-300 r / min, and the addition time is controlled to be 10-15 minutes. Ultrasonic dispersion is performed at a power of 200 W for 20 minutes, and the mixture is concentrated to one-third of the original volume at a temperature of 40-50°C and a vacuum degree of 0.08 MPa. The concentrate is added to anhydrous ethanol and stirred at a stirring rate of 50-100 r / min for 30 minutes. The mixture is allowed to settle, filtered, washed three times with an ethanol-water solution, and the precipitate is dried at 40-50°C for 24 hours to obtain a modified polyacrylamide blended with PNIPAM.

[0013] The usage ratio of 2-hydroxybenzaldehyde, 2-aminophenol, benzil, ammonium acetate and acetonitrile in step A1 is 40.94-81.88 mmol: 40.94-81.88 mmol: 40.94-81.88 mmol: 81.89-163.77 mmol: 100-200 mL.

[0014] The usage ratio of tetraphenylimidazole diphenol, anhydrous potassium carbonate, anhydrous N,N-dimethylformamide, chloroacetic acid, ice water and hydrochloric acid in step A2 is 2.5-5g:25-50mmol:250-500mL:15-30mmol:250-500mL:5-10mL:5-10g.

[0015] The concentration of hydrochloric acid in step A2 is 1 mol / L.

[0016] The usage ratio of polyacrylamide and deionized water in step A3 is 1-2 g: 20-40 mL.

[0017] The CAS number of the polyacrylamide described in step A3 is 9003-05-8.

[0018] The amount ratio of the carboxylated tetraphenyl substituted imidazole diphenol, N,N-dimethylformamide, N-hydroxysuccinimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, MES buffer, polyacrylamide aqueous solution, hydrochloric acid, anhydrous ethanol and deionized water in step A4 is 1-2 g: 5-10 mL: 2.4-4.8 g: 1.5-3 g: 5-10 mL: 20-40 mL: 2.5-5 mL: 50-100 mL: 25-50 mL.

[0019] The concentration of the MES buffer in step A4 is 50 mmol / L.

[0020] The concentration of hydrochloric acid in step A4 is 0.1 mol / L.

[0021] The ratio of PNIPAM to deionized water in step A5 is 5-10 g: 20-40 mL.

[0022] The CAS number of PNIPAM in step A5 is 25189-55-3.

[0023] In step A6, the ratio of the tetraphenylimidazole diphenol grafted polyacrylamide, N,N-dimethylformamide, PNIPAM aqueous solution and anhydrous ethanol is 1-2 g: 10-20 mL: 10-20 mL: 100-200 mL.

[0024] Wherein, the ethyl cellulose grafted amino-modified silica is prepared by the following steps:

[0025] Step B1: Add silica, anhydrous ethanol, and distilled water to a three-necked flask equipped with a stirrer and a thermometer, and stir the mixture at a temperature of 70-80°C and a stirring rate of 300-400 r / min for 1 hour. After the reaction, the solution is maintained at 60°C, and ammonia water is added dropwise to adjust the pH to 8-9. 3-aminopropyltriethoxysilane is added dropwise to the three-necked flask, and the reaction is continued for 1 hour. The mixture is then heated to 80°C and reacted for 2 hours. The mixture is then cooled and filtered. The filter cake is dried in an oven at 50°C and ground to obtain amino-grafted silica powder.

[0026] Step B2: Ethyl cellulose and dichloromethane are added to a three-necked flask equipped with a thermometer and a stirrer, stirred at a stirring rate of 100-200 r / min for 10-20 minutes, succinic anhydride and pyridine are added, and the reaction is carried out at 35-45° C. and 100-200 r / min for 6-8 hours. After the reaction is completed, the reaction solution is added to ice water, filtered, and the filter cake is washed with deionized water 3-5 times, and vacuum dried at 60° C. for 12 hours to obtain carboxylated ethyl cellulose;

[0027] Step B3: Add amino silica and N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer, ultrasonically disperse for 20-30 minutes, add carboxylated ethyl cellulose, mix for 20-30 minutes at a stirring rate of 100-200 r / min, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, stir for 0.5-1 hour at 24-26°C and 100-200 r / min, heat to 50-60°C, react for 12-24 hours, and after the reaction is completed, collect the solid by centrifugation, wash twice with N,N-dimethylformamide, and then wash three times with anhydrous ethanol. The solid is vacuum dried at 50-60°C for 24 hours to obtain ethyl cellulose grafted amino-modified silica.

[0028] The amount ratio of silicon dioxide, anhydrous ethanol, distilled water and 3-aminopropyltriethoxysilane used in step B1 is 9.4g:45-48g:175mL:10-15mL:10.34g.

[0029] The mass fraction of the ammonia water in step B1 is 20-35%.

[0030] In step B2, the usage ratio of ethyl cellulose, dichloromethane, succinic anhydride, pyridine and ice water is 1-2 g: 20-40 mL: 0.5-1 g: 0.2-0.4 mL: 50-100 mL.

[0031] The amount ratio of the amino silica, N,N-dimethylformamide, carboxylated ethyl cellulose, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide in step B3 is 0.3-3 g: 30-300 mL: 0.5-5 g: 0.15-1.5 g: 0.09-0.9 g.

[0032] As a further solution of the present invention: a method for preparing a hydrophilic thermosensitive resin comprises the following steps:

[0033] Step 1: Weigh 50-100 parts of modified polyacrylamide blend PNIPAM, 10-20 parts of ethyl cellulose grafted amino-modified silica, and 5-10 parts of starch according to weight;

[0034] Step 2: Add modified polyacrylamide blended with PNIPAM, ethyl cellulose grafted with amino-modified silica, and starch into a twin-screw mixer, melt-blend, extrude and granulate to obtain a hydrophilic thermosensitive resin.

[0035] As a further solution of the present invention: a method for preparing a hydrophilic thermosensitive resin and application of the hydrophilic thermosensitive resin prepared in temperature-sensitive medical treatment.

[0036] Beneficial effects of the present invention:

[0037] The present invention discloses a hydrophilic thermosensitive resin and a preparation method and application thereof. The invention introduces imidazole rings into polyacrylamide and grafts the modified polyacrylamide onto PNIPAM to improve the hydrophilicity of PNIPAM. Amino groups are introduced into the surface of silica by amino treatment. Carboxyl groups are introduced into ethyl cellulose and react with the amino groups on the surface of silica to form amide bonds, thereby improving the hydrophilicity. When the resin is used in a specific environment, it can absorb or release water in response to changes in ambient temperature, thereby achieving effective control and sensing of temperature and humidity.

[0038] In the process of preparing hydrophilic thermosensitive resin, modified polyacrylamide blended PNIPAM was first prepared. The diketone structure in benzil was first condensed with the amino group in 2-aminophenol and ammonium acetate through dehydration condensation, and then condensed with the aldehyde group in 2-hydroxybenzaldehyde to obtain an imidazole ring structure. The phenolic hydroxyl group in tetraphenylimidazole diphenol was deprotonated under alkaline conditions to generate phenol oxide anion, which enhanced the nucleophilicity. The α-carbon in chloroacetic acid was partially positively charged and had strong electrophilicity. The phenol oxide anion reacted with the α-carbon in chloroacetic acid to form an ether bond while retaining the carboxyl group. 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide reacted with the carboxyl group in the carboxylated tetraphenyl substituted imidazole diphenol to generate O-acylisourea intermediate. N-hydroxysuccinimide reacted with the O-acylisourea intermediate to generate N-hydroxysuccinimide ester. The amino group in polyacrylamide underwent nucleophilic substitution reaction with the ester group. Aminolysis is carried out to generate amide groups, and the hydrogen ions of the phenolic hydroxyl groups in the tetraphenylimidazole diphenol grafted polyacrylamide form hydrogen bonds with the oxygen ions in the amide bond to obtain a modified polyacrylamide blend PNIPAM. Succinic anhydride reacts with the hydroxyl groups in the ethyl cellulose to generate succinate and release water, while also generating carboxyl groups. The carboxyl groups in the carboxylated ethyl cellulose react with the amino groups to generate amide bonds, and the ethyl cellulose is grafted onto silica. The introduction of amide groups increases the hydrophilicity of the resin and the thermal sensitivity of PNIPAM. At low temperatures, the hydrophilic groups in the resin molecular chain are tightly bound to water molecules through hydrogen bonds. At high temperatures, the increase in temperature intensifies the thermal motion of the water molecules, destroying the hydrogen bonds between the hydrophilic groups and water, and at the same time, the hydrophobic groups in the molecular chain aggregate. Due to its excellent hydrophilicity and thermal sensitivity, the resin can be widely used in industrial fields such as temperature control systems and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0040] Figure 1 Schematic diagram of the changes in the hydrophilic properties of Examples 1-3 of the present invention and Comparative Examples 1-3.

[0041] Figure 2 Schematic diagram of the changes in light transmittance of Examples 1-3 of the present invention and Comparative Examples 1-3. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] Example 1:

[0044] This embodiment is a method for preparing a hydrophilic thermosensitive resin, comprising the following steps:

[0045] Step S1: 40.94 mmol of 2-hydroxybenzaldehyde, 40.94 mmol of 2-aminophenol, 40.94 mmol of benzil, 81.89 mmol of ammonium acetate, and 100 mL of acetonitrile were added to a three-necked flask equipped with a reflux condenser and a thermometer. The mixture was reacted at 110° C. for 22 h. After the reaction was completed, the solid was filtered under reduced pressure to obtain a solid. The solid was recrystallized from a mixed solution of ethanol and N,N-dimethylformamide, and the product was vacuum dried to obtain tetraphenylimidazole diphenol.

[0046] Step S2: 2.5 g of tetraphenyl imidazole diphenol, 25 mmol of anhydrous potassium carbonate and 250 mL of anhydrous N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and nitrogen was introduced for protection. The mixture was reacted at a temperature of 24° C. and a stirring rate of 100 r / min for 30 min. 15 mmol of chloroacetic acid was added, the temperature was raised to 60° C., and the mixture was reacted at a stirring rate of 100 r / min for 6 h. After the reaction was completed, the mixture was cooled and the reaction solution was added to 250 mL of ice water with a stirring rate of 50 r / min. 5 mL of 1 mol / L hydrochloric acid was added dropwise to adjust the pH to 3. The precipitate was extracted with ethyl acetate 3 times, washed with deionized water 4 times, added with 5 g of anhydrous sodium sulfate, dried for 2 h, filtered, and rotary evaporated to remove ethyl acetate to obtain carboxylated tetraphenyl substituted imidazole diphenol;

[0047] Step S3: adding 1 g of polyacrylamide and 20 mL of deionized water to a three-necked flask equipped with a stirrer, and stirring at a stirring rate of 200 r / min for 10 min to obtain a polyacrylamide aqueous solution;

[0048] Step S4: 1 g of carboxylated tetraphenyl substituted imidazole diphenol and 5 mL of N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, stirred until dissolved, 2.4 g of N-hydroxysuccinimide and 1.5 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, and 5 mL of The pH value of the mixture was adjusted to 5.5 with MES buffer, nitrogen was introduced for protection, and the mixture was reacted for 20 minutes at a stirring rate of 50 r / min. After the reaction, 20 mL of polyacrylamide aqueous solution was added dropwise, and the mixture was reacted for 12 hours at a temperature of 28°C. After the reaction, 2.5 mL of 0.1 mol / L hydrochloric acid was added and stirred for 8 minutes. The reaction solution was added to 50 mL of anhydrous ethanol and stirred for 20 minutes at a stirring rate of 50 r / min. The mixture was allowed to stand for precipitation, filtered, and washed three times with ethanol aqueous solution. The solid was added to 25 mL of deionized water, transferred to a 10 kDa dialysis bag, and dialyzed for 48 hours. The dialyzed solution was freeze-dried to obtain tetraphenylimidazole diphenol grafted polyacrylamide.

[0049] Step S5: 5 g of PNIPAM and 20 mL of deionized water were added to a three-necked flask equipped with a stirrer, and stirred at a stirring rate of 100 r / min for 1 h to obtain a PNIPAM aqueous solution;

[0050] Step S6: 1 g of tetraphenylimidazole diphenol grafted polyacrylamide and 10 mL of N,N-dimethylformamide were added to a single-necked flask, ultrasonically dispersed at a power of 300 W for 10 minutes, a magnetic rotor was added, and 10 mL of PNIPAM aqueous solution was added dropwise at a stirring rate of 200 r / min, and the addition time was controlled to be 10 minutes. The mixture was ultrasonically dispersed at a power of 200 W for 20 minutes, and the mixture was concentrated to one-third of the original volume at a temperature of 40° C. and a vacuum degree of 0.08 MPa. The concentrate was added to 100 mL of anhydrous ethanol and stirred at a stirring rate of 50 r / min for 30 minutes. The mixture was allowed to settle, filtered, washed three times with an ethanol aqueous solution, and dried at 40° C. for 24 hours to obtain a modified polyacrylamide blended with PNIPAM;

[0051] Step S7: 9.4 g of silica, 45 g of anhydrous ethanol, and 175 mL of distilled water were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at 70° C. and a stirring rate of 300 r / min for 1 h. After the reaction, the solution was maintained at 60° C., 10 mL of ammonia water was added dropwise to adjust the pH to 8, and 10.34 g of 3-aminopropyltriethoxysilane was added dropwise to the three-necked flask. After the reaction for 1 h, the mixture was heated to 80° C. and reacted for 2 h. After cooling, the mixture was filtered, and the filter cake was dried in an oven at 50° C. and ground to obtain amino-grafted silica powder;

[0052] Step S8: 1 g of ethyl cellulose and 20 mL of dichloromethane were added to a three-necked flask equipped with a thermometer and a stirrer, and stirred for 10 min at a stirring rate of 100 r / min. 0.5 g of succinic anhydride and 0.2 mL of pyridine were added, and the mixture was reacted at 35° C. and 100 r / min for 6 h. After the reaction, the reaction solution was added to 50 mL of ice water, filtered, and the filter cake was washed three times with deionized water, and vacuum dried at 60° C. for 12 h to obtain carboxylated ethyl cellulose;

[0053] Step S9: 0.3 g of amino-modified silica and 30 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a thermometer and a stirrer, and ultrasonically dispersed for 20 min. 0.5 g of carboxylated ethyl cellulose was added, and the mixture was mixed for 20 min at a stirring rate of 100 r / min. 0.15 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.09 g of N-hydroxysuccinimide were added, and the mixture was stirred for 0.5 h at 24 ° C and 100 r / min. The mixture was heated to 50 ° C and reacted for 12 h. After the reaction was completed, the solid was collected by centrifugation, washed twice with N,N-dimethylformamide, and then washed three times with anhydrous ethanol. The solid was vacuum dried at 50 ° C for 24 h to obtain ethyl cellulose grafted amino-modified silica;

[0054] Step S10: Weighing 50 parts of modified polyacrylamide blend PNIPAM, 10 parts of ethyl cellulose grafted amino-modified silica, and 5 parts of starch according to weight;

[0055] Step S11: adding modified polyacrylamide blended with PNIPAM, ethyl cellulose grafted with amino-modified silica, and starch into a twin-screw mixer, melt-blending, extruding and granulating to obtain a hydrophilic thermosensitive resin.

[0056] Example 2:

[0057] This embodiment is a method for preparing a hydrophilic thermosensitive resin, comprising the following steps:

[0058] Step S1: 61.41 mmol of 2-hydroxybenzaldehyde, 61.41 mmol of 2-aminophenol, 61.41 mmol of benzil, 122.84 mmol of ammonium acetate, and 150 mL of acetonitrile were added to a three-necked flask equipped with a reflux condenser and a thermometer. The mixture was reacted at 115° C. for 23 h. After the reaction was completed, the solid was filtered under reduced pressure to obtain a solid. The solid was recrystallized from a mixed solution of ethanol and N,N-dimethylformamide, and the product was vacuum dried to obtain tetraphenylimidazole diphenol.

[0059] Step S2: 3.75 g of tetraphenyl imidazole diphenol, 37.5 mmol of anhydrous potassium carbonate and 375 mL of anhydrous N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and nitrogen was introduced for protection. The mixture was reacted at a temperature of 25° C. and a stirring rate of 150 r / min for 35 min. 22.5 mmol of chloroacetic acid was added, the temperature was raised to 70° C., and the mixture was reacted at a stirring rate of 150 r / min for 7 h. After the reaction was completed, the mixture was cooled and the reaction solution was added to 275 mL of ice water with a stirring rate of 75 r / min. 7.5 mL of 1 mol / L hydrochloric acid was added dropwise to adjust the pH to 3. The precipitate was extracted with ethyl acetate 3 times, washed with deionized water 4 times, and dried with 7.5 g of anhydrous sodium sulfate for 2 h. The mixture was filtered and the ethyl acetate was removed by rotary evaporation to obtain a carboxylated tetraphenyl substituted imidazole diphenol;

[0060] Step S3: 1.5 g of polyacrylamide and 30 mL of deionized water were added to a three-necked flask equipped with a stirrer, and stirred at a stirring rate of 250 r / min for 15 min to obtain a polyacrylamide aqueous solution;

[0061] Step S4: 1.5 g of carboxylated tetraphenyl substituted imidazole diphenol and 7.5 mL of N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, stirred until dissolved, 3.6 g of N-hydroxysuccinimide and 2.25 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, and 7.5 mL of The pH value of the mixture was adjusted to 5.5 with MES buffer, nitrogen was introduced for protection, and the mixture was reacted for 25 minutes at a stirring rate of 75 r / min. After the reaction, 30 mL of polyacrylamide aqueous solution was added dropwise, and the mixture was reacted for 18 hours at a temperature of 29°C. After the reaction, 3.75 mL of 0.1 mol / L hydrochloric acid was added and stirred for 9 minutes. The reaction solution was added to 75 mL of anhydrous ethanol and stirred for 25 minutes at a stirring rate of 75 r / min. The mixture was allowed to settle, filtered, and washed three times with ethanol aqueous solution. The solid was added to 37.5 mL of deionized water, transferred to a 10 kDa dialysis bag, and dialyzed for 48 hours. The dialyzed solution was freeze-dried to obtain tetraphenylimidazole diphenol grafted polyacrylamide.

[0062] Step S5: 7.5 g of PNIPAM and 30 mL of deionized water were added to a three-necked flask equipped with a stirrer, and stirred at a stirring rate of 150 r / min for 1.5 h to obtain a PNIPAM aqueous solution;

[0063] Step S6: 1.5 g of tetraphenylimidazole diphenol grafted polyacrylamide and 15 mL of N,N-dimethylformamide were added to a single-necked flask, ultrasonically dispersed at a power of 300 W for 10 min, a magnetic rotor was added, and 15 mL of PNIPAM aqueous solution was added dropwise at a stirring rate of 250 r / min, and the addition time was controlled to be 12 min. The mixture was ultrasonically dispersed at a power of 200 W for 20 min, and the mixture was concentrated to one-third of the original volume at a temperature of 45° C. and a vacuum degree of 0.08 MPa. The concentrate was added to 150 mL of anhydrous ethanol and stirred at a stirring rate of 75 r / min for 30 min. The mixture was allowed to settle, filtered, washed three times with an ethanol aqueous solution, and dried at 45° C. for 24 h to obtain a modified polyacrylamide blended with PNIPAM;

[0064] Step S7: 9.4 g of silica, 46.5 g of anhydrous ethanol, and 175 mL of distilled water were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 75° C. and a stirring rate of 350 r / min for 1 h. After the reaction, the solution was maintained at 60° C., 12.5 mL of ammonia water was added dropwise to adjust the pH to 8, and 10.34 g of 3-aminopropyltriethoxysilane was added dropwise to the three-necked flask. After reacting for 1 h, the temperature was raised to 80° C., reacted for 2 h, and then cooled. The mixture was filtered, and the filter cake was dried in an oven at 50° C. and ground to obtain amino-grafted silica powder;

[0065] Step S8: 1.5 g of ethyl cellulose and 30 mL of dichloromethane were added to a three-necked flask equipped with a thermometer and a stirrer, and stirred for 15 minutes at a stirring rate of 150 r / min. 0.75 g of succinic anhydride and 0.3 mL of pyridine were added, and the mixture was reacted at 40° C. and 150 r / min for 7 hours. After the reaction, the reaction solution was added to 75 mL of ice water, filtered, and the filter cake was washed four times with deionized water, and vacuum dried at 60° C. for 12 hours to obtain carboxylated ethyl cellulose;

[0066] Step S9: 1.65 g of amino-modified silica and 165 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a thermometer and a stirrer, and ultrasonically dispersed for 25 min. 2.75 g of carboxylated ethyl cellulose was added, and the mixture was mixed for 25 min at a stirring rate of 150 r / min. 0.83 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.32 g of N-hydroxysuccinimide were added, and the mixture was stirred at 25° C. and 150 r / min for 0.75 h. The mixture was heated to 55° C. and reacted for 18 h. After the reaction was completed, the solid was collected by centrifugation, washed twice with N,N-dimethylformamide, and then washed three times with anhydrous ethanol. The solid was vacuum dried at 55° C. for 24 h to obtain ethyl cellulose grafted amino-modified silica;

[0067] Step S10: Weighing 75 parts of modified polyacrylamide blend PNIPAM, 15 parts of ethyl cellulose grafted amino-modified silica, and 7.5 parts of starch in parts by weight;

[0068] Step S11: adding modified polyacrylamide blended with PNIPAM, ethyl cellulose grafted with amino-modified silica, and starch into a twin-screw mixer, melt-blending, extruding and granulating to obtain a hydrophilic thermosensitive resin.

[0069] Example 3:

[0070] This embodiment is a method for preparing a hydrophilic thermosensitive resin, comprising the following steps:

[0071] Step S1: 81.88 mmol 2-hydroxybenzaldehyde, 81.88 mmol 2-aminophenol, 81.88 mmol benzil, 163.77 mmol ammonium acetate, and 200 mL acetonitrile were added to a three-necked flask equipped with a reflux condenser and a thermometer, and the mixture was reacted at 120° C. for 24 hours. After the reaction was completed, the solid was filtered under reduced pressure to obtain a solid, which was recrystallized from a mixed solution of ethanol and N,N-dimethylformamide. The product was vacuum dried to obtain tetraphenylimidazole diphenol;

[0072] Step S2: 5 g of tetraphenyl imidazole diphenol, 50 mmol of anhydrous potassium carbonate and 500 mL of anhydrous N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer, a thermometer, and protected by nitrogen. The reaction was carried out at a temperature of 26°C and a stirring rate of 200 r / min for 40 min. Then 30 mmol of chloroacetic acid was added, and the reaction was carried out at a temperature of 80°C and a stirring rate of 200 r / min for 8 h. After the reaction was completed, the reaction solution was cooled and added to 500 mL of ice water, stirred at a stirring rate of 100 r / min, and 10 mL of 1 mol / L hydrochloric acid was added dropwise to adjust the pH to 3. The precipitate was extracted with ethyl acetate for 3 times, washed with deionized water for 4 times, dried with 10 g of anhydrous sodium sulfate for 2 h, filtered, and rotary evaporated to remove ethyl acetate to obtain carboxylated tetraphenyl substituted imidazole diphenol;

[0073] Step S3: 2 g of polyacrylamide and 40 mL of deionized water were added to a three-necked flask equipped with a stirrer, and stirred at a stirring rate of 300 r / min for 20 min to obtain a polyacrylamide aqueous solution;

[0074] Step S4: 2 g of carboxylated tetraphenyl substituted imidazole diphenol and 10 mL of N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred until dissolved. Then 4.8 g of N-hydroxysuccinimide and 3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, 10 mL of MES buffer was added to adjust the pH to 5.5, and the reaction was carried out at a stirring rate of 100 r / min for 30 min. After the reaction was completed, 40 mL of the polyacrylamide aqueous solution was added dropwise, and the reaction was carried out at a temperature of 30°C for 24 h. After the reaction was completed, 5 mL of 0.1 mol / L hydrochloric acid was added and stirred for 10 min. The reaction solution was added to 100 mL of anhydrous ethanol, stirred at a stirring rate of 100 r / min for 30 min, and the precipitate was obtained by standing. After filtration, the solid was washed with an ethanol aqueous solution for 3 times, added to 50 mL of deionized water, transferred to a 10 kDa dialysis bag, and dialyzed for 48 h. The dialyzed solution was freeze-dried to obtain tetraphenyl imidazole diphenol grafted polyacrylamide;

[0075] Step S5: 10 g of PNIPAM and 40 mL of deionized water were added to a three-necked flask equipped with a stirrer, and stirred at a stirring rate of 200 r / min for 2 h to obtain a PNIPAM aqueous solution;

[0076] Step S6: 2 g of tetraphenyl imidazole diol grafted polyacrylamide, 20 mL of N, N-dimethylformamide were added into a single-necked flask, ultrasonic dispersion was performed for 10 min under the condition of a power of 300 W, a magnetic rotor was added, 20 mL of PNIPAM aqueous solution was added dropwise under the condition of a stirring rate of 300 r / min, the dropwise adding time was controlled to be 15 min, ultrasonic dispersion was performed for 20 min under the condition of a power of 200 W, the blending liquid was concentrated to one third of the original volume under the condition of a temperature of 50 ℃ and a vacuum degree of 0.08 MPa, the concentrated liquid was added into 200 mL of anhydrous ethanol, stirring was performed at a stirring rate of 100 r / min for 30 min, precipitation was performed after standing, and the precipitate was washed with an ethanol aqueous solution for 3 times after suction filtration, and the precipitate was dried at 50 ℃ for 24 h to obtain modified polyacrylamide blended with PNIPAM;

[0077] Step S7: 9.4 g of silicon dioxide, 48 g of anhydrous ethanol, 175 mL of distilled water were added into a three-necked flask equipped with a stirrer and a thermometer, and stirring reaction was performed at a temperature of 80 ℃ and a stirring rate of 400 r / min for 1 h, after the reaction was completed, the solution was kept at 60 ℃, 15 mL of ammonia water was added dropwise, the pH was adjusted to be between 9, 10.34 g of 3-aminopropyl triethoxysilane was added dropwise into the three-necked flask, after reaction for 1 h, the temperature was increased to 80 ℃, and reaction was performed for 2 h, then the solution was cooled, suction filtration was performed, and the filter cake was dried in an oven at 50 ℃, and then ground to obtain an amino-grafted silicon dioxide powder;

[0078] Step S8: 2 g of ethyl cellulose, 40 mL of dichloromethane were added into a three-necked flask equipped with a thermometer and a stirrer, stirring was performed at a stirring rate of 200 r / min for 20 min, 1 g of succinic anhydride and 0.4 mL of pyridine were added, and reaction was performed at 45 ℃ and a stirring rate of 200 r / min for 8 h, after the reaction was completed, the reaction liquid was added into 100 mL of ice water, and the filter cake was washed with deionized water for 5 times after filtration, and then vacuum drying was performed at 60 ℃ for 12 h to obtain carboxylated ethyl cellulose;

[0079] Step S9: 3 g of amino-modified silicon dioxide, 300 mL of N, N-dimethylformamide were added into a three-necked flask equipped with a thermometer and a stirrer, ultrasonic dispersion was performed for 30 min, 5 g of carboxylated ethyl cellulose was added, and mixing was performed at a stirring rate of 200 r / min for 30 min, 1.5 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide and 0.9 g of N-hydroxysuccinimide were added, and stirring was performed at 26 ℃ and a stirring rate of 200 r / min for 1 h, the temperature was increased to 60 ℃, and reaction was performed for 24 h, after the reaction was completed, the solid was collected by centrifugation, washed with N, N-dimethylformamide for 2 times, and then washed with anhydrous ethanol for 3 times, and the solid was vacuum dried at 60 ℃ for 24 h to obtain ethyl cellulose grafted amino-modified silicon dioxide;

[0080] Step S10: Weighing 100 parts of modified polyacrylamide blend PNIPAM, 20 parts of ethyl cellulose grafted amino-modified silica, and 10 parts of starch according to weight;

[0081] Step S11: adding modified polyacrylamide blended with PNIPAM, ethyl cellulose grafted with amino-modified silica, and starch into a twin-screw mixer, melt-blending, extruding and granulating to obtain a hydrophilic thermosensitive resin.

[0082] Comparative Example 1:

[0083] This comparative example is a method for preparing a hydrophilic thermosensitive resin, comprising the following steps:

[0084] Step S1: Weigh 100 parts of PNIPAM, 20 parts of silicon dioxide, and 10 parts of starch according to weight;

[0085] Step S2: adding PNIPAM, silicon dioxide, and starch into a twin-screw mixer, melt-blending, extruding, and granulating to obtain a hydrophilic thermosensitive resin.

[0086] Comparative Example 2:

[0087] This comparative example is a method for preparing a hydrophilic thermosensitive resin, comprising the following steps:

[0088] Step S1: 81.88 mmol 2-hydroxybenzaldehyde, 81.88 mmol 2-aminophenol, 81.88 mmol benzil, 163.77 mmol ammonium acetate, and 200 mL acetonitrile were added to a three-necked flask equipped with a reflux condenser and a thermometer, and the mixture was reacted at 120° C. for 24 hours. After the reaction was completed, the solid was filtered under reduced pressure to obtain a solid, which was recrystallized from a mixed solution of ethanol and N,N-dimethylformamide. The product was vacuum dried to obtain tetraphenylimidazole diphenol;

[0089] Step S2: 5 g of tetraphenyl imidazole diphenol, 50 mmol of anhydrous potassium carbonate and 500 mL of anhydrous N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and nitrogen was introduced for protection. The mixture was reacted at a temperature of 26 ° C. and a stirring rate of 200 r / min for 40 min. 30 mmol of chloroacetic acid was added, the temperature was raised to 80 ° C., and the mixture was reacted at a stirring rate of 200 r / min for 8 h. After the reaction was completed, the mixture was cooled and the reaction solution was added to 500 mL of ice water at a stirring rate of 100 r / min. 10 mL of 1 mol / L hydrochloric acid was added dropwise to adjust the pH to 3. The precipitate was extracted with ethyl acetate 3 times, washed with deionized water 4 times, added with 10 g of anhydrous sodium sulfate, dried for 2 h, filtered, and rotary evaporated to remove ethyl acetate to obtain carboxylated tetraphenyl substituted imidazole diphenol;

[0090] Step S3: adding 2 g of polyacrylamide and 40 mL of deionized water into a three-necked flask equipped with a stirrer, and stirring at a stirring rate of 300 r / min for 20 min to obtain a polyacrylamide aqueous solution;

[0091] Step S4: 2 g of carboxylated tetraphenyl substituted imidazole diphenol and 10 mL of N, N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, stirred until dissolved, 4.8 g of N-hydroxysuccinimide and 3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, and 10 mL of The pH of the mixture was adjusted to 5.5 with MES buffer, nitrogen was introduced for protection, and the mixture was reacted for 30 minutes at a stirring rate of 100 r / min. After the reaction, 40 mL of polyacrylamide aqueous solution was added dropwise, and the mixture was reacted at a temperature of 30°C for 24 hours. After the reaction, 5 mL of 0.1 mol / L hydrochloric acid was added and stirred for 10 minutes. The reaction solution was added to 100 mL of anhydrous ethanol and stirred for 30 minutes at a stirring rate of 100 r / min. The mixture was allowed to settle, filtered, and washed three times with ethanol aqueous solution. The solid was added to 50 mL of deionized water, transferred to a 10 kDa dialysis bag, and dialyzed for 48 hours. The dialyzed solution was freeze-dried to obtain tetraphenylimidazole diphenol grafted polyacrylamide;

[0092] Step S5: 10 g of PNIPAM and 40 mL of deionized water were added to a three-necked flask equipped with a stirrer, and stirred at a stirring rate of 200 r / min for 2 h to obtain a PNIPAM aqueous solution;

[0093] Step S6: 2 g of tetraphenylimidazole diphenol grafted polyacrylamide and 20 mL of N,N-dimethylformamide were added to a single-necked flask, ultrasonically dispersed at a power of 300 W for 10 minutes, a magnetic rotor was added, and 20 mL of PNIPAM aqueous solution was added dropwise at a stirring rate of 300 r / min, and the addition time was controlled to be 15 minutes. The mixture was ultrasonically dispersed at a power of 200 W for 20 minutes, and the mixture was concentrated to one-third of the original volume at a temperature of 50° C. and a vacuum degree of 0.08 MPa. The concentrate was added to 200 mL of anhydrous ethanol and stirred at a stirring rate of 100 r / min for 30 minutes. The mixture was allowed to settle, filtered, washed three times with an ethanol aqueous solution, and dried at 50° C. for 24 hours to obtain a modified polyacrylamide blended with PNIPAM;

[0094] Step S7: Weigh 100 parts of modified polyacrylamide blend PNIPAM, 20 parts of silicon dioxide, and 10 parts of starch according to weight;

[0095] Step S8: adding the modified polyacrylamide blend PNIPAM, silicon dioxide, and starch into a twin-screw mixer, melt-blending, extruding, and granulating to obtain a hydrophilic thermosensitive resin.

[0096] Comparative Example 3:

[0097] This comparative example is a method for preparing a hydrophilic thermosensitive resin, comprising the following steps:

[0098] Step S1: 9.4 g of silica, 48 g of anhydrous ethanol, and 175 mL of distilled water were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 80° C. and a stirring rate of 400 r / min for 1 hour. After the reaction, the solution was maintained at 60° C., 15 mL of ammonia water was added dropwise to adjust the pH to 9, and 10.34 g of 3-aminopropyltriethoxysilane was added dropwise to the three-necked flask. After reacting for 1 hour, the temperature was raised to 80° C., reacted for 2 hours, and then cooled. The mixture was filtered, and the filter cake was dried in an oven at 50° C. and ground to obtain amino-grafted silica powder;

[0099] Step S2: 2 g of ethyl cellulose and 40 mL of dichloromethane were added to a three-necked flask equipped with a thermometer and a stirrer, and stirred for 20 min at a stirring rate of 200 r / min. 1 g of succinic anhydride and 0.4 mL of pyridine were added, and the mixture was reacted at 45° C. and 200 r / min for 8 h. After the reaction, the reaction solution was added to 100 mL of ice water, filtered, and the filter cake was washed with deionized water 5 times, and vacuum dried at 60° C. for 12 h to obtain carboxylated ethyl cellulose;

[0100] Step S3: 3 g of amino-modified silica and 300 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a thermometer and a stirrer, and ultrasonically dispersed for 30 min. 5 g of carboxylated ethyl cellulose was added, and the mixture was mixed for 30 min at a stirring rate of 200 r / min. 1.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.9 g of N-hydroxysuccinimide were added, and the mixture was stirred at 26° C. and 200 r / min for 1 h. The mixture was heated to 60° C. and reacted for 24 h. After the reaction was completed, the solid was collected by centrifugation, washed twice with N,N-dimethylformamide, and then washed three times with anhydrous ethanol. The solid was vacuum dried at 60° C. for 24 h to obtain ethyl cellulose grafted amino-modified silica;

[0101] Step S4: Weigh 100 parts of PNIPAM, 20 parts of ethyl cellulose grafted amino-modified silica, and 10 parts of starch in parts by weight;

[0102] Step S5: adding PNIPAM, ethyl cellulose grafted amino-modified silica, and starch into a twin-screw mixer, melt-blending, extruding, and granulating to obtain a hydrophilic thermosensitive resin.

[0103] See Figure 1 The particles of the hydrophilic thermosensitive resin of Examples 1-3 and Comparative Examples 1-3 were placed in a flat vulcanizer for tableting, and then blown to obtain a hydrophilic thermosensitive resin film. The static liquid contact angle test was used to characterize the hydrophilicity and hydrophobicity of the hydrophilic thermosensitive resin.

[0104] See Figure 2 The hydrophilic thermosensitive resin particles of Examples 1-3 and Comparative Examples 1-3 were dissolved in 10 mL of distilled water at 0°C to form a solution, maintained at 25°C. The LCST value was measured using a UV-VIS spectrometer, and the transmitted light was recorded by a computer. A 2 mg / mL sample was placed in a 1 cm sample cell and subjected to thermal control. The solution was heated by varying the temperature by 0.2°C / 5 min, and the change in transmittance at 500 nm was observed.

[0105] See Figure 1-2 As shown, according to the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the modification of polyacrylamide and grafting it onto PNIPAM and the addition of ethyl cellulose grafted onto the surface of silica improve the hydrophilicity and thermosensitivity of the resin.

[0106] Comparison between Example 3 and Comparative Example 1 shows that the hydrophilicity and thermosensitivity of the resins modified with polyacrylamide and grafted onto PNIPAM and grafted with ethyl cellulose onto the surface of silica are better than those of ordinary PNIPAM and silica, indicating that the modified polyacrylamide grafted onto PNIPAM and grafted with ethyl cellulose onto the surface of silica have excellent hydrophilicity and thermosensitivity.

[0107] According to the comparison between Example 3 and Comparative Example 2, it can be seen that the hydrophilicity and thermosensitivity of the resin obtained by modifying polyacrylamide and grafting it onto PNIPAM and grafting ethyl cellulose onto the surface of silica are better than those obtained by modifying polyacrylamide and grafting it onto PNIPAM and silica, indicating that modifying polyacrylamide and grafting it onto PNIPAM and grafting ethyl cellulose onto the surface of silica have excellent hydrophilicity and thermosensitivity.

[0108] Comparison between Example 3 and Comparative Example 3 shows that the hydrophilicity and thermosensitivity of the resin obtained by adding modified polyacrylamide and grafting it onto PNIPAM and grafting ethyl cellulose onto the surface of silica are better than those obtained by grafting PNIPAM and ethyl cellulose onto the surface of silica, indicating that the resin obtained by adding modified polyacrylamide and grafting it onto PNIPAM and grafting ethyl cellulose onto the surface of silica has excellent hydrophilicity and thermosensitivity.

[0109] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0110] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the scope of protection of the present invention.

Claims

1. A hydrophilic thermosensitive resin, characterized in that: It comprises the following components in parts by weight: Weigh 50-100 parts of modified polyacrylamide blend PNIPAM, 10-20 parts of ethyl cellulose grafted amino-modified silica, and 5-10 parts of starch according to weight; Wherein, the modified polyacrylamide blended PNIPAM is prepared by the following steps: Step A1: reacting 2-hydroxybenzaldehyde, 2-aminophenol, benzil, ammonium acetate, and acetonitrile. After the reaction, filtering under reduced pressure, recrystallizing the solid from a mixed solution of ethanol and N,N-dimethylformamide, and drying under vacuum to obtain tetraphenylimidazole diphenol; Step A2: Tetraphenylimidazole diphenol, anhydrous potassium carbonate, and anhydrous N,N-dimethylformamide are stirred for reaction, chloroacetic acid is added, and the mixture is heated and stirred. After the reaction is completed, the mixture is cooled and added to ice water. Hydrochloric acid is added dropwise to adjust the pH. The precipitate is extracted with ethyl acetate, washed with deionized water, dried over anhydrous sodium sulfate, filtered, and rotary evaporated to obtain a carboxylated tetraphenyl-substituted imidazole diphenol; Step A3: stirring polyacrylamide and deionized water to obtain a polyacrylamide aqueous solution; Step A4: Dissolve carboxylated tetraphenyl-substituted imidazole diphenol and N,N-dimethylformamide by stirring, add N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, add MES buffer to adjust the pH, introduce nitrogen protection, and react with stirring. After the reaction, add polyacrylamide aqueous solution dropwise for reaction. After the reaction, add hydrochloric acid and stir. Add the reaction solution to anhydrous ethanol and stir, let it stand and precipitate, filter and wash with ethanol aqueous solution, add the solid to deionized water, transfer to a dialysis bag for dialyzing, and freeze-dry the dialyzed solution to obtain tetraphenyl imidazole diphenol grafted polyacrylamide; Step A5: Stir PNIPAM and deionized water to obtain a PNIPAM aqueous solution; Step A6: Ultrasonic dispersion of tetraphenylimidazole diphenol grafted polyacrylamide and N,N-dimethylformamide, adding a magnetic rotor, adding PNIPAM aqueous solution, controlling the addition time, ultrasonic dispersion, concentrating the blend, adding the concentrate to anhydrous ethanol, stirring, standing and precipitating, filtering and washing with ethanol aqueous solution, and drying the precipitate to obtain modified polyacrylamide blended with PNIPAM.

2. A hydrophilic thermosensitive resin according to claim 1, characterized in that: The usage ratio of 2-hydroxybenzaldehyde, 2-aminophenol, benzil, ammonium acetate and acetonitrile in step A1 is 40.94-81.88 mmol: 40.94-81.88 mmol: 40.94-81.88 mmol: 81.89-163.77 mmol: 100-200 mL.

3. A hydrophilic thermosensitive resin according to claim 1, characterized in that: The amount ratio of tetraphenylimidazole diphenol, anhydrous potassium carbonate, anhydrous N, N-dimethylformamide, chloroacetic acid, ice water and hydrochloric acid in step A2 is 2.5-5g:25-50mmo l:250-500mL:15-30mmo l:250-500mL:5-10mL:5-10g; the concentration of hydrochloric acid is 1mol / L.

4. A hydrophilic thermosensitive resin according to claim 1, characterized in that: The usage ratio of the polyacrylamide and deionized water in step A3 is 1-2 g: 20-40 mL; the CAS number of the polyacrylamide is 9003-05-8.

5. The hydrophilic thermosensitive resin according to claim 1, characterized in that: The amount ratio of the carboxylated tetraphenyl substituted imidazole diphenol, N,N-dimethylformamide, N-hydroxysuccinimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, MES buffer, polyacrylamide aqueous solution, hydrochloric acid, anhydrous ethanol and deionized water in step A4 is 1-2 g: 5-10 mL: 2.4-4.8 g: 1.5-3 g: 5-10 mL: 20-40 mL: 2.5-5 mL: 50-100 mL: 25-50 mL; the concentration of the MES buffer is 50 mmol / L; the concentration of the hydrochloric acid is 0.1 mol / L.

6. The hydrophilic thermosensitive resin according to claim 1, characterized in that: The usage ratio of PNIPAM and deionized water in step A5 is 5-10 g:20-40 mL; the CAS number of PNIPAM is 25189-55-3.

7. The hydrophilic thermosensitive resin according to claim 1, characterized in that: In step A6, the ratio of the tetraphenylimidazole diphenol grafted polyacrylamide, N,N-dimethylformamide, PNIPAM aqueous solution and anhydrous ethanol is 1-2 g: 10-20 mL: 10-20 mL: 100-200 mL.

8. The hydrophilic thermosensitive resin according to claim 1, characterized in that: The ethyl cellulose grafted amino-modified silica is prepared by the following steps: Step B1: stirring silica, anhydrous ethanol, and distilled water to react. After the reaction, adding ammonia water dropwise to adjust the pH, adding 3-aminopropyltriethoxysilane dropwise to react, heating the reaction, cooling, filtering, drying the filter cake, and grinding to obtain amino-grafted silica powder; the amount ratio of the silica, anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane is 9.4g:45-48g:175mL:10-15mL:10.34g; the mass fraction of the ammonia water is 20-35%; Step B2: Ethyl cellulose and dichloromethane are stirred, succinic anhydride and pyridine are added, and the reaction is carried out for 6-8 hours. After the reaction is completed, the reaction solution is added to ice water, filtered, and the filter cake is washed with deionized water and vacuum dried to obtain carboxylated ethyl cellulose; the dosage ratio of the ethyl cellulose, dichloromethane, succinic anhydride, pyridine and ice water is 1-2 g: 20-40 mL: 0.5-1 g: 0.2-0.4 mL: 50-100 mL; Step B3: Ultrasonic dispersion of amino silica and N,N-dimethylformamide, addition of carboxylated ethyl cellulose, mixing, addition of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide with stirring, heating for reaction, and after completion of the reaction, centrifugation to collect the solid, washing with N,N-dimethylformamide, and then washing with anhydrous ethanol, and vacuum drying the solid to obtain ethyl cellulose grafted amino-modified silica; the amount ratio of the amino silica, N,N-dimethylformamide, carboxylated ethyl cellulose, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is 0.3-3 g:30-300 mL:0.5-5 g:0.15-1.5 g:0.09-0.9 g.

9. A method for preparing a hydrophilic thermosensitive resin, characterized in that: The following steps are involved: Step 1: Weigh 50-100 parts of modified polyacrylamide blend PNIPAM, 10-20 parts of ethyl cellulose grafted amino-modified silica, and 5-10 parts of starch according to weight; Step 2: Add modified polyacrylamide blended with PNIPAM, ethyl cellulose grafted with amino-modified silica, and starch into a twin-screw mixer, melt-blend, extrude and granulate to obtain a hydrophilic thermosensitive resin.

10. Use of the hydrophilic thermosensitive resin prepared by the method for preparing a hydrophilic thermosensitive resin according to claim 9 in temperature-sensitive medical treatment.

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