TEMPERATURE-RESPONSIVE POLY(2-HYDROXYETHYL METHACRYLATE) (PHEMA) AND PREPARATION METHOD THEREOF

Abstract

Temperature-responsive poly(2-hydroxyethyl methacrylate) (PHEMA) and a preparation method thereof are disclosed. In the preparation method, with a system consisting of benzoyl peroxide (BPO) (an oxidant) and 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-acrylamide (MPAEMA) or 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-propionamide (MEMA) (a reducing agent monomer) as a redox initiation system, water and toluene as media, a nonionic surfactant as an emulsifier, and 2-hydroxyethyl methacrylate (HEMA) as a polymerization monomer, polymerization is conducted at room temperature and atmospheric pressure to obtain the PHEMA. An alcohol solution of the PHEMA has an upper critical solution temperature (UCST). The method has the advantages of simple and stable polymerization system, low polymerization cost, easy operation, mild conditions, small impact on the environment, and low energy consumption. Moreover, a molecular weight and UCST of a product are controllable within a specified range.

Claims

1. Use of poly(2-hydroxyethyl methacrylate) (PHEMA) in a temperature-responsive intelligent material, comprising preparing the PHEMA into an i-propanol solution of the PHEMA or an n-propanol solution of the PHEMA to obtain the temperature-responsive intelligent material, wherein temperature-responsive intelligent material undergoes an abrupt increase in absorbance during a temperature decreasing process at a temperature range of 2° C. to 25° C., indicating a temperature response; the PHEMA has a weight average molecular weight (WAMW) of 133,000 g/mol to 2,442,000 g/mol.

2. The use of the PHEMA in the temperature-responsive intelligent material according to claim 1, wherein the PHEMA has a concentration of 1 mg/mL to 15 mg/mL in the i-propanol solution or the n-propanol solution; and the i-propanol solution or the n-propanol solution of the PHEMA has a cloud point of 2° C. to 23° C.

3. The use of the PHEMA in the temperature-responsive intelligent material according to claim 1, wherein a preparation method of the PHEMA is as follows: with a system consisting of benzoyl peroxide (BPO) (an oxidant) and 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-acrylamide (MPAEMA) or 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-propionamide (MEMA) (a reducing agent monomer) as a redox initiation system, water and toluene as media, Tween 80 and Span 85 as an emulsifier, and 2-hydroxyethyl methacrylate (HEMA) as a polymerization monomer, conducting a free-radical inverse emulsion polymerization at room temperature to obtain the PHEMA.

4. The use of the PHEMA in the temperature-responsive intelligent material according to claim 3, wherein the MPAEMA is prepared by a method comprising: (1) dissolving N-(3-aminopropyl)-N-methylaniline, triethylamine (TEA), and methacryloyl chloride (MAC) in tetrahydrofuran (THF) separately to obtain an N-(3-aminopropyl)-N-methylaniline solution, a TEA solution and a MAC solution with a concentration of 1 g/10 mL; and (2) mixing the N-(3-aminopropyl)-N-methylaniline solution with the TEA solution at 0° C. to 5° C. to obtain a first resulting mixture, slowly adding the MAC solution dropwise to a-the first resulting mixture while the first resulting mixture is vigorously stirred to obtain a second resulting mixture, and conducting a reaction on the second resulting mixture for 24 h to obtain a resulting system; filtering the resulting system to obtain a filtrate, and removing a solvent from the filtrate by a rotary evaporation to obtain a crude product; and dissolving the crude product in diethyl ether to obtain a resulting solution, and adding the resulting solution dropwise to cold n-hexane for a recrystallization to obtain the reducing agent monomer MPAEMA, wherein the N-(3-aminopropyl)-N-methylaniline, the TEA, and the MAC have a molar ratio of 4:6:5.

5. The use of the PHEMA in the temperature-responsive intelligent material according to claim 3, wherein the MEMA is prepared by a method comprising: (1) dissolving N-(3-aminopropyl)-N-methylaniline, TEA, and isobutyryl chloride in THF separately to obtain an N-(3-aminopropyl)-N-methylaniline solution, a TEA solution and an isobutyryl chloride solution with a concentration of 1 g/10 mL; and (2) mixing the N-(3-aminopropyl)-N-methylaniline solution with the TEA solution at 0° C. to 5° C. to obtain a first resulting mixture, slowly adding the isobutyryl chloride solution dropwise to the first resulting mixture while the first resulting mixture is vigorously stirred to obtain a second resulting mixture, and conducting a reaction on the second resulting mixture for 24 h to obtain a resulting system; filtering the resulting system to obtain a filtrate, and removing a solvent from the filtrate by a rotary evaporation to obtain a crude product; and dissolving the crude product in diethyl ether to obtain a resulting solution, and adding the resulting solution dropwise to cold n-hexane for a recrystallization to obtain a model reducing agent MEMA, wherein the N-(3-aminopropyl)-N-methylaniline, the TEA, and the isobutyryl chloride have a molar ratio of 1:1.5:1.2.

6. The use of the PHEMA in the temperature-responsive intelligent material according to claim 3, wherein the reducing agent monomer has a concentration of 25% in an aqueous solution of the reducing agent monomer; and a molar ratio of the oxidant to the reducing agent monomer is 1:1.

7. The use of the PHEMA in the temperature-responsive intelligent material according to claim 3, wherein a molar ratio of the reducing agent monomer to the polymerization monomer is 1:80 to 1:200; and a mass ratio of the water to the toluene is 1:1.

8. The use of the PHEMA in the temperature-responsive intelligent material according to claim 3, wherein a total mass of the Tween 80 and the Span 85 is 10% of a mass of the toluene, and a mass ratio of the Tween 80 to the Span 85 is 1:1.

9. The use of the PHEMA in the temperature-responsive intelligent material according to claim 3, wherein the free-radical inverse emulsion polymerization is conducted at 25° C. for 1 h to 8 h.

10. The use of the PHEMA in the temperature-responsive intelligent material according to claim 2, wherein a preparation method of the PHEMA is as follows: with a system consisting of benzoyl peroxide (BPO) (an oxidant) and 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-acrylamide (MPAEMA) or 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-propionamide (MEMA) (a reducing agent monomer) as a redox initiation system, water and toluene as media, Tween 80 and Span 85 as an emulsifier, and 2-hydroxyethyl methacrylate (HEMA) as a polymerization monomer, conducting a free-radical inverse emulsion polymerization at room temperature to obtain the PHEMA.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a relationship between the absorbance of a solution of each of the polymers obtained in Examples 1 and 2 in i-propanol and the temperature.

[0024] FIG. 2 shows a relationship between the absorbance of a solution of each of the polymers obtained in Examples 3 and 4 in i-propanol and the temperature.

[0025] FIG. 3 shows a relationship between the absorbance of a solution of each of the polymers obtained in Examples 5 and 6 in i-propanol and the temperature.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present disclosure is further described below with reference to examples, but is not limited thereto.

Example 1

[0027] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=40:1:1. A specific process was as follows: HEMA (0.0400 mol) was dissolved in water (300 wt % HEMA) to obtain an HEMA aqueous solution (25 wt %); the HEMA aqueous solution was added to a reaction flask with toluene (400 wt % HEMA), Span 85 (5 wt % toluene), Tween 80 (5 wt % toluene), and MEMA (0.0010 mol), a resulting mixture was thoroughly stirred, and oxygen was evacuated by vacuum-pumping; BPO (0.0010 mol) was added, and a resulting mixture reacted in a 25° C. water bath for 8 h, at which time, an HEMA conversion rate was determined to be 94.3%; demulsification was conducted with THF; and a resulting product was washed three times with water and dried, and then purified three times and dried to obtain the polymer. As measured by static and dynamic light scattering (SLS/DLS), the polymer had an absolute WAMW of M.sub.w.MALLS=133,000 g/mol.

[0028] 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 7° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 2° C. to 3° C. during the temperature decreasing process, indicating a temperature response.

[0029] The MEMA was prepared by the following method: N-(3-aminopropyl)-N-methylaniline (commercially available), TEA, and isobutyryl chloride were dissolved in THF separately to obtain dilute solutions with a concentration of 1 g/10 mL; the N-(3-aminopropyl)-N-methylaniline solution was mixed with the TEA solution at 0° C. to 5° C., then the isobutyryl chloride solution was slowly added dropwise to a resulting mixture while the mixture was vigorously stirred, and reaction was conducted for 24 h; a resulting system was filtered to obtain a filtrate, and the solvent was removed from the filtrate by rotary evaporation to obtain a crude product; and the crude product was dissolved in diethyl ether, and a resulting solution was added dropwise to cold n-hexane for recrystallization to obtain the model reducing agent MEMA, where the N-(3-aminopropyl)-N-methylaniline, TEA, and isobutyryl chloride had a molar ratio of 1:1.5:1.2.

Example 2

[0030] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=200:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=1,605,000 g/mol. 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 18° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 12° C. to 14° C. during the temperature decreasing process, indicating a temperature response.

Example 3

[0031] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MPAEMA]:[BPO]=80:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=2,442,000 g/mol. 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 20° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 16° C. to 17° C. during the temperature decreasing process, indicating a temperature response.

[0032] The MPAEMA was prepared by the following method: N-(3-aminopropyl)-N-methylaniline (commercially available), TEA, and MAC were dissolved in THF separately to obtain dilute solutions with a concentration of 1 g/10 mL; the N-(3-aminopropyl)-N-methylaniline solution was mixed with the TEA solution at 0° C. to 5° C., then the MAC solution was slowly added dropwise to a resulting mixture while the mixture was vigorously stirred, and reaction was conducted for 24 h; a resulting system was filtered to obtain a filtrate, and the solvent was removed from the filtrate by rotary evaporation to obtain a crude product; and the crude product was dissolved in diethyl ether, and a resulting solution was added dropwise to cold n-hexane for recrystallization to obtain the reducing agent monomer MPAEMA, where the N-(3-aminopropyl)-N-methylaniline, TEA, and MAC had a molar ratio of 4:6:5.

Example 4

[0033] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MPAEMA]:[BPO]=120:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=1,671,000 g/mol. 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 18° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 13° C. to 15° C. during the temperature decreasing process, indicating a temperature response.

Example 5

[0034] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=200:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=1,605,000 g/mol. 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 15 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 28° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 19° C. to 25° C. during the temperature decreasing process, indicating a temperature response.

Example 6

[0035] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MPAEMA]:[BPO]=120:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=1,671,000 g/mol. 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 15 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 27° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 21° C. to 24° C. during the temperature decreasing process, indicating a temperature response.

Example 7

[0036] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=40:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=133,000 g/mol. 1 mg of the polymer was weighed and dissolved in n-propanol to obtain a 5 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the n-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 13° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 8° C. to 10° C. during the temperature decreasing process, indicating a temperature response.

Example 8

[0037] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MPAEMA]:[BPO]=120:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=1,671,000 g/mol. 1 mg of the polymer was weighed and dissolved in i-propanol to obtain a 7.5 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the i-propanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 24° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent an abrupt increase at 19° C. to 22° C. during the temperature decreasing process, indicating a temperature response.

Comparative Example 1

[0038] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=40:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=133,000 g/mol. 1 mg of the polymer was weighed and dissolved in methanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the methanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 40° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent no significant change at 0° C. to 40° C. during the temperature decreasing process.

Comparative Example 2

[0039] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=40:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=133,000 g/mol. 1 mg of the polymer was weighed and dissolved in ethanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the ethanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 40° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent no significant change at 0° C. to 40° C. during the temperature decreasing process.

Comparative Example 3

[0040] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MPAEMA]:[BPO]=80:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=2,442,000 g/mol. 1 mg of the polymer was weighed and dissolved in ethanol to obtain a 1 mg/mL solution, the solution was weighed, and an obtained mass was recorded; the solution was placed in a 60° C. oven for more than 24 h to ensure that the polymer was completely dissolved in the ethanol, during which period, the solution was weighed at all times such that the volatilized solvent could be supplemented to ensure a constant concentration for the solution; after the solution was equilibrated at 40° C. for 1 h, the absorbance was determined with a UV-visible spectrophotometer; and then the temperature was gradually decreased, and at each temperature, the absorbance was determined after the solution was equilibrated for 10 min. It was found from the test that the absorbance of the solution underwent no significant change at 0° C. to 40° C. during the temperature decreasing process.

Comparative Example 4

[0041] PHEMA was prepared by inverse emulsion polymerization according to a ratio of [HEMA]:[MEMA]:[BPO]=40:1:1 (other conditions were the same as in Example 1). As measured by SLS/DLS, the polymer had an absolute WAMW of M.sub.w.MALLS=133,000 g/mol. 1 mg of the polymer was weighed and added to butanol to prepare a 1 mg/mL solution, but PHEMA was unable to be dissolved in butanol.

[0042] The above examples are preferred implementations of the present disclosure, but the present disclosure is not limited to the above implementations. Any obvious improvement, substitution, or modification made by those skilled in the art without departing from the essence of the present disclosure should fall within the protection scope of the present disclosure.