Homopolymer with UCST thermosensitivity and pH responsiveness and preparation method thereof
By synthesizing monomers such as isopropylacrylamide and glycine, homopolymers with UCST-type phase transition properties were prepared, solving the problems of inconvenient synthesis and imprecise response behavior in existing technologies. This enabled pH-responsive UCST behavior and expanded the application potential of smart materials.
Patent Information
- Application Number
- CN202610118156.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies struggle to synthesize homopolymers that are simple in structure, easy to synthesize, and simultaneously exhibit clear UCST behavior and pH responsiveness, resulting in significant batch-to-batch performance variations and inaccurate response behavior.
By preparing isopropylacrylamide and glycine as monomers, and combining them with reagents such as acryloyl chloride and azobisisobutyronitrile, homopolymers with UCST-type phase transition properties were synthesized under specific reaction conditions, and their phase transition behavior was controlled by pH.
A homopolymer with UCST-type phase transition properties in water was achieved, and the phase transition behavior can be controlled by pH, which broadens the application prospects of stimulus-responsive smart materials.
Smart Images
Figure CN121991268A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of stimulus-responsive polymer technology, specifically relating to a homopolymer with UCST temperature sensitivity and pH responsiveness and its preparation method. Background Technology
[0002] Stimulus-responsive polymers have garnered significant attention from academia and industry over the past two decades due to their immense application potential in biomedicine, sensing, and smart devices. Among them, thermosensitive polymers and pH-responsive polymers are two of the most widely studied smart materials. In practical applications, single-stimulus-responsive materials sometimes lack the precision required for precise control due to the singular stimulus source, making it difficult to meet the practical needs of some complex systems. To achieve more flexible and refined control, integrating different stimulus triggers into a single system has become an effective strategy. Temperature and pH, as easily manipulated stimulus sources, have led to the favoring of dual-stimulus-responsive polymers, which have demonstrated broad application prospects in various fields, particularly biomedicine.
[0003] Currently, most common temperature and pH-responsive polymers are synthesized through copolymerization. This method is not only cumbersome in its synthesis steps, but also results in uncontrollable structural variations in the synthesized polymers, leading to significant batch-to-batch performance differences and imprecise response behavior. Multistimulus-responsive homopolymers offer a theoretical solution, but monomer design and synthesis remain significant challenges, resulting in a limited number of reported temperature and pH-responsive homopolymers. Furthermore, thermosensitive polymers are mainly divided into two categories: polymers with a low critical cosolubility temperature (LCST) and polymers with a high critical cosolubility temperature (UCST). Current research on common thermosensitive polymers focuses primarily on LCST-type polymers, with fewer reports on UCST-type polymers, which is related to the high development difficulty of UCST-type polymers. Developing a homopolymer with a simple structure, convenient synthesis, and clear UCST behavior and pH responsiveness is crucial to overcoming the current bottlenecks in the preparation of dual-response smart materials and propelling them towards precision applications. Summary of the Invention
[0004] To address the above problems, this invention provides a homopolymer with UCST-type temperature-sensitive and pH-responsive properties, and a method for its preparation. The polymer exhibits UCST-type phase transition properties in water, and its phase transition behavior can be modulated by pH, potentially broadening the application prospects of stimulus-responsive smart materials.
[0005] To achieve the above objectives, the present invention includes the following technical solutions:
[0006] In a first aspect, the present invention provides a homopolymer with UCST temperature sensitivity and pH responsiveness, the structure of which is as shown in formula (I): (I).
[0007] The homopolymer exhibits UCST-type phase transition properties in water, and its phase transition behavior can be controlled by pH.
[0008] Secondly, the present invention provides monomers for synthesizing the homopolymers having UCST temperature sensitivity and pH responsiveness, the structures of which are as shown in formula (II): (II).
[0009] The monomer is prepared as follows: a. Isopropylacrylamide, glycine, and water were mixed and dissolved. The pH was adjusted to 10 with a 5 mol / L potassium hydroxide aqueous solution. The mixture was reacted at 60°C for 48 hours. The water was removed by rotary evaporation. The crude product was washed three times with methanol and once with diethyl ether. The intermediate was obtained by vacuum drying. b. Dissolve the above intermediate in 10% NaOH solution, and gradually add acryloyl chloride dropwise to the solution under ice bath conditions. Then react at room temperature for 6 hours. After the reaction is complete, adjust the pH to 2 with concentrated hydrochloric acid, concentrate by rotary evaporation, filter and collect the precipitated solid, and dry under vacuum to obtain the monomer.
[0010] Furthermore, in the monomer preparation step a, the mass ratio of isopropylacrylamide, glycine, and water is (1.1~1.3):1:(6~9).
[0011] Furthermore, in the monomer preparation step b, the mass ratio of the intermediate, 10% NaOH, and acryloyl chloride is 1:(2~3):(0.6~0.8).
[0012] Thirdly, the present invention provides a method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness, comprising the following steps: Take 484.0 mg of the monomer, 1.3 mg of azobisisobutyronitrile, 11.1 mg of 4-cyano-4-[[(propylthio)thiomethyl]thio]valeric acid, and 2 mL of DMF, mix them evenly in an ampere tube, and perform the liquid nitrogen cooling-vacuuming-nitrogen circulation operation 3 times. Seal the tube and react at 65°C for 24 h. Cool, break the tube, precipitate in diethyl ether, and vacuum dry to obtain the target polymer. Attached Figure Description
[0013] Figure 1 The NMR spectrum of the intermediate prepared in Example 1.
[0014] Figure 2 The NMR spectrum of the monomer prepared in Example 1.
[0015] Figure 3 The spectrum of the polymer GPC prepared in Example 1 is shown.
[0016] Figure 4 The graph shows the permeability-temperature curve of the polymer prepared in Example 1 in water.
[0017] Figure 5 The graph shows the permeability-temperature curves of the polymer prepared in Example 1 in aqueous solutions at different pH values. Detailed Implementation
[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.
[0019] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.
[0020] Example 1 This embodiment provides a method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness: 1. Synthesis of intermediates 11.0 g of isopropylacrylamide, 10.0 g of glycine, and 60 mL of water were mixed and dissolved. The pH was adjusted to 10 with a 5 mol / L potassium hydroxide aqueous solution. The mixture was reacted at 60 °C for 48 hours. The water was removed by rotary evaporation. The crude product was washed three times with methanol and once with diethyl ether. The intermediate was then dried under vacuum. The NMR spectrum of the obtained intermediate is shown below. Figure 1 As shown, the synthesis of the intermediate was confirmed, and its structural formula is as follows: .
[0021] 2. Monomer Synthesis 5.0 g of the above intermediate was dissolved in 10.0 g of 10% NaOH solution. 3.0 g of acryloyl chloride was gradually added dropwise to the solution under ice bath conditions, and the reaction was carried out at room temperature for 6 hours. After the reaction was complete, the pH was adjusted to 2 with concentrated hydrochloric acid, the solution was concentrated by rotary evaporation, the precipitated solid was collected by filtration, and the solid was dried under vacuum to obtain the monomer. The structure of the obtained monomer was confirmed by NMR spectroscopy, as shown in the figure. Figure 2 As shown, its structural formula is: .
[0022] 3. Polymer Synthesis 484.0 mg of monomer, 1.3 mg of azobisisobutyronitrile, 11.1 mg of 4-cyano-4-[[(propylthio)thiomethyl]thio]valeric acid, and 2 mL of DMF were mixed thoroughly in an ampoule. The mixture was cooled with liquid nitrogen, evacuated, and purged with nitrogen three times. The ampoule was then sealed and reacted at 65 °C for 24 h. After cooling, the ampoule was broken, the precipitate was placed in diethyl ether, and dried under vacuum to obtain the target polymer. The obtained polymer was characterized by GPC. Figure 3 As shown, the synthesis of the polymer is confirmed, and its structural formula is: .
[0023] 4. Phase transition performance testing The obtained polymer was dissolved in distilled water to prepare a 1 mg / mL aqueous solution, and the transmittance at different temperatures was measured using a UV-Vis spectrometer. Figure 4 The figure shows the transmittance-temperature curve of the polymer aqueous solution. As the temperature increases, the polymer's solubility changes from insoluble to soluble, and the transmittance gradually increases, indicating that it has typical UCST phase transition properties.
[0024] 5. pH responsiveness test The obtained polymer was dissolved in distilled water to prepare a 1 mg / mL aqueous solution. The pH was adjusted with concentrated hydrochloric acid and sodium hydroxide solution, and the thermosensitivity of the solution at different pH values was measured. As the pH of the solution increased, the carboxyl groups of the polymer monomer units gradually deprotonated, the solubility of the polymer gradually increased, the intramolecular and intermolecular forces of the polymer gradually decreased, the affinity for water gradually increased, and the required phase transition temperature gradually decreased. When the pH was 10, the polymer became completely water-soluble and no longer exhibited thermosensitivity.
[0025] Example 2 This embodiment provides a method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness. The difference from Example 1 is that in step 1, 12.0 g of isopropyl acrylamide and 75 mL of water are used; in step 2, 12.5 g of 10% NaOH solution and 3.5 g of acryloyl chloride are added.
[0026] Example 3 This embodiment provides a method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness. The difference from Example 1 is that in step 1, 13.0 g of isopropyl acrylamide and 90 mL of water are used; in step 2, 15.0 g of 10% NaOH solution and 4.0 g of acryloyl chloride are added.
Claims
1. A homopolymer exhibiting UCST temperature sensitivity and pH responsiveness, characterized in that, It has a structure as shown in equation (Ⅰ): (I).
2. A homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 1, characterized in that, It is prepared by polymerization reaction from monomers having the structure shown in formula (II): （Ⅱ）。 3. A homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 2, characterized in that, The monomer is prepared as follows: a. Isopropylacrylamide, glycine, and water were mixed and dissolved. The pH was adjusted to 10 with a 5 mol / L potassium hydroxide aqueous solution. The mixture was reacted at 60°C for 48 hours. The water was removed by rotary evaporation. The crude product was washed three times with methanol and once with diethyl ether. The intermediate was obtained by vacuum drying. b. Dissolve the above intermediate in 10% NaOH solution, and gradually add acryloyl chloride dropwise to the solution under ice bath conditions. Then react at room temperature for 6 hours. After the reaction is complete, adjust the pH to 2 with concentrated hydrochloric acid, concentrate by rotary evaporation, filter and collect the precipitated solid, and dry under vacuum to obtain the monomer.
4. A homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 3, characterized in that, In the monomer preparation step a, the mass ratio of isopropylacrylamide, glycine, and water is (1.1~1.3):1:(6~9).
5. A homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 3, characterized in that, In the monomer preparation step b, the mass ratio of the intermediate, 10% NaOH, and acryloyl chloride is 1:(2~3):(0.6~0.8).
6. A homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 3, characterized in that, The steps for preparing the homopolymer from the monomer via polymerization are as follows: Take 484.0 mg of the monomer, 1.3 mg of azobisisobutyronitrile, 11.1 mg of 4-cyano-4-[[(propylthio)thiomethyl]thio]valeric acid, and 2 mL of DMF, mix them evenly in an ampere tube, and perform the liquid nitrogen cooling-vacuuming-nitrogen circulation operation 3 times. Seal the tube and react at 65°C for 24 h. Cool, break the tube, precipitate in diethyl ether, and vacuum dry to obtain the target polymer.
7. A method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness, characterized in that, The steps are as follows: Take 484.0 mg of the monomer with the structure shown in formula (II), 1.3 mg of azobisisobutyronitrile, 11.1 mg of 4-cyano-4-[[(propylthio)thiomethyl]thio]valeric acid, and 2 mL of DMF, mix them evenly in an ampere tube, and perform the liquid nitrogen cooling-vacuum-nitrogen circulation operation 3 times. Seal the tube and react at 65°C for 24 h. Cool, break the tube, precipitate in diethyl ether, and vacuum dry to obtain the target polymer, wherein the structure of formula (II) is: (II).
8. The method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 7, characterized in that, The monomer is prepared as follows: a. Isopropylacrylamide, glycine, and water were mixed and dissolved. The pH was adjusted to 10 with a 5 mol / L potassium hydroxide aqueous solution. The mixture was reacted at 60°C for 48 hours. The water was removed by rotary evaporation. The crude product was washed three times with methanol and once with diethyl ether. The intermediate was obtained by vacuum drying. b. Dissolve the above intermediate in 10% NaOH solution, and gradually add acryloyl chloride dropwise to the solution under ice bath conditions. Then react at room temperature for 6 hours. After the reaction is complete, adjust the pH to 2 with concentrated hydrochloric acid, concentrate by rotary evaporation, filter and collect the precipitated solid, and dry under vacuum to obtain the monomer.
9. The method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 8, characterized in that, In the monomer preparation step a, the mass ratio of isopropylacrylamide, glycine, and water is (1.1~1.3):1:(6~9).
10. The method for preparing a homopolymer with UCST temperature sensitivity and pH responsiveness according to claim 8, characterized in that, In the monomer preparation step b, the mass ratio of the intermediate, 10% NaOH, and acryloyl chloride is 1:(2~3):(0.6~0.8).