Microgel with controllable hardness and preparation method and application thereof

Abstract

The invention discloses hardness-controllable microgel and a preparation method and application thereof.The preparation method comprises the steps that styrene, N-isopropylacrylamide, a cross-linking agent and a surfactant are dissolved in water and stirred in the inert atmosphere, and when the preset temperature is reached, an initiator is added for a reaction; and dialyzing a product obtained by the reaction by using a dialysis bag, and then carrying out vacuum rotary evaporation to collect a sample, so as to obtain the hardness modified microgel poly (styrene-co-N-isopropylacrylamide) microgel. According to the preparation method of the hardness-controllable microgel provided by the invention, different amounts of styrene are introduced in the polymerization process to prepare modified poly (styrene-co-N-isopropylacrylamide) microgel with different hardness, and the microgel has good customizability, stability, uniformity and swelling property; the material can be widely applied to life as a material with excellent performance.

Description

Technical Field

[0001] The invention belongs to the technical field of microgels, and in particular relates to a microgel with controllable hardness and softness, and a preparation method and application thereof. Background Art

[0002] Microgels are soft, deformable colloidal particles that swell and shrink when exposed to external stimuli (temperature, pH, light, and solvents, etc.), which have great advantages over hard particles. Regarding the temperature-responsive microgels - poly (N-isopropylacrylamide) (PNIPAM) and its derivatives, which have attracted much attention in recent years, the complex phase behavior of their suspensions, particle-particle interactions, near-wall effects, and interference dynamics have received extensive attention.

[0003] Above the lowest critical solution temperature (LCST) of PNIPAM microgels, the microgel polymer chains become hydrophobic and exclude internal water, which causes the size to shrink dramatically and become more hydrophobic. Therefore, the phase change behavior of the suspension can be adjusted by changing the temperature. Based on the stimulus responsiveness of the above PNIPAM-based microgel suspensions, it shows great potential in drug delivery, smart homes, sensors and biomedical engineering. For example, the introduction of electrolyte monomers such as acrylic acid or methacrylic acid during the PNIPAM polymerization process can amplify the effect of the surface charge density on the phase behavior of the corresponding suspension, resulting in characteristic temperatures that change one by one within a range that depends on the pH value.

[0004] At present, the much-discussed styrene acts more as an independent hard core during the copolymerization process, while the PNIPAM microgel acts as an independent shell layer, but it is still unclear how the amount of styrene monomer introduced during the copolymerization of N-isopropylacrylamide regulates the softness of individual microgels, interparticle interactions, and rheological behavior of the suspension, which further affects its wide application in life. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a microgel with controllable hardness.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing a microgel with controllable hardness and softness, comprising:

[0009] Dissolve styrene, N-isopropylacrylamide, a crosslinking agent and a surfactant in water, stir under an inert atmosphere, and when the preset temperature is reached, add an initiator to react;

[0010] The product obtained by the reaction was dialyzed using a dialysis bag, and then a sample was collected by vacuum rotary evaporation to obtain a soft and hardness modified microgel poly(styrene-co-N-isopropylacrylamide) microgel.

[0011] As a preferred embodiment of the preparation method of the present invention, the mass ratio of styrene, N-isopropylacrylamide and cross-linking agent is (0-100):100:(1-10).

[0012] As a preferred embodiment of the preparation method of the present invention, the cross-linking agent includes N,N'-methylenebisacrylamide.

[0013] As a preferred embodiment of the preparation method of the present invention, the initiator comprises potassium persulfate.

[0014] As a preferred embodiment of the preparation method of the present invention, the surfactant comprises sodium dodecyl sulfate.

[0015] As a preferred embodiment of the preparation method of the present invention, the stirring temperature is 20-25° C. and the stirring time is 30-50 min.

[0016] As a preferred embodiment of the preparation method of the present invention, the preset temperature is 65-75° C., and the reaction time is 2-6 hours.

[0017] As a preferred embodiment of the preparation method of the present invention, the molecular weight cutoff of the dialysis bag is 3500-10000Da, and the rotary evaporation temperature is 45-65°C.

[0018] Another object of the present invention is to overcome the deficiencies in the prior art and provide a microgel with controllable hardness.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a microgel with controllable hardness and softness for use in drug delivery, smart homes and sensors.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention provides a method for preparing microgels with controllable hardness and softness, wherein different amounts of styrene are introduced during the polymerization process to produce poly(styrene-co-N-isopropylacrylamide) microgels with different hardness and softness. The microgels have good customizability, stability, uniformity and swelling properties, and can be used as materials with excellent performance and widely used in drug delivery, smart homes, sensors and biomedical engineering.

[0022] (2) The present invention doped different proportions of styrene into the PNIPAM network structure to prepare poly(styrene-co-N-isopropylacrylamide) microgels with different hardness and softness. The introduction of styrene affected the deformability, surface charge density and hydrophilicity of individual microgels. The rheological properties of poly(styrene-co-N-isopropylacrylamide) microgel suspensions can be easily adjusted by various doping of styrene into the macromolecular chain. The intrinsic hydrophobicity of the styrene benzene ring completely changes the hydration capacity and surface charge density of the microgels, further affecting the collective behavior of the assembly, thereby affecting the fluidity of the suspension. In addition, the degree of styrene doping also changes the deformation capacity of the original thermally responsive PNIPAM-derived material, adjusts the contraction and expansion of individual microgels, and ultimately changes the viscoelasticity of the soft colloid system.

[0023] (3) The present invention provides a method for regulating the performance of PNIPAM microgels, and for the first time proposes to adjust the hardness and hydrophilicity of PNIPAM microgels by adding styrene, thereby expanding the application scenarios of PNIPAM microgels. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0025] Figure 1 This is an atomic force microscope characterization image of the microgel of Example 1 of the present invention.

[0026] Figure 2 This is an atomic force microscope characterization image of the microgel of Example 2 of the present invention.

[0027] Figure 3 This is an atomic force microscope characterization image of the microgel of Example 3 of the present invention.

[0028] Figure 4 This is an atomic force microscope characterization image of the microgel of Example 4 of the present invention.

[0029] Figure 5It is a particle size characterization diagram of the microgels of Examples 1-4 of the present invention.

[0030] Figure 6 It is a characterization diagram of the zeta potential of the microgels of Examples 1-4 of the present invention.

[0031] Figure 7 It is a contact angle characterization diagram of the microgels of Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0035] In the examples of the present invention, N-isopropylacrylamide was purchased from Tokyo Chemical Industry Co., Ltd., N,N'-methylenebisacrylamide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and styrene was purchased from Sinopharm Chemical Reagent Co., Ltd.; other raw materials were all common commercially available products.

[0036] Example 1

[0037] This embodiment relates to a method for preparing a microgel with controllable hardness and softness, comprising the following steps:

[0038] (1) 0.25 ml of styrene, 8.69 g of N-isopropylacrylamide, 0.61 g of N,N'-methylenebisacrylamide and 0.025 g of sodium dodecyl sulfate were dissolved in 296 mL of water and stirred under an inert atmosphere. When the temperature reached 70° C., 0.243 g of initiator potassium persulfate (dissolved in 4 mL of water) was added to react.

[0039] (2) The product obtained by the reaction was dialyzed using a dialysis bag with a molecular weight cutoff of 3500Da, and then the sample was collected by vacuum rotary evaporation to obtain PNIPAM microgels with different hardness and softness modifications.

[0040] Atomic force microscopy characterization of microgels can be found in Figure 1 , demonstrating the successful preparation of poly(styrene-co-N-isopropylacrylamide) microgels.

[0041] Example 2

[0042] This embodiment relates to a method for preparing a microgel with controllable hardness and softness, comprising the following steps:

[0043] (1) 0.50 ml of styrene, 8.71 g of N-isopropylacrylamide, 0.61 g of N,N'-methylenebisacrylamide and 0.030 g of sodium dodecyl sulfate were dissolved in 296 mL of water and stirred under an inert atmosphere. When the temperature reached 70° C., 0.243 g of initiator potassium persulfate (dissolved in 4 mL of water) was added to react.

[0044] (2) The product obtained by the reaction was dialyzed using a dialysis bag with a molecular weight cutoff of 3500Da, and then the sample was collected by vacuum rotary evaporation to obtain PNIPAM microgels with different hardness and softness modifications.

[0045] Atomic force microscopy characterization of microgels can be found in Figure 2 , demonstrating the successful preparation of poly(styrene-co-N-isopropylacrylamide) microgels.

[0046] Example 3

[0047] This embodiment relates to a method for preparing a microgel with controllable hardness and softness, comprising the following steps:

[0048] (1) 1.00 ml of styrene, 8.73 g of N-isopropylacrylamide, 0.61 g of N,N'-methylenebisacrylamide and 0.040 g of sodium dodecyl sulfate were dissolved in 296 mL of water and stirred under an inert atmosphere. When the temperature reached 70° C., 0.243 g of initiator potassium persulfate (dissolved in 4 mL of water) was added to react.

[0049] (2) The product obtained by the reaction was dialyzed using a dialysis bag with a molecular weight cutoff of 3500Da, and then the sample was collected by vacuum rotary evaporation to obtain PNIPAM microgels with different hardness and softness modifications.

[0050] Atomic force microscopy characterization of microgels can be found in Figure 3 , demonstrating the successful preparation of poly(styrene-co-N-isopropylacrylamide) microgels.

[0051] Example 4

[0052] This embodiment relates to a method for preparing a microgel with controllable hardness and softness, comprising the following steps:

[0053] (1) 2.00 ml of styrene, 8.73 g of N-isopropylacrylamide, 0.61 g of N,N'-methylenebisacrylamide and 0.045 g of sodium dodecyl sulfate were dissolved in 296 mL of water and stirred under an inert atmosphere. When the temperature reached 70° C., 0.243 g of initiator potassium persulfate (dissolved in 4 mL of water) was added to react.

[0054] (2) The product obtained by the reaction was dialyzed using a dialysis bag with a molecular weight cutoff of 3500Da, and then the sample was collected by vacuum rotary evaporation to obtain PNIPAM microgels with different hardness and softness modifications.

[0055] Atomic force microscopy characterization of microgels can be found in Figure 4 , demonstrating the successful preparation of poly(styrene-co-N-isopropylacrylamide) microgels.

[0056] See the particle size characterization diagram of the microgels of Examples 1-4. Figure 5 It can be seen that by changing the doping ratio of styrene, the swelling ability of the microgel in water is changed when the temperature changes, which further proves that the hardness of the microgel is different. When the doping ratio of styrene is small, the microgel is softer, and the particle size changes more with temperature. On the contrary, when the doping ratio of styrene is large, the microgel is hard, and the particle size changes more with temperature.

[0057] The zeta potential characterization diagram of the microgels of Examples 1-4 is shown in Figure 6 It can be seen that the change of zeta potential of microgel is affected by temperature change.

[0058] The contact angle characterization diagrams of the microgels of Examples 1-4 are shown in Figure 6 It can be seen that the benzene ring of styrene makes it more hydrophobic, so adding different proportions of styrene can change the hydrophilic and hydrophobic properties of the microgel.

[0059] Comparative Example 1

[0060] This embodiment relates to a method for preparing a PNIPAM microgel, comprising the following steps:

[0061] (1) 8.73 g of N-isopropyl acrylamide, 0.61 g of N,N'-methylenebisacrylamide and 0.045 g of sodium dodecyl sulfate were dissolved in 296 mL of water and stirred under an inert atmosphere. When the temperature reached 70°C, 0.243 g of initiator potassium persulfate was added to react.

[0062] (2) The product obtained by the reaction was dialyzed using a dialysis bag with a molecular weight cutoff of 3500Da, and then the sample was collected by vacuum rotary evaporation to obtain PNIPAM microgel.

[0063] Although the PNIPAM microgel synthesized in Comparative Example 1 has temperature responsiveness and softness, its fixed nature makes it limited in scope in practical application;

[0064] Therefore, the present invention provides a method for preparing a microgel with controllable hardness and softness to expand its application range.

[0065] The present invention adds styrene during the polymerization process of N-isopropylacrylamide, so that the two can be evenly mixed, thereby changing the overall properties of the microgel; currently, styrene is polymerized into small balls alone as the core, and then N-isopropylacrylamide is added for polymerization. The microgel shell layer prepared by this method is still poly(N-isopropylacrylamide). When the ambient temperature changes, only the shell layer of the particle, that is, poly(N-isopropylacrylamide), swells or shrinks; the microgel particles prepared by the invention can adjust the shrinkage degree of the particle size when the temperature changes, the Zeta potential and the hydrophilicity by introducing different proportions of styrene during the polymerization process.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A method for preparing a microgel with controllable hardness, characterized in that: include, Dissolve styrene, N-isopropylacrylamide, a crosslinking agent and a surfactant in water, stir under an inert atmosphere, and when the preset temperature is reached, add an initiator to react; The product obtained by the reaction was dialyzed using a dialysis bag, and then a sample was collected by vacuum rotary evaporation to obtain a soft and hardness modified microgel poly(styrene-co-N-isopropylacrylamide) microgel.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the styrene, N-isopropylacrylamide and the crosslinking agent is (0-100):100:(1-10).

3. The preparation method according to claim 1 or 2, characterized in that: The cross-linking agent includes N,N'-methylenebisacrylamide.

4. The preparation method according to claim 3, characterized in that: The initiator includes potassium persulfate.

5. The preparation method according to claim 4, characterized in that: The surfactant includes sodium lauryl sulfate.

6. The preparation method according to claim 1, characterized in that: The stirring temperature is 20-25° C., and the stirring time is 30-50 min.

7. The preparation method according to claim 6, characterized in that: The preset temperature is 65-75° C., and the reaction time is 2-6 hours.

8. The preparation method according to claim 7, characterized in that: The molecular weight cut-off of the dialysis bag is 3500-10000Da, and the rotary evaporation temperature is 45-65°C.

9. Microgel with controllable hardness obtained by the preparation method according to any one of claims 1 to 8.

10. Application of the microgel with controllable softness and hardness as claimed in claim 9 in drug delivery, smart home and sensor.

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