A kind of polymer Janus microparticles and preparation method thereof

Abstract

The present invention discloses a polymer Janus microparticle and a preparation method thereof. Specifically, polystyrene microspheres are first prepared as seeds by a dispersion polymerization method, and then glycidyl methacrylate (GMA) is used as a functional monomer and dipentaerythritol penta- / hexyl-acrylic acid (DPEPA) is used as a crosslinking agent to prepare Janus microparticles with epoxy functional groups on the surface by a photoinitiated seed emulsion polymerization method. The prepared Janus microparticles have an asymmetric heterogeneous structure and provide unique physical and chemical properties. Compared with other materials with uniform components, they have broad application prospects in the fields of biomedicine, catalysis, and sensors.

Description

Technical Field

[0001] The present invention relates to a Janus particle and a preparation method thereof, and belongs to the field of high molecular polymers. Specifically, polystyrene microspheres are used as seeds, glycidyl methacrylate (GMA) is used as a functional monomer, and dipentaerythritol penta- / hexyl-acrylic acid (DPEPA) is used as a crosslinking agent. Janus particles with epoxy functional groups on the surface are prepared by a photoinitiated seed emulsion polymerization method. The Janus particles have three morphologies, namely, a half raspberry shape, an egg shape, and a spindle shape. Background Art

[0002] The morphology control of polymer particles is a hot topic in the field of materials research and is crucial to the preparation of functional colloidal materials. Since the expected function of colloidal materials is closely related to their structure, morphology and composition, it is of great scientific significance to control the structure, morphology and local composition of materials at the micro / nano scale (reference 1. J. Yoon, et.al. Multifunctional polymer particles with distinct compartmens, J. Mater. Chem., 2011, 21, 8502.). Asymmetric particles can also be called anisotropic particles or Janus particles. The word Janus comes from the ancient Roman two-faced god (Janus god). In ancient Roman mythology, the god Janus has two faces on his head, and it is said that he can look back to the past and look into the future. In 1985, Lee et al. synthesized polystyrene / polymethyl methacrylate (PS / PMMA) core-shell particles by seed emulsion polymerization, which were the earliest polymer-based Janus particles with asymmetric structures (Reference 2. I. Cho, et.al. Morphology of latex particles formed by Poly (methylmethacrylate)-seeded emulsion polymerization of styrene, J. Appl. Polym. Sci., 1985, 30, 1903-1926.). In 1991, Pierre-Gilles de Gennes proposed the concept of "two-sided particles" as anisotropic particle materials to the scientific community at the Nobel Prize ceremony, and named the particles with two different or even opposite surface characteristics as Janus (Reference 3. PG de Gennes, Soft matter, Rev. Mod. Phys., 1992, 64, 645-648.). The anisotropy of Janus particles is manifested not only by integrating different components into one structure to reduce the input material, but also by promoting the development of multiple functions through structural combination (reference 4. A. Kirillova, et.al. Hybrid Janus particles: challenges and opportunities towards the design of active functional interfaces and surfaces, ACS Appl. Mater. Interfaces, 2019, 11, 9643-9671.).

[0003] Janus particles are usually synthesized by phase separation or by functionalization of uniform particle surfaces. Since the particles need to be spatially selectively chemically or physically modified in a stable monolayer, the number of Janus particles prepared by surface functionalization technology is limited, while the preparation based on the phase separation mechanism is widely used (reference 5. H. Yabu, Fabrication of nanostructured composite microspheres based on the self-assembly of polymers and functional nanomaterials, Part. Part. Syst. Char., 2019, 36, 1900178). In recent years, the synthesis methods and application research of Janus particles have developed rapidly. Common preparation methods include seed emulsion polymerization, seed dispersion polymerization, phase separation, microfluidic synthesis and self-assembly. Since the composition and morphology of Janus particles are highly dependent on the interaction between precursors, Janus particles formed by different preparation methods have diverse morphologies, among which the representative ones are dumbbell-shaped, snowman-shaped, half raspberry-shaped, mushroom-shaped and bowl-shaped (Reference 6. Zhou Wanrong et al. Preparation and functionalization application of Janus particles, Progress in Chemistry, 2018, 30, 1601-1614.). E. Dehghani et al. prepared cauliflower-like and dumbbell-shaped Janus particles by seed emulsion polymerization using polyhydroxyethyl methyl acrylate (PHEMA) as seed and methacrylic acid (MAA) as monomer (Reference 7. E. Dehghani, et.al. Fabricating cauliflower-like and dumbbell-like Janus particles: Loading and simultaneous release of DOX and ibuprofen, Colloid. Surface. B, 2019, 173, 155-163.). S. Ghosh et al. prepared micron-sized snowman-shaped poly (N-isopropylacrylamide) (PNIPAM) Janus hydrogel particles using microfluidic synthesis (Document 8. S. Ghosh, et.al. Microfluidic production of snowman-shaped Janus hydrogel particles, Colloid. Surface. A, 2019, 573, 205-210.). In general, the surface of Janus particles has different morphologies or functional groups, thus having different physical and chemical properties. Janus particles with asymmetric heterogeneous structures at the micro / nano scale provide unique physical and chemical properties, which are difficult to achieve in symmetrical or uniform structures.Therefore, Janus particles have broad prospects in applications (reference 9.X.Zhang, et.al.Janus nanoparticles:From fabrication to (bio)applications, ACS Nano, 2021, 15, 6147-6191.). Summary of the invention

[0004] The present invention relates to a polymer Janus particle and a preparation method thereof. Using polystyrene microspheres as seeds, glycidyl methacrylate (GMA) as a functional monomer, and dipentaerythritol penta- / hexyl-acrylic acid (DPEPA) as a crosslinking agent, Janus particles with half-raspberry shape, egg shape and spindle shape are prepared by photoinitiated seed emulsion polymerization.

[0005] The specific preparation process of the Janus particles includes the following steps:

[0006] (1) Preparation of polystyrene seed microspheres by dispersion polymerization: 0.2-0.3 g of azobisisobutyronitrile (AIBN), 1-2 g of polyvinylpyrrolidone (PVP), 90-100 mL of ethanol and 5-10 mL of water were added to a 250 mL single-mouth round-bottom flask, and ultrasonicated for 20-30 min until the solid was completely dissolved; 20-30 mL of styrene was added thereto, and mechanically stirred at 60-80° C. and 100-200 rpm for 20-24 h; after the reaction was completed, the product was washed with 100-200 mL of ethanol for 3-4 times, and stored in a 0.2% (w%) sodium dodecyl sulfate (SDS) solution.

[0007] (2) Preparation of Janus particles by seed emulsion polymerization: 70-90 mg of the polystyrene seeds prepared above were added to a 100 mL quartz conical flask and shaken at 200-250 rpm for 30-60 min at room temperature in a light-controlled constant temperature shaker; 9-10 mL of a mixed aqueous solution of 0.2% SDS and 5% (w%) polyvinyl alcohol (PVA) was placed in a 25 mL beaker, and 200-400 μL of GMA, 100-300 mg of DPEPA, 200-500 μL porogen, 20-40 mg dimethyl benzoate (DMPA), demulsify in a cell disruptor in the dark until the oil droplets are evenly dispersed under an optical microscope; add the emulsified mixture to the above-mentioned polystyrene seed solution after shaking, and continue to shake at a speed of 200-250 rpm for 12-24 hours; turn on ultraviolet light (350-380 nm, 1000-2000×100 μJ / cm 2) for 1 to 3 hours, turn off the ultraviolet light and oscillate for another 1 to 3 hours; after the reaction is completed, wash with 100 to 200 mL of water for 3 to 4 times, wash with 100 to 200 mL of ethanol for 3 to 4 times, and dry in a vacuum drying oven for 6 to 12 hours to obtain Janus particles, which are named poly (GMA-co-DPEPA).

[0008] The prepared Janus particles have an asymmetric heterogeneous structure, providing unique physical and chemical properties. Compared with other materials with uniform composition, they have broad application prospects in the fields of biomedicine, catalysis and sensors.

[0009] The present invention has the following advantages:

[0010] (1) The raw materials are cheap and easily available, and the experimental process is simple to operate, which is suitable for industrialization;

[0011] (2) The photoinitiated polymerization reaction is fast and has a high conversion rate;

[0012] (3) The prepared Janus particles have diverse morphologies and special properties, and have good application prospects in the fields of biomedicine and catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the preparation of Janus particles in the examples.

[0014] Figure 2 The following are helium ion scanning electron micrographs of polystyrene seed microspheres and Janus particles in the examples. (a) is polystyrene seed microspheres; (b) is Janus particles in Example 1; (c) is Janus particles in Example 2; (d) is Janus particles in Example 3.

[0015] Figure 3 This is the infrared analysis diagram of the Janus particles in Example 1.

[0016] Figure 4 The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the Janus particles in the examples are shown in Figure 1. (a) is the nitrogen adsorption-desorption isotherms of the Janus particles in the examples; (b) is the pore size distribution diagram of the Janus particles in Example 1; (c) is the pore size distribution diagram of the Janus particles in Example 2; (d) is the pore size distribution diagram of the Janus particles in Example 3. DETAILED DESCRIPTION

[0017] Polymer Janus particles with various morphologies and preparation method thereof

[0018] Example 1

[0019] Preparation of poly(GMA-co-DPEPA)-1:

[0020] 1) Preparation of polystyrene seed microspheres by dispersion polymerization: 0.2 g of azobisisobutyronitrile (AIBN), 1.5 g of PVP, 95 mL of ethanol and 5 mL of water were added to a 250 mL single-necked round-bottom flask and ultrasonicated for 30 min until the solid was completely dissolved; 20 mL of styrene was added thereto and mechanically stirred at 70°C and 200 rpm for 24 h; after the reaction, the product was washed four times with 200 mL of ethanol and stored in a 0.2% (w%) sodium dodecyl sulfate (SDS) solution (0.3 g / L).

[0021] 2) Preparation of Janus particles by seed emulsion polymerization: 90 mg of the polystyrene seeds (0.3 g / L) prepared above were added to a 100 mL quartz conical flask and shaken at 200 rpm for 30 min at room temperature in a light-irradiated constant temperature shaker; 9.8 mL of a mixed aqueous solution of 0.2% (w%) SDS and 5% (w%) PVA was taken in a 25 mL beaker, 341 μL of GMA, 131 mg of DPEPA, 227 μL of dodecanol, 227 μL of cyclohexanol, and 40 mg of DMPA were added thereto, and the mixture was demulsified in a cell disruptor in the dark until the oil droplets were uniformly dispersed under an optical microscope; the emulsified mixture was added to the shaken polystyrene seed solution and continued to shake at 200 rpm for 14 h; UV light (365 nm, 1200×100 μJ / cm 2 ) for 1 h, turn off the ultraviolet light and shake for another 3 h; after the reaction, wash with 100 mL of water 3 times, wash with 100 mL of ethanol 3 times, and dry in a vacuum drying oven for 12 h to obtain Janus particles.

[0022] Example 2

[0023] Preparation of poly(GMA-co-DPEPA)-2:

[0024] The preparation of polystyrene seed microspheres was the same as in Example 1.

[0025] Preparation of Janus particles by seed emulsion polymerization: 70 mg of the polystyrene seeds (0.3 g / L) prepared above were added to a 100 mL quartz conical flask, and shaken at 200 rpm for 30 min at room temperature in a light-irradiated constant temperature shaker; 9.8 mL of a mixed aqueous solution of 0.2% (w%) SDS and 5% (w%) PVA was taken in a 25 mL beaker, 272 μL of GMA, 210 mg of DPEPA, 454 μL of cyclohexanol, and 20 mg of DMPA were added thereto, and the mixture was demulsified in a cell disruptor in the dark until the oil droplets were uniformly dispersed under an optical microscope; the emulsified mixture was added to the above-mentioned shaken polystyrene seed solution, and the mixture was shaken at 200 rpm for 14 h; UV light (365 nm, 1200×100 μJ / cm 2 ) for 1 h, turn off the ultraviolet light and shake for another 3 h; after the reaction, wash with 100 mL of water 3 times, wash with 100 mL of ethanol 3 times, and dry in a vacuum drying oven for 12 h to obtain Janus particles.

[0026] Example 3

[0027] Preparation of poly(GMA-co-DPEPA)-3:

[0028] The preparation of polystyrene seed microspheres was the same as in Example 1.

[0029] Preparation of Janus particles by seed emulsion polymerization: 70 mg of the polystyrene seeds (0.3 g / L) prepared above were added to a 100 mL quartz conical flask, and shaken at 200 rpm for 30 min at room temperature in a light-irradiated constant temperature shaker; 9.8 mL of a mixed aqueous solution of 0.2% (w%) SDS and 5% (w%) PVA was taken in a 25 mL beaker, 272 μL of GMA, 210 mg of DPEPA, 114 μL of toluene, 340 μL of cyclohexanol, and 20 mg of DMPA were added thereto, and the mixture was demulsified in a cell disruptor in the dark until the oil droplets were uniformly dispersed under an optical microscope; the emulsified mixture was added to the above-mentioned shaken polystyrene seed solution, and the mixture was shaken at 200 rpm for 14 h; ultraviolet light (365 nm, 1200×100 μJ / cm 2 ) for 1 h, turn off the ultraviolet light and shake for another 3 h; after the reaction, wash with 100 mL of water 3 times, wash with 100 mL of ethanol 3 times, and dry in a vacuum drying oven for 12 h to obtain Janus particles.

[0030] Material characterization

[0031] Figure 1Schematic diagram of the preparation of Janus microparticles in the embodiment. Seed emulsion polymerization is a method of first preparing small-size monodisperse seed microspheres by emulsion polymerization or dispersion polymerization, absorbing monomers, crosslinking agents and inert components, and then swelling, initiating and polymerizing the seeds to swell, thereby obtaining a polymer larger than the seed microspheres. The present invention uses styrene as a monomer and polyvinyl pyrrolidone as a dispersion stabilizer to synthesize polystyrene microspheres by dispersion polymerization. The microspheres are used as seeds and seed emulsion polymerization is used to synthesize Janus microparticles. The seed microspheres absorb GMA and DPEPA and initiate polymerization. During the polymerization process, the monomers (GMA and DPEPA) are easily squeezed out by the elastic force in the crosslinked network, and the difference in compatibility between the polymer formed by the monomers and the seeds causes the seeds to change from spherical to non-spherical.

[0032] Figure 2 The following are helium ion scanning electron micrographs of the polystyrene seed microspheres and Janus microparticles in the examples. Figure a shows polystyrene seed microspheres, which have good uniformity and dispersion, a smooth surface and no pores, and a particle size of about 2 μm. Figure b shows the Janus microparticles prepared in Example 1, which have many protruding small balls on one side and a smooth hemisphere on the other side, so they are named half-raspberry-shaped, with a diameter of about 2.8 μm; Figure c shows the spindle-shaped Janus microparticles prepared in Example 2, which are about 3 μm long and 2 μm wide; Figure d shows the egg-shaped Janus microparticles prepared in Example 3, with a diameter of about 2.8 μm. The three prepared Janus microparticles have uniform particle sizes and good monodispersity.

[0033] Figure 3 The infrared analysis diagram of Janus particles in the example is shown in Figure 1. The α,β-unsaturated carbonyl (C=O) in GMA and DPEPA is at 1724 cm -1 and 1732cm -1 There is an obvious characteristic absorption peak at 1725 cm -1 The C=C stretching vibration peaks in GMA and DPEPA appear at 1636 cm -1 and 1638cm -1 , and has strong absorption. However, this peak is hardly observed in poly(GMA-co-DPEPA), which indicates that the double bonds in GMA and DPEPA are almost exhausted during the polymerization reaction. GMA is at 910cm -1 The peak at is the CO vibration peak in the epoxy group, and this peak also appears on poly(GMA-co-DPEPA), which shows that the prepared Janus particles have epoxy functional groups.

[0034] Figure 4The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the Janus particles in the examples. (a) is the nitrogen adsorption-desorption isotherms of the Janus particles in the examples; (b) is the pore size distribution diagram of the Janus particles in Example 1; the specific surface areas of the three materials are all less than 10 m 2 / g, combined with the BJH pore size distribution diagram, it can be seen that the prepared Janus particles are all non-porous materials.

[0035] Table 1 is the Janus particle N in the examples 2 Adsorption / desorption parameter table, samples 1-3 correspond to the products of Examples 1-3, respectively.

[0036] Table 1

[0037]

Claims

1. A polymer Janus particle, which uses polystyrene microspheres as seeds, glycidyl methacrylate (GMA) as a functional monomer, and dipentaerythritol penta- / hexyl-acrylate (DPEPA) having multiple acrylate functional groups as a crosslinking agent. Janus particles with epoxy functional groups on the surface are prepared by photoinitiated seed emulsion polymerization.

2. A method for preparing the microparticles according to claim 1, characterized in that: The Janus particles with epoxy functional groups on the surface are prepared by photo-initiated seed emulsion polymerization, using polystyrene microspheres as seeds, glycidyl methacrylate as functional monomer, and dipentaerythritol penta- / hexyl-acrylate with multiple acrylate functional groups as crosslinking agent. The polymer Janus particles can be operated as follows: (1) Preparation of polystyrene seed microspheres by dispersion polymerization: 0.2-0.3 g of azobisisobutyronitrile, 1-2 g of polyvinylpyrrolidone, 90-100 mL of ethanol and 5-10 mL of water were added to a container and ultrasonicated for 20-30 min until the solid was completely dissolved; 20-30 mL of styrene was added thereto and mechanically stirred at 100-200 rpm for 20-24 h at 60-80 °C; after the reaction, the product was washed 3-4 times with 100-200 mL of ethanol to obtain the product, which was then stored in a 0.1-0.2 wt. % sodium dodecyl sulfate solution to obtain polystyrene seed microspheres with a concentration of 0.1-0.4 g / L; (2) Preparation of Janus particles by seed emulsion polymerization: 70-90 mg of the polystyrene seed microspheres prepared above with a concentration of 0.1-0.4 g / L were added into a transparent container and shaken at 200-250 rpm for 30-60 min at room temperature in a light-controlled constant temperature shaker. Take another 9-10 mL of a mixed aqueous solution of 0.1-0.2 wt.% sodium dodecyl sulfate and 3-5 wt.% polyvinyl alcohol, add 200-400 μL GMA, 100-300 mg DPEPA, 200-500 μL porogen, and 20-40 mg benzoin dimethyl ether, and break the emulsion in a cell disruptor in the dark; add the emulsified mixture to the above-mentioned shaken polystyrene seed solution, and continue to shake at a speed of 200-250 rpm for 12-24 h; turn on the ultraviolet light at 350-380 nm, 1000-2000 ×100μJ / cm 2 Irradiate for 1-3 h, turn off the UV light and oscillate at a speed of 200-250 rpm for 1-3 h; after the reaction, wash with 100-200 mL of water 3-4 times, wash with 100-200 mL of ethanol 3-4 times, and dry in a vacuum drying oven for 6-12 h to obtain Janus particles; The porogens used in step (2) are: dodecanol and cyclohexanol in a volume ratio of 1 / 1 to 1 / 2, toluene and cyclohexanol in a volume ratio of 1 / 1 to 1 / 2, or pure cyclohexanol, and the volumes of the three porogens are the same as the total volume of GMA and DPEPA.

3. The method for preparing microparticles according to claim 2, characterized in that: The morphology of Janus can be controlled by changing the type of porogen, the amount of seeds, and the ratio of GMA to DPEPA.

4. The method for preparing microparticles according to claim 3, characterized in that: When the amount of seeds accounted for 16% to 18% of the total mass of GMA and DPEPA, and the porogens were dodecanol and cyclohexanol in a volume ratio of 1 / 1 to 1 / 2, the Janus particles were half raspberry-shaped with a diameter of 2.8 μm; When the seed dosage accounted for 18% to 20% of the total mass of GMA and DPEPA, and the porogens were toluene and cyclohexanol in a volume ratio of 1 / 1 to 1 / 2, the Janus particles were egg-shaped with a diameter of 2.8 μm; When the seed dosage accounted for 18% to 20% of the total mass of GMA and DPEPA and the porogen was only cyclohexanol, the Janus particles were spindle-shaped, 3 μm long and 2 μm wide.

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