CN1200006C - Method for synthesizing nano microsphere of inorganic/polymer huds with narrow decentralization - Google Patents

Abstract

The present invention relates to a method for preparing an inorganic / polymer core-shell nanometer microsphere of which the dimensions and the core-shell thickness are controllable by combining the surface modification and the emulsion polymerization of inorganic particles. The method comprises the synthesis of inorganic nanometer particles, the surface modification of the inorganic nanometer particles and the preparation of inorganic / polymer core-shell nanometer microspheres by emulsion polymerization. The functionalized modification of the surfaces of the inorganic nanometer particles is carried out by adding a silane coupling agent with reactive activity double bonds in situ to make the surfaces of the inorganic nanometer particles have free radical polymerization reactive activity, and then, the surfaces of the inorganic nanometer particles and an organic monomer with double bonds are processed by emulsion polymerization. The dimension of the inorganic / polymer core-shell nanometer microsphere is uniform and controllable, and the emulsion stability is good. The method is an effective and easy method for preparing narrow dispersed inorganic / polymer core-shell composite nanometer microspheres.

Description

Synthesis of Narrowly Dispersed Inorganic/Polymer Core-Shell Nanospheres

technical field

The invention relates to a method for preparing narrowly dispersed inorganic/polymer core-shell nano-microspheres, in particular to a method for preparing narrowly dispersed inorganic/polymer core-shell nanospheres with controllable size and structure, which combines surface modification of inorganic nanoparticles and emulsion polymerization technology. A method for polymer core-shell nanospheres.

Background technique

With the deepening and perfection of nanoscience research and technology development, the research of nano-hybrid and nano-composite materials has developed into a very active research field in the disciplines of physics, chemistry, and materials science, especially with the development of photonic crystals. With the continuous deepening of research, the preparation technology of narrowly dispersed inorganic/polymer core-shell nanospheres used to assemble photonic crystals has more excellent properties (such as tunable optical, magnetic, electrical, and catalytic properties). Attract people's attention. The most common methods suitable for preparing narrowly dispersed inorganic/polymer core-shell nanospheres include physical methods such as deposition on inorganic nanoparticles, Layer-by-Layer (LbL) assembly, and surface modification of inorganic nanoparticles. Afterwards, chemical methods such as emulsion polymerization, microemulsion polymerization, dispersion polymerization, suspension polymerization, and atom transfer radical polymerization are carried out. Although the physical method is easy to operate and low in cost, the structural and morphological uniformity of the inorganic/polymer core-shell nanospheres prepared by this method needs to be improved, and its chemical stability and thermal stability are also poor. The chemical method of preparing inorganic/polymer core-shell nanospheres has been studied for a long time, but the common problem is that the synthesis process is relatively complicated, and the size and structure of the prepared composite nanoparticles are not well controlled, such as Bourgeat-Lami et al. The silica/polystyrene core-shell particles prepared by dispersion polymerization have obvious core-shell structure, but the size distribution of the particles is wide (ranging from hundreds of nanometers to several microns), which is not suitable for the assembly of photonic crystals ; Although atom transfer radical polymerization can achieve good control of particle morphology and structure, it cannot be widely used because it requires the use of expensive initiators and high synthesis costs.

Contents of the invention

Emulsion polymerization is one of the effective methods to prepare polymer nanospheres with uniform and controllable size. The present invention organically combines the preparation, surface modification and emulsion polymerization technology of inorganic nanoparticles, and provides a simple and easy preparation of narrowly dispersed inorganic/polymer core-shell nanoparticles with controllable size and structure and good stability. microsphere method.

The object of the present invention is achieved through the following technical solutions: the present invention adopts the colloidal method to directly synthesize inorganic nanoparticles of different particle sizes, and realizes the modification of the particles in situ to achieve surface functionalization, so that it has reactivity, and then combines Emulsion polymerization technology prepares narrowly dispersed inorganic/polymer core-shell nanospheres with good stability and controllable size and structure. The invention comprises the following steps: 1. Synthesis of inorganic nanoparticles; 2. Surface modification of inorganic nanoparticles; 3. Emulsion polymerization of functionalized inorganic nanoparticles with surface modification and organic monomers containing double bonds.

The present invention adopts colloidal method to prepare inorganic nanoparticles, such as silicon dioxide, titanium dioxide, gold, silver, zinc sulfide, cadmium sulfide, cadmium telluride, iron oxide and rare earth particles, etc., these inorganic nanoparticles (such as silicon dioxide, titanium dioxide) It can be synthesized in one step by sol-gel method. For gold, silver, zinc sulfide, cadmium sulfide, cadmium telluride, iron oxide and rare earth particles, etc., it can be stabilized with silica or silane coupling agent.

The preparation of inorganic nanoparticles (such as silicon dioxide) is completed in one step by the sol-gel method, and generally 6.0-20ml of ethyl orthosilicate (or other silicate such as methyl orthosilicate, orthosilicate, etc.) is used as For the reaction precursor, the amount of absolute ethanol (or other alcohol corresponding to the applied precursor) used as a dispersant is 180-280ml, and 8-40ml of ammonia water is used as a catalyst to be added to the reaction bottle at one time, using electric stirring, stirring The speed is 400-500 rev/min, and the inorganic nanoparticles with an average particle diameter of 60-300nm are prepared after stirring for 20-30 hours at 18-30°C.

The surface modification of inorganic nanoparticles is achieved by in-situ addition of a silane coupling agent with a reactive double bond (such as 3-methacryl propylethoxysilane, etc.), and the silane coupling agent with a double bond The ratio of the amount of the agent to the amount of tetraethyl orthosilicate is 1: 8-12 (mol/mol), and the silane coupling agent is diluted with absolute ethanol to a concentration of 0.04-0.16mol/ml, within 10-14 hours Dropping it into the previous reaction system, the reaction temperature and stirring speed remain unchanged, and after 34-38 hours of reaction, the surface-modified inorganic nanoparticles can be obtained. The alcohol solution of the surface-modified inorganic nanoparticles is centrifuged, washed and dried at low temperature to obtain purified functional inorganic nanoparticles powder. After other inorganic nanoparticles (such as gold, silver, zinc sulfide, cadmium sulfide, cadmium telluride, iron oxide and rare earth particles, etc.) are synthesized by colloidal method, they can be modified and stabilized with silica or silane coupling agent, and then Its surface modification has reactive double bonds.

Prepare narrowly dispersed inorganic/polymer core-shell nanospheres using emulsion polymerization technology, redisperse 1.0-1.5g of surface-modified inorganic nanoparticle powder in 8-12ml of absolute ethanol, add reaction monomers (such as benzene Ethylene, methyl methacrylate and other monomers suitable for emulsion polymerization) 0.5-23ml, water 80-120ml, then add 0.2-0.3% of buffering agent (such as sodium bicarbonate) accounting for the total mass of the reaction system, 0.03-0.04% of Emulsifier (such as sodium dodecylbenzenesulfonate SDBS and other anionic surfactants), 0.8-1.2% initiator (such as potassium persulfate, ammonium persulfate and other water-soluble initiators), using electric stirring, the stirring speed is 200-250 rpm, the reaction temperature is 75-80°C, and the reaction time is 10-12 hours. After the reaction is stopped, a small amount of gel produced is filtered to synthesize a narrowly dispersed emulsion of inorganic/polymer core-shell nano-microspheres, and the average particle size of the microspheres ranges from 200nm to 470nm. The size and structure of inorganic/polymer core-shell nanospheres can be controlled by adjusting the size of inorganic particles and the addition of organic monomers, and controlling the addition of inorganic particles and emulsifiers achieves narrowly dispersed inorganic/polymer cores. Control of shell nanosphere structure morphology.

The invention organically combines the sol preparation technology, surface modification technology and emulsion polymerization technology of inorganic nanoparticles, and the prepared inorganic/polymer core-shell nano-microspheres have uniform size, better core-shell structure and good stability properties, and can be well applied to the assembly of photonic crystals and other nano-hybrid and nano-composite materials. The size and structure of the synthesized narrowly dispersed inorganic/polymer core-shell nanospheres can be controlled by simply adjusting the amount of reactants, which has the advantages of simple process and easy preparation of inorganic/polymer core-shell nanospheres. Advantages of designing for structural performance.

Description of drawings

Figure 1: ²⁹ Si solid-state nuclear magnetic spectrum of inorganic nanoparticles with double bonds modified on the surface;

Figure 2: Transmission electron micrograph of inorganic nanoparticles with double bonds modified on the surface;

Figure 3: Transmission electron micrograph of narrowly dispersed inorganic/polymer core-shell nanospheres (the inserted picture is a transmission electron micrograph of inorganic nanoparticles with double bonds modified on the surface, and the picture scale is 200nm);

Figure 4: The change curve of the size of inorganic/polymer core-shell nanospheres with the amount of monomer added;

Figure 5: The size of inorganic/polymer core-shell nanospheres varies with the particle size of inorganic particles;

Figure 6: The graph of the change of the size of inorganic/polymer core-shell nanospheres with the amount of emulsifier;

Figure 7: Schematic diagram of the reaction for preparing surface-modified inorganic nanoparticles;

Figure 8: Schematic diagram of the preparation of narrowly dispersed inorganic/polymer core-shell nanospheres;

^{The 29} Si solid-state nuclear magnetic spectrum of inorganic particles modified with double bonds on the surface shown in Figure 1 and the transmission electron microscope photos of inorganic particles modified with double bonds on the surface shown in Figure 2 illustrate that surface bands can be prepared by sol technology and in-situ surface modification. Functional inorganic nanoparticles with double bonds.

The transmission electron microscope photos in Figure 3 show the size and morphology of the inorganic/polymer core-shell nanospheres, showing their better narrow dispersion.

Figure 4 shows the change curve of the size of the inorganic/polymer core-shell nano-microspheres as the amount of monomer added increases, indicating the controllability of the shell thickness of the inorganic/polymer core-shell nano-microspheres.

Figure 5 shows that the size of inorganic/polymer core-shell nanospheres varies with the particle size of inorganic particles, which shows that controlling the particle size of inorganic nanoparticles within a certain range can realize the control of the size and shape of inorganic/polymer core-shell particles.

Figure 6 illustrates that the amount of emulsifier has a great influence on the size of inorganic/polymer core-shell nanospheres. By changing the amount of emulsifier, it is possible to determine the appropriate amount of emulsifier for preparing narrowly dispersed inorganic/polymer core-shell nanospheres.

The narrowly dispersed inorganic/polymer core-shell nano-microspheres prepared by the invention have better stability, can stand still for 6 months with only a small amount of gel, and can be redispersed after being stirred.

Specific preparation examples

The present invention will be further elaborated below in conjunction with specific examples, rather than limiting the present invention. The inventive point of the present invention lies in the organic combination of the sol preparation technology of inorganic nanoparticles, surface modification technology and emulsion polymerization technology, as for the nanoparticles other than the application examples, use other double-bond silane coupling agents to carry out surface modification, and combine with other single-bond silane coupling agents Bulk polymerization, and the use of different initiators, emulsifiers, buffers, etc. are all within the scope of the present invention.

1. Synthesis of inorganic nanoparticles

Reaction principle:

Example 1:

250ml of anhydrous ethanol as a dispersant, 15.0ml of tetraethyl orthosilicate as a reaction precursor, and 20.0ml of ammonia water are added as a catalyst to a four-necked bottle equipped with a reflux condensing device and a stirrer at one time, with a stirring speed of 450 rpm, After stirring for 24 hours in a water bath at 25° C., the reaction was stopped to obtain 285 ml of an alcohol solution (mass concentration of about 5%) of silicon dioxide nanoparticles with an average particle diameter of about 124 nm. No post-treatment was required and it was ready for use.

The synthetic procedure of the inorganic nanoparticle of other particle size is as above-mentioned, adopts the addition of the raw material that is numbered as 1,2,3,4,5,6 in table 1, can obtain the inorganic nanoparticle of different particle size, average particle diameter The range is from 60nm to 300nm, the dispersion is less than 3%, and it has good shape and narrow dispersion.

Table 1: Synthetic formula of inorganic nanoparticles

Inorganic particle size

Absolute ethanol (ml) NH ₃ ·H ₂ O (ml) TEOS (ml)

(nm)

1 250 10.0 6.5 61

2 250 13.0 10.0 102

3 200 12.0 15.0 110

4 250 15.0 20.0 124

5 250 17.5 12.5 145

6 200 17.0 15.0 181

7 200 20.0 17.0 211

8 200 25.0 17.0 252

9 200 35.0 17.0 290

2. Synthesis of surface-modified inorganic nanoparticles (the reaction principle is shown in Figure 7)

Example 2:

The reaction system of the 285ml alcohol solution of the prepared 124nm inorganic nanoparticles was continuously stirred at a speed of 450 rpm in a water bath at 25°C, and at the same time, 14ml of 3-methacrylic acid propane was added dropwise with a dropping funnel. The dehydrated ethanol solution of phenylethoxysilane, the addition of 3-methacrylic acid propylethoxysilane is 2.2ml, is 10% (mol/mol) of reaction precursor orthosilicate ethyl ester, drops Complete within 12 hours, and continue to stir for 36 hours to obtain 300 ml of surface-modified inorganic nanoparticles alcohol solution with an average particle diameter of 126 nm. The surface-modified inorganic nanoparticles were separated from the alcohol solution at a centrifugal speed of 9500 rpm, and then re-dispersed with absolute ethanol. This process was repeated 4 times to obtain surface-modified inorganic nanoparticle gels. The gel was dried overnight in an oven at 40° C. to obtain a purified surface-modified inorganic nanoparticle powder, ready for use.

The surface modification steps of inorganic nanoparticles of other particle sizes are as described above, and the addition of 3-methacrylic acid propyl ethoxysilane is 10% (mol/mol) of the reaction precursor orthosilicate ethyl ester, and the inorganic nanoparticles After the surface modification of the microparticles, the particle size increases very little (less than 3%), and the stability in ethanol is improved compared to the inorganic nanoparticles due to the surface modification with double bonds.

3. Synthesis of narrowly dispersed inorganic/polymer core-shell nanospheres (the reaction principle is shown in Figure 8)

Example 3-1:

Put 1.2 g of surface-modified silicon dioxide powder with an average particle size of 145 nm in a small beaker, add 10 ml of absolute ethanol for ultrasonic dispersion for about 30 minutes, until the powder is uniformly dispersed in the alcohol solution, and simultaneously add buffer sodium bicarbonate ( NaHCO ₃ ) 0.24g, emulsifier sodium dodecylbenzene sulfonate (SDBS) 0.03g, and water 100ml, after continuing to ultrasonically disperse for 15 minutes, add the mixed solution into a four-necked bottle equipped with a reflux condensing device, add 10ml Monomer styrene (St), under the condition of passing _N2 to remove _O2 , keep the temperature of water bath at 50°C at a stirring speed of 250 rpm for pre-emulsification for one hour, then raise the temperature of water bath to 80°C, and dropwise add Add 15ml (0.1g/15ml) of an aqueous solution of potassium persulfate (KPS), after the dropwise addition, react at this temperature for 12 hours, and stop the reaction to obtain narrowly dispersed inorganic/polymer core-shell nanoparticle with an average particle size of 330nm. Ball emulsion, if there is a small amount of gel in the reaction bottle, just filter it out.

The particle diameter and the addition amount of the silicon dioxide nanoparticles of fixed surface modification, change the addition (as table 2) of reaction monomer St, the consumption of initiator changes thereupon (the molar consumption of initiator is 1% of reaction monomer ), the consumption of other reagents is constant, and the emulsion polymerization step is as described above, and the emulsion of narrowly dispersed inorganic/polymer core-shell nanospheres with different polymer shell thicknesses can be obtained.

Table 2: Emulsion Polymerization Formulation I of Narrowly Dispersed Inorganic/Polymer Core-Shell Nanospheres

SiO ₂      St KPS NaHCO ₃ SDBS core-shell microspheres

Particle Size Mass (g) (ml) (g) (g) (g) Diameter (nm)

(nm)

1 145 1.2 0.5 0.005 0.24 0.03 205

2 145 1.2 1.0 0.010 0.24 0.03 214

3 145 1.2 2.0 0.020 0.24 0.03 223

4 145 1.2 4.0 0.040 0.24 0.03 259

5 145 1.2 10.0 0.100 0.24 0.03 330

6 145 1.2 13.0 0.100 0.24 0.03 427

7 145 1.2 16.0 0.100 0.24 0.03 455

8 145 1.2 22.0 0.150 0.24 0.03 467

Example 3-2:

Put 1.2 g of surface-modified silicon dioxide powder with an average particle size of 120 nm in a small beaker, add 10 ml of absolute ethanol for ultrasonic dispersion for about 30 minutes, until the powder is uniformly dispersed in the alcohol solution, and simultaneously add buffer sodium bicarbonate ( NaHCO ₃ ) 0.24g, emulsifier sodium dodecylbenzene sulfonate (SDBS) 0.03g, and water 100ml, after continuing to ultrasonically disperse for 15 minutes, add the mixed solution into a four-necked bottle equipped with a reflux condensing device, add 10ml Monomer styrene (St), under the condition of passing _N2 to remove _O2 , keep the temperature of water bath at 50°C at a stirring speed of 250 rpm for pre-emulsification for one hour, then raise the temperature of water bath to 80°C, and dropwise add An aqueous solution of 15ml (0.1g/15ml) of potassium persulfate (KPS), after the dropwise addition, was reacted at this temperature for 12 hours, and the reaction was stopped to obtain narrowly dispersed inorganic/polymer core-shell nanoparticle particles with an average particle size of 212nm. Ball emulsion, if there is a small amount of gel in the reaction bottle, just filter it out.

The adding amount of the silica nanoparticle of fixed reaction monomer St and surface modification changes the particle diameter (as table 3) of the silica nanoparticle of surface modification, and other emulsion polymerization steps are as mentioned above, can obtain the narrow Emulsions of Dispersed Inorganic/Polymer Core-Shell Nanospheres.

Table 3: Emulsion polymerization formulation II of narrowly dispersed inorganic/polymer core-shell nanospheres

Si0 ₂  St KPS NaHCO ₃ SDBS core-shell microspheres

Particle Size Mass (ml) (g) (g) (g) Diameter (nm)

(nm) (g)

1 120 1.2 10 0.1 0.24 0.03 212

2 124 1.2 10 0.1 0.24 0.03 229

3 136 1.2 10 0.1 0.24 0.03 234

4 145 1.2 10 0.1 0.24 0.04 275

5 177 1.2 10 0.1 0.24 0.03 330

6 181 1.2 10 0.1 0.24 0.04 370

Embodiment 3-3:

Put 1.2g of surface-modified silica powder with a particle size of 120nm in a small beaker, add 10ml of absolute ethanol to ultrasonically disperse for about 30 minutes, until the powder is uniformly dispersed in the alcohol solution, and add buffer sodium bicarbonate (NaHCO ₃ ) 0.24g, emulsifier sodium dodecylbenzenesulfonate (SDBS) 0.04g, and water 100ml, after continuing ultrasonic dispersion for 15 minutes, add the mixed solution into a four-necked bottle equipped with a reflux condensing device, add 10ml single Bulk styrene (St), in the case of passing _N2 to remove _O2 , keep the water bath temperature at 50°C for pre-emulsification for one hour at a stirring speed of 250 rpm, then raise the water bath temperature to 80°C, and add the initiator dropwise Aqueous solution 15ml (0.1g/15ml) of potassium persulfate (KPS), after dropping, reacted at this temperature for 12 hours, stop reaction and obtain mean particle diameter and be that the inorganic/polymer core-shell nanosphere of 220nm narrow dispersion Emulsion, if there is a small amount of gel in the reaction bottle, it can be removed by filtration.

Embodiment 3-2 is compared with 3-3, and the add-on of emulsifier sodium dodecylbenzene sulfonate changes to some extent, but the dispersibility of inorganic/polymer core-shell nano-microspheres obtained by reaction is better, and the There is no obvious change in structure and form, and the emulsion is stable and uniform. Comparing the morphology of the inorganic/polymer core-shell nanospheres synthesized under the dosage of other emulsifier SDBS, the appropriate emulsifier dosage is determined to be 0.03-0.04% of the total mass of the reaction system.

Claims (3)

1. A method for synthesizing narrowly dispersed inorganic/polymer core-shell nanospheres, comprising three steps: synthesis of inorganic nanoparticles, surface modification of inorganic nanoparticles, and emulsion polymerization with organic monomers containing double bonds, characterized in that : (1) The preparation of inorganic nanoparticles is completed in one step by sol-gel method, 6.0-20ml of tetraethyl orthosilicate is used as a reaction precursor, the amount of absolute ethanol as a dispersant is 180-280ml, and 8-40ml of ammonia water is used as The catalyst is added to the reaction bottle at one time, and after 20-30 hours at 18-30°C, electric stirring is used at a stirring speed of 400-500 rpm to prepare inorganic nanoparticles with an average particle size of 60-300nm; (2) The surface modification of inorganic nanoparticles is achieved by in-situ addition of a silane coupling agent with a reactive double bond, the molar ratio of the amount of the silane coupling agent with a double bond to the amount of orthosilicate 1:8-12, the silane coupling agent is diluted with absolute ethanol to a concentration of 0.04-0.16mol/ml, and is dropped into the previous reaction system within 10-14 hours. The reaction temperature and stirring speed remain unchanged. After 34- After 38 hours of reaction, the surface-modified inorganic nanoparticles are obtained; the alcohol solution of the surface-modified inorganic nanoparticles is centrifuged, washed, and dried at low temperature to obtain purified functional inorganic nanoparticle powder; (3) Emulsion polymerization with organic monomers containing double bonds is to redisperse 1.0-1.5g of surface-modified inorganic nanoparticle powder in 8-12ml of absolute ethanol, adding styrene or methyl methacrylate is suitable Emulsion polymerized monomer 0.5-23ml, water 80-120ml, then add 0.2-0.3% buffering agent, 0.03-0.04% emulsifier, 0.8-1.2% initiator accounting for the total mass of the reaction system, use electric stirring, stirring The speed is 200-250 rpm, the reaction temperature is 75-80°C, and the time required for the reaction is 10-12 hours. After the reaction is stopped, the small amount of gel produced can be filtered to synthesize a narrowly dispersed inorganic/polymeric It is an emulsion of core-shell nano-microspheres, and the average particle size of the microspheres is from 200nm to 470nm. 2. The method for synthesizing narrowly dispersed inorganic/polymer core-shell nano-microspheres as claimed in claim 1, characterized in that: the reaction precursor can also be methyl orthosilicate or butyl orthosilicate, as a dispersion The reagent used is the alcohol corresponding to the precursor used. 3. The synthesis method of narrowly dispersed inorganic/polymer core-shell nano-microspheres as claimed in claim 1, characterized in that: the silane coupling agent with double bonds is 3-methacrylic acid propyl ethyl Oxysilane, sodium bicarbonate as a buffer, sodium dodecylbenzenesulfonate anion surfactant as an emulsifier, and potassium persulfate or ammonium persulfate water-soluble initiator as an initiator.

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