Disclosure of Invention
In order to overcome the defect that the conventional polymerization method is difficult to synthesize the fusiform polymer particles, the invention provides the fusiform structure polymer nano particles and the preparation method thereof. Compared with methods such as a spherical particle stretching method, the stepwise polymerization method provided by the invention can avoid the defects of complex and complicated synthesis steps, special synthesis equipment, low preparation efficiency and the like, and can efficiently synthesize spindle-shaped polymer particles, and the prepared polymer conductive microspheres have uniform sizes.
In order to achieve the above purpose, the invention adopts the following specific technical scheme:
the invention provides a preparation method of polymer nano particles with a fusiform structure, which comprises the following steps:
(1) Uniformly dispersing a stabilizer, an initiator and a comonomer in ethanol to obtain a solution A, wherein the comonomer is a mixture of styrene and 4-vinylpyridine, and the volume ratio of the styrene to the 4-vinylpyridine is (18-22);
(2) Reacting the solution A in an inert gas atmosphere to obtain micelle solution B;
(3) Divinylbenzene is added into styrene to obtain a solution C;
(4) And (3) injecting the solution C into the micelle solution B for reaction, centrifuging and washing.
Preferably, the stabilizer in step (1) is at least one selected from polyvinylpyrrolidone, polyethylene glycol and sodium hexadecyl benzene sulfonate.
Preferably, the initiator in step (1) is selected from at least one of Azobisisobutyronitrile (AIBN), dimethyl azobisisobutyrate, dibenzoyl peroxide and ammonium persulfate.
Preferably, in step (1), the stabilizer, initiator, comonomer, ethanol are used in a ratio of (0.1-0.5 g): (20-80 mg): (30-50 ml): (10-40 ml).
Preferably, in the step (2), the reaction condition is that the reaction is carried out for 6-10 hours at 60-80 ℃.
Preferably, in step (2), the inert gas is nitrogen.
Preferably, in step (3), the ratio of divinylbenzene to styrene is from 0.02 to 0.10mL to 1 to 3 mL.
Preferably, in the step (4), the reaction condition is that the reaction is carried out for 4-8 hours at 60-80 ℃ under the atmosphere of inert gas, and preferably, the inert gas is nitrogen.
The invention also provides a polymer nanoparticle with a fusiform structure, which is prepared by adopting the preparation method.
The invention has the following beneficial effects:
1. According to the invention, by changing the proportion of different specific monomers, the precise conversion from spherical particles to fusiform particles can be realized, and the synthesis of large-size fusiform polymer particles is realized.
2. The stepwise polymer method designed by the invention can synthesize a large amount of spindle-shaped polymer particles in one pot, has simple synthesis equipment, and is lower in energy consumption and higher in synthesis efficiency compared with the existing spherical particle stretching method, and is suitable for large-scale production.
3. The stepwise polymer method designed by the invention has high synthesis efficiency, and the prepared fusiform polymer particles have uniform size, thereby being beneficial to improving the optical performance of fusiform polymer materials.
4. Pyridine functional groups are uniformly distributed on the surfaces of the fusiform polymer particles prepared by the method, so that subsequent functionalization is facilitated, and surface modification of the fusiform polymer particles is realized.
5. The surface of the fusiform polymer particles prepared by the method has a cross-linked structure, so that the structural stability of the fusiform polymer particles can be improved.
Detailed Description
The invention provides a suitable preparation method, which is to prepare a soluble polymer with longer chain by a stepwise polymer method, and take a polymer chain as a macromolecular stabilizer, and in the further cross-linking polymerization process, the deformed polymer particles formed by shearing can keep the stability of shape and size in the polymerization process due to the stabilization of the macromolecular chain on the surface of the polymer particles, so that the fusiform polymer particles are obtained. However, in the preparation of long chain soluble polymers, the control of the comonomer ratio is critical. Because the proportion of the polymer chain fragments of the cosolubility generated by the polymerization of the functional monomers is low, the solubility of the polymer chains in the system is reduced, the chain length of the polymer is shortened, the stabilizing effect is weakened in the further cross-linking polymerization process, and the synthesis of the spindle-shaped polymer particles is difficult to realize.
Specifically, the preparation method of the polymer nanoparticle with the fusiform structure comprises the following steps:
(1) Uniformly dispersing 0.1-0.5g of stabilizer, 20-80mg of initiator and 30-50ml of comonomer in 10-40ml of ethanol by a step polymerization method to obtain solution A;
The stabilizer is at least one selected from polyvinylpyrrolidone (average molecular weight 20000-360000), polyethylene glycol (average molecular weight 2000-80000) and sodium hexadecyl benzene sulfonate. The main function of the stabilizer is to prevent the polymer particles from agglomerating or agglomerating during the reaction. They form a protective layer by adsorbing onto the particle surface, ensuring that the particles remain uniformly dispersed during the polymerization reaction. At the same time, stabilizers also help to control the morphology of the particles, especially when synthesizing fusiform particles, which can provide morphology preservation and dimensional stability to the particles.
The initiator is at least one selected from the group consisting of azobisisobutyronitrile, dimethyl azobisisobutyrate, dibenzoyl peroxide and ammonium persulfate. The initiator is used to initiate the polymerization of the comonomer, and by providing free radicals, initiates the free radical copolymerization of styrene and 4-vinylpyridine to form a long chain polymer.
The comonomer is styrene and 4-vinyl pyridine, and preferably the volume ratio of the styrene to the 4-vinyl pyridine is (18-22). These two comonomers react together to form the polymer backbone. Styrene as a comonomer provides the main structure of the polymer backbone, forming a stable carbon chain basis. The presence of styrene can help to produce long chain polymers with good mechanical properties, providing strength and morphological stability to subsequent deformed particles. The 4-vinyl pyridine introduces a pyridine group in the copolymerization process, and the pyridine group has stronger reactivity and functionalization potential and can provide the possibility of subsequent chemical modification on the surface of polymer particles. In addition, the presence of 4-vinylpyridine also contributes to the structural stability of the particles, and the morphology of the particles can be controlled by adjusting the proportion of the 4-vinylpyridine, so that the conversion from spherical to fusiform particles is realized. The ratio of styrene to 4-vinylpyridine is a critical factor in determining the morphology of the polymer particles.
(2) Reacting the solution A for 6-10 hours at 60-80 ℃ in an inert gas atmosphere to obtain micelle solution B;
Preferably, the inert gas is nitrogen;
(3) 0.02-0.10mL of divinylbenzene was added to 1-3mL of styrene to give solution C. Divinylbenzene is used as a crosslinking monomer, two vinyl groups of which are capable of undergoing crosslinking reactions with the polymer chains to form crosslinked structures. The cross-linking not only enhances the mechanical strength of the particles, but also improves the morphological stability of the particles, so that the fusiform structure can be kept intact under external stress or environmental changes. In addition, the cross-linked structure can also reduce the risk of morphology collapse of the particles during long-time storage or use, and ensure the service life and functional stability of the particles. Styrene is used as a diluent and a comonomer, and not only participates in the copolymerization reaction, but also ensures that the crosslinking reaction is more uniform by adjusting the viscosity and the reaction rate of the solution.
(4) And (3) injecting the solution C into the micelle solution B, reacting for 4-8 hours at 60-80 ℃ in an inert gas atmosphere, centrifuging and washing to obtain the polymer nano particles with the fusiform structures. The function of this stage is to form a cross-linked structure on the surface of the fusiform polymer particles through a cross-linking reaction, thereby further enhancing the stability and mechanical strength of the particles. After the reaction is completed, unreacted materials and byproducts are removed through centrifugation and washing, and finally the target spindle-shaped structure polymer nano particles are obtained.
The invention provides a preparation method of polymer nano particles with a fusiform structure, which adopts a step polymerization method, generates a particle skeleton by precisely controlling the proportion of comonomer styrene and 4-vinyl pyridine, wherein the styrene provides a stable carbon chain structure, the 4-vinyl pyridine introduces a modifiable pyridine group, and the conversion from spherical to fusiform particles can be realized by regulating the proportion. The initiator is used for initiating free radical polymerization, and the stabilizer is adsorbed on the surface of the particles to prevent aggregation, so that the uniform dispersion and the morphological stability of the particles are maintained. The reaction is carried out under an inert atmosphere, and divinylbenzene is added as a crosslinking monomer, so that the mechanical strength and structural stability of the particles are further enhanced, and the integrity of the fusiform structure under environmental changes is ensured. And unreacted substances are removed through centrifugation and washing, so that the high-quality spindle-shaped structure polymer nano particles are finally obtained, and the method is suitable for large-scale production and various functional applications.
The technical scheme of the present invention will be further described with reference to specific examples, but the scope of the present invention is not limited to these examples. All changes and equivalents that do not depart from the gist of the invention are intended to be within the scope of the invention.
Polyvinylpyrrolidone (PVP), polyvinylpyrrolidone, average molecular weight 24000, K23-27, aba Ding Pinpai, CAS number 9003-39-8.
Example 1
(1) 0.3G of polyvinylpyrrolidone and 50mg of AIBN are added into 25mL of ethanol, 2mL of styrene monomer and 2mL of 4-vinylpyridine monomer are added, and the mixture is uniformly mixed to obtain solution A;
(2) Transferring the solution A into a round-bottom flask, stirring for 30min to make the solution uniform, heating to 70 ℃ under nitrogen atmosphere, and reacting for 8h to obtain homogeneous micelle solution B;
(3) Adding 0.06mL of divinylbenzene monomer into 2mL of styrene monomer, and uniformly mixing to obtain a solution C;
(4) The solution C is injected into a round bottom flask containing the micelle solution B, the reaction is continued for 6 hours under the nitrogen environment at 70 ℃ to obtain a light yellow suspension solution, the product is collected by centrifugation, and the product is washed with ethanol to obtain large-size spindle-shaped structure polymer nano particles, the particle length is about 40 mu m, and the diameter is about 15 mu m, as shown in figure 1. Fig. 2 is an SEM photograph of the polymer nanoparticles of the spindle structure of example 1 in a larger range.
Example 2
(1) 0.4G of polyvinylpyrrolidone and 80mg of AIBN are added into 25mL of ethanol, 2mL of styrene monomer and 2mL of 4-vinylpyridine monomer are added, and the mixture is uniformly mixed to obtain solution A;
(2) Transferring the solution A into a round-bottom flask, stirring for 30min to make the solution uniform, heating to 70 ℃ under nitrogen atmosphere, and reacting for 8h to obtain homogeneous micelle solution B;
(3) Adding 0.06mL of divinylbenzene monomer into 2mL of styrene monomer, and uniformly mixing to obtain a solution C;
(4) And injecting the solution C into a round-bottom flask containing the micelle solution B, continuously reacting for 6 hours at 70 ℃ in a nitrogen environment, centrifugally collecting a product, and washing with ethanol to obtain the spindle-shaped structured polymer nano particles.
Example 3
(1) 0.2G of polyvinylpyrrolidone and 30mg of AIBN are added into 25mL of ethanol, 2mL of styrene monomer and 2mL of 4-vinylpyridine monomer are added, and the mixture is uniformly mixed to obtain solution A;
(2) Transferring the solution A into a round-bottom flask, stirring for 30min to make the solution uniform, heating to 70 ℃ under nitrogen atmosphere, and reacting for 8h to obtain homogeneous micelle solution B;
(3) Adding 0.06mL of divinylbenzene monomer into 2mL of styrene monomer, and uniformly mixing to obtain a solution C;
(4) And injecting the solution C into a round-bottom flask containing the gum bundle solution B, continuously reacting for 6 hours at 70 ℃ in a nitrogen environment, centrifugally collecting a product, washing with ethanol, and washing with a mixed solution of ethanol and water to obtain the spindle-shaped structured polymer nano particles.
Example 4
Example 4 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 2.2mL of styrene monomer and 1.8mL of 4-vinylpyridine monomer were further added thereto, followed by mixing uniformly to obtain solution A.
The end result is a polymer nanoparticle with a spindle structure, the particle length of which is about 36 μm and the diameter of which is about 15 μm, as shown in FIG. 3.
Example 5
Example 5 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 1.8mL of styrene monomer and 2.2mL of 4-vinylpyridine monomer were further added thereto, followed by mixing uniformly to obtain solution A.
The end result is a polymer nanoparticle with a spindle structure, the particle length of about 38 μm and the diameter of about 14 μm, as shown in FIG. 4.
Comparative example 1
Comparative example 1 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 2.3mL of styrene monomer and 1.7mL of 4-vinylpyridine monomer were further added thereto, followed by mixing uniformly to obtain solution A.
The end result is a mixture of spherical, fusiform and irregularly shaped nanoparticles, as shown in fig. 5, that cannot produce uniform fusiform structured nanoparticles.
Comparative example 2
Comparative example 2 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 2.7mL of styrene monomer and 1.3mL of 4-vinylpyridine monomer were further added thereto, followed by mixing uniformly to obtain solution A.
The end result is a mixture of spherical and irregularly shaped nanoparticles, as shown in fig. 6, that cannot be produced with corresponding spindle-structured nanoparticles.
Comparative example 3
Comparative example 3 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, 3.2mL of styrene monomer and 0.8mL of 4-vinylpyridine monomer were further added, and the mixture was uniformly mixed to obtain solution A.
The end result is that only microspheres of non-uniform size are obtained, as shown in fig. 7, and no corresponding spindle-structured nanoparticles can be prepared.
Comparative example 4
Comparative example 4 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 1.7mL of styrene monomer and 2.3mL of 4-vinylpyridine monomer were further added thereto, followed by mixing uniformly to obtain solution A.
The end result is that only transparent solutions are obtained and no corresponding spindle-structured nanoparticles can be prepared.
Comparative example 5
Comparative example 5 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 1.3mL of styrene monomer and 2.7mL of 4-vinylpyridine monomer were further added thereto, followed by mixing uniformly to obtain solution A.
The end result is that only transparent solutions are obtained and no corresponding spindle-structured nanoparticles can be prepared.
Comparative example 6
Comparative example 6 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and then 0.8mL of styrene monomer and 3.2mL of 4-vinylpyridine monomer were added thereto, followed by mixing uniformly to obtain solution A.
The end result is that only transparent solutions are obtained and no corresponding spindle-structured nanoparticles can be prepared.
When the proportion of the 4-vinylpyridine monomer is too low, the resulting soluble polymer chain is short, and sufficient stability is not provided during the subsequent polymerization, resulting in failure of the morphology of the particles to be maintained, and thus failure to form spindle polymer particles. In contrast, when the proportion of the 4-vinylpyridine monomer is too high, the solubility of the polymer chain is too high, so that the micelles in the system are too stable, and finally a soluble micelle solution is formed, and polymer particles with a fusiform structure cannot be generated.
Comparative example 7
Comparative example 7 the only difference in example 1 is the difference in step (3).
Step (3) was carried out using 2.06mL of styrene monomer as solution C.
As a result, only a transparent solution was obtained, and it was impossible to prepare the nanoparticle of the spindle structure.
The lack of divinylbenzene monomer with crosslinking function in the system during the second polymerization results in excessive solubility of the polymer product, failure to form stable morphological structure, and finally only the soluble micelle solution, so that polymer particles with fusiform structure cannot be obtained.
Comparative example 8
Comparative example 8 the only difference in example 1 is the difference in step (3).
Step (3) was carried out using 2.06mL of divinylbenzene monomer as solution C.
The end result is that only irregular morphology of solid precipitate is obtained, as shown in fig. 8, and corresponding spindle-shaped structured nanoparticles cannot be prepared.
In the second polymerization, excessive divinylbenzene monomer is added into the system, so that excessive crosslinking occurs between polymer products, the solubility of the polymer products is rapidly reduced, irregular solid precipitation is generated, the morphology of particles cannot be controlled, and therefore, polymer particles with a fusiform structure cannot be prepared.
Comparative example 9
Comparative example 1 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and then 4mL of styrene monomer was added thereto, and the mixture was uniformly mixed to obtain a solution A.
The end result is that only polymeric microspheres are obtained and spindle-structured nanoparticles cannot be prepared.
Comparative example 10
Comparative example 1 the only difference in example 1 is the difference in step (1).
Specifically, 0.3g of polyvinylpyrrolidone and 50mg of AIBN were added to 25mL of ethanol, and 4mL of 4-vinylpyridine monomer was added thereto, followed by mixing uniformly to obtain solution A.
The end result is that only transparent solutions are obtained and no spindle-structured nanoparticles can be prepared.
Comparative example 11
Compared with example 1, this comparative example modifies the ratio of the comonomer in step (1), specifically, adding 2mL of styrene monomer and 2mL of 4-vinylpyridine to ethanol is changed to adding 2mL of styrene monomer and 0.2mL of 4-vinylpyridine to ethanol, and step (3) is deleted, as a result, only microspheres with smooth surfaces but uneven sizes are obtained, and as shown in FIG. 9, corresponding spindle-structured nanoparticles cannot be prepared.
Comparative example 12
Compared with example 1, the composition of the monomers in step (1) is modified, specifically, 2mL of styrene monomer and 2mL of 4-vinylpyridine are added into ethanol, only 2mL of styrene monomer is added into ethanol, and step (3) is deleted, so that only microspheres with smooth surfaces and uniform sizes are obtained, and corresponding spindle-shaped structure nanoparticles cannot be prepared as shown in FIG. 10.
The present embodiments are merely illustrative of the invention and not limiting of the invention, and any changes made by those skilled in the art after reading the specification of the invention will be protected by the patent laws within the scope of the appended claims.