A silica / polymer composite hybrid nanofiller based on polymeric induced self-assembly, and a preparation method and application thereof

Abstract

The application relates to a silica / polymer hybrid nanofiller prepared by polymerization-induced self-assembly, a preparation method and application of the hybrid nanofiller, which comprises nanosilica and polymer monomers, the polymer monomers comprising first block polymer monomers and second block polymer monomers; the first or second block polymer monomers are at least one of glycidyl methacrylate (GMA), hydroxypropyl methacrylate (HPMA), methoxyethyl acrylate (MEA) and hydroxyethyl methacrylate (HEMA), and the content of the nanosilica is 10wt%-50wt% of the hybrid nanofiller. The composite hybrid nanofiller has the advantages of excellent reinforcing effect, good compatibility with a rubber matrix, excellent dispersibility and the like, and can be well applied to the rubber material preparation field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of materials, in particular to a silica / polymer composite hybrid nanofiller, a preparation method and application thereof. BACKGROUND

[0002] Nanosilica (SiO2) as a high-quality filler is widely used in rubber reinforcement. The advantages of nanosilica as a rubber filler mainly lie in overcoming the limitation of weight increase of traditional micro-composites, and only a very low loading amount can achieve the effect of rubber reinforcement. Meanwhile, the high specific surface area of nanosilica helps to better transfer stress from the rubber matrix to the SiO2 nanoparticles, thereby better applying to rubber reinforcement. However, nanosilica particles have defects such as poor compatibility with the rubber matrix and easy aggregation between particles. In addition to using inorganic nanoparticles as rubber fillers, polymer particles prepared by polymerization and subsequent crosslinking treatment can also be applied to rubber reinforcement. Compared with inorganic nanoparticles, the advantages of polymer fillers mainly lie in: lightweight due to low density of filled rubber and diversity and customizability of fillers due to controllable polymerization. Polymer fillers have better compatibility with the rubber matrix. However, polymer fillers also have defects such as poor stability and poor reinforcement effect.

[0003] Therefore, it is particularly important to develop a simple and effective method to combine polymer fillers with nanosilica fillers to integrate the advantages of the two types of fillers, so as to prepare a nanohybrid filler with excellent reinforcement effect, good compatibility with the rubber matrix, excellent dispersion and the like. SUMMARY

[0004] In view of the problems of nanosilica particles, such as poor compatibility with the rubber matrix and easy aggregation between particles, the present application provides a silica / polymer composite hybrid nanofiller. The composite hybrid nanofiller of the present application solves the above technical problems and has advantages such as excellent reinforcement effect, good compatibility with the rubber matrix, excellent dispersion and the like, and can be well applied to the field of rubber material preparation.

[0005] One of the purposes of the present application is to provide a silica / polymer composite hybrid nanofiller. The filler comprises nanosilica (SiO2) and a polymer monomer, the polymer monomer comprises a first block polymer monomer and a second block polymer monomer; the first or second block polymer monomer is at least one of glycidyl methacrylate (GMA), hydroxypropyl methacrylate (HPMA), methoxyethyl acrylate (MEA) and hydroxyethyl methacrylate (HEMA), and the content of the nanosilica is 10wt%-50wt% of the hybrid nanofiller.

[0006] In the technical solution, the polymer formed by the first block polymer monomer has a polymerization degree of 50-400, and the low polymerization degree of the first block polymer facilitates obtaining the hybrid nano filler with higher morphology, preferably 50-200; the polymer formed by the second block polymer monomer has a polymerization degree of 200-1000, and the polymerization degree of the second block polymer monomer is preferably 200-400 to realize the ideal morphology of the hybrid nano filler.

[0007] In the technical solution, the filler is obtained by fixing the nano SiO2 particles on the first block polymer monomer, then initiating the polymerization of the first block polymer monomer, and then initiating the polymerization of the second block polymer monomer to drive the in-situ self-assembly of the block copolymer.

[0008] In the technical solution, the first block polymer monomer is glycidyl methacrylate, and the filler includes the following structure:

[0009]

[0010] The nano SiO2 is grafted on the ring-opening position of the epoxy group of the first polymer block polyglycidyl methacrylate in the structure.

[0011] The second object of the application is to provide a preparation method of a silica / polymer composite hybrid nano filler. The method includes the following steps: (1) fixing the nano SiO2 particles on the first block polymer monomer; (2) initiating the polymerization of the first block polymer monomer by using a dithio carbonic acid ester RAFT reagent to obtain a soluble block; (3) initiating the polymerization of the second insoluble block by using the obtained soluble first block, and simultaneously driving the in-situ self-assembly of the copolymer to obtain the hybrid nano filler. The RAFT reagent is preferably 4-cyano-4-(((ethylthio)thiocarbonyl)thio) pentanoic acid due to its good water solubility.

[0012] In the technical solution, the step (1) includes: stirring and refluxing the nano SiO2 sol, the first block polymer monomer and deionized water at 80-90°C for 9-48h, and the mass ratio of the nano SiO2 to the first block polymer monomer is (0.2-2):1.

[0013] In the technical scheme, the step (2) comprises: adding the solution obtained in the step (1), a RAFT reagent and a water-soluble initiator into a container, stirring and dissolving, removing oxygen by freezing and pumping, heating to 50-60 DEG C for 1-3 hours, and quenching the reaction in air, wherein the mass ratio of the monomer, the RAFT reagent and the water-soluble initiator in the solution obtained in the step (1) is (100-800):(0.5-1):0.1, preferably (20-200):(0.5-1):0.1, and the water-soluble initiator is preferably azobisimidozolin hydrochloride (VA-044).

[0014] In the technical scheme, the reagent, the second monomer and the water-soluble initiator obtained in the step (2) are added into a container, oxygen is removed by freezing and pumping, the solid content is set to 10%-20%, and the reaction is carried out at 50-60 DEG C for 2-4 hours to obtain the product.

[0015] In the technical scheme, the container is a polymerization tube.

[0016] The third object of the present application is to provide the application of the silica / polymer composite hybrid nanofiller in the preparation of rubber materials.

[0017] Compared with the prior art, the present application has the following advantages: the silica / polymer composite hybrid nanofiller has excellent reinforcing effect, good compatibility with rubber matrix and excellent dispersibility, because the SiO2 nanoparticles are finally fixed on the hybrid nanofiller by the covalent bond in the chemical bond, and the covalent bond connection ensures the good stability of the hybrid nanofiller. The SiO2 sol and the first block polymer monomer are heated and stirred together by one-pot method, which ensures the sufficient contact between the SiO2 nanoparticles and the first block polymer monomer, and the epoxy groups of the first block polymer monomer can be grafted with the SiO2 nanoparticles while being ring-opened. In addition, the method of preparing the hybrid nanofiller by polymerization-induced self-assembly overcomes the shortcomings of the traditional self-assembly method, such as complicated steps and low solid content. The polymerization-induced self-assembly can realize the preparation with high solid content and is easy to realize mass production, which is also beneficial to the large-scale preparation of the filler involved in the subsequent application. In addition, the assembly has various morphologies and is easy to control, and the morphology and particle size of the hybrid filler can be controlled by controlling the feeding ratio of the monomer. In addition, the hybrid nanofiller has a polymer matrix, which can realize better compatibility with the rubber matrix. The hybrid nanofiller combines the inorganic filler and the polymer matrix, and has the advantages of good reinforcing effect of the inorganic filler and good compatibility of the polymer filler with the rubber matrix. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1NMR of unopened GMA monomer and opened GMA monomer 1 H NMR comparison chart

[0019] Figure 2 NMR of polymer grafted with nano-SiO2 SiO2@PGMA 1 H NMR chart

[0020] Figure 3 NMR of hybrid nanofiller grafted with nano-SiO2 SiO2@PGMA-b-PHPMA 1 H NMR chart

[0021] Figure 4a TEM chart of hybrid nanofiller grafted with nano-SiO2 SiO2@PGMA-b-PHPMA (SiO2@PGMA 50 -b-PHPMA 200 )

[0022] Figure 4b TEM chart of hybrid nanofiller grafted with nano-SiO2 SiO2@PGMA-b-PHPMA (SiO2@PGMA 50 -b-PHPMA 400 )

[0023] Figure 5 Thermogravimetric curve of pure SiO2 and polymer grafted with SiO2 nano-particles SiO2@PGMA-SiO2

[0024] Figure 6 Flow chart of preparing SiO2@PGMA-PHPMA based on polymerization induced self-assembly. DETAILED DESCRIPTION

[0025] The following specific description of the application is made in conjunction with specific examples. It is necessary to point out that the following examples are only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application. Some non-essential improvements and adjustments of the application made by those skilled in the art based on the content of the application still fall within the scope of protection of the application.

[0026] The raw materials in the following examples are all commercially available.

[0027] Example 1

[0028] (1) Ring-opening grafting of SiO2 nano-particles with the first block monomer with an epoxy group, glycidyl methacrylate (GMA):

[0029] Into a round bottom flask, 10 g SiO2 sol (containing 30% SiO2 nanoparticles), 5 g GMA monomer, 38 g deionized water were added, and stirred at 85 °C for 9 h to obtain a relatively clear homogeneous solution. Part of the homogeneous solution was taken for NMR 1 H NMR was used to determine the ring opening of the monomer. As shown in Figure 1 , the peaks at 2.68 ppm and 2.85 ppm were both attributed to the characteristic peaks of the GMA monomer. By comparing the peak positions of the GMA monomer before and after ring opening, we can observe the disappearance of the GMA monomer characteristic peaks, which proves that we have obtained ring-opened monomers successfully. (Structure of the ring-opened monomer and its NMR 1 spectrum are shown in Figure 1 ) and

[0030] (2) RAFT polymerization of the ring-opened monomer grafted with SiO2 nanoparticles

[0031] Into a polymerization tube, 2.5 g of the solution obtained in step (1), 8.2 mg of RAFT agent, 1.02 mg of water-soluble initiator azobisisobutyrimidazole hydrochloride (VA-044), 2.5 g of deionized water were added and stirred to dissolve. The mixed solution was subjected to three cycles of freezing and oxygen removal, and then heated to 50 °C for 4 h. The reaction was quenched in air. Part of the reaction product was freeze-dried to remove water for NMR 1 determination. Similarly, by identifying the characteristic peaks of the polymer, the peaks at 0.8-1.5 ppm were attributed to the characteristic peaks on the main chain of the GMA monomer, and the peaks at 3.6-3.9 ppm were attributed to the characteristic peaks on the side chain of the GMA monomer. The conversion of the monomer can be calculated by integration, which proves that we have successfully polymerized. (NMR 1 spectrum is shown in Figure 2 ); the remaining product was dialyzed through a 3000 MW dialysis bag for 48 h to remove the monomers that did not participate in the polymerization, and a pure polymer grafted with SiO2 nanoparticles, SiO2@PGMA (polymerization degree 50), was obtained. Finally, part of the dialyzed product was freeze-dried to remove water for thermogravimetric analysis (thermogravimetric curve of SiO2@PGMA is shown in Figure 5 ).

[0032] (3) Using SiO2@PGMA with a polymerization degree of 50 in step 2 as a macromolecular RAFT agent to initiate the second block polymerization and induce self-assembly:

[0033] The polymerization product obtained in step (2) was used as a macro-RAFT agent, and the product 2.25 g (containing PGMA 0.11 g) after dialysis, monomer HPMA 0.41 g, water-soluble initiator VA-044 0.46 mg were added into a polymerization tube, and oxygen was removed by three cycles of freezing and pumping. The solid content was set to 15%, and the reaction was carried out at 50°C for 2 h. A milky white homogeneous assembly solution was obtained (polymerization degree 200). The obtained reaction product was subjected to nuclear magnetic resonance 1 HNMR and transmission electron microscopy analysis, as shown in Figure 3 , the peaks at 1.01 ppm, 3.8 ppm and 4.8 ppm are characteristic peaks of PHPMA, proving the successful polymerization of the second block monomer HPMA. (Product hybrid nanofiller nuclear magnetic resonance 1 HNMR spectrum is shown in Figure 3 , and the morphology of the hybrid nanofiller is shown in Figure 5 ).

[0034] Example 2

[0035] (1) Open ring grafting of the first block monomer glycidyl methacrylate (GMA) with SiO2 nanoparticles:

[0036] In a round-bottom flask, add SiO2 sol 10 g (containing SiO2 nanoparticles 30%), GMA monomer 5 g, and deionized water 38 g. Stir and reflux at 85°C for 9 h to obtain a relatively clear homogeneous solution.

[0037] (2) RAFT polymerization of the open ring monomer grafted with SiO2 nanoparticles

[0038] In a polymerization tube, add 5 g of the solution obtained in step (1), RAFT agent 8.2 mg, and water-soluble initiator azobisimidozoline hydrochloride (VA-044) 1.02 mg. Stir and dissolve, remove oxygen by three cycles of freezing and pumping, then heat to 50°C and react for 4 h. Quench the reaction in air; then dialyze the remaining product through a 3000 MW molecular weight dialysis bag for 48 h to remove monomers not involved in the polymerization, and obtain pure polymer grafted with SiO2 nanoparticles SiO2@PGMA (polymerization degree 100).

[0039] (3) Inducing self-assembly of the second block polymerization with SiO2@PGMA as a macro-RAFT agent:

[0040] The polymerization product obtained in step (2) was used as a macro-RAFT agent, and the product after dialysis, 2.1 g (containing PGMA 0.25 g), monomer HPMA 0.96 g, water-soluble initiator VA-044 0.52 mg, were added into a polymerization tube, and oxygen was removed by three cycles of freezing and pumping. The solid content was set to 15%, and the reaction was carried out at 50°C for 2 h. The product was a milky white homogeneous assembly solution (polymerization degree 400).

[0041] Example 3

[0042] (1) Open ring grafting of the first block monomer glycidyl methacrylate (GMA) with SiO2 nanoparticles:

[0043] SiO2 sol 10 g (containing SiO2 nanoparticles 30%), GMA monomer 5 g, deionized water 38 g were added into a round-bottom flask, and stirred at 85°C for 9 h to obtain a relatively clear homogeneous solution.

[0044] (2) RAFT polymerization of the open ring monomer grafted with SiO2 nanoparticles

[0045] The solution obtained in step (1) 10 g, RAFT agent 8.2 mg, water-soluble initiator azobisimidozolinium hydrochloride (VA-044) 1.02 mg were added into a polymerization tube, and the mixture was dissolved by stirring. Oxygen was removed by three cycles of freezing and pumping, and then the mixture was heated to 50°C for 4 h. The reaction was quenched in air; part of the reaction product was freeze-dried to remove water for nuclear magnetic resonance 1 H NMR detection; the remaining product was dialyzed through a 3000 MW molecular weight dialysis bag for 48 h to remove the monomers not involved in the polymerization, and a pure polymer grafted with SiO2 nanoparticles, SiO2@PGMA (polymerization degree 200) was obtained.

[0046] (3) Inducing self-assembly by polymerization of the second block using SiO2@PGMA as a macro-RAFT agent:

[0047] The polymerization product obtained in step (2) was used as a macro-RAFT agent, and the product after dialysis, 2.1 g (containing PGMA 0.25 g), monomer HPMA 0.96 g, water-soluble initiator VA-044 0.52 mg, were added into a polymerization tube, and oxygen was removed by three cycles of freezing and pumping. The solid content was set to 15%, and the reaction was carried out at 50°C for 2 h. The product was a milky white homogeneous assembly solution (polymerization degree 400).

[0048] In addition, by Figure 4a and 4bTEM analysis, we successfully obtained hybrid assemblies with different morphologies and different particle sizes, such as spheres, vesicles, etc. For example, when the PGMA polymerization degree was 50 and the second block polymer PHPMA polymerization degree was 200, vesicle assemblies with a particle size of about 150 nm were obtained (as shown in Figure 4a ), and when the second block polymer PHPMA polymerization degree was 400, spherical assemblies with a particle size of about 500 nm were obtained (as shown in Figure 4b ). In addition, the presence of SiO2 nanoparticles in the assembly morphologies of Figure 4a and 4b can also be clearly observed, further proving the successful preparation of hybrid filler.

[0049] Comparative Example 1

[0050] The silica / polymer composite hybrid nanofiller prepared in Example 1 and pure SiO2 nanoparticles were compared. In order to avoid the influence of water adsorbed by the hydroxyl groups on the surface of the SiO2 nanoparticles, the temperature was set to 100-800°C, and the heating rate was 10°C / min under a nitrogen atmosphere. It was found that, compared with pure SiO2 nanoparticles, the SiO2 / silica / polymer composite hybrid nanofiller grafted with polymer monomers showed greater weight loss, as shown in Figure 5 , proving that we successfully grafted SiO2 nanoparticles onto polymers.

Claims

1. A silica / polymer hybrid nanofiller, comprising nanosilica and polymer monomers, the polymer monomers comprising a first block polymer monomer and a second block polymer monomer; the first block polymer monomer is glycidyl methacrylate; the second block polymer monomer is hydroxypropyl methacrylate; the nanosilica is present in an amount of 10 wt%-50 wt% of the hybrid nanofiller; the first block polymer monomer forms a soluble block; the second block polymer monomer forms an insoluble block; the filler comprises the following structure: the nanosilica is grafted to the first polymer block, glycidyl methacrylate, at the ring-opening position of the epoxy group. 2.The hybrid nanofiller of claim 1, wherein the first block polymer monomer forms a polymer with a degree of polymerization of 50-400; and the second block polymer monomer forms a polymer with a degree of polymerization of 200-1000. 3.The hybrid nanofiller of claim 1, wherein the first block polymer monomer forms a polymer with a degree of polymerization of 50-200; and the second block polymer monomer forms a polymer with a degree of polymerization of 200-400. 4.The hybrid nanofiller of claim 1, wherein the filler is prepared by fixing nanosilica particles to the first block polymer monomer, then initiating polymerization of the first block polymer monomer, and then initiating polymerization of the second block polymer monomer, and driving in-situ self-assembly of the copolymer to obtain the product. 5.A method for preparing the hybrid nanofiller of any one of claims 1-4, comprising polymerization-induced self-assembly, and the specific steps are as follows: (1) fixing nanosilica particles to the first block polymer monomer; (2) initiating polymerization of the first block polymer monomer using a dithio carbonic ester RAFT agent to obtain a soluble block; and (3) initiating polymerization of the second insoluble block using the obtained soluble first block, and driving in-situ self-assembly of the copolymer to obtain the hybrid nanofiller. 6.The method of claim 5, wherein step (1) comprises: stirring and refluxing a nanosilica sol, the first block polymer monomer, and deionized water at 80-90ºC for 9-48 h, wherein the mass ratio of the nanosilica sol to the first block polymer monomer is (0.2-2) :

1. 7.The method of claim 5, wherein step (2) comprises: stirring and dissolving the solution obtained in step (1), a RAFT agent, and a water-soluble initiator in a container, removing oxygen by freezing and pumping, heating to 50-60ºC for 1-3 h, and quenching the reaction in air, wherein the mass ratio of the monomer, the RAFT agent, and the water-soluble initiator contained in the solution obtained in step (1) is (100-800) : (0.5-1) : 0.

1. wherein ​ ​ ​ ​ ​ 2. The hybrid nanofiller of claim 1, wherein, ​ 3. The hybrid nanofiller of claim 2, wherein, ​ 4. The hybrid nanofiller of claim 1, wherein, ​ ​ 6. The production method according to claim 5, wherein ​ 7. The preparation method according to claim 5, characterized in that, ​ 8. The method of claim 7, wherein, The mass ratio of monomer, RAFT agent and water-soluble initiator contained in the solution obtained in step (1) is (20-200):(0.5-1):0.

1.

9. The method of claim 5, wherein, The reagent obtained in step (2), the second block polymer monomer and the water-soluble initiator are added into a container, oxygen is removed by freezing and pumping, the solid content is set to 10-20%, and the reaction is carried out at 50-60°C for 2-4h to obtain the product.

10. The method according to any one of claims 7 to 9, characterized in that, The container is a polymerization tube.

11. Use of the hybrid nanofiller according to any one of claims 1-4, or of the hybrid nanofiller obtained by the preparation process according to any one of claims 6-10, in the preparation of rubber.

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