CN114620735A - Modified silicon dioxide and preparation method thereof - Google Patents

Modified silicon dioxide and preparation method thereof Download PDF

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CN114620735A
CN114620735A CN202011458461.5A CN202011458461A CN114620735A CN 114620735 A CN114620735 A CN 114620735A CN 202011458461 A CN202011458461 A CN 202011458461A CN 114620735 A CN114620735 A CN 114620735A
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silane coupling
coupling agent
acid
group
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王树东
杨勍
苏宏久
邹海良
任高远
高云峰
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Dalian Institute of Chemical Physics of CAS
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    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • C01B33/113Silicon oxides; Hydrates thereof
    • C01B33/12Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/146After-treatment of sols
    • C01B33/149Coating
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    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • C01P2004/01Particle morphology depicted by an image
    • C01P2004/03Particle morphology depicted by an image obtained by SEM
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    • C01PINDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00Particle morphology
    • C01P2004/51Particles with a specific particle size distribution
    • C01P2004/52Particles with a specific particle size distribution highly monodisperse size distribution
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    • C01P2004/00Particle morphology
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    • C01P2004/62Submicrometer sized, i.e. from 0.1-1 micrometer
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    • C01P2004/64Nanometer sized, i.e. from 1-100 nanometer
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    • C01P2006/40Electric properties

Abstract

The application discloses modified silicon dioxide and a preparation method thereof. The modified silica surface has hydrophilic groups and hydrophobic groups. The nano silicon oxide can have better monodispersity and stability by adjusting the type, the number and the proportion of hydrophilic groups and hydrophobic groups on the surface of the nano silicon oxide.

Description

Modified silicon dioxide and preparation method thereof
Technical Field
The application relates to modified silicon dioxide and a preparation method thereof, belonging to the field of material preparation.
Background
Based on the characteristics of no toxicity, five flavors, no pollution and recycling of silicon oxide materials, silicon oxide has been widely applied in the industries of glass, ceramics, monocrystalline silicon and the like. The nano-scale silicon oxide has the excellent characteristics of small particle size, large specific surface area, small size effect, quantum size effect, surface interface effect and the like which are unique to nano materials, and has wide application in the industries of biomedicine, electronics, catalyst carriers, buildings, coatings and the like. Especially, the property controllability of the silicon oxide surface can realize the fusion of the silicon oxide surface with materials such as organic, inorganic, high polymer and the like, and the performance and the application field of the nano silicon oxide particles are greatly expanded.
The surface properties of silica are generally silanol-containing groups, which are mainly classified into three types of isolated hydroxyl groups (Si-OH), twin hydroxyl groups (HO-Si-OH) and hydrogen-bonded silicon hydroxyl groups, because silicon hydroxyl groups are relatively strong in polarity and relatively high in hydrophilicity. Therefore, the regulation of the hydrophilicity and the hydrophobicity of the surface can be realized by a bonding mode so as to realize different performances. Domestic patent CN103013182 discloses a method for modifying aminopropyl, which is mainly to put powder silicon oxide into absolute ethyl alcohol solution, then to add hydrolyzed KH-550, to obtain bonded silicon dioxide powder through reaction, and the powder can improve the dispersibility and wettability of silicon oxide in polymer. CN 109337411A discloses a surface hydrophilic modification method of nano-silica, which mainly comprises the steps of adding long-chain acrylate and hydroxyl acrylate through an amino-containing silane micro-surfactant under the catalytic action of alkali, linking long carbon chains and a large number of hydroxyl groups on the surface of silica through the Michael addition reaction of double bonds and amino groups, endowing the silica with high stability by virtue of the long carbon chains, endowing the silica with hydrophilicity by virtue of the hydroxyl groups, realizing the stable dispersion of the silica, and preventing the agglomeration and precipitation of the silica. In the principle, CN109370265 introduces a long chain into the surface of silicon dioxide by adding acrylic acid long-chain ester or long-chain amino and performing ring-opening reaction of amino and epoxy to realize the regulation and control of lipophilicity. However, the above preparation process requires a large amount of alcohols as solvents, and the operation steps are complicated and the operation cost is high, wherein the hydrophilic group is mainly hydroxyl and is relatively single. Patent CN 106633078 discloses a sulfhydryl nanosilicon dioxide and polyether dual-modified organosilicon surfactant and a preparation method thereof, which mainly combines a sulfhydryl-alkene click chemistry method and a hydrosilylation method to carry out dual-modified organosilicon surfactant, and the modified nanosilicon oxide has good hydrophilic, oleophilic and compatible performances. However, the synthesis of the above preparation method not only needs a large amount of solvents (such as ethanol, methanol, tetrahydrofuran, and the like), but also needs to add catalysts such as sulfuric acid, trifluoromethanesulfonic acid, chloroplatinic acid, and the like in the reaction, and the reaction operation process is complicated.
The surface modification methods of the nano silicon dioxide are more, and mainly comprise water phase modification and surface modification under an anhydrous condition, most of the existing modifications are based on modification under the anhydrous condition, the cost of a solvent is higher, and the preparation process is more complex.
Disclosure of Invention
According to one aspect of the present application, a modified silica is provided, the nano silica can realize monodispersity and stability by adjusting the types, the number and the proportion of hydrophilic groups and hydrophobic groups on the surface of the nano silica.
A modified silica having a hydrophilic group and a hydrophobic group on the surface thereof.
Optionally, the hydrophilic group is selected from at least one of amino, thiol, and chlorine;
the hydrophobic group is at least one selected from methyl, ethyl, vinyl, phenyl, epoxy and acyloxy propyl.
Optionally, the molar ratio of the hydrophilic group to the hydrophobic group is 10-100: 10 to 100.
Optionally, the particle size D of the modified silica5010-150 nm; the concentration PDI value is 0.01-0.08.
Optionally, the particle size D of the modified silica50The lower limit is selected from 10nm, 15nm, 25nm, 35nm, 40nm, 50nm, 58nm, 60nm, 65nm, 70nm, 80nm, 83nm, 85nm, and 90 nm; the upper limit is selected from 15nm, 25nm, 35nm, 40nm, 50nm, 58nm, 60nm, 65nm, 70nm, 80nm, 83nm, 85nm, 90nm, and 100 nm.
Optionally, the particle size D of the modified silica50=45~95nm。
According to another aspect of the present application, there is provided a method for preparing the modified silica described in any one of the above, comprising the steps of:
(S1) reacting the solution containing the silane coupling agent in the presence of an acid catalyst to obtain a solution I;
the silane coupling agent comprises a silane coupling agent I containing hydrophilic groups and a silane coupling agent II containing hydrophobic groups;
(S2) adding the solution I into a silicon source to obtain a solution II;
(S3) aging the solution II to obtain the modified nano silicon dioxide.
Alternatively, in the step (S1), the solvent in the solution containing the silane coupling agent is a mixed solution of water and alcohol.
Alternatively, in the step (S1), the hydrophilic group-containing silane coupling agent I is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl γ -aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and 3-aminopropylethoxysilane;
the silane coupling agent II containing hydrophobic groups is at least one selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, beta- (3, 4) epoxycyclohexylethyltrimethoxysilane, 1, 2-bistrimethoxysilyl ethane, methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane.
Optionally, in the step (S1), the molar ratio of the hydrophilic group-containing silane coupling agent I to the hydrophobic group-containing silane coupling agent II is 10 to 100: 10 to 100 parts;
optionally, in the step (S1), the acidic catalyst is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, and citric acid.
Optionally, the acidic catalyst is 1 to 10 wt.% solution.
Optionally, the acidic catalyst is 2 to 5 wt.% solution.
Optionally, the alcohol is selected from at least one of methanol, ethanol, n-propanol, isopropanol, and ethylene glycol.
Alternatively, in the step (S1), the silane coupling agent, the acidic catalyst, water, and the alcohol are in a molar ratio of 1: 0.01-2: 10-700: 0.05 to 20;
wherein the silane coupling agent is SiO contained therein2Calculating the mole number of the active carbon; the acid catalyst is calculated by the mole number of the acid contained in the acid catalyst; water is calculated as moles of water on its own; the alcohol is calculated as moles of alcohol on its own.
Alternatively, in the step (S1), the silane coupling agent, the acidic catalyst, water, and the alcohol are present in a molar ratio of 1: 0.04-1: 100-500: 1 to 10.
Alternatively, in the step (S1), the silane coupling agent, the acidic catalyst, water, and the alcohol are present in a molar ratio of 1: 0.04-0.2: 120-300: 1 to 5.
Alternatively, in the step (S1), the reaction conditions include: the reaction temperature is 20-80 ℃, and the stirring time is 0.5-3 h.
Optionally, in the step (S1), the reaction temperature has a lower limit selected from 25 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ and an upper limit selected from 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃; the stirring time is 0.5-1.5 h.
Optionally, in step (S2), the silicon source is selected from alkaline silica sol.
Optionally, the alkaline silica sol has a PH of 7 to 11, a silica content of 5 to 40 wt.%, and a dimension range of 10 to 150 nm; the concentration PDI value is 0.01-0.08;
optionally, the nanosilica sol has a lower PH limit selected from 7, 8, 9, 9.5, 10, 10.8; the upper limit is selected from 8, 9, 9.5, 10, 10.8, 11.
Optionally, the pH of the nano silica sol is 9-10.
Optionally, the lower limit of the size of the silica contained in the alkaline silica sol is selected from 10nm, 15nm, 25nm, 35nm, 40nm, 50nm, 58nm, 60nm, 65nm, 70nm, 80nm, 83nm, 85nm, 90 nm; the upper limit is selected from 15nm, 25nm, 35nm, 40nm, 50nm, 58nm, 60nm, 65nm, 70nm, 80nm, 83nm, 85nm, 90nm, and 100 nm.
Optionally, the alkaline silica sol has a PH of 9 to 10.8, a silica content of 5 to 13 wt.%, and a dimension of 45 to 95 nm.
Optionally, in the step (S2), the molar ratio of the silicon source to the solution I is 1: 0.0005 to 0.1;
wherein the silicon source is SiO contained in the silicon source2Calculating; solution I with SiO contained therein2And (4) calculating.
Optionally, in the step (S2), the molar ratio of the silicon source to the solution I is 1: 0.005-0.05.
Optionally, in the step (S2), the molar ratio of the silicon source to the solution I is 1: 0.01 to 0.03.
Optionally, in step (S2), the adding conditions of the solution I to the silicon source include: adding the mixture at the temperature of 20-100 ℃; the time for adding is 0.5-6 h.
Optionally, the lower limit of the temperature condition for the addition is selected from 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 85 ℃, 90 ℃; the upper limit is selected from 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C, 80 deg.C, 85 deg.C, 90 deg.C, and 100 deg.C.
Optionally, the upper time limit of the addition is selected from 1.5h, 3h, 3.5h, 6 h; the lower limit is selected from 0.5h, 1.5h, 3h and 3.5 h.
Alternatively, in the step (S3), the aging conditions include: the aging temperature is 70-100 ℃; the aging time is 1-6 h.
Optionally, the upper aging temperature limit is selected from the group consisting of 70 deg.C, 80 deg.C, 90 deg.C, 96 deg.C, 98 deg.C at a lower limit and 80 deg.C, 90 deg.C, 96 deg.C, 98 deg.C at an upper limit and 100 deg.C at a higher limit.
Optionally, the aging time is 3-5 h.
The beneficial effects that this application can produce include:
(1) the modified silicon dioxide provided by the application has the hydrophilic groups and the hydrophobic groups on the surface, is simple in structure and easy to regulate, and can realize monodispersion of particles and easily improve the surface activity of nanoparticles through regulating the types and the number of the hydrophilic groups and the hydrophobic groups.
(2) According to the preparation method of the modified silicon dioxide, the silicon dioxide is modified by the silane coupling agent I containing the hydrophilic group and the silane coupling agent II containing the hydrophobic group, so that the surface of the modified silicon dioxide has the hydrophilic group and the hydrophobic group, and the monodispersity and the stability of the modified silicon dioxide are realized.
(3) According to the preparation method of the modified silicon dioxide, a segmented control method is adopted, the reaction time and temperature of the silane coupling agent under the action of the acid catalyst are controlled, and the phenomenon that the efficiency of bonding modification is reduced due to self-polymerization of a hydrolysate is avoided; and a large amount of organic solvent and any surfactant are not used in the preparation process, and a complicated post-treatment process is not needed, so that the cost is reduced.
(4) The preparation method of the modified silicon dioxide is simple in process operation and easy for industrial amplification.
Drawings
FIG. 1 is a graph showing a particle size distribution of the modified silica obtained in example 1.
FIG. 2 is a particle size distribution test chart of the modified silica obtained in example 2.
FIG. 3 is a particle size distribution test chart of the modified silica obtained in example 3.
FIG. 4 is a particle size distribution test chart of the modified silica obtained in example 4.
FIG. 5 is a SEM representation of the modified silica obtained in examples 1 and 2 and base sample Q, where A corresponds to base sample Q, B corresponds to the modified silica obtained in example 1 (sample # 1), and C corresponds to the modified silica obtained in example 2 (sample # 2).
Fig. 6 is a particle size distribution detection chart of the modified silica obtained in comparative example 1.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
The particle size data in the embodiment of the application are results obtained by adopting Malvern laser particle size analysis and electronic scanning electron microscope detection.
The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.
Among them, organosilane reagents, alcohol solvents, sodium hydroxide, hydrochloric acid, nitric acid and other raw materials are purchased from Chinese medicines.
In order to overcome the above-mentioned drawbacks and disadvantages of the prior art, according to an embodiment of the present application, there is provided a modified silica having a simple structure of hydrophilic groups and hydrophobic groups, the surface of which can achieve monodispersity and stability thereof by the kind, number, and ratio of the hydrophilic and hydrophobic groups, and a method for preparing the same; unlike the complex structures disclosed in the patents mentioned in the background, the hydrophilic groups of the modified silica disclosed in the present application mainly include amino groups, mercapto groups, chlorine groups, etc., and the hydrophobic groups mainly include methyl groups, ethyl groups, vinyl groups, phenyl groups, epoxy groups, etc. Wherein the ratio of the hydrophilic group to the hydrophobic group can be regulated within a range of 100: 10-10: 100, respectively; the hydrophilic and hydrophobic performance regulation can be realized through the regulation of the hydrophilic-hydrophobic groups, so that the stability and monodispersity of the nano silicon oxide can be improved, the activity of the nano silicon oxide in hydrophilic group catalysis can be improved, and the efficiency is improved.
According to a specific embodiment of the present application, the present application further provides a preparation method of the modified silica, which is simple to operate and has a wide application range. Firstly, the silane coupling agent containing hydrophilic groups and hydrophobic groups is hydrolyzed under the catalysis of acidic conditions, and condensation aggregation between hydrolysis products is avoided by controlling the reaction time and the temperature. And mixing the hydrolysate with the nano-silica sol, and performing bonding condensation reaction on the hydrolysate and the hydroxyl of the silica only on the surface of the nano-silica sol to finally obtain the surface-modified nano-silica particles containing the hydrophilic groups and the hydrophobic groups in a certain ratio. The modification process is finely controlled in the aspects of mass transfer and heat transfer, so that the whole operation process is simple, the post-treatment is convenient, and the production efficiency is high.
The object of the present application is achieved by the following method:
step (S1): firstly, mixing a certain proportion of a silane coupling agent I containing a hydrophilic group and a silane coupling agent II containing a hydrophobic group to obtain a silane coupling agent mixture, then adding an acid catalyst, deionized water and alcohol, mixing, and fully stirring to prepare a solution I;
step (S2): then slowly adding the solution I in the step (S1) into alkaline silica sol to prepare a solution II;
step (S3): finally, aging the solution II obtained in the step (S2) for a certain time to obtain the modified silicon dioxide;
in order to better achieve the object of the present application, the silane coupling agent I containing hydrophilic groups described in the step (S1) is selected from one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl γ -aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane;
the silane coupling reagent containing hydrophobic groups is selected from one or more of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, beta- (3, 4) epoxycyclohexylethyltrimethoxysilane, 1, 2-bis-trimethoxysilylethane, methacryloxypropyltrimethoxysilane and vinyl trimethoxysilane;
the molar ratio of the hydrophilic group-containing silane coupling agent I to the hydrophobic group-containing silane coupling agent in the step (S1) is 100: 10-10: 100, respectively;
the acidic catalyst in the step (S1) is one or more selected from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid and citric acid;
the acid catalyst in the step (S1) is an aqueous solution with a mass concentration of 1% to 10%, preferably an aqueous solution with a mass concentration of 2% to 5%;
optionally, the solution IpH has a value of 1-4.0, and a further preferable pH value of 2-3.5;
in the step (S1), the alcohol is one or more selected from methanol, ethanol, n-propanol, isopropanol and ethylene glycol;
the silane coupling agent mixture (in SiO) in the step (S1)2Calculated), the molar ratio of the acidic catalyst, the deionized water and the alcohol is 1: (0.01-2): (10-700): (0.05-20);
in the step (S1), the stirring time is 0.5-3 h, and the reaction temperature is 20-80 ℃;
the alkaline silica sol in the step (S2) is selected from commercially available nano silica sols; the pH range is 7-11; the size range of the contained silicon dioxide particles is 10 nm-150 nm; the silica sol concentration (calculated by the mass of the silicon oxide) is 5-40 wt.%;
optionally, the pH of the alkaline silica sol is 9-10.8;
optionally, the alkaline silica sol comprises silica particles in the size range of: 10nm to 100 nm;
optionally, the alkaline silica sol contains silica particles with a size of 10nm, 15nm, 25nm, 35nm, 40nm, 50nm, 58nm, 60nm, 65nm, 70nm, 80nm, 83nm, 85nm, 90nm, 100 nm;
basic silica sol (in SiO) in the step (S2)2Calculated) with the solution I (in SiO)2In terms of) is 1: (0.0005 to 0.1);
the time for adding the alkaline silica sol into the solution I in the step (S2) is 0.5-6 hours, preferably 1-3 hours;
the reaction temperature in the step (S2) is 20-100 ℃;
the aging temperature of the solution II in the step (S3) is 70-100 ℃; the aging time is 1-6 h.
Example 1: preparation of modified silica
(S1) separately, 5g of methyltrimethoxysilane, 1.6g of aminopropyltriethoxysilane, 5g of nitric acid with a concentration of 2.5 wt.%, 220g of deionized water and 2g of methanol were added to a 500ml beaker and stirred at 50 ℃ for 60min to form a clear, homogeneous solution I.
(S2) selecting the particle size D50Placing 2500g of nano silica sol (marked as a raw sample Q) with the concentration of 6 wt.% into a flask and heating the flask at 47nm and the pH of 9.5, controlling the temperature to be 80 ℃, and after the temperature is stabilized, uniformly adding the solution I into the silica sol for 3.5h to form a solution II;
(S3) continuing to heat the solution II to 98 ℃, and continuing to age for 5h to obtain the modified silicon oxide nano particles.
The resulting sample was designated # 1 and the product was analyzed for particle size using a malvern laser particle sizer (Marlven NanoZS90 test instrument) having an average particle size of 47.84nm and a concentration PDI value of 0.075, the results of which are shown in figure 1.
Example 2: preparation of modified silica
(S1) 8.125g of 3-aminopropyltrimethoxysilane, 1g of methyltrimethoxysilane, 50g of oxalic acid having a concentration of 1.58% by weight, 125g of deionized water and 8g of ethanol were added to a 250ml beaker and stirred at 30 ℃ for 60min to form solution I.
(S2) selecting the particle size D50Placing 2500g of nano silica sol with the concentration of 6 wt.% into a flask and heating, wherein the pH value is 47nm and 9.5, the heating temperature is controlled to be 80 ℃, and after the temperature is stabilized, uniformly adding the solution I into the silica sol for 3.5h to form a solution II;
(S3) continuing to heat the solution II to 98 ℃, and continuing to age for 5h to obtain the modified silicon oxide nano particles.
The sample obtained is designated # 2 and the product obtained is analyzed for particle size using a malvern laser particle sizer, having an average particle size of 47.21nm and a concentration PDI value of 0.022, the results of which are shown in figure 2.
Example 3: preparation of modified silica
(S1) 10.5g of 3-mercaptopropyltrimethoxysilane, 3.2g of ethyltrimethoxysilane, 15g of acetic acid with a concentration of 2 wt.%, 350g of deionized water and 3.3g of methanol were added to a 500ml beaker and stirred at 40 ℃ for 30min to form solution I.
(S2) subsequently adding 2100g, D50Heating the nano silica sol with pH of 9 and 13 wt.% to 85 ℃ to stabilize the temperature, then adding the solution I into the silica sol for 3h to form a solution II.
(S3) continuing to heat the solution II to 90 ℃, and continuing to age for 5h to obtain the modified silicon oxide nano particles.
The product obtained is designated as number 3#, and the particle size was analyzed by a Malvern laser particle sizer, the average particle size was 89.43nm, the concentration PDI value was 0.016, and the results are shown in FIG. 3.
Example 4: preparation of modified silica
(S1) 3.5g of methyltriethoxysilane, 1.73g of 3-aminopropylethoxysilane, 5.2g of nitric acid having a concentration of 2.1 wt.%, 27g of deionized water and 1.5g of ethanol were added to a 50ml beaker and stirred at 25 ℃ for 50min to form solution I.
(S2) 2800g of a powder having a particle diameter D50At 70nm, pH 10, 5 wt.% of the nanosilica sol was heated to 90 ℃, solution I was metered into the silica sol after the temperature had stabilized over 1.5h to form solution II.
(S3) finally, solution II is heated to 96 ℃ and aged for 3 h.
The sample obtained is labeled 4#, the particle size of the product obtained is analyzed by a malvern laser particle sizer, the average particle size is 71.22nm, the concentration PDI value is 0.02, and the results are shown in fig. 4.
Example 5: original sample Q and sample 1# to 2# morphology characterization
And respectively carrying out morphology test on the original sample Q and the samples 1# to 2# by using a JEOL JSM-7800F Scanning Electron Microscope (SEM).
The results of the tests are shown in FIG. 5 (where A corresponds to original sample Q, B corresponds to sample # 1, and C corresponds to sample # 2), in which original samples Q and # 1-2 # had particle sizes of 46.7nm, 47.8nm, and 48.0nm, respectively.
Comparative example 1: preparation of modified silica
The preparation method of comparative example 1 is different from that of example 1 in that aminopropyltriethoxysilane having a hydrophilic group in the step (S1) in example 1 is removed, and the other steps are the same, and the obtained sample is labeled as # 6. The resulting product was analyzed for particle size using a malvern laser particle sizer, having an average particle size of 48.80nm and a concentration PDI value of 0.029, and the results are shown in fig. 6.
Example 6: measurement of zeta potentials of base sample Q, sample # 1 and sample # 6
The samples numbered 1#, 6# and Q were subjected to different pH adjustments (selected to have pH values of 3, 6 and 10, respectively), and the change in zeta potential was measured with a pH adjusting reagent of 2 wt.% nitric acid, with the following results:
Figure BDA0002830285240000101
as can be seen from the above-mentioned examples 1 and 2(Marlven NanoZS90 test results) and example 5(SEM characterization results), the case of hydrophilic groups and hydrophobic groups bonding on the surface of the nano-silica did not change the particle size of the nano-silica, but changed the surface properties of the nano-silica;
as can be seen from the above examples 2, 3 and 4, the kind of the acidic catalyst has a relatively small influence on the hydrolysis, and can complete the hydrophilic and hydrophobic surface property modification process for particles with representative dimensions of 47.7nm, 70nm, 90nm and the like;
with respect to the influence of the hydrophilic group and the hydrophobic group on the surface properties of the nanoparticles, as can be seen from the measurement of zeta potentials of example 1, comparative example 1 and the base sample Q, in comparative example 1, the sample 6# modified only with the hydrophobic group is rapidly delaminated under an acidic condition (e.g., pH 3); although no delamination occurred in the original sample Q, the sol formed a gel after 24 hours at pH 6, and could not be used further. While sample No. 1 subjected to surface modification by the hydrophobic group and the hydrophilic group in example 1 shows good particle stability under acidic, neutral and alkaline conditions, and no phenomena such as turbidity occur, which illustrates that the stability control of the nano silica particles can be realized by the control of the hydrophilic group and the hydrophobic group.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (10)

1. A modified silica having a hydrophilic group and a hydrophobic group on the surface thereof.
2. The modified silica according to claim 1, wherein the hydrophilic group is selected from at least one of amino group, mercapto group, chlorine;
the hydrophobic group is at least one selected from methyl, ethyl, vinyl, phenyl, epoxy and acyloxy propyl,
preferably, the molar ratio of the hydrophilic group to the hydrophobic group is 10-100: 10 to 100 parts;
preferably, the particle diameter D of the modified silica5010-150 nm; the concentration PDI value is 0.01-0.08.
3. A process for the preparation of a modified silica according to any one of claims 1 to 2, characterized in that it comprises the following steps:
(S1) reacting the solution containing the silane coupling agent in the presence of an acid catalyst to obtain a solution I;
the silane coupling agent comprises a silane coupling agent I containing hydrophilic groups and a silane coupling agent II containing hydrophobic groups;
(S2) adding the solution I to a silicon source to obtain a solution II;
(S3) aging the solution II to obtain the modified nano silicon dioxide.
4. The production method according to claim 3, wherein in the step (S1), the solvent in the solution containing the silane coupling agent is a mixed solution of water and alcohol;
preferably, in the step (S1), the hydrophilic group-containing silane coupling agent I is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl γ -aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and 3-aminopropylethoxysilane;
the silane coupling agent II containing hydrophobic groups is at least one selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, beta- (3, 4) epoxycyclohexylethyltrimethoxysilane, 1, 2-bistrimethoxysilyl ethane, methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane;
preferably, in the step (S1), the molar ratio of the hydrophilic group-containing silane coupling agent I to the hydrophobic group-containing silane coupling agent II is 10 to 100: 10 to 100 parts by weight;
preferably, in the step (S1), the acidic catalyst is at least one selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, and citric acid.
5. The method according to claim 4, wherein the acidic catalyst is a 1 to 10 wt.% solution.
6. The method according to claim 4, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol and ethylene glycol.
7. The production method according to claim 3, wherein in the step (S1), the silane coupling agent, the acidic catalyst, water, and the alcohol are present in a molar ratio of 1: 0.01-2: 10-700: 0.05 to 20;
wherein the silane coupling agent is SiO contained therein2Calculating the mole number of the active carbon; the acid catalyst is calculated by the mole number of the acid contained in the acid catalyst; water is calculated as moles of water on its own; the alcohol is calculated as moles of alcohol on its own.
8. The method according to claim 3, wherein in the step (S1), the reaction conditions include: the reaction temperature is 20-80 ℃, and the stirring time is 0.5-3 h.
9. The method according to claim 3, wherein in step (S2), the silicon source is selected from the group consisting of an alkaline silica sol;
preferably, the pH of the alkaline silica sol is 7-11, the content of silica is 5-40 wt.%, and the dimension range is 10-150 nm;
preferably, in the step (S2), the molar ratio of the silicon source to the solution I is 1: 0.0005 to 0.1;
wherein the silicon source is SiO contained in the silicon source2Calculating; solution I with SiO contained therein2Calculating;
preferably, in step (S2), the adding conditions of the solution I to the silicon source include: adding the mixture at the temperature of 20-100 ℃; the time for adding is 0.5-6 h.
10. The method according to claim 3, wherein in the step (S3), the aging conditions include: the aging temperature is 70-100 ℃; the aging time is 1-6 h.
CN202011458461.5A 2020-12-10 2020-12-10 Modified silicon dioxide and preparation method thereof Pending CN114620735A (en)

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