TWI404677B - Fabrication of amino-modified silica nanoparticles - Google Patents

Abstract

The present invention expresses that the amino-modified silica nanoparticles (denoted by ASNPs) with particle's diameter less than 60 nm were successful fabricated, using the alkoxyl silane, by two separate steps of condensation reaction and the adjusted parameters of the reaction conditions. Two separate steps included that the silica suspension was centrifuged in the first step to obtain the precipitate of raw silica nanoparticles (denoted by RSNPs). Then, APTMS was added to re-disperse RSNPs solution in the second step. A drastic aggregation was occurred upon treatment of the silica suspension without centrifugation with APTMS. Due to the equilibrium of static electricity of stable silica suspension was rapidly broken down while APTMS was added. Therefore, the smaller particle size of ASNPs was obtained in two separate steps to compare with the one-step process. The amino-modified silica nanoparticles (ASNPs) have wide commercial applications in many fields, including composite materials, catalysts and biochemistry.

Description

Method for preparing amine-based modified vermiculite nano particles

The invention relates to a method for synthesizing nano materials, in particular to a method for synthesizing raw silica nanoparticles (RSNPs).

At present, the conventional synthetic method uses a vermiculite nanoparticle or a sol-gel one-step method to carry out the amine-based modification of the vermiculite nanoparticle surface, and the commercially available vermiculite nanoparticle is mostly subjected to acidic hydrolysis. It is obtained by sodium citrate, but the particle size is small but the decyloxy group and oxyalkyl group possessed on the surface of the particle are better than St. There are few berite stones, and the surface amine group is not easy to modify. The one-step modification method of the sol-gel method has two kinds of co-condensation and grafting, and the meteorite particles have an amine functional group.

Referring to the chemical formula 1, the co-condensation method is to simultaneously add all organic decane (Tetraethoxysilane (TEOS)) and γ-aminopropyltrimethoxydecane (APTMS) to produce copolymerization; however, The amine functional groups are not necessarily distributed on the surface of the vermiculite particles.

Referring to the chemical formula 2, the grafting method firstly produces a suspension of vermiculite nanoparticles, and then adds a cerium coupling agent to graft onto the surface of the vermiculite nanoparticles. However, the formation of the vermiculite nanoparticle suspension exhibits a stable dispersion state, meaning that the vermiculite nanoparticles remain electrostatically charged with other components in the solution (solvent, aqueous ion and unreacted helium oxide monomer). Balance, at this time, the addition of ruthenium coupler will cause severe instability, resulting in severe agglomeration, especially the smaller the gangue nanoparticle is.

At present, synthetic methods for the use of amino-functionalized silica nanoparticles (ASNPs) have the following disadvantages:

1. Commercially available vermiculite nanoparticles are mostly obtained by acid hydrolysis of sodium citrate. The particle size is small but the methoxyl and oxyalkyl groups on the surface of the particles are better than St. There is less ber gangue, and subsequent amine-based modification of vermiculite nanoparticles is not easy.

2. Synthesized by sol-gel method, the addition of ruthenium coupling agent will destroy the electrostatic equilibrium of the suspension and cause serious agglomeration, so it is impossible to obtain amine-modified vermiculite nanoparticles with particle size less than 50 nm.

3. Previous literature and technical methods can only synthesize larger-sized amine-modified vermiculite nanoparticles, and 60nm is produced by co-condensation according to literature search: Ceram. Int. 35(2009) 1883-1888. The amine-modified vermiculite nanoparticle and J. Colloid Interface Sci. 304 (2006) 119-124. The 150 nm amine-modified vermiculite nanoparticle is produced by grafting, and there is currently no better The method produces smaller diameter micro-amine modified vermiculite nanoparticles for use in various fields.

In view of the current preparation method for the surface amine modification of vermiculite nanoparticles, it is impossible to obtain an amine-modified vermiculite nanoparticle having a particle diameter of less than 60 nm. The invention produces an amine-based modified vermiculite nanoparticle having a particle diameter of less than 60 nm by various efforts by improving the process and adjusting various parameters in the reaction.

The technical means used in the present invention is to provide a method for preparing an amine-based modified vermiculite nanoparticle, comprising: providing an alkoxysilane solution, an aqueous ammonia solution, a deionized water and a methanol solvent by a sol-gel method. a step of condensation reaction to obtain a solution of vermiculite nanoparticle, and centrifuging the vermiculite nanoparticle solution to precipitate a precipitate of vermiculite nanoparticle; dispersing the precipitate of vermiculite nanoparticle in anhydrous ethanol to form vermiculite The nanoparticle dispersion liquid is provided by adding γ-aminopropyltrimethoxydecane, ammonia water and deionized water to the dispersion of the vermiculite nanoparticle, and performing the second step condensation reaction by a sol-gel method to obtain an amine group modification. The rare earth nanoparticle solution is obtained by centrifuging the amine-modified vermiculite nanoparticle solution to obtain an amine-modified vermiculite nanoparticle.

Preferably, the method for preparing the amine-modified vermiculite nanoparticle, wherein the reaction condition of the first step condensation reaction is: the alkoxysilane solution is provided by tetraethoxynonane and the molar concentration thereof 0.33M, ammonia molar concentration of 1.2 M, deionized water molar concentration of 8 M and methanol solvent molar concentration of 13.6 M, reacted at 60 ° C.

Preferably, the method for preparing the amino-modified vermiculite nano-particles, wherein the reaction condition of the first step condensation reaction is added to sodium dodecyl sulfate (SDS) 3.5×10 ^-5 M.

Preferably, the method for preparing the amine-modified vermiculite nanoparticle comprises the reaction condition of the first step condensation reaction, the alkoxysilane solution is provided by tetraethoxynonane and the molar concentration thereof 0.29M, added triethoxyethyl silane (TEES) 0.042 M, ammonia molar concentration 1.2 M, deionized water molar concentration 8 M and methanol solvent molar concentration 13.6 M, at 60 ° C reaction.

Preferably, the method for preparing the amine-modified vermiculite nanoparticle comprises the reaction condition of the second step condensation reaction: γ-aminopropyltrimethoxydecane molar concentration 0.02 M, ammonia molar concentration 0.02 M, deionized water molar concentration of 0.8 M and ethanol molar concentration of 16.7 M, reacted under heating and reflux.

Preferably, the method for preparing the amino-modified vermiculite nano-particles, wherein the amine-modified vermiculite nano-particles are separated by water and ethanol and washed and purified.

Preferably, the method for preparing the amine-modified vermiculite nanoparticle is characterized in that the surface of the amine-modified vermiculite nanoparticle is measured by a Fourier Transform Infrared Spectrometer (FT-IR) Determination of the functional structure after grafting of the amino decane coupling agent.

The preparation method of the amine-based modified vermiculite nano particles provided by the invention provides the following advantages: after a plurality of experiments, a monodisperse vermiculite with a particle diameter of 41 nm is prepared through process adjustment of the process. Nanoparticles. The knowledge obtained from the present invention will be helpful and convenient in the preparation of vermiculite nanoparticles and amine-based modified vermiculite nanoparticles, monodisperse amine-based modified vermiculite nanoparticles intended to be Find more practical uses for specific applications such as composites, catalysts and biology.

In order to understand the technical features and practical effects of the present invention in detail, and in accordance with the contents of the specification, the following embodiments are further described in detail as follows:

[Example 1]

The invention provides a method for preparing an amine-based modified vermiculite nanoparticle comprising the following steps:

Please refer to Chemical Formula 3: Preparing the Meteorite Nanoparticle Precipitate

Providing an alkoxy decane solution, an aqueous ammonia solution, a deionized water and a methanol solvent to carry out a first step condensation reaction by a sol-gel method to obtain a vermiculite nanoparticle solution, and centrifuging the vermiculite nanoparticle solution to remove vermiculite Nanoparticle precipitate;

Please refer to Chemical Formula 4: Subsequent Preparation of Amine-Modified Vermiculite Nanoparticles

Dispersing the vermiculite nanoparticle precipitate in anhydrous ethanol to form a dispersion of the vermiculite nanoparticle, providing γ-aminopropyltrimethoxydecane, ammonia water and deionized water to the dispersion of the vermiculite nanoparticle. The second step condensation reaction is carried out by a sol-gel method to obtain an amine-modified vermiculite nanoparticle solution, and the amine-modified vermiculite nanoparticle solution is centrifuged to obtain an amine-modified vermiculite nanoparticle. .

The following examples are for the purpose of specifically illustrating the technical means of the present invention. By the above-mentioned manufacturing process and adjusting various parameter conditions in the reaction, an amine-based modified vermiculite nanoparticle having a particle diameter of less than 60 nm is produced, which is described in detail as follows:

[Example 2]

The flask was placed with 100 ml of methanol (MeOH), 1 ml of deionized water (H ₂ O) and 28 wt% of aqueous ammonia (NH ₄ OH) 10 ml, and the mixture was stirred and mixed. Then 8.32 g of tetraethoxy decane was added to the above solution, and the final composition of the solution was 0.33 M tetraethoxy decane, 1.2 M ammonia, 8 M deionized water and 13.6 M methanol. The reaction was carried out at 60 ° C for 3 hours. Finally, a blue-white suspension containing vermiculite particles was obtained. Next, the centrifuge was centrifuged at 13,000 rpm for 15 minutes, and the product vermiculite nanoparticles were separated from the vermiculite suspension and precipitated in the lower layer.

The precipitate was redispersed in absolute ethanol to form a dispersion of vermiculite nanoparticles, followed by an amine group modification of the surface of the vermiculite below. a mixed solution comprising 1.6×10 ⁻³ mol γ-aminopropyltrimethoxydecane, 28 wt% ammonia water 0.1 ml and deionized water 1 ml, added to the above-mentioned vermiculite nanoparticle dispersion in vigorous stirring, The surface of the vermiculite nanoparticles is subjected to amine functionalization. The liquid concentrations were 0.02 M gamma-aminopropyltrimethoxydecane, 0.02 M ammonia, 0.8 M deionized water, and 16.7 M ethanol, respectively. Then, the mixture was reacted under heating and reflux for 3 hours to increase the covalent bonding between the γ-aminopropyltrimethoxydecane and the vermiculite nanoparticles, and then centrifuged to obtain an amine-modified vermiculite nanoparticle precipitate. . After washing with water and ethanol, the separation/washing process was repeated 6 times, and finally the amine-modified vermiculite nanoparticles were dried in a vacuum oven at 50 ° C for 24 hours.

RESULTS: As shown in Fig. 1 and Fig. 2, in the chemical structure, the vermiculite nanoparticles were modified with γ-aminopropyltrimethoxydecane and then scanned using a scanning electron microscope (SEM). Jeol, JSM-6700F (Tokyo, Japan) was subjected to particle surface scanning detection to obtain a particle diameter of 41 nm of vermiculite nanoparticles and a particle diameter of 52 nm of an amine-modified vermiculite nanoparticle.

[Example 3]

100 ml of methanol was placed in the flask, and 1 ml of deionized water, 0.0012 g of sodium lauryl sulfate and 10 ml of 28 wt% aqueous ammonia were added, and the mixture was uniformly stirred. Then 8.32 g of tetraethoxy decane was added to the above solution. The final composition of the solution was 0.33 M tetraethoxy decane, 1.2 M ammonia, 8 M deionized water, 3.5 x 10 ^-5 M sodium lauryl sulfate and 13.6 M methanol. The reaction was carried out at 60 ° C for 3 hours, and the subsequent steps were the same as in Example 2.

RESULTS: As shown in Fig. 3 and Fig. 4, in the chemical structure, the vermiculite nanoparticles were modified by γ-aminopropyltrimethoxydecane and scanned by scanning electron microscopy to obtain the meteorite nanoparticle. The particle size of the particles was 26 nm and the particle size of the amine-modified vermiculite nanoparticles was 28 nm.

[Embodiment 4]

100 ml of methanol was placed in the flask, and 1 ml of deionized water and 10 ml of 28 wt% aqueous ammonia were added, and the mixture was stirred and mixed. Then, 7.28 g of tetraethoxydecane and 0.96 g of triethoxyethyl decane were added to the above solution. The final composition of the solution was 0.29 M tetraethoxy decane, 0.042 M triethoxyethyl decane, 1.2 M ammonia. , 8 M deionized water and 13.6 M methanol. The reaction was carried out at 60 ° C for 3 hours, and the subsequent steps were the same as in Example 2.

RESULTS: As shown in Fig. 5 and Fig. 6, in the chemical structure, the vermiculite nanoparticles were modified by γ-aminopropyltrimethoxydecane and scanned by scanning electron microscopy to obtain the meteorite nanoparticle. The particle diameter of the particles was 29 nm and the particle size of the amine-modified vermiculite nanoparticles was 33 nm.

[Embodiment 5]

In this embodiment, the Fourier transform infrared spectroscopy is used to determine the condition of the grafting of the amino decane onto the surface of the gangue nanoparticle, and the measurement of the surface of the vermiculite on the functional structure of the amino decane coupling agent after grafting is carried out by using a Fourier transform infrared spectrometer. The above-mentioned synthesized amine-based modified vermiculite nanoparticles were subjected to Fourier transform infrared spectroscopy, and a new weak absorption peak appeared at 2925 and 2853 cm ^-1 in the spectral curve, which was -CH ₂ . Symmetrical and symmetric stretching vibration, which is produced by the amine propyl group in the γ-aminopropyltrimethoxydecane coupling agent, indicating that γ-aminopropyltrimethoxydecane is hydrolyzed and grafted to the vermiculite On the surface of the microparticles, it was confirmed that the aminodecane can be grafted onto the surface of the vermiculite nanoparticles.

in conclusion:

Through the parameter adjustment in the above research report, after several experiments, tetraethoxy decane was hydrolyzed and condensed in a methanol-solvent reaction system with a high concentration of ammonia as a catalyst, and the particle size was 41. The meteorite nanoparticle of nm. Further, the amine-modified vermiculite nanoparticles were prepared from the vermiculite nanoparticles to obtain an amine-modified vermiculite nanoparticle monodisperse particle having a final yield of 77% and a particle diameter of 55 nm. Through the FT-IR spectroscopy study, the -CH ₂ absorption peak at 2925 and 2853 cm ^-1 confirmed that the amino decane could be grafted onto the surface of the vermiculite nanoparticles. The present invention is useful and convenient in the preparation of vermiculite nanoparticles and amine-based modified vermiculite nanoparticles, and in monodisperse amine-based modified vermiculite nanoparticles, in certain applications, such as Find more practical uses for composites, catalysts and biology.

Fig. 1 is an electron micrograph showing the surface detection of a 41 nm vermiculite nanoparticle by a scanning electron microscope in Example 2.

2 is an electron micrograph of Example 2 for surface detection of a 52 nm amino group-modified vermiculite nanoparticle by a scanning electron microscope.

Fig. 3 is an electron micrograph showing the surface detection of a 26 nm vermiculite nanoparticle by a scanning electron microscope in Example 3.

4 is an electron micrograph of Example 3 for surface detection of a 28 nm-ammine modified vermiculite nanoparticle by a scanning electron microscope.

Fig. 5 is an electron micrograph showing the surface detection of a 29 nm vermiculite nanoparticle by a scanning electron microscope in Example 4.

Fig. 6 is an electron micrograph showing the surface detection of an ammine-modified vermiculite nanoparticle having a particle diameter of 33 nm by a scanning electron microscope in Example 4.

Claims (6)

The invention relates to a method for preparing an amine-based modified vermiculite nanoparticle, comprising: providing an alkoxysilane solution, an aqueous ammonia solution, a deionized water and a methanol solvent to carry out a condensation reaction by a sol-gel method to obtain a vermiculite nanoparticle solution; Dissolving the vermiculite nanoparticle solution to remove the vermiculite nanoparticle precipitate; dispersing the vermiculite nanoparticle precipitate in anhydrous ethanol to form a vermiculite nanoparticle dispersion; providing γ-aminopropyl Trimethoxy decane, ammonia water and deionized water are added to the gangue nanoparticle dispersion, and a condensation reaction is carried out by a sol-gel method to obtain an amine-modified vermiculite nanoparticle solution; the amine group is modified 矽The stone nanoparticle solution is centrifuged to obtain an amine-modified vermiculite nanoparticle. The method of claim 1, wherein the reaction condition of the condensation reaction is such that the alkoxysilane solution is provided by tetraethoxynonane and has a molar concentration of 0.33 M and an ammonia molar concentration of 1.2 M. The deionized water has a molar concentration of 8 M and a methanol molar concentration of 13.6 M, and is reacted at 60 ° C. The method of claim 2, wherein the reaction conditions of the condensation reaction are added to sodium lauryl sulfate 3.5 × 10 ^-5 M. The method of claim 1, wherein the reaction condition of the condensation reaction is such that the alkoxy decane solution is provided by tetraethoxy decane and has a molar concentration of 0.29 M, and is added to triethoxy B. The reaction was carried out at 60 ° C with a decane 0.042 M, an ammonia molar concentration of 1.2 M, a deionized water molar concentration of 8 M and a methanol molar concentration of 13.6 M. The method of claim 1, wherein the reaction condition of the condensation reaction is γ-aminopropyltrimethoxydecane molar concentration of 0.02 M, ammonia molar concentration of 0.02 M, and deionized water molar concentration of 0.8. M and ethanol molar concentration of 16.7 M, reacted under heating and reflux. The method of any one of claims 1 to 5, wherein the amine-modified vermiculite nanoparticle is separated and purified by washing with water and ethanol.