CN112919483B - A method for preparing mesoporous silica nanospheres by a double-template method - Google Patents

Abstract

The invention relates to the technical field of mesoporous silica, and provides a method for preparing mesoporous silica nanospheres by a double-template method. In the present invention, cationic surfactants (CTAB and/or CTAC) and sulfonated calixarene (SC[n], n=4 or 8) are used as templates, and tetraethyl orthosilicate is used as a silicon source, and a one-pot reaction is adopted The silica nanospheres are obtained, and then the template agent is removed by calcining to obtain the mesoporous silica nanospheres. The present invention can conveniently realize the regulation and control of the particle size of the silica nanospheres by regulating the dosage ratio of the cationic surfactant and the sulfonated calixarene, the particle size of the obtained product can be adjusted in a wide range, and the preparation method is simple and the yield is high . The results of the examples show that the method of the present invention can be used to prepare mesoporous silica nanospheres with a particle size of 50-160 nm.

Description

A method for preparing mesoporous silica nanospheres by a double-template method

technical field

The invention relates to the technical field of mesoporous silica, in particular to a method for preparing mesoporous silica nanospheres by a double-template method.

Background technique

Mesoporous silica nanospheres are nanomaterials with porous structures formed by using organic molecules as templates. They have the advantages of high specific surface area, easy surface functionalization, good biocompatibility and strong thermal stability. It has great application value in adsorption and drug delivery. The Kresge team successfully synthesized mesoporous silica ordered molecular sieve MCM-41 for the first time in 1992, which aroused an upsurge in the research of mesoporous materials.

In the field of drug delivery, it is necessary to adjust the particle size of the carrier according to the drug to be delivered. At present, most of the research on mesoporous material drug carriers is centered on MCM-41, but the adjustable range of MCM-41 particle size is narrow, and only mesoporous silica nanospheres with a particle size of 100-200nm can be prepared. , it is difficult to prepare mesoporous silica nanospheres with a particle size of less than 100 nm, which cannot meet the loading requirements of various drug molecules as carriers.

Patent CN105236417A discloses a method for preparing spherical mesoporous silica with adjustable particle size, wherein amphiphilic polymer modified SiO ₂ (SiO ₂ -PBA-PDMAEMA), hexadecyl trimethyl ammonium bromide and ethyl tetrasilicate as reaction raw materials, hydrochloric acid and ammonia water are used to adjust the pH value of the reaction solution, and mesoporous silica is obtained by self-assembly reaction and calcination, and mesoporous silica can be realized by adjusting the amount of CTAB added. Control of particle size. However, in this patent, only mesoporous silica nanospheres with a particle diameter in the range of 25-90 nm can be prepared, and silica nanospheres with a particle diameter above 100 nm cannot be obtained, and the controllable range of the particle diameter is still relatively narrow.

Contents of the invention

In view of this, the present invention provides a method for preparing mesoporous silica nanospheres by a dual-template method with a wide range of adjustable particle diameters. The method provided by the invention can prepare mesoporous silicon dioxide nanospheres whose particle size is adjustable in the range of 50-160 nm.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A method for preparing mesoporous silica nanospheres by a double-template method, comprising the following steps:

Mix cationic surfactant, sulfonated calixarene, ethyl orthosilicate, alkaline substance and water for reaction to obtain product material liquid;

Separating the product material from liquid into solid, washing and drying the obtained solid product, and then calcining to obtain mesoporous silica nanospheres;

The cationic surfactant includes cetyltrimethylammonium bromide and/or cetyltrimethylammonium chloride; the sulfonated calixarene includes sulfonated calix[4]arene and/or sulfonated calixarene Calix[8]arene;

The molar ratio of the tetraethyl orthosilicate, the cationic surfactant and the sulfonated calixarene is 1:(0.055-0.065):(0-0.0029).

Preferably, in the feed liquid obtained from the mixing, the concentration of the cationic surfactant is 21-63 mmol/L, and the concentration of the sulfonated calixarene is 0.0525-2.1 mmol/L.

Preferably, the charge ratio of the positive charge of the cation in the cationic surfactant to the negative charge of the sulfonated calixarene is (5-200):1.

Preferably, the alkaline substance includes one or more of triethanolamine, triethylamine and ammonia water.

Preferably, the molar ratio of tetraethyl orthosilicate, alkaline substance and water is 1:(0.020～0.030):(75～85); when the basic substance is ammonia water, the molar amount of ammonia water Measured in moles of solute.

Preferably, the temperature of the reaction is 60-90° C., and the reaction time is 1-3 hours.

Preferably, the drying temperature is 70-90° C., and the drying time is 1-3 hours.

Preferably, the temperature of the calcination treatment is 400-700° C., and the calcination time is 3-7 hours.

Preferably, the particle size of the mesoporous silica nanospheres is 50-160 nm.

The invention provides a method for preparing mesoporous silica nanospheres by a double-template method. The invention uses cationic surfactants (CTAB and/or CTAC) and sulfonated calixarene (SC[n], n=4 or 8 ) as a template, using ethyl orthosilicate as a silicon source, adopting a one-pot reaction to obtain silica nanospheres, and then removing the template by calcination to obtain mesoporous silica nanospheres, in which ethyl orthosilicate The molar ratio of ester, cationic surfactant and sulfonated calixarene is 1:(0.055-0.065):(0-0.0029). In the present invention, when the amount of sulfonated calixarene is 0, the cationic surfactant is used as a single template to prepare mesoporous silica nanospheres, and the silicate formed by hydrolysis of tetraethyl orthosilicate oligomerizes Compounds and cationic surfactants (CTAB and/or CTAC) cooperate to self-assemble to form aggregates. Under the template action of the aggregates, silicate oligomers nucleate and grow slowly to form silica nanospheres. At this time, the obtained The particle size of mesoporous silica nanospheres is small; when the amount of sulfonated calixarene is not 0, sulfonated calixarene and cationic surfactant (CTAB and/or CTAC) form a super amphiphile molecule, the super amphiphile Molecules and silicate oligomers form self-assembled aggregates, and the hydroxyl groups exposed at the lower edge of sulfonated calixarene and silicon hydroxyl groups can form hydrogen bonds, which induces the silicate generated by hydrolysis to deposit on the surface of the aggregates, increasing the formation of silica. Nucleus growth rate, thereby increasing the particle size of the obtained mesoporous silica nanospheres; on the other hand, with the increase of the amount of sulfonated calixarene, it gradually approaches the ratio of cationic surfactant (CTAB and/or CTAC) and sulfonated calixarene. The stoichiometric ratio, the volume of the supramphiphile aggregates formed by the two increases, and the apparent charge density decreases, thereby increasing the pore size of the mesoporous silica nanospheres. Since SC[8] has a higher ratio than SC[4 ] Larger hydrophobic cup cavity, thus the pore size of the resulting mesoporous silica nanospheres is also larger.

In the present invention, the charge ratio (recorded as CTA ⁺ /SC [n] ^n- ), when the amount of sulfonated calixarene is 0, the particle size of the obtained mesoporous silica nanospheres is the smallest, and the specific surface area is the largest. When the amount of sulfonated calixarene is not 0, the With the gradual decrease of the charge ratio (that is, with the gradual increase of the amount of sulfonated calixarene), the particle size of the obtained mesoporous silica nanospheres gradually increases, the pore diameter gradually increases, and the surface roughness gradually increases. By controlling the dosage of the sulfonated calixarene, the invention can conveniently realize the regulation and control of the particle size of the mesoporous silica nanospheres.

In the present invention, through the compounding of cationic surfactants and sulfonated calixarene in different proportions, mesoporous silica nanospheres with uniform dispersion, stable structure, and adjustable particle and pore diameters can be obtained, and the preparation method provided by the present invention has simple steps , high yield, wide adjustable range of product particle size. The results of the examples show that the method of the present invention can be used to prepare silica nanospheres with a particle size of 50-160 nm, and the pores inside the obtained mesoporous silica nanospheres are highly ordered.

Description of drawings

Fig. 1 is the transmission electron microscope picture of the obtained mesoporous silica nanosphere of embodiment 1～3;

Fig. 2 is the particle size distribution figure of the obtained mesoporous silica nanosphere of embodiment 1;

Fig. 3 is the particle size distribution figure of the obtained mesoporous silica nanosphere of embodiment 2;

Fig. 4 is the particle size distribution figure of the obtained mesoporous silica nanosphere of embodiment 3;

Fig. 5 is the transmission electron microscope picture of the obtained mesoporous silica nanosphere of embodiment 1,4,5;

Fig. 6 is the particle size distribution figure of the mesoporous silica nanosphere obtained in embodiment 4;

7 is a particle size distribution diagram of mesoporous silica nanospheres obtained in Example 5.

Detailed ways

The invention provides a method for preparing mesoporous silica nanospheres by a double-template method, comprising the following steps:

Mix cationic surfactant, sulfonated calixarene, ethyl orthosilicate, alkaline substance and water for reaction to obtain product material liquid;

The product material liquid is subjected to solid-liquid separation, and the obtained solid product is washed, dried, and then calcined to obtain mesoporous silica nanospheres.

The invention mixes cationic surfactant, sulfonated calixarene, ethyl orthosilicate, alkaline substance and water for reaction to obtain product material liquid. In the present invention, the cationic surfactant includes cetyltrimethylammonium bromide (CTAB) and/or cetyltrimethylammonium chloride (CTAC), and the sulfonated calixarene includes sulfonate Calix[4]arene (SC[4]) and/or sulfonated calix[8]arene (SC[8]); the mol ratio of tetraethyl orthosilicate, cationic surfactant and sulfonated calixarene is 1:(0.055～0.065):(0～0.0029), preferably 1:(0.058～0.062):(0.0001～0.002), more preferably 1:0.06:(0.001～0.002), specifically, when the sulfur When the calixarene is SC[8], the molar ratio of the tetraethyl orthosilicate, cationic surfactant and SC[8] is more preferably 1:(0.055-0.065):(0-0.0011).

In the present invention, in the mixed feed liquid, the concentration of cationic surfactant is preferably 21-63mmol/L, more preferably 25-60mmol/L, and the concentration of sulfonated calixarene is preferably 0.0525-2.1mmol/L , more preferably 0.06～1.5mmol/L; In a specific embodiment of the present invention, the concentration of the cationic surfactant and the sulfonated calixarene is mixed with the molar amount of the cationic surfactant (or sulfonated calixarene) The ratio of the volume of water in the feed liquid is calculated, and the addition of other substances is ignored. In the present invention, the charge ratio of the positive charge of the cation in the cationic surfactant to the negative charge of the sulfonated calixarene (denoted as CTA ⁺ /SC[n] ^n- ) is preferably (5-200) :1, more preferably (10-180):1, even more preferably (50-150):1. The present invention can realize the control of CTA ⁺ /SC[n] ^n- by adjusting the molar ratio of the cationic surfactant and the sulfonated calixarene, and then realize the control of the particle size of the mesoporous silica nanosphere, the sulfonated calixarene The larger the dosage of the obtained mesoporous silica nanospheres, the larger the particle size, the smaller the specific surface area, the larger the pore size, and the larger the surface roughness.

In the present invention, the alkaline substance preferably includes one or more of triethanolamine, triethylamine and ammonia; the molar ratio of tetraethyl orthosilicate, alkaline substance and water is preferably 1:(0.020 ~0.030): (75 ~ 85), more preferably 1: (0.022 ~ 0.025): (78 ~ 82); when the alkaline substance is ammonia water, the molar weight of the ammonia water is based on the molar weight of the solute; In the present invention, alkaline substances are used to adjust the pH value of the reaction feed liquid to be in the range of 7.5-10, so as to promote the hydrolysis of tetraethyl orthosilicate.

In the present invention, the temperature of the reaction is preferably 60-90°C, more preferably 80°C, the reaction time is preferably 1-3h, more preferably 2h; the reaction is preferably carried out under stirring conditions, and the The stirring speed is preferably 500-1500 rpm, more preferably 1200 rpm. In a specific embodiment of the present invention, it is preferred to firstly mix the cationic surfactant, sulfonated calixarene, alkaline substance and deionized water, and stir for 1 hour at 60-90°C and 500-1500 rpm to obtain a premixed solution. Then tetraethyl orthosilicate is quickly added into the premixed solution for reaction.

After the reaction is completed, the present invention separates the obtained product from the solid and liquid, washes and dries the obtained solid product, and then performs calcination treatment to obtain mesoporous silica nanospheres (MSNs). In the present invention, the method of solid-liquid separation is preferably centrifugation, and the rotational speed of the centrifugation is preferably 10000rpm; the washing detergent is preferably ethanol, and the number of times of washing is preferably 3 times; the drying The temperature is preferably 70-90°C, more preferably 80°C, and the drying time is preferably 1-3h, more preferably 2h.

In the present invention, the temperature of the calcination treatment is preferably 400-700°C, more preferably 550-600°C, and the calcination time is preferably 3-7h, more preferably 5-6h; The heating rate is preferably 2°C/min, and the calcination treatment is preferably carried out in a muffle furnace. In the invention, the template agent in the solid product is removed through calcination, and the mesoporous channel is formed in the silicon dioxide nanosphere to obtain the mesoporous silicon dioxide nanosphere.

In the present invention, the particle diameter of the mesoporous silica nanospheres is preferably 50 to 160 nm, more preferably 60 to 150 nm, and the pore diameter of the mesoporous silica nanospheres is mesoporous (the pore diameter specified in the IUPAC classification standard Pores ranging from 2.0 to 50 nm are called mesopores). In a specific embodiment of the present invention, when the molar ratio of tetraethylorthosilicate, cationic surfactant and SC[4] is 1:0.055-0.065:0-0.0029, the obtained mesoporous silica nanospheres The diameter is preferably 52-160nm, the specific surface area is preferably 286-85m ² /g, and the pore diameter is preferably 2.9-3.3nm; when the molar ratio of ethyl orthosilicate, cationic surfactant and SC[4] is 1:0.055～ 0.065:0~0.0011, the particle size of the obtained mesoporous silica nanospheres is preferably 52~155nm, the specific surface area is preferably 286~109m ² /g, and the pore diameter is preferably 2.9~3.5nm; when a single CTAB is used as the template , the obtained mesoporous silica nanospheres have a particle diameter of 52±5nm, a specific surface area of 286m ² /g, and a pore diameter of 2.9nm.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

Example 1

(1) Mix 0.38g of CTAB, 0.068g of triethanolamine and 25mL of deionized water, stir at 80°C at a speed of 1200rpm for 1h to obtain a premix, then quickly add 4mL of tetraethyl orthosilicate to the premix, and The reaction was stirred at 1200 rpm for 2 h under the condition of °C to obtain the product liquid. Wherein, the concentration of CTAB in the feed liquid obtained by mixing each component is 42mmol/L.

(2) Centrifuge the obtained product feed liquid at a speed of 10000rpm, wash the obtained solid product with ethanol for 3 times, dry the washed white product in a drying oven at 80°C for 2 hours, and place the dried product in a muffle furnace In the process, the temperature was raised to 550° C. at a rate of 2° C./min, calcined at 550° C. for 5 h, and the mesoporous silica nanospheres were obtained after natural cooling. The yield of the obtained mesoporous silica nanospheres was 1.01 g.

Example 2

Other conditions are identical with embodiment 1, only add SC[4] 0.0097g in step (1), the concentration of CTAB in the mixed gained feed liquid is 42mmol/L, and the concentration of SC[4] is 0.52mmol/L, and the obtained medium The yield of porous silica nanospheres was 1.03 g.

Example 3

Other conditions are the same as in Example 2, only the amount of SC[4] is changed to 0.0391g, the concentration of CTAB in the mixed feed solution is 42mmol/L, and the concentration of SC[4] is 2.1mmol/L, and the obtained mesoporous two The yield of silica nanospheres was 0.58 g.

The mesoporous silica nanospheres prepared in Examples 1 to 3 were tested by transmission electron microscopy, and the results are shown in Figure 1, and (a) to (b) in Figure 1 are the mesoporous silica nanospheres obtained in Example 1 (c)～(d) are the transmission electron microscope pictures of the mesoporous silica nanospheres obtained in Example 2, (e)～(f) are the transmission electron microscope pictures of the mesoporous silica nanospheres obtained in Example 3 Electron microscope pictures, where the scale bar of (a), (c), (e) is 200nm, and the scale bar of (b), (d), (f) is 100nm. As can be seen from Figure 1, the mesoporous silica nanospheres obtained in Examples 1 to 3 are uniform spherical, and the particle size of the mesoporous silica nanospheres obtained in Example 1 is the smallest, and the SC[ 4] gradually increased, the particle size of the obtained mesoporous silica nanospheres gradually increased; in addition, ordered mesoporous lattice structures can be observed in (a) to (f) in Figure 1, indicating that the obtained mesoporous silica nanospheres The pores of silicon nanospheres are mesopores.

The particle size distribution of the mesoporous silica nanospheres prepared in Examples 1 to 3 was tested, and the obtained results are shown in Figures 2 to 4, and Figures 2 to 4 are the mesoporous silica obtained in Examples 1 to 3 in turn Diagram of the particle size distribution of the nanospheres. The test results in Figures 2 to 4 show that the particle diameter of the mesoporous silica nanospheres obtained in Example 1 is 52 ± 5nm, and the particle diameter of the mesoporous silica nanospheres obtained in Example 2 is 72 ± 5nm. 3 The particle size of the obtained mesoporous silica nanospheres is 160±10nm.

In addition, the specific surface area and pore diameter of the mesoporous silica nanospheres obtained in Examples 1 and 3 were tested, and the results showed that the specific surface area of the mesoporous silica obtained in Example 1 was 286 m ² /g, and the pore diameter was 2.9 nm. The specific surface area of the mesoporous silica obtained in Example 3 is 85 m ² /g, and the pore diameter is 3.3 nm.

Example 4

Other conditions are the same as in Example 2, only SC[4] is replaced by SC[8], the amount of SC[8] is 0.0098g, the concentration of CTAB in the mixed feed liquid is 42mmol/L, the concentration of SC[8] is 0.2625mmol/L, and the yield of the obtained mesoporous silica nanospheres is 0.98g.

Example 5

Other conditions are the same as in Example 4, only the amount of SC[8] is changed to 0.028g, the concentration of CTAB in the mixed feed solution is 42mmol/L, and the concentration of SC[8] is 0.75mmol/L, and the obtained mesoporous two The yield of silica nanospheres was 0.78 g.

The mesoporous silica nanospheres prepared in Examples 4-5 were tested by a transmission electron microscope, and the transmission electron microscope images of the mesoporous silica nanospheres obtained in Example 1 are listed in Fig. 5 together, in Fig. 5, ( a)～(b) are transmission electron microscope pictures of mesoporous silica nanospheres obtained in Example 1, (c)～(d) are transmission electron microscope pictures of mesoporous silica nanospheres obtained in Example 4, (e) ~(f) is the transmission electron microscope picture of the mesoporous silica nanosphere obtained in Example 5, wherein the scale of (a), (c), (e) is 200nm, (b), (d), (f) The scale bar is 100 nm. According to Figure 5, it can be seen that after adding SC[8], the particle size of the obtained mesoporous silica nanospheres gradually increases with the increase of the amount of SC[8]; in addition, in Figure 5 (a)～(f ) can observe an ordered mesoporous lattice structure, indicating that the pores of the obtained silica nanospheres are mesoporous.

The particle size distribution of the mesoporous silica nanospheres prepared in Examples 4-5 is tested, and the results are shown in Figures 6-7, and Figures 6-7 are the mesoporous silica obtained in Examples 4-5 in turn Diagram of the particle size distribution of the nanospheres. The test results in FIGS. 4-5 show that the particle diameter of the mesoporous silica nanospheres obtained in Example 4 is 80±5 nm, and the particle diameter of the mesoporous silica nanospheres obtained in Example 5 is 155±10 nm.

In addition, the specific surface area and pore diameter of the mesoporous silica nanospheres obtained in Example 5 were tested, and the results showed that the specific surface area of the mesoporous silica obtained in Example 5 was 109 m ² /g, and the pore diameter was 3.5 nm.

The productive rate of the obtained mesoporous silica nanospheres of Examples 1 to 5 is calculated, and the results are listed in Table 1. The charging capacity of ethyl orthosilicate in Examples 1 to 5 is 4mL, according to the ethyl orthosilicate According to the hydrolysis equation of the ester, the theoretical yield of the mesoporous silica nanospheres is 1.07 g, and the yield = actual yield/1.07×100%.

Table 1 Yield of mesoporous silica nanospheres (MSNs) obtained in Examples 1-5

Can find out according to the data in table 1, adopt the method provided by the invention to prepare mesoporous silica nanosphere, the productive rate of the product obtained is higher, can reach 96.26%, and productive rate is lower among the embodiment 3, and this is because With the increase of the amount of sulfonated calixarene, the negative charge of the system will decrease when the stoichiometric ratio is close to the stoichiometric ratio, but the yield can reach 54.2%.

It can be seen from the results of the above examples that the present invention uses cationic surfactants (CTAB and/or CTAC) and SC[n] as dual templates, and the obtained mesoporous silica nanometers can be easily controlled by adjusting the ratio of the two. The particle size of the spheres, the particle size of the obtained product can be adjusted in a wide range, the preparation method is simple, and the product yield is high.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (8)

1. a method for preparing mesoporous silica nanospheres by a double template method, is characterized in that, comprises the following steps: Cationic surfactant, sulfonated calixarene, ethyl orthosilicate, alkaline substance and water are mixed and reacted to obtain product feed liquid; in the mixed feed liquid, the concentration of cationic surfactant is 21-63mmol/L, The concentration of sulfonated calixarene is 0.0525～2.1mmol/L; Separating the product material from liquid into solid, washing and drying the obtained solid product, and then calcining to obtain mesoporous silica nanospheres; The cationic surfactant includes cetyltrimethylammonium bromide and/or cetyltrimethylammonium chloride; the sulfonated calixarene includes sulfonated calix[4]arene and/or sulfonated calixarene Calix[8]arene; The molar ratio of the tetraethyl orthosilicate, the cationic surfactant and the sulfonated calixarene is 1:(0.055-0.065):(0-0.0029). 2. The method according to claim 1, characterized in that, the charge ratio of the positive charge of the cation in the cationic surfactant to the negative charge of the sulfonated calixarene is (5～200):1. 3. The method according to claim 1, characterized in that, the alkaline substance comprises one or more of triethanolamine, triethylamine and ammoniacal liquor. 4. according to the described method of claim 1 or 3, it is characterized in that, the mol ratio of described ethyl orthosilicate, alkaline substance and water is 1:(0.020～0.030):(75～85); When the basic substance is ammonia water, the molar amount of the ammonia water is based on the molar amount of the solute. 5. The method according to claim 1, characterized in that the temperature of the reaction is 60-90°C, and the reaction time is 1-3h. 6 . The method according to claim 1 , characterized in that, the drying temperature is 70-90° C., and the drying time is 1-3 hours. 7. The method according to claim 1, characterized in that the temperature of the calcination treatment is 400-700° C., and the calcination time is 3-7 hours. 8. The method according to claim 1, characterized in that the particle size of the mesoporous silica nanospheres is 50-160 nm.