Double-stranded molecular template-driven homogeneous nanosilver and preparation method thereof

Abstract

This invention belongs to the field of nanomaterial preparation technology and discloses a method for preparing uniform silver nanoparticles driven by a double-chain molecular template. The method involves mixing an aqueous solution of silver salt with a solution of a double-chain surfactant to form microemulsion A; mixing an aqueous solution of a reducing agent with the solution of the double-chain surfactant to form microemulsion B; mixing microemulsion B with microemulsion A in an inert atmosphere to carry out a reduction reaction to obtain a reaction solution; and purifying the reaction solution to obtain silver nanoparticles. This invention utilizes the inherent, precise nanoscale structure of specific double-chain molecules as a "molecular ruler," allowing direct and effective control of the size of the generated silver nanoparticles by simply adjusting the physical length or rigidity of the template.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a uniform silver nanoparticle driven by a double-stranded molecular template and its preparation method. Background Technology

[0002] In the field of nanomaterials science, silver nanoparticles, due to their unique physicochemical properties such as high specific surface area, excellent electrical conductivity, and antibacterial properties, have broad application prospects in many fields such as electronics, catalysis, and biomedicine. However, the properties of nanomaterials are strongly dependent on their size, morphology, and dispersibility, with size being one of the most critical parameters affecting their optical, electrical, and chemical properties. Therefore, developing methods to achieve precise and controllable preparation of silver nanoparticles has always been a research hotspot and challenge in this field. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention aims to provide a uniform silver nanoparticle driven by a double-stranded molecular template and its preparation method. The present invention utilizes the inherent and precise nanoscale structure of a specific double-stranded molecule as a "molecular ruler". By simply adjusting the physical length or rigidity of the template, the size of the generated silver nanoparticle can be directly and effectively controlled.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing uniform silver nanoparticles driven by a double-stranded molecular template includes the following steps: A silver salt aqueous solution was mixed with a double-chain surfactant solution to form microemulsion A. A reducing agent aqueous solution is mixed with a double-chain surfactant solution to form microemulsion B; In an inert atmosphere, microemulsion B and microemulsion A are mixed and a reduction reaction is carried out to obtain a reaction solution; The reaction solution was purified to obtain nano-silver.

[0005] Preferably, the solute in the double-chain surfactant solution is a double-chain sulfosuccinate.

[0006] Preferably, the solute in the double-chain surfactant solution is at least one of sodium bis(2-ethylhexyl)sulfosuccinate, sodium dihexylsulfosuccinate, sodium dicyclohexylsulfosuccinate, sodium lauryl sulfosuccinate mixed diester, disodium fatty alcohol polyoxyethylene ether sulfosuccinate, and Gemini surfactant succinate sulfonate.

[0007] Preferably, the solvent for the double-chain surfactant solution is the nonpolar organic solvent dodecane.

[0008] Preferably, the silver salt aqueous solution is an aqueous solution of silver nitrate.

[0009] Preferably, the reducing agent aqueous solution is a hydrazine hydrate aqueous solution.

[0010] Preferably, when purifying the reaction solution, the reaction solution is centrifuged at 9500-10500 rpm for 10-15 min, the supernatant is discarded, the precipitate obtained by centrifugation is ultrasonically dispersed with a dispersant, and then the above process is repeated 3-5 times to obtain nano-silver; wherein, the power of each ultrasonic dispersion is 95-105 W and the time is 5-10 min.

[0011] Preferably, the preparation method of the present invention further includes the following process: dispersing the purified nano-silver in dodecane and subjecting it to ultrasonic treatment, wherein the ultrasonic treatment adopts a pulse mode, the ultrasonic power is 95-105 W, the on is 1.8-2.2 s, the off is 0.8-1.2 s, and the ultrasonic treatment time is 9-11 min.

[0012] Preferably, in the above-described scheme of the present invention, the concentration of the silver salt aqueous solution is 0.1-1.0M, the concentration of the double-chain surfactant solution is 0.1-1.0M, and the concentration of the reducing agent aqueous solution is 0.1-1.0M; When preparing microemulsion A, the volume ratio of silver salt aqueous solution to double-chain surfactant solution is (1.6-2.0):50; When preparing microemulsion B, the volume ratio of the reducing agent aqueous solution to the double-chain surfactant solution is (1.6-2.0):50; In an inert atmosphere, microemulsion B and microemulsion A are mixed and a reduction reaction is carried out to obtain a reaction solution. Microemulsion B and microemulsion A are mixed in equal volumes, and the reaction time is controlled at 1-2 hours.

[0013] The present invention also provides a nano-silver, which is prepared by the preparation method of the present invention as described above, and the nano-silver has a particle size of 10-100 nm.

[0014] The present invention has the following beneficial effects: In this invention, a method for preparing uniform silver nanoparticles driven by a double-chain molecular template involves mixing an aqueous solution of silver salt and an aqueous solution of a reducing agent with a solution of a double-chain surfactant to form microemulsions A and B in steps. These microemulsions are then mixed in an inert atmosphere for a reduction reaction, followed by purification to obtain silver nanoparticles. This method effectively solves the problem of precise size control of silver nanoparticles in existing technologies. The double-chain surfactant is arranged in the oil phase with hydrophobic chains anchoring the oil phase and hydrophilic groups facing the aqueous phase, forming 10-100 nm nanoscale aqueous microdroplets. These microdroplets act as molecular scales, strictly confining the reduction process of silver ions within the microdroplets. Their size directly determines the particle size range of the silver nanoparticles and can be adjusted... The physical length or rigidity of the double-chain surfactant directly transmits the physical scale information of the template to the silver nanoparticles, enabling precise control of the silver nanoparticle size within the range of 10-100 nm, and ensuring the stability of its optical, electrical, and chemical properties. At the same time, the double-chain surfactant adsorbs onto the surface of the silver nanoparticles after their formation, preventing particle aggregation through steric hindrance. Combined with subsequent purification processes, this results in silver nanoparticles with excellent monodispersity. The entire preparation process consists of only three core steps: microemulsion stepwise preparation, inert atmosphere mixing and reduction, and purification. It requires no complex equipment or harsh reaction conditions, is easy to operate, and has good repeatability, enabling the stable preparation of silver nanoparticles with uniform particle size, good dispersibility, and qualified purity. Attached Figure Description

[0015] Figure 1 This is a TEM image of the nanosilver prepared in Example 1 of the present invention.

[0016] Figure 2 These are TEM images of the silver nanoparticles prepared in Examples 2 to 5 and Comparative Examples 1 to 2 of the present invention.

[0017] Figure 3 These are TEM images of the silver nanoparticles prepared in Examples 6-7 and Comparative Examples 3-4 of this invention. Detailed Implementation

[0018] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0019] Unless otherwise specified, the test methods and detection methods involved in the following scheme are all conventional methods; unless otherwise specified, the reagents and raw materials are all commercially available.

[0020] This invention provides a method for synthesizing metal nanoparticles with precise controllable size by utilizing the template effect of biomacromolecules. Specifically, it uses a class of double-chain surfactants with specific structures as templates to controllably prepare silver nanoparticles with particle sizes of 10-100 nm. Specifically, this invention employs a surfactant with a specific double-chain molecular structure, dissolved in dodecane to form an oil phase, which is then separated into two portions. A silver salt solution and a reducing agent solution are then prepared and added to the oil phase to obtain two microemulsions. The reaction is carried out under an inert gas atmosphere. The reaction solution is purified, and the supernatant is removed. The resulting solution is dissolved in dodecane to obtain silver nanoparticle sol with a particle size of 10-100 nm, achieving precise controllable particle size.

[0021] Specifically, the method for preparing uniform silver nanoparticles driven by double-stranded molecular templates of the present invention includes the following steps: 1) Dissolve the double-chain surfactant in 100 ml of the non-polar organic solvent dodecane to prepare an oil phase solution (i.e., a double-chain surfactant solution with a concentration of 0.1-1.0 M), and divide it into two equal portions. In this scheme, the double-chain surfactant can be a double-chain sulfosuccinate, which includes, but is not limited to, at least one of sodium bis(2-ethylhexyl)sulfosuccinate (AOT), sodium dihexyl sulfosuccinate (DHS), sodium dicyclohexyl sulfosuccinate (DCHS), sodium lauryl sulfosuccinate mixed diester (DLS), disodium fatty alcohol polyoxyethylene ether sulfosuccinate (MES), and succinate sulfonate Gemini surfactant (BSSG). By anchoring hydrophobic chains in the oil phase and arranging hydrophilic groups towards the water phase, 10-100 nm water phase microdroplets are formed in the oil phase and adsorbed onto the surface of nano-silver after its formation. The steric hindrance effect is used to prevent particle aggregation and strictly limit the particle size within the microdroplet range, ultimately achieving monodispersity of the product.

[0022] 2) Dissolve silver nitrate in 1.8 ml of ultrapure water to prepare a silver salt aqueous solution with a concentration of 0.1-1.0 M, and dissolve hydrazine hydrate in 1.8 ml of ultrapure water to prepare a reducing agent aqueous solution with a concentration of 0.1-1.0 M; 3) Under stirring conditions, the silver salt aqueous solution obtained in step 2) is added to a portion of the oil phase solution obtained in step 1), and a thermodynamically stable microemulsion A is spontaneously formed; 4) Under stirring conditions, the reducing agent aqueous solution obtained in step 2) is added to another portion of the oil phase solution obtained in step 2), and a thermodynamically stable microemulsion B is spontaneously formed; 5) Under stirring conditions, add the microemulsion B obtained in step 4) to the microemulsion A obtained in step 3). A reduction reaction is carried out under an inert gas atmosphere (purity above 99.99%, pressure controlled at 101-120 kPa, flow rate controlled at 20-200 sccm). After the reaction is completed in 1-2 hours, the resulting reaction solution is purified to remove unreacted impurities and byproducts. The resulting precipitate is nano-silver (particle size 10-100 nm). During purification, the reaction solution is centrifuged (centrifugation speed 10000±500 rpm, time 10-15 min), the supernatant is discarded, and the precipitate is ultrasonically dispersed in 20 mL of cyclohexane (ultrasonic power 100±5 W, time 5-10 min). This process is repeated three times to obtain the precipitate.

[0023] In addition, the obtained nano-silver can be ultrasonically dispersed in 10-20 ml of dodecane to obtain a nano-silver dispersion. Specifically, when ultrasonically dispersing nano-silver in dodecane, the ultrasonic treatment adopts pulse mode with an ultrasonic power of 100±5W. In pulse mode, the ultrasonic on is 2±0.2 s and off is 1±0.2 s, and the ultrasonic time is 9-11 min.

[0024] In the above-described solution of this invention, the data before the ± sign represents the device setting value of the corresponding parameter, and the data after the ± sign represents the device deviation value of the corresponding parameter. It can be understood that within the defined range of the device setting value and the deviation value, the technical solution of this invention is feasible. In the following embodiments and comparative examples of this invention, only the device setting value is given for the corresponding parameter.

[0025] Example 1: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.2 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.2 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.6 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 101 kPa, flow rate 50 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0026] TEM images of the silver nanoparticles prepared in this embodiment are shown below. Figure 1 As shown, from Figure 1 As can be seen from the data, the product obtained in this embodiment is a spherical silver nanoparticle with regular morphology, no obvious agglomeration, excellent particle size uniformity, and a particle size of about 20 nm, which falls completely within the controllable particle size range of 10-100 nm of this invention. The particles are uniformly dispersed in the field of view, without large-sized aggregates or irregular morphological products. This proves that the silver nanoparticles prepared by using AOT as a double-stranded template and through microemulsion method + purification process have achieved the technical effect of precise particle size control and good monodispersity, and verified the "molecular ruler" role of the double-stranded molecular template and the feasibility of the preparation process of this invention.

[0027] Example 2: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.1 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.2 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.4 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 105 kPa, flow rate 100 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1.5 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0028] Example 3: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve sodium dihexyl sulfosuccinate (DHS) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.4 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.1 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.2 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 110 kPa, flow rate 100 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 2 h to obtain reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0029] Example 4: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve sodium lauryl sulfosuccinate (DLS) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.5 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.3 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.6 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 105 kPa, flow rate 100 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1.5 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0030] Example 5: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve disodium fatty alcohol polyoxyethylene ether sulfosuccinate (MES) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.3 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.5 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 1.0 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 105 kPa, flow rate 100 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1.5 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0031] Comparative Example 1: The comparative method for preparing nano-silver includes the following steps: 1. Dissolve hexadecyltrimethylammonium bromide (CTAB) in 100 ml of dodecane to prepare a 0.2 M oil phase solution, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.2 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.6 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 101 kPa, flow rate 50 sccm), the reducing agent microemulsion B was added to the silver salt microemulsion A, and the mixture was stirred for 1 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min, repeat the purification process three times, and finally disperse the precipitate in 10 mL of dodecane and sonicate for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse.

[0032] Comparative Example 2: The comparative method for preparing nano-silver includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.2 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.2 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.6 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 101 kPa, flow rate 50 sccm), the reducing agent microemulsion B was added to the silver salt microemulsion A, and the mixture was stirred for 1 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, disperse the precipitate in 10 mL of dodecane, and sonicate for 10 min in a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse.

[0033] TEM images of the silver nanoparticles prepared in Examples 2-5 and Comparative Examples 1-2 are shown below. Figure 2 As shown, from Figure 2As can be seen from the results, the products described in Examples 2 to 5 all exhibit spherical, uniformly sized, and well-dispersed silver nanoparticles, with measured particle sizes of 40 nm, 30 nm, 20 nm, and 30 nm, respectively, all within the range of 10-100 nm. Within the nm range, different double-chain sulfosuccinates (AOT / DHS / DLS / MES) as templates can all achieve precise control of the nanoparticle size of silver nanoparticles, proving that the double-chain molecular template system of the present invention has universality, and the purification process effectively avoids particle aggregation. In Comparative Example 1, the surfactant used was the single-chain surfactant CTAB. No regular spherical nanoparticles were visible in the field of view, only amorphous aggregates appeared, and no effective silver sol was formed, proving that single-chain surfactants cannot form precise nanoscale aqueous microdroplets and do not have the function of "molecular scale", which is the key defect in achieving controllable nanoparticle size of silver nanoparticles. In Comparative Example 2, no purification process was performed, and it can be seen that the nanoparticles were severely aggregated, forming large-sized aggregates with no monodispersity. This proves that the purification process of the present invention is a necessary step to ensure the dispersibility of nanoparticles, and can effectively remove impurities and deagglomerate slightly aggregated particles.

[0034] Example 6: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 1.0 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.1 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.5 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 110 kPa, flow rate 40 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0035] Example 7: The method for preparing nano-silver in this embodiment includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.5 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.5 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 1.0 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 101 kPa, flow rate 50 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0036] Comparative Example 3: The comparative method for preparing nano-silver includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.5 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 2.0 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.6 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 101 kPa, flow rate 50 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 1 h to obtain the reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0037] Comparative Example 4: The comparative method for preparing nano-silver includes the following steps: 1. Dissolve sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in 100 ml of dodecane to prepare an oil phase solution with a concentration of 0.2 M, and divide it into two equal portions; 2. Dissolve silver nitrate in 1.8 ml of ultrapure water to obtain a 0.2 M silver salt aqueous solution; dissolve hydrazine hydrate in 1.8 ml of ultrapure water to obtain a 0.6 M reducing agent aqueous solution; 3. Under stirring, the silver salt aqueous solution is added to one portion of the oil phase obtained in step 1, spontaneously forming microemulsion A; the reducing agent aqueous solution is added to another portion of the oil phase obtained in step 1, spontaneously forming microemulsion B; 4. Under 99.99% nitrogen protection (pressure 101 kPa, flow rate 50 sccm), add microemulsion B obtained in step 3 to microemulsion A, stir and react for 0.5 h to obtain reaction solution; 5. Centrifuge the reaction solution at 10,000 rpm for 10 min, discard the supernatant, and disperse the precipitate in 20 mL of cyclohexane using ultrasonication at 100 W for 5 min. Repeat the purification process three times to obtain uniform silver nanoparticles with a particle size of 10-100 nm. Finally, disperse the precipitate in 10 mL of dodecane and sonicate it for 10 min using a pulse mode with a power of 100 W and a 2 s on / 1 s off pulse to obtain a silver nanoparticle dispersion.

[0038] TEM images of the silver nanoparticles prepared in Examples 6-7 and Comparative Examples 3-4 are shown below. Figure 3 As shown, from Figure 3As can be seen from the TEM images of Examples 6 and 7, all particles are spherical silver nanoparticles with regular morphology and smooth edges. The particles show no aggregation and are uniformly distributed in a monodisperse state. The measured particle sizes are 20 nm and 25 nm, respectively, both strictly falling within the controllable particle size range of 10-100 nm specified in this invention. This result proves that within the process parameters defined in this invention, silver nanoparticles with uniform particle size and excellent dispersibility can be stably prepared, verifying the rationality of the parameter range and the stability of the process. In Comparative Example 3, the silver salt concentration exceeds the 0.1-1.0 M limit, and the TEM image shows severe aggregation of silver nanoparticles, forming irregular large-sized aggregates without any monodisperse independent particles. The measured aggregate particle size reaches 110 nm, exceeding the upper limit of the controllable particle size of this invention. In Comparative Example 4, the reduction reaction time is shorter than the 1-2 h limit, and the silver nanoparticles in the TEM image show a large-area aggregation into clumps, with aggregate particle sizes reaching the 1 μm level, completely losing the uniformity and dispersibility at the nanoscale.

[0039] The morphology and particle size of the silver nanoparticles in Examples 1-5 and Comparative Examples 1-2 are shown in Table 1, and the morphology and particle size of the silver nanoparticles in Examples 6-7 and Comparative Examples 3-4 are shown in Table 2. Table 1

[0040] Table 2

[0041] As can be seen from Tables 1 and 2, only by using double-chain sulfosuccinate as a template can uniform silver nanoparticles of 10-100 nm be prepared. Single-chain surfactants cannot form an effective silver sol at all, directly proving that double-chain surfactants are the key to achieving precise control of silver nanoparticle size. Under the same template, purified Example 1 can obtain monodisperse 20 nm silver nanoparticles, while unpurified Comparative Example 2 has no effective particle size data, indicating that the purification process can effectively remove unreacted impurities, deagglomerate particles, and ensure product dispersibility. Furthermore, the parameter range of this invention is a necessary condition for achieving controllable silver nanoparticle size and good dispersibility.

[0042] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing uniform silver nanoparticles driven by a double-stranded molecular template, characterized in that, The process includes the following: A silver salt aqueous solution was mixed with a double-chain surfactant solution to form microemulsion A. A reducing agent aqueous solution is mixed with a double-chain surfactant solution to form microemulsion B; In an inert atmosphere, microemulsion B and microemulsion A are mixed and a reduction reaction is carried out to obtain a reaction solution; The reaction solution was purified to obtain nano-silver.

2. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 1, characterized in that, The solute used in the double-chain surfactant solution is a double-chain sulfosuccinate.

3. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 2, characterized in that, The solute in the double-chain surfactant solution is at least one of the following: sodium bis(2-ethylhexyl)sulfosuccinate, sodium dihexylsulfosuccinate, sodium dicyclohexylsulfosuccinate, sodium lauryl sulfosuccinate mixed diester, disodium fatty alcohol polyoxyethylene ether sulfosuccinate, and Gemini surfactant succinate sulfonate.

4. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 1, characterized in that, The solvent used for the double-chain surfactant solution is the nonpolar organic solvent dodecane.

5. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 1, characterized in that, The silver salt aqueous solution is an aqueous solution of silver nitrate.

6. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 1, characterized in that, The reducing agent aqueous solution is hydrazine hydrate aqueous solution.

7. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 1, characterized in that, To purify the reaction solution, centrifuge it at 9500-10500 rpm for 10-15 min, discard the supernatant, and ultrasonically disperse the precipitate obtained by centrifugation with a dispersant. Repeat the above process 3-5 times to obtain nano-silver. The ultrasonic dispersion power is 95-105 W and the time is 5-10 min each time.

8. The method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to claim 1, characterized in that, The process also includes the following steps: dispersing the purified silver nanoparticles in dodecane and subjecting them to ultrasonic treatment. The ultrasonic treatment is performed in pulse mode with an ultrasonic power of 95-105 W, an on-time of 1.8-2.2 s, an off-time of 0.8-1.2 s, and an ultrasonic treatment time of 9-11 min.

9. A method for preparing uniform silver nanoparticles driven by a double-stranded molecular template according to any one of claims 1-8, characterized in that, The concentration of the silver salt aqueous solution is 0.1-1.0M, the concentration of the double-chain surfactant solution is 0.1-1.0M, and the concentration of the reducing agent aqueous solution is 0.1-1.0M. When preparing microemulsion A, the volume ratio of silver salt aqueous solution to double-chain surfactant solution is (1.6-2.0):50; When preparing microemulsion B, the volume ratio of the reducing agent aqueous solution to the double-chain surfactant solution is (1.6-2.0):50; In an inert atmosphere, microemulsion B and microemulsion A are mixed and a reduction reaction is carried out to obtain a reaction solution. Microemulsion B and microemulsion A are mixed in equal volumes, and the reaction time is controlled at 1-2 hours.

10. A type of nano-silver, characterized in that, The silver nanoparticles are prepared by any one of the preparation methods of claims 1-9, and the particle size of the silver nanoparticles is 10-100 nm.

Images