"METHOD FOR PRODUCING SILVER NANOWIRES AND DEVICE FOR CARRYING OUT THE METHOD"

Technical field

This application relates to a method for producing silver nanowires and a method for producing nanowires on carbonbased materials , as well as a method to produce a perylene bisimide compound . The application also relates to a device suitable to carry out both methods described herein .

Background art

Several methods for producing silver nanowires have been proposed previously .

Document US7585349 B discloses a process for producing silver nanoparticles consisting of a silver nitrate reaction with polyvinylpyrrolidone ( PVP ) in the presence of ethylene glycol . Depending on the reaction conditions di f ferent morphology and dimensions , namely silver nanowires , can be obtained .

Document WO14169487 Al discloses the synthesis of silver nanowires using polyquaterniums and silver salts .

Document US2015336173 AA discloses silver nanowires produced by mixing and heating (polyol method) a silver salt precursor, a reducing solvent ( a reduction agent ) , and capping agent such as vinylpyrrolidone-co-vinylimidazole copolymers ( PIC ) instead of PVP . Document US 10220441 B2 discloses a method for producing silver nanowires , in an alcohol solvent having dissolved therein a silver compound, a chloride , a bromide , an alkali metal hydroxide , an aluminium salt and an organic protective agent .

Document US2020157657 discloses a metal aerogel includes a plurality of metal nanowires formed into a porous three- dimensional structure where pores in the structure are anisotropic, however there is no mention of using perylene bisimide in the synthesis , using PVP instead .

Document US 8454721 B2 discloses a method of forming monodispersed metal nanowires from silver nitrate , no mention is made to using perylene bisimide in the method .

Document KR20200098256 A discloses a method for manufacturing a functional polymer nanofiber composite and a method for manufacturing a functional substrate using the same . No mention is made to using perylene bisimide in the method .

Summary

The present invention relates to a method for producing silver nanowires comprising the following steps :

Heating and stirring a mixture of perylene bisimide of formula ( 3 ) and a silver metal salt m a 1 : 25 to 1 : 35 mass ratio , at a temperature between 130 ° C and 170 ° C, during 3 h to 14 h, in the presence of a solvent ; Cooling the solution between 20 and 25 ° C for 16 h to 20 h; Collecting and filtering the resulting precipitate to isolate the silver nanowires . In one embodiment the silver metal salt is selected from silver nitrate or silver acetate.

In one embodiment a carbon-based material is added to the mixture in a ratio of perylene bisimide of formula (3) , silver metal salt and carbon-based material in a 1:4:2.3 to 1:35:2.3 mass ratio.

In one embodiment the carbon-based material is selected from carbon nanotubes, multi-walled carbon nanotubes, single wall carbon nanotube, carbon nanofibers and graphene nanoplatelets .

In one embodiment the solvent is selected from ethylene glycol, or a mixture of dimethylformamide and water.

In one embodiment ethylene glycol is added in a variable amount maintaining the concentration of silver metal salt between 4 mg/ml to 18 mg/ml.

In one embodiment a mixture of dimethylformamide and water in a ratio of 30:1 to 100:1 is added in a variable amount, maintaining the concentration of silver metal salt between 6 mg/ml to 50 mg/ml.

In one embodiment the resulting precipitate is washed with ethanol and dried at a temperature between 70 °C and 100 °C to obtain dried silver nanowires.

In one embodiment the mixture is sonicated before heating when ethylene glycol is used as solvent. In one embodiment, when a mixture of dimethylformamide and water is used as solvent, two additional aliquots of the initial amount of water are added every two hours to the mixture under heat.

The present invention also relates to a method for producing of perylene bisimide of formula (3) comprising the following steps :

Heating and stirring a mixture of 1 , 3-diaminopentane (2) and perylenetetracarboxilic dianhydride (1) in a minimum mole ratio of 2:1, at a temperature between 90 °C to 160 °C, during 3 min to 3 h;

Adding water in a ratio between 40 ml/g and 120 ml/g per starting reagents;

Collecting and filtering the resulting suspension to isolate the perylene bisimide formula of (3) .

In one embodiment the perylene bisimide formula of (3) isolated and filtered is washed with water, ethanol, diethyl ether and dried.

The present invention also relates to a device for carrying out any of the methods described above.

General description

The present disclosure relates to a method for producing silver nanowires, through reduction and silver precipitation in the form of wire in a solvent having dissolved therein a silver compound and a perylene bisimide (FBI) of formula (3) , as well as a method to produce said perylene bisimide compound . Depending on the solvent and reducing agent used, silver nanowires with di f ferent shapes are obtained . Furthermore , this disclosure also relates to the synthesis of silver nanowires in si tu on carbon-based materials , such as carbon nanotubes ( CNT ) .

The present invention proposes to solve the problems in the field and provide a simple method for the production of silver nanowires with industrial potential to be used as conductive filler in fields of application, such as conductive adhesives and conductive inks for electronic applications .

According to the invention, short and long silver nanowires can be stably produced with high yields . Silver nanowires can be advantageous for di f ferent applications , such as production of conductive adhesives or conductive inks . The simplicity of the production methods herein presented may allow industriali zation at very competitive costs .

Furthermore , the use of perylene bisimides of formula ( 3 ) coordinated with silver salts enables the synthesis of silver nanowires with high yields using dimethyl formamide/water ( DMF/H2O) or ethylene glycol (EG) as solvent and reducing agent , with no need to use high molecular weight protective agents , such as PVP .

Brief description of drawings

For easier understanding of this application, figures are attached in the annex that represent the preferred forms of implementation which nevertheless are not intended to limit the technique disclosed herein . Figure 1 shows the reaction of dianhydride ( 1 ) with diamine ( 2 ) to obtain perylene bisimide ( 3 ) .

Figure 2 shows two scanning electron microscopy images of the silver nanowires synthes i zed according to the experimental protocol described in Example 2 .

Figure 3 shows three scanning electron microscopy images of the silver nanowires synthes i zed according to the experimental protocol described in Example 3 .

Figure 4 shows four scanning electron microscopy images of the silver nanoparticles synthesi zed in the presence of multi-walled and single-walled carbon nanotubes according to the experimental protocol described in Example 4 . A relates to silver nanowires in the presence of multi-walled carbon nanotubes and B relates to silver nanowires in the presence single wall carbon nanotubes .

Figure 5 shows four scanning electron microscopy images of the silver nanoparticles synthesi zed in the presence of multi-walled and single-walled carbon nanotubes according to the experimental protocol described in Example 5 . A relates to silver nanowires in the presence of multi-walled carbon nanotubes and B relates to silver nanowires in the presence single wall carbon nanotubes .

Figure 6 shows two scanning electron microscopy images of silver nanoparticles synthesi zed in the presence of singlewalled carbon nanotubes according to the experimental protocol described in Example 6 . Description of embodiments

Now, preferred embodiments of the present application will be described in detail with reference to the annexed drawings. However, they are not intended to limit the scope of this application.

The method for producing silver nanowires comprises the following steps:

- Heating and stirring a mixture of perylene bisimide of formula (3) and a silver metal salt in a 1:25 to 1:35 mass ratio, at a temperature between 130 °C and 170 °C, during 3 h to 14 h, in the presence of a solvent;

- Cooling the solution between 20 and 25°C for 16 h to 20 h;

- Collecting and filtering the resulting precipitate to isolate the silver nanowires.

The silver nanowires of the present invention can also be produced in the presence of cabon-based materials, following the same method.

The method for producing silver nanowires on carbon-based materials comprises the following steps:

- Heating and stirring a mixture of perylene bisimide of formula (3) , silver metal salt and a carbon-based material in a 1:4:2.3 to 1:35:2.3 mass ratio, at a temperature between 130 °C and 170 °C, during 3 h to 14 h, in the presence of a solvent;

- Cooling the solution between 20 and 25°C for 16 h to 2 Oh; - Collecting and filtering the resulting precipitate to isolate the silver nanowires in the presence of the carbon nanomaterial.

In one embodiment, the silver metal salt is selected from silver nitrate or silver acetate.

In one embodiment the solvent is selected from ethylene glycol in a variable amount maintaining the concentration of silver metal salt between 4 mg/ml to 18 mg/ml, or a mixture of dimethylformamide and water in a ratio of 30:1 to 100:1, in a variable amount, maintaining the concentration of silver metal salt between 6 mg/ml to 50 mg/ml.

In the present method the solvent acts as a reducing agent.

The synthesis of silver nanowires was carried out in the presence of FBI of formula (3) coordinated with the silver ion that is reduced in the presence of ethylene glycol or dimethylformamide/water .

In one embodiment the mixture is preferably heated at 150°C.

In one embodiment the resulting precipitate obtained is washed with ethanol and dried at a temperature between 70 °C and 100 °C, preferably 100°C, to obtain dried silver nanowires .

In one embodiment the mixture is sonicated before heating when ethylene glycol is used as solvent.

In one embodiment, when a mixture of dimethylformamide and water is used as solvent, two additional aliquots of the initial amount of water are added every two hours to the mixture under heat.

In one embodiment the cabon-based materials are selected from, but not limited to, carbon nanotubes (CNT) , multiwalled carbon nanotubes (MWCNTs) , single wall carbon nanotube (SWCNTs) , carbon nanofibers and graphene nanoplatelets .

The synthesis of FBI (3) resulted from the combination of the commercially available perylenetetracarboxilic dianhydride with 1 , 3-diaminopentane (Figure 1) at 100 °C.

The possibility to prepare silver nanowires in the presence of carbon-based material, such as CNT was also demonstrated in Examples 4 and 5; Figure 4 and 5.

Method for producing perylene bisimide of formula (3) comprises the following steps:

- Heating and stirring a mixture of 1 , 3-diaminopentane (2) and perylenetetracarboxilic dianhydride (1) in a minimum mole ratio of 2:1, at a temperature between 90 °C to 160 °C, during 3 min to 3 h;

- Adding water in a ratio between 40 ml/g and 120 ml/g per starting reagents;

- Collecting and filtering the resulting suspension to isolate the perylene bisimide formula of (3) .

In one embodiment the perylene bisimide formula of (3) isolated and filtered is washed with water, ethanol, diethyl ether and dried. Once again, the concentration of FBI showed to be determinant for the synthesis of silver nanowires. For reactions carried out in ethylene glycol the range of FBI concentration varied from 0.13 mg/mL to 2.5 mg/mL, the best results were obtained with 0.28 mg/mL (example 3) . In DMF/water the range of FBI concentration varied from 0.26 mg/mL to 2.17 mg/mL and the best results were obtained with 2.17 mg/mL (example 2) .

Parameters such as temperature and reaction time can influence the shape and growth of the silver nanoparticles. The synthesis of silver nanowires was performed in a temperature range from 130 °C to 170 °C and reaction time from 3 h to 7 h. The best results were obtained at 150 °C for 7 h.

The morphology of the silver nanowires depends on the concentration of FBI (3) . The studies showed that, depending on the solvent, different shapes of silver nanowires can be obtained .

In one embodiment, short silver nanowires can be obtained when DMF/H2O is used as solvent (Example 2; Figure 2) .

In another embodiment, long silver nanowires with a length up to 0.5 mm can be obtained when ethylene glycol is used as solvent (Example 3; Figure 3) .

The present invention also relates to a device that is suitable for carrying out the method of producing silver nanowires or a device suitable for carrying out the method of producing perylene bisimide of formula (3) . Herein below, specific examples of the present disclosure will be presented. The examples described below are intended to facilitate the understanding of the present disclosure, however the present disclosure is not limited to these examples .

Examples

Example 1 - Synthesis of FBI of formula (3)

Approximately 10 equiv. (4.83 mL) of 1 , 3-diaminopentane (2) were added to 3.96 mmol (1.56 mg) of perylenetetracarboxilic dianhydride (1) (as shown in scheme of Figure 1) . The mixture was heated at 100 °C under magnetic stirring for approximately 3.5 h. Distilled water was added to the mixture and the suspension was filtered and washed with additional water, ethanol and diethyl ether. The product (FBI) was finally dried under vacuum at 100 °C for 16 h (reaction yield : 98 % ) .

Example 2

In a 50 mL flask, 1.06 mmol (179.3 mg) of AgNOs, 20 mL of dimethylformamide (DMF) and 200 pL of water were added to 0.08 mmol (44.6 mg) of FBI (3) , prepared according to the procedure described in Example 1, and the mixture was maintained under magnetic stirring (100 rpm) at a temperature between 20 and 30°C for 16 h. The reaction proceeded at 150 °C for 7 h under magnetic stirring (50 rpm) and two additional aliquots of water were added during the reaction time, one after 2h and the other after 4 h of reaction. The solution was cooled to 25 °C during 16 h and the precipitated solid was collected by filtration, washed with ethanol and dried at 100 °C under vacuum for 16 h. Final weight: 89.8 mg; reaction yield 79 %. The material obtained was finally observed by scanning electron microscopy (Figure 2) . Example 3

In a 50 mL flask, 0.01 mmol (5.6 mg) of FBI (3) prepared according to the procedure described in Example 1 and 1.04 mmol (177.4 mg) of AgNO3 were dissolved in 20 mL of EG under sonication in an ultra-sound bath at a temperature between 20 and 30°C for 5 min. After sonication, the reaction was carried out at 150 °C for 7 h under magnetic stirring (50 rpm) . The solution was cooled to 25 °C during 16 h and the precipitated solid was collected by filtration, washed with ethanol and dried at 100 °C under vacuum for 16 h. Final weight: 105.3 mg; reaction yield: 93 %. The material obtained was finally observed by scanning electron microscopy (Figure 3) .

Example 4

In a 50 mL flask, 1.06 mmol of AgNO3 and 100 mg of CNTs (MWCNTs or SWCNTs) were combined with 0.08 mmol of FBI (3) prepared according to the procedure described in Example 1 and added to 20 ml of dimethylformamide with 200 .1 of water. The mixture was maintained under magnetic stirring (300 rpm) at a temperature between 20 and 30°C for 16 h. The reaction proceeded at 150 °C for 7 h under magnetic stirring (100 rpm) . The solution was cooled to a temperature between 20 and 25°C for 16 h and the precipitated solid was collected by filtration, washed with ethanol, dried at 100 °C under vacuum for 16 h. Final weight: 240 - 260 mg; reaction yield: 90 - 95 %. The material obtained was finally observed by scanning electron microscopy (Figure 4) .

Example 5

In a 50 mL flask, 0.08 mmol of FBI (3) prepared according to the procedure described in Example 1, 1.04 mmol of AgNCh and 100 mg of CNTs (MWCNTs or SWCNTs) were dissolved/dispersed in 20 mL of EG under sonication in an ultra-sound bath at a temperature between 20 and 30°C for 1 h. After sonication, the reaction was carried out at 150 °C for 7 h under magnetic stirring (50 rpm) . The solution was cooled to 25 °C during 16 h and the precipitated solid was collected by filtration, washed with ethanol, dried at 100 °C under vacuum for 16 h. Final weight: 190 - 240 mg; reaction yield: 40 - 87 %. The material obtained was finally observed by scanning electron microscopy (Figure 5) .

Example 6

The production of silver nanowires in the presence of carbon nanotubes was conducted in three main steps:

1) Complexation of silver ion with FBI (3)

A solution 1 of synthesized FBI (0.53 g; 0.94 mmol) , in DMF (40 mL) and another solution 2 of AgNO3, (0.32 g; 1.88 mmol; 2 equiv.) in ethanol (20 mL) , were stirred for 15 min at room temperature. Solution 2 was added to solution 1 and the resulting mixture was stirred at room temperature for 8 days. At the end of the reaction, diethyl ether and n-hexane (1:1) were added and the solid was filtered, washed with diethyl ether and n-hexane and dried for 24h at 100°C under vacuum. Final weight of PBI-Ag: 457.4 mg.

2) Adsorption of PBI (3) previously complexed with silver ion on the surface of SWCNTs

A suspension 1 of functionalized SWCNTs (73.4 mg) in 8 mL of DMF and a solution 2 with the PBI— Ag (36.4 mg) , in 6 mL of ethanol, were stirred for 15 min between 20 and 30 °C. Solution 2 was added to suspension 1 and the resulting mixture was stirred at 20 to 30 °C for 1 day. At the end of