Method for continuously fabricating silver nanowire

Abstract

The invention discloses a method for continuously fabricating silver nanowires. The method mixes a glycol solution of a silver salt and a glycol solution of a polyvinyl pyrrolidone, and the mixed solution reacts in a temperature range and a time range to form the silver nanowires. The polyvinyl pyrrolidone has high boiling point and reduction ability so as to reduce the silver salt to the silver nanoparticles, and simultaneously, the polyvinyl pyrrolidone can provide barriers for limiting the particle growth. Besides, the oxygen functional groups on the long chains of the polyvinyl pyrrolidone can keep the stably one-dimensional growth of the silver nanoparticles to form the silver nanowires during the aging process.

1 . A method for continuously fabricating silver nanowires, the method comprising the following steps of:
 feeding a first solution into a reacting tank and an aging tank, and heating the first solution to a first temperature range in the reacting tank and the aging tank;   continuously feeding a silver-salt solution and a protecting agent solution into the reacting tank according to a ratio, the silver-salt solution and the protecting agent solution mixing with each other in a second temperature range and staying in the reacting tank for a first staying duration to form a second solution;   feeding the second solution into the aging tank and making the second solution to stay in the aging tank for a second staying duration to form a third solution; and   purifying the third solution to obtain at least one silver nanowire.   
     
     
         2 . The method of  claim 1 , wherein the first solution is a glycol solution. 
     
     
         3 . The method of  claim 1 , wherein the silver-salt solution is formed by dissolving a water-soluble silver salt in a first solvent. 
     
     
         4 . The method of  claim 3 , wherein the silver-salt solution is formed by dissolving a silver nitrate in the first solvent. 
     
     
         5 . The method of  claim 3 , wherein the silver-salt solution is formed by dissolving a silver acetate or a silver nitrite in the first solvent. 
     
     
         6 . The method of  claim 3 , wherein the concentration of the water-soluble silver salt of the silver-salt solution is larger than 0.5 wt %. 
     
     
         7 . The method of  claim 4 , wherein the protecting agent solution is formed by dissolving a polyvinyl pyrrolidone in a second solvent. 
     
     
         8 . The method of  claim 7 , wherein the first solvent and the second solvent are glycol. 
     
     
         9 . The method of  claim 8 , wherein the step for purifying the third solution comprises the following steps of:
 feeding an excess of acetone into the third solution to mix with the glycol to make the third solution to form a clear liquid portion and a precipitate portion;   removing the clear liquid portion and dissolving the precipitate portion in a hot water to form a fourth solution;   processing the fourth solution by ion exchange process to form a fifth solution;   repeatedly heating, stirring, and solid-liquid separating the fifth solution for a plurality times to obtain a sixth solution; and   spray drying the sixth solution to remove the water of the sixth solution to obtain a powder of the at least one silver nanowire.   
     
     
         10 . The method of  claim 9 , wherein the volume ratio of the acetone to the third solution comprises 2˜6. 
     
     
         11 . The method of  claim 7 , wherein the weight ratio of the polyvinyl pyrrolidone to the silver nitrate comprises 0.5˜6 when the silver-salt solution and the protecting agent solution are fed into the reacting tank. 
     
     
         12 . The method of  claim 7 , wherein the molecular weight of the polyvinyl pyrrolidone of the protecting agent solution comprises 5000˜360000. 
     
     
         13 . The method of  claim 1 , wherein the silver-salt solution and the protecting agent solution are fed into the reacting tank by continuous feeding. 
     
     
         14 . The method of  claim 1 , wherein the first temperature range comprises 170° C. to 180° C. 
     
     
         15 . The method of  claim 1 , wherein the second temperature range comprises 140° C. to 180° C. 
     
     
         16 . The method of  claim 15 , wherein the second temperature range comprises 150° C. to 170° C. 
     
     
         17 . The method of  claim 1 , wherein the first staying duration comprises a range of 10 minutes to 30 minutes. 
     
     
         18 . The method of  claim 1 , wherein the second staying duration comprises 30 minutes. 
     
     
         19 . The method of  claim 1 , wherein the first temperature range is provided by micro-wave heating. 
     
     
         20 . The method of  claim 1 , wherein the second temperature range is provided by micro-wave heating.