Studies On Preparation And Properties Of Electroless Silver-plated PAN Nanofibers

With the increasing development of science and technology, studies on composite nanofibers has drawed more and more attentions. Electrospinning technique is a novel method to prepare nanofibers, with the use of chemical plating method, the nanofibers’surface can be metallized, significantly improve it’s performance. The electroless sliver plating does not need current, the metal ions in electrolyte solution is reduced by reducing agent and then become uniform, thickness and good density metal plating on nanofibers.In this thesis, whether electroless sliver plating is feasible is studied firstly. The change of Gibbs free energy of electroless sliver plating reaction is-323.65KJ/mol under standard condition, it shows that electroless plating sliver is completely feasible when using glucose as reducing agent. In addition, from the angel of electrochemical analysis, the standard electromotive force of electrolss sliver plating reaction is1.251V when using ammonia as complexing agent, it also shows that electroless plating sliver is feasible.Then with the technique of electrospinng, PAN nanofibers is prepared, using low temperature oxygen plasma as etching method. When the plasma rough treatment pressure is20Pa, the power for the40W, the processing time is90S, coarse fiber surface can adsorb large agglomerates of colloid palladium which will be center of the catalytic reaction. When palladium chloride concentration is0.2g/L, stannous chloride16g/L, hydrochloric acid150ml/L, temperature of30degrees, the time for5min to obtain the proper sensitization and activation technology.Also studied the method of doping silver nitrate to the spinning solution, and then with the reducing solution silver nitrate will be reduced to Elemental silver and plating on nanofibers, this granular elemental silver will be catalytic agent on electroless plating silver reaction. When polyacrylonitrile spinning solution is12wt%, it fits in different amounts of silver nitrate added to the spinning solution, which were added to the mass fraction of2%,4%,6%,8%. etc., according to still restore the surface to be covered with liquid granular elemental silver, silver in the fiber surface chemical reaction, when the spinning solution of silver nitrate in the amount of doping more for a long time, get the better silver fiber membrane morphology, electrical conductivity the better. And further discussed the pH value, complexing agent concentration of ammonia’s effections on electroless sliver plating. The results show that:when the pH value is13.0, the complexing agent concentration of ammonia is100ml/L, we can get a good coating surface morphology, the conductivity of the nanofibers is also very well.Furthermore, properities of silver-plated PAN nanofibers prepared by the two methods were also researched. The result indicated that after silver-plated the nanofibers have good conductive properties, antibacterial properties, UV and electromagnetic shielding performance. Doping in the spinning solution after the chemical reduction of silver nitrate by silver’s performance in all aspects of fiber membrane is good with the spinning solution increases the amount of silver nitrate showing a growing trend, and8%doped of silver nitrate will get the final plating fiber membrane performance but also significantly better than the pure polyacrylonitrile coarsening after chemical sensitization of silver nanofiber membrane performance. Doped with8%silver nitrate of silver to the final fiber membrane have a significant increase in electrical conductivity, electrical conductivity of19×102Scm-1, against gram-negative bacteria and Gram-positive bacteria typical of E. coli and Staphylococcus Staphylococcus aureus inhibition rate reached100%, with very good inhibitory effect; the UPF value is greater than120, far more than50, and can be used as a nano-level "anti-UV products"; In the electromagnetic wave frequency, the electromagnetic shielding effectiveness value reached more than20dB during1000MHz～3000MHz, which meas the product can shield over99.6%of the electromagnetic radiation.