Synthesis Of Silver Microstructures And Their Applications In The Preparation Of Conductive Polymer Materials

As one of the pillars of modern science and technology,new materials attract extensive attention in recent years.As a branch of new materials,conducting polymer-based materials have been widely used in many fields,such as modern electronics industry and information industry,and have become one of the hot topics in new materials research.Based on those,the following works are mainly carried out in this paper.(1)With sodium citrate and silver nitrate as raw materials,two kinds of silver citrate with special morphologies were obtained by changing the experimental conditions.Then two kinds of spherical and lump silver microstructures were synthesized by rapid reduction with sodium borohydride under the wet chemical reaction.The results show that at room temperature,when both the concentration of silver nitrate and citric acid solution is 1% and the volume ratio is 1:1,regularly globular silver citrate can be obtained.Under this condition,the silver powder formed under the rapid reduction of silver citrate by high concentration of sodium borohydride(10%)displays porous and spherical morphologies;At 140 ?,when the concentration of silver nitrate and citric acid solution is 3% and 10% and the volume ratio is 1:1,regularly lumpy silver citrate can be prepared.In that case,lumpy silver microstructures can be synthesized by the rapid reduction under the same condition.(2)Two kinds of conductive silver paste were firstly prepared by using porous spherical and lump silver powders as conductive phase and epoxy resin as matrix,respectively.and then their properties were tested.The results show that the silver paste has the best hardness(3H),adhesion(0 grade)and conductivity(electrical conductivity is 500s/cm and block resistance is 100 m ?/?)when the content of porous spherical silver powder is 55%-70%,55%-65% and 75%,respectively.While the content of lump silver powder is 55%-70% and 55%-60%,respectively,the silver paste has the best hardness(3H)and adhesion(0 grade).As the content of lump silver powder is 75% and 70%,the silver paste can exhibit the highest conductivity(1700s/cm)and lowest block resistance(78.5 m?/?).Those two kinds of silver pastes have good thermal conductivity.Compared with the conductive silver paste prepared by spherical silver powder,the conductive silver paste prepared from lump silver powder is superior in overall performance.(3)Two kinds of stretchable and flexible conductors were prepared by using porous spherical and lump silver powders as the conductive phase and fluoro rubber as the matrix,and their properties were also tested.When the content of porous spherical silver powder is 60%,as-prepared flexible conductor has the highest conductivity(4300 s/cm)and lowest block resistance(47.3 m?/?).As the tensile ratio is 2,theconductivity of that conductor is 357 s/cm and the block resistance is 628 m?/?).For the flexible conductor fabricated by using lump silver powder,while the content ofsilver powder is 50%,the obtained flexible conductor has the highest conductivity(3900 s/cm)and lowest block resistance(46.3 m?/?).As the tensile ratio is 2,the conductivity of that conductor is 246 s/cm and the block resistance is 703m?/?).These results indicate that those two kinds of flexible conductors can display good electrical conductivity after stretching.