| The polypyrrole(PPy)is widely used in the fields of electrical cell,electromagnetic shielding,electrode material in consideration of its electrical conductivity.Meanwhile,the conductivity of PPy can be improved when combined with nano silver,through which PPy could meet the increasing requirement about conductivity performance.In this paper,PPy/Ag composite films on PET were prepared through directly polymerization of the pyrrole monomer with the oxidation of silver nitrate solution.And then the obtained films were characterized and tested about their conductivity and stability.The concrete research is as follows:Firstly,the pretreatment processes were studied about their effect on the conductivity of composite film,and the polymerization method and polymerization process were also researched.Experiments showed that the optimum pretreatment processes were:50 g·L-1 NaOH,5 g·L-1 SDS,30℃ static degreasing 10 min,and 15 g·L-1 KMnO4,20 g·L-1 H2SO4,0.1 wt%emulsifier,0.5 wt%coupling agent,30℃ static roughing 3 min,roughing 6 times.The optimum polymerization method and process were mixing pyrrole solution directly with silver nitrate solution and static polymerization respectively.Secondly,the polymerization temperature,time,pH value,pyrrole monomer concentration as well as the molar ratio between pyrrole and silver nitrate were researched to determine their impact on conductivity and deposition rate of composite film.And on this basis,orthogonal experiment was adopted to find out the best experimental conditions for preparing high conductivity PPy/Ag composite film,with electrical conductivity,sheet resistance and deposition rate being the experimental index.The optimal conditions for high conductivity PPy/Ag film were as shown below:temperature 30℃,pH 2.6,polymerization 4 h,pyrrole 1 mol·L-1,molar ratio 1.The obtained film under this condition had the sheet resistance of 0.0027 KΩ,electrical conductivity 4141.74 S·m-1,and deposition rate 5.51 mg·cm-2·h-1。Thirdly,the structure and morphology of these obtained PPy/Ag composite films were characterized.FTIR,Raman and XRD results showed that silver nanoparticles were actually combined with PPy,the Ag+ was actually reduced as silver nanoparticles,and the PPy in the composite had a low doping level with NO3-.SEM showed that the film prepared under the optimal condition held good conductivity owing to the uniformly distribution of silver nanoparticles into PPy,the recombination particle was core-shell structure,with size about 1.0 μm～2.0 μm.Finally,the performance of the obtained PPy/Ag composite films were tested.Linear scanning cyclic voltammetry,TG,thermal shock tests and environmental stability tests showed that the prepared composite film under optimum condition had preferable conductivity and conductivity stability which was 40 times higher than that of PPyCl under the same prepration conditions and can be preserved for more than 200 d at room temperature.And the composite film also exhibited good heat resistance with 10.44%decreases of conductivity at 150℃,which exhibited the properity of metal materials.What’s more,the decomposition temperature of the film was 270℃(in air)which was increased by 40℃owing to the incooperation of silver nanoparticles.However,the conductivity loss of the composite film reached to 98.82%when treated with ultrasonic thermal shock,which is to be enhanced in our later work.Concisely,PPy/Ag composite films were prepared after research of pretreatment,polymerization process and process optimization.And the desired composite film had high conductivity,conductivity and thermal stability with silver nanoparticles and polypyrrole completely covered. |
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