Preparation Of Polyimide/Silver Composite Nanofibers Via Electrospinning

Polyimide/silver(PI/Ag) composite nanofibers were prepared by electrospinning from polyamide(PAA)/silver salt solution in this paper. Influencing factors to electrospinning process and fibers were discussed, including solvent, content of PAA, different silver salt solution, thermal curing and content of silver. Viscosity and conductivity of different resin solutions were characterized. Fibers and silver particles were characterized by FTIR, XRD, SEM, TEM, etc.Feasibility of electrospinning from solutions of different solvents were compared, finding that N,N-dimethylformamide(DMF) is more fit for electrospinning than N,N-dimethylacetamide(DMAc). The apparent viscosities of PAA solutions were 700mPa·s to 4200mPa·s when the contents of PAA were 8 wt.% to 14 wt.%. The diameters of PI fibers containing less dropping were uniform when the contents of PAA were 10 wt.% and 12 wt.%. SEM photos indicated that fibers from PAA/AgTFA solution had uniform diameters, less dropping and less conglutination than that from PAA/ AgNO₃ solution.The PAA/AgTFA solution containing 10 wt.% PAA was electrospun at a positive voltage of 15 kV, a working distance of 10 cm and a solution flow rate of 0.2 ml/h by a needle of 6.5mm inner diameter. The PI/Ag fibers were taken out after curing for 3 hours. The average diameters of the fibers, in which Ag were 0, 1, 2, and 7 wt.%, were 200, 190, 180, and 60 nm, respectively. The average diameters of the Ag particles were 10, 12, and 14-20 nm when 1, 2 and 7 wt.% Ag were doped, respectively. Face-centered-cubic silver crystallite was formed. When the content of Ag did not exceed 2 wt.%, the largest stretching stress of parallel PI/Ag fibers was 5-9MPa.