Controlling macrovoid formation in wet-spun polyaniline fibers

The mesoscopic morphology of wet-spun polyaniline fibers determines their mechanical strength. Macrovoid formation in the coagulation bath is responsible for poor mechanical properties of these fibers. The effects of polymer concentration, coagulation bath temperature, polymer molecular weight and coagulant on the morphology of wet-spun polyaniline fibers have been investigated. The fibers were spun from concentrated solutions of low/medium and medium molecular weight emeraldine base dissolved in N-methyl-2-pyrrolidinone containing heptamethyleneimine as a gel inhibitor. The impact of the fiber morphology on the mechanical properties of the fibers prepared under different conditions is studied. A wet-spinning method, which minimizes macrovoid formation in the polyaniline fiber, is reported, and consequently the strength of the unstretched polyaniline fibers increased dramatically.