Effects Of Magnetic Field On Morphology And Properties Of Conductived Polyaniline Nanofibers By Emulsion Polymerization

Polyaniline （PANI） has the the most interest due to its low cost, ease of synthesis,good environmental stability and unique oxidation resistance. In addition, as one of themost promising commercial, PANI has promising applications in various fields, such asstorage battery, marine anticorrosive, electromagnetic shielding and sensors, and etc。Many synthesizing methods such as electrospinning, hard/soft templates,interfacial polymerization and chemical oxidative polymerization have been developedfor preparing polyaniline. Chemical oxidative polymerization is one of the traditionalmethods for synthesizing polyaniline, people have examined how the morphology ofpolyaniline particles evolves in the traditional chemical oxidative polymerization. Studyindicates that PANI nanofibers are indeed existence in the conventional polymerizationprocess, however, renucleation of polyaniline on their surface rapidly producesagglomerates as the reaction proceeds. The key to obtaining pure polyaniline nanofibersis to prevent the subsequent overgrowth of polyaniline on the preformed nanofibers. Forthe present, the formation mechanism of PANI nanofibers in chemical oxidativepolymerization is still unclear.Due to PANI has anisotropic diamagnetic susceptibility, its internal structure unitprefer to grow and arrange with the particular direction in the presence of magnetic field,that is to say, PANI will take a certain degree of orientation, which makes PANImolecular chains aligned more orderly and with more regular structure; In addition,magnetic field will also influence in PANI’s macroeconomic property （such aselectrochemical performance） via influence in micro-structure. So far, it is rarelyreported that about the effect of magnetic field in the grow and performance of PANInanofibers synthesized by emulsion polymerization. In consideration of emulsionpolymerization is one of the effective methods for prepared conducting PANInanomaterials, this paper aims to explore the effect of magnetic field on the formationand morphology of PANI nanofibers.PANI nanofibers was prepared by emulsion polymerization with APS and NaClOas composite oxidant,_SDBS as emulsifying agent,_An as oil phase, HCl as aqueousphase, the effect of the reaction time, concentrations of HCl, concentrations of APS,sodium dodecylbenzenesulfonate (_SDBS) and NaClO on electrochemical properties andyield of PANI was discussed. Compare the micro morphology, electrochemical properties, yield, FI-IR and UV-vis of PANI which synthesized by APS alone andcomposite oxidant. In addition, the effect of magnetic field in the micro morphology,electrochemical properties, FI-IR and XRD were also discussed. The conclusion was asfollow:（1） By comparing the single factor under conditions of electrochemical propertiesand yield, it was shows that the optimal properties of PANI nanofibers was achievedwhen the reaction time was5h, the concentrations of HCl is1.5mol/L, the molar ratioof aniline （An） to APS was8:7, the molar ratio of An to_SDBS was10:4and NaClO was5%.（2） Compared with the PANI synthesized by APS alone, the PANI synthesized byAPS and NaClO composite oxidant has higher redox peak current and higherconductivity. UV-Vis and FT-IR indicated that the composite oxidant was not effect thestructure of PANI.（3） Compared with the PAN synthesized in the absence of magnetic field, the PANInanofibers synthesized in the presence of constant magnetic field has more orderarrange, large length/diameter ratio and the micro orientation was more obvious. thePANI nanofibers synthesized in the presence of constant magnetic field has higherconductivity and the crystallinity of PANI was better.