Preparation Of Electric Field Induced Material And Its Electromagnetic Property Investigation

Conjugated polymers (CPs) generally exhibit at least two oxidation states, neutral or uncharged forms having low conductivity and charged (usually oxidised) forms being highly conducting. The low conductivity forms of CPs are highly transmissive to microwaves, whilst the conducting forms are highly reflective. Thus, a microwave’smart window’capable of controlling the transmission of microwave radiation requires that the CP is able to undergo a redox reaction under the influence of an applied stimulus. The main aim of the research work is to develop a new material for their potential application in electromagnetic shielding (EMS) under the influence of electric field. The research work consists of:(1) The polyanilines were prepared by solution polymerization and micellar chemical polymerization. The conductivity of polyaniline prepared by the latter route is higher than that of the polyaniline by the former route. However, the former one is harder to be dispersed. The poly(3,4-ethylenedioxythiophene) was prepared and the conductivity is14S/CM.(2) The carbon nanotubes encapsulated by polyaniline(PANI) and poly(3,4-ethylenedioxythiophene)(PEDOT) have been synthesized by in-situ polymerization. The structure and conductivity of the composites were studied. It is important to point out that the conductivity increase with the decrease of carbon nanotube and the conductivity reach100S/CM when carbon nanotube is added to composites by1wt%.(3) Mineral clay(MMT) is organically modified through ionic exchange method. The organ-MMT used in intercalation composites was prepared. The structure of intercalation composites was studied.(4) Polymer electrolyte(LiBF4/PEO) containing organ-MMT was prepared, and another sample containing propylene carbonate (PC) and ethylene carbonate(EC) as plasticizer was prepared. The results indicate that ionic conductivity is higher than other contents when MMT is added to electrolyte by3wt%. In addition, increasing the plasticizer content also improve the ionic conductivity.(5) Polymer electrolyte(LiBF4/PEO) was prepared using poly(ethylene oxide) of different molecular weight. Ionic conductivity decreased as the molecular weight increasing. The result indicate that Ionic conductivity will be increased when the PEO which molecular weight is5×104or10×104is added to the PEO whose molecular weight is1×106and5×106. (6) Polymer electrolyte(LiBF4/PEO) was prepared, which containing organ-MMT、propylene carbonate (PC)and ethylene carbonate(EC) simultaneously. The additive of MMT and plasticizer improve the ionic conductivity to5×10-4S/CM when organ-MMT is3wt%, plasticizer is15wt%.(7) The composites was prepared using lithium tetrafluoroborate(LiBF4)、 propylene carbonate (PC) and ethylene carbonate(EC)、copper tetrafluoroborate(CuBF4)、copper metal particle and conducting composites. Then the composites was sprayed onto substrate which is glass-fiber reinforced plastic and is millimeter in thickness to form coat.(8) A device was designed to test electromagnetic shielding(EMS) property. The composite coat was test by applied5V field. The result showed that the electromagnetic shielding (EMS) property changed when electric field is applied to the composites, which indicate that cell reaction was occurred in the composites and conducting polymer has undergo a redox reaction.