In Situ Synthesis And Electromagnetic Properties Of PANi/Fe₃O₄ On The Surface Of Tetra-Needle Like ZnO Whisker

After tetra-needle-like ZnO whisker (T-ZnOw) being modified,polyaniline (PANi) and Fe₃O₄ were synthesized in situ on the surface of T-ZnOw,resultinig in the formation of core-shell composoites of T-ZnOw/PANi and T-ZnOw/Fe₃O₄/PANi.In the preparation process of the T-ZnOw/PANi core-shell composite,T-ZnOw and aniline were used as the raw materials,tetraethyl orthosilicate (TEOS) and y-aminopropyltriethoxysilane (APTES) were used as the modified reagents,ammonium peroxydisulphate (APS) and p-methylbenzene sulfonic acid (TSA) were used as the initiation and the dopant,respectively.The best condition for synthesizing of T-ZnOw/PANi core-shell composite was as follows,firstly,T-ZnOw was modified by TEOS and APTES,then aniline (AN) was in situ synthesized on the surface of the modified T-ZnOw.The volume ratio of ethanol to H₂O was 7:3,the molar ratio of T-ZnOw to aniline was 2:1,and the concentration of TSA was around 0.15-0.20 mol/L.The results showed that the T-ZnOw/PANi composite had much better thermal stability than that of polyaniline.The electrical conductivity of the T-ZnOw/PANi core-shell composite was at the range of 10^-3-10^-2 S/cm,which was much higher than T-ZnOw,and only 1-2 orders of magnitude lower than that of polyaniline in the same doped.The test of the electromagnetic parameters of the samples indicated that the dielectric loss of T-ZnOw/PANi composite was much higher than those of polyaniline in the same doped and T-ZnOw,moreover,with the increase of the conductivity,the dielectric loss of the composite was much higher.Similar to the situation of the electromagnetic parameters,the microwave reflectivity of the T-ZnOw/PANi composite had the best microwave absorption ability among the three samples,and the microwave absorption ability of the T-ZnOw/PANi composite was much higher when the thickness increased from 1mm to 3 mm.T-ZnOw/Fe₃O₄/PANi core-shell composite was synthesized via two steps.Firstly,nanosized magnetic particles were in situ synthesized on the surface of modified T-ZnOw,with T-ZnOw and FeCl₂ were used as the raw materials,polyethylene glycol (PEG) was used as the surface active reagent.Secondly,polyaniline was grafted on the surface of T-ZnOw/Fe₃O₄ composite,and the APTES was the self-assembled monolayer.The results showed that the thermal stability of T-ZnOw/Fe₃O₄/PANi composite was little lower than that of T-ZnOw/PANi composite.The T-ZnOw/Fe₃O₄/PANi composite was paramagnetism material.The electric conductivity of T-ZnOw/Fe₃O₄/PANi composite was the same order of magnitude as T-ZnOw/PANi composite,just little lower than that of it.The test of the electromagnetic parameters of the samples indicated that the dielectric loss of T-ZnOw/Fe₃O₄/PANi composite was much higher than T-ZnOw/Fe₃O₄ composite and its magnetism loss was much higher than T-ZnOw/PANi composite,suggesting that the T-ZnOw/Fe₃O₄/PANi composite would have much better microwave absorption ability compare with T-ZnOw/PANi and T-ZnOw/Fe₃O₄ composites.