Advanced Functional Materials, Vol.18, No.3, 432-440, 2008
Structural, electrical, and thermal Behavior of graphite-polyaniline composites with increased crystallinity
Conductive materials are at the forefront of materials science research because of the large number of applications that have been developed around their interesting and unique properties. This work reports for the first time a correlation between the structural, electrical, and thermal behavior of novel graphite-polyaniline (G-PANI) composites with electrical conductivities greater than either of the individual components. The G:PANI mass ratio was varied during synthesis of the composites (90:10,95:5, 96:4, 97:3, and 98:2 G:PANI mass ratios) and the highest electrical conductivity was determined for the composite having a G:PANI mass ratio of 96:4. The structural changes related to this increase in electrical conductivity were clearly reflected by the Raman spectra of the new composites, which indicated an improved crystallinity through a better stacking along the c-axis of graphite when PANI was present (as evidenced by the G and 2 x D modes at 1582 and 2684 cm(-1)). X-ray diffraction data showed a slight increase in the (0 0 2) graphite crystal plane distance that was associated with a dilute stage intercalation or a possible "pseudo-intercalation" of the polymer species between the graphite layers facilitating charge transfer in the composites. It is proposed that polyaniline acts as a charge transfer component between basal planes of graphite. Thermogravimetric analyses of the samples showed similar trends for the thermal stability in accordance with the electrical conductivity, the Raman and X-ray diffraction data. The potential impact of this work is evident in the many areas that utilize graphite as conductive filler in electrically conducting materials. The composites can be used for a large number of applications in nanoelectronics, electromagnetic interference shielding, rechargeable batteries or as other advanced nanocomposite materials With improved electrical, structural, and thermal properties.