Electrical double percolation and carbon nanotubes distribution in solution processed immiscible polymer blend

Carbon nanotubes (CNT) were dispersed in immiscible (50/50 vol/vol) polycarbonate (PC)/polystyrene (PS) blend by solution processing. The microstructure, electrical properties and conduction mechanism of the blend were investigated as function of CNT content. Optical microscopy and transmission electron microscopy were used for microstructure analyses. At low nanofiller loadings, the PC/PS blend was found to exhibit a phase-separated morphology with a domain size in the range of tens of microns. The location of CNT in the immiscible blend was found to be function of the CNT concentration. At 0.05 wt% CNT loading, CNT was found to preferentially reside in the PS phase. However, at 5 wt%, the nanotubes were observed in both phases without preferential localization. Regardless of CNT location, good level of nanotubes dispersion was observed. The selective localization of CNT in the PS phase at low filler loading and the proper dispersion of CNT led to construction of conductive network within the polymer blend at CNT content of only 0.05 wt% (∼0.034 vol%).