Electron microscopic studies on disintegration of core/shell polymer structure during heat treatment process in carbon nanotube preparation by polymer blend technique

抄録

The polymer blend technique has been revealed to give a poor yield in the preparation of carbon nanotubes (CNTs) by spinning three-layered core/shell polymer particles having different thermal decomposition properties. In order to elucidate the reason for the low yields obtained by this method, we carried out the present study on employing three-layered core/shell particles, (core) PMMA / PAN-PMAA / PMMA (shell), with electron microscopic techniques. The core/shell structure was not disintegrated by the stabilization and carbonization processes. The influences of the copolymer composition of the carbon precursor polymer (CPP), PAN-PMAA, on the deformation of the core/shell structures were studied. When the concentration of PMAA in the PAN-PMAA copolymer is 3 mol%, the core/shell structure was retained, but when the concentration of PMAA was increased to 7.5 mol%, the core/shell structure disintegrated. By using a copolymer with 4 mol% PMAA, a hollow cigar-like nanostructured carbon was formed; this can be considered to be an indication for the formation of a CNT. Thus, the copolymer composition was found to be an important parameter for the preparation of CNTs by the polymer blend technique. The results obtained in this study indicated the possibility of obtaining CNTs by properly tuning the copolymer composition of the CPP.