solution with the assistance of dispersion agents, dispersion agents
cover an isolatedMWNT chain and stabilize the chain in the solution
without re-aggregation. In the dispersion agent-assisted MWNTs
in aqueous solution, the polar parts of dispersion agents form the
interface with water. In spite of similarity of anionic head groups
of SDS and PSS, their molecular weights are very different with
each other. Krishnamoorti et al. [21] suggested that chains of dispersion
agents are randomly adsorbed on the sidewall of CNT with
no preferential arrangement of the head and tail. Therefore, MWNT
dispersion with PSS, in which PSS has higher anionic head groups
per unit chain length than oligomeric SDS, shows more anionic
character than MWNT dispersion with SDS. As considering that the
electrostatic interaction is a critical driving force to make nanocomposites
of GNPs and MWNTs, it is understandable that PSS is more
effective dispersion agent to prepare Au-MWNT nanocomposite
than SDS.
Au-MWNT nanocomposite of Fig. 2(d), in which MWNTs were
dispersed in an aqueous solution with PVP assistance, showed that
GNPs were most evenly distributed on the MWNT chains among
three Au-MWNT nanocomposites. Dissimilarly with SDS and PSS,
PVP showed highly non-ionic, polar characteristics in an aqueous
solution. Therefore, binding of GNPs and MWNTs dispersed with
PVP could be somewhat different from the case of MWNT dispersions
with SDS or PSS. The improved distribution of GNPs in the