Nanocomposites Based on Dendrimers and Layered Molybdenum Disulfide

Nanocomposites consisting of molybdenum disulfide (MoS 2 ) and an organometallic dendrimer were synthesized by taking advantage of the exfoliating/restacking properties of lithiated molybdenum disulfide (LiMoS 2 ). Based on the molecular weight of the dendrimer, nine different mole ratios of MoS 2 to dendrimer were utilized in order to investigate the upper and lower limit of the dendrimer loading into the restacked MoS 2 . The developed nanocomposites were characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and variable-temperature electrical conductivity measurements. Our studies revealed that the ideal condition for preparing reproducible monophasic systems is at low dendrimer concentration, no greater than 1:0.125 mole ratio of MoS 2 to dendrimer, and no lower than 1:0.002 mole ratio of MoS 2 to dendrimer. Biphasic systems can be produced at mole ratio of MoS 2 to dendrimer higher than 1:0.125. Additionally, the average crystallite size decreased as the mole ratio of the MoS 2 to dendrimer was increased. Specifically, a change from 1:0.002 to 1:0.5 resulted in a noticeable decrease from 365 to 155 Å. The electrical conductivity of the nanocomposites drops as the amount of dendrimer increases. Variable-temperature conductivity data are consistent with a variable-range hopping model.