Synthesis and self-assembly hyper-branched pattern aggregation of monodisperse polyvinylpyrrolidone-stabilized CdS nanocrystals

Monodisperse polyvinylpyrrolidone(PVP)-stabilized CdS nanoc rystals were synthesized by spray precipitation method(SPM) at room temperature. Their morphology was examined by scanning electron microscopy and the crystal structure of them was characterized by X-ray diffractometry. The PVP-stabilized CdS nanocrystals were characterizated by FTIR. The PVP-stabilized CdS nanocrystals synthesized by SPM formed homogeneous spherical particles approximately 10 nm in diameter. The nanocrystals exhibit a zinc blende crystal structure. we comfirm the polyvinylpyrrolidone exists in the PVP-stabilized CdS nanocrystals by FTIR. In addition, this paper reports that the PVP-stabilized CdS nanocrystals are successfully assembled hyper-branched pattern in homogeneous ethanol solution by solvent evaporation. We have studied the whole self-assembly progress by SEM and given a reasonable self-assembly mechanism. Our research result is that the system energy and entropy cooperates to make the nanocrystalline spontaneously reunite hyper-branched pattern.