Composition of hyperbranched conjugated polymers with nanosized cadmium sulfide particles

On the basis of a series of hyperbranched conjugated polymers (HPV) synthes ized in our laboratory, the composition of HPV with nanosized cadmium sulfi de (CdS) particles is investigated by means of static and dynamic fluoresce nce spectroscopies and atomic force microscopy (AFM). The apparent associat ion constant between HPV and CdS can be obtained from the plot of the relat ive fluorescence quantum yields versus the reciprocal concentrations of CdS . The electron injection rate from excited HPV to the conduction band of Cd S can also be calculated. Both the constant and the electron injection rate are related to the chain length of the alkoxy group on the connecting modu les, leading to the conclusion that the modification of HPV at certain subs titution sites can control the interaction between HPV and nanosized CdS pa rticles. The CdS particles with different surface charge may result in sign ificant changes of the apparent association constants, which shows that the electrostatic force probably plays a key role in the combination of HPV wi th CdS. AFM images indicate that films with good qualities can be formed on a mica substrate using the composite of HPV with nanosized CdS particles. The presence of HPV can decrease the self-aggregation of cadmium sulfide pa rticles.