Synthesis of PbS nanoclusters within block copolymer nanoreactors

We have demonstrated the synthesis of PbS nanoclusters within the microphase-separated films of diblock copolymers containing carboxylic acid units on one of the blocks. Lead was selectively sequestered into the acid containing domains by treating the polymer films with tetraethyllead, and PbS was formed by subsequently treating the films with H2S. The PbS nanoclusters were characterized by X-ray diffraction, X-ray fluorescence, electron microscopy, and UV-vis spectroscopy. The cluster size could be controlled by varying processing parameters such as temperature, the presence of coordinating bases, and the H2S exposure time. Increasing the size of the nanoreactors increased the cluster size. The universal cluster synthesis scheme enabled multiple passes through the process, which were used to increase the cluster size and which could in principle be used to passivate the surface of the PbS cluster or to produce mixed semiconductor clusters.