(95r) Formation of Nano-Composites by Using Ionomers: Lead Sulfide and Cadmium Sulfide

Semiconductor nano-particles have been studied extensively in the past few decades, mainly due to the blue-shifts in their band-gap compared to those of the bulk. This phenomenon is also known as the quantum size effect. These nano-sized semiconductors also exhibit unique electrical, optical, and mechanical properties that have potential applications in electronic devices. Semiconductors such as Lead sulfide (PbS) and Cadmium sulfide (CdS) were synthesized in various concentrations of poly (methyl methacrylate-methacrylic acid) (MMA-MAA) ionomer by a solid-state method. Lead and Cadmium were exposed to Hydrogen sulfide (H2S) for a sufficient amount of time in order to completely convert Pb2+ and Cd2+ ions to PbS and CdS. From this step, the changes in color were apparent, indicating the formation of the semiconductors. The characteristics of the nano-composites were then tested. One of the tests used was Differential Scanning Calorimetry (DSC), which was adapted to measure the glass transition temperatures (Tg). Using DSC, the increase in Tg with the increase in ion content was observed. The ion concentrations were confirmed by titrating with a base and measuring the conductance. UV-vis spectroscopy was used to determine the sizes and size distributions of the nano-particles. Upon analysis, the UV-spectrum showed that the size of the nano-particles decreased with decreasing ion content.