SYNTHESIS OF ZINC-SULFIDE CLUSTERS AND ZINC PARTICLES WITHIN MICROPHASE-SEPARATED DOMAINS OF ORGANOMETALLIC BLOCK-COPOLYMERS

Block copolymers of methyltetracyclododecene (MTD) and bTAN(ZnPh)2 [where bTAN = 2,3-trans-bis((tert-butylamido)methyl)norborn-5-ene] were prepared via ring-opening metathesis polymerization. Microphase-separated films of these copolymers exhibiting either lamellar or spherical morphology were reacted with hydrogen sulfide yielding zine sulfide (ZnS) clusters within the organometallic domains. Clusters with diameters up to 30 angstrom were prepared and characterized by X-ray diffraction and electron microscopy. The effects of processing parameters such as temperature, copolymer morphology, and the presence of coordinating bases on cluster size were investigated, and the results were explained on basis of nucleation theory. Investigation of these clusters by X-ray photoelectron spectroscopy (XPS) revealed a distinct increase in their band-edge separation (5.7 eV for 30-angstrom clusters) relative to the bulk ZnS bandgap (3.5 eV) indicative of quantum size effects. Also investigated was the formation of zinc particles and clusters by thermal treatment of the block copolymer films.