Study Of Large Molecular Weight Poly(Isoprene-B-Styrene-B-Ethylene Oxide) And Of Its Hybrid Oxides And Nitrides

Abstract

In this study, poly(isoprene-block-styrene-block-ethylene oxide) (ISO) with molecular weight of 93,496 g mol-1 was synthesized to investigate the effect of large molecular weight on polymer phase behavior. This polymer was used to direct aluminosilicate hybrids and results compared with a 23,180 g mol-1 ISOaluminosilicate hybrid system, i.e. with work of previous Wiesner group member, Juho Kim. Results showed that, despite the occurrence of more mixed phases with the larger ISO, both ISO-aluminosilicate hybrid systems display the same sequence of phases with those of the 93,496 g mol-1 ISO aluminosilicate hybrid structures shifted down to lower O + inorganic volume fractions as compared to the 23,180 g mol-1 ISO. Subsequently, several other metal oxide hybrids derived from 93,496 g mol-1 ISO were studied. The goal of the study was, again to learn about the structuredirecting behavior of large molecular weight polymer, and identify ways to obtain uniform phases. This is usually a challenge as a result of the much slower chain dynamics observed for large molecular weight polymer. Uniform structures from large polymers enable access to large pore and strut size mesoporous materials desirable for a numbers of applications. Titanium (IV) oxide and niobium(V) oxide hybrids were studied, which have been previously examined with smaller molecular weight ISO. Niobium (V) oxide can be further nitrided into niobium nitride, which has the potential to show superconductivity. The temperature- and time-dependence of nitriding were investigated to identify optimal conditions. Finally, mesoporous 3 gallium nitride was prepared, by nitriding 93,496 g mol-1 ISO-derived gallium (III) oxide hybrids, but further studies are needed to bring this part of work to full fruition. 4