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2005 Nuggets

Highly oriented mesoporous silica from porous templates
(Lu, Gao. Komarneni and Mallouk, IRG3)

Many different kinds of materials (biomolecules, fluids, metals, superconductors) display unusual emergent behavior when they are confined to quasi-one dimensional (1-D) forms. For example, we have found interesting effects such as residual resistance and very high critical fields in single crystal tin nanowires below their superconducting transition temperature. Biological molecules such as DNA experience a resistance to flow through very small channels because of their entropy-driven tendency to exist in a coiled form. In order to explore these effects at truly nanoscale dimensions, new ways are needed to synthesize templates or "molds" for making 1-D materials. Template membranes with straight channels are available for making and studying these materials but their minimum diameter has so far been about 20 nm. By growing mesoporous silicates inside the channels of these membranes, we can fill each channel with highly oriented rods that contain uniform pores in the 6 nm diameter range. These pores are oriented over macroscopic distances (60 µm), and they can be accessed at one or both ends to make electrical, electrochemical, or other contacts.