GEOLOGICAL SOCIETY OF THE PHILIPPINES

 

 

GEONICS : Utilization of Philippine Clay Minerals for Nanotechnology

 

Chelo S. Pascua1, Hirohisa Yamada2, Kenji tamura2, M.L.L Honrado1 and Carlo A. Arcilla1

1National Institute of Geological Sciences,
University of the Philippines, Diliman
2National Institute for Materials Science,
Namiki, Tsukuba, Japan

 

Abstract

 

The way nature designs specific structures for well-defined funcitonalities has been well copied in the biological sciences – a term that is now referred to as biomimicry. A similar idea was promulgated in the geosciences termed geomimicry. It refers to processes and technologies that mimic long term geological processes.

 

We introduce another new concept – GEONICS. It is a concept wherein the nanostructure of common earth materials are modified and altered for their application in nanotechnology. There are two ways to go about this modification that has been applied to other materials used in nanotechnology: (1) a top-down approach or bulk materials are reduced to their nanometer-sized components by physical and chemical means; and (2) a bottom-up approach where the desired nanostructure is built from basic molecular raw materials to its full nanometer-sized structure.

 

The former is more applicable to natural materials such as clays which are already considered as natural nanomaterials. Although other materials can also be used through a process of benficiation, clay minerals are by their crystallographic nature are already natural nanostructures. On the other hand, the latter is applicable in synthesizing new breeds of nanomaterials from commonly available natural materials such as silica-rich geothermal fluids.

 

The utilization of Philippine clay minerals in nanotechnology is a blessing-in-disguise for the mining industry. Clays are normally considered as gangue materials in the exploitation of metallic ores. Their foreseen usefulness far exceeds their utilization in alteration mapping. There are several clay mineral groups that are presently being utilized in nanotechnology. These are montmorillonites of the smectite group; and halloysite which is a tubular kaolinite species.

 

Montmorillonites are expandable clay minerals that can intercalate a variety of organic compounds such as organic polymers (i.e. plastics). Their utilization in clay – organic polymer composites have made a large market for thermoplastics and other plastic-based materials that are also useful as packaging. Figure 1 illustrates the nature of clay-polymer nanocomposites.

 
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