Nanomaterials Research in Chemical and Environmental Engineering
 

The Chemical Engineering discipline is situated at the cross-road of science and engineering and has evolved rapidly with progress in the sciences. Notably in advanced materials research, chemical engineers focus on molecular level and not just the processing of chemicals. Nanomaterials research has been a main research focus of the Department of Chemical & Environmental Engineering.

One such area is in the use of ultra fine pore of around 0.1 Å titanium silicate as molecular sieves. Ion exchanges under controlled regeneration conditions show significant capacity improvement of the Sr-exchanged material over the Na-form. Effect of exchange on the kinetics of adsorption and protocol of pore size tailoring are being investigated. The investigators involved are Profs S Farooq and M P Srinivasan.

Another area is in the application of metallic and multi-metallic nanoparticles in fuel cells, particularly in the preparation of noble metal nanoparticles that are catalytically active at room temperature fuel cell reactions. Particles of size 3-5 nm Pt, Ru and RuPt on carbon have been successfully prepared using microwave-assisted processes. The affinity between complimentary sequences of single strand DNA is being exploited to self-assemble the metal nanoparticles into model catalysts with predetermined nanostructures. Prof JY Lee heads this particular area of research.

There is also interest in the development of novel synthesis methods for nanobuilding blocks and their self-assemblies. The formation and assembly processes of low-dimensional metals, carbons, oxides, sulfides, and hydroxides with various nanoarchitectures are being studied (Figure 1) by Prof HC Zeng.

Figure 1: Formation process of lined beta-Co(OH)2 butterflies, which explains
 a general formation mechanism of one-dimensional nanorods.

A “Bottom-up” technique is currently being used to fabricate 3D photonic crystal heterostructures with tunable photonic bandgaps and reflective indexes. A novel self-assembly method, termed flow-controlled evaporation which affords crystallization of microspheres into a single crystal lattice in large domains, has been recently developed in Dr GXS Zhao’s laboratory. 

There is also an interest in the use of organised molecular assemblies to form bilayers on patterned supports for membrane-related applications. While patterned self-assembled monolayers (SAMs) adsorbed on adjacent regions of a gold substrate are being used as supports for two dissimilar lipid bilayers, confinement of lipid bilayers to pre-specified areas is being studied by Prof MP Srinivasan to retrieve spatial information and control spatial geometry. 

Dr L Hong has successfully synthesized nano-sized mixed conductive oxide, La1-xSrxCoO3-y, powders by means of thermal decomposition of a coordination metallo-organic polymer network. The unique aspect of this development is the successful control of nucleation of the oxide in nano-scale during the pyrolysis of the polymer precursor.

The development of nanoparticles of biodegradable polymers and bioadhesives for controlled drug delivery is being researched into by Prof SS Feng. These materials are used to provide a solution to the problem caused by the toxic adjuvant in the current clinical administration of anticancer drugs for better efficacy and less side effects. Similar developments for oral chemotherapy are also being investigated.

The use of nanostructured polymer and metal films for nanoelectronics is also being investigated by Profs ET Kang and KG Neoh. Nanostructured, fluoropolymer films have been prepared by RF magnetron sputtering deposition, while nanostructured metal films have been prepared via controlled electroless plating. The ultra-low dielectric constant polymer films and highly conductive metal films are being exploited for use in nano-interconnects and nano wafer level packaging.
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