Mr Thusara Chandrasekera
|Position||Post doctoral researcher|
|Qualifications/honours||BA MEng Chemical Engineering|
|Research group||Magnetic Resonance|
|Research project title||Application of advanced NMR techniques to agrochemical systems|
MRI, i.e. nuclear magnetic resonance imaging, is great. It gives us the ability to look inside objects and explore their internal structure, even with 3D images. We can resolve images (of convenient samples) down to about the 10 um scale. There are, however, other major areas of nuclear magnetic resonance (NMR), which, arguably, can give us even more information than the usual images. Chemists and physicists may well be familiar with the use of NMR in the identification of structures of molecules and the establishment of the composition of solutions/ liquid mixtures. So, as well as imaging, we have spectroscopy for chemical studies. Add to those, measurements in two other areas: motion and relaxation. We can measure velocity distributions of flowing liquids or gases, even in porous media such as rocks. We can measure diffusion coefficients (a measure of molecular mobility) of chemicals to do chromatography-like experiments on mixtures. Such average measurements of molecular motion allow us to probe length scales even shorter than the ~10 um limit for imaging. Relaxation refers to the lifetime of magnetic resonance signal intensity, and is particularly useful for probing multiphase systems. Diffusion and relaxation measurements also allow us to probe pore size distributions in rocks and droplet size distributions in emulsions (and cheese too).
My research adapts these types of NMR techniques to study complex formulations such as suspoemulsions (typically an oil-in-water emulsion mixed with a solid suspension in water) used to deliver agrochemicals in crop sprays. Studies include the development of early stability indicators for the phase separation of suspoemulsions (creaming and sedimentation) and in situ monitoring of liquid-liquid phase transfer catalysed reactions for active ingredient manufacture.