Tuesday, 10/19/2004
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Paul Callaghan
Victoria University of Wellington, New Zealand

"Rheo-NMR-microscopy: Localising the Physics of Soft Matter"

(Will also be presenting a Physics Colloquium on Wednesday, 10/20/2004 at 4:00 PM "Using magnetic resonance to study complex fluids")


A central problem in the physics of soft matter concerns the molecular basis of complex mechanical properties, and especially the response of the material to deformation and deformational flow. The key to addressing central questions concerning the role of molecular organisation and dynamics in macroscopic constitutive behaviour, lies in the use of spectroscopic techniques that are capable of accessing information at the molecular level during deformational flow. Examples include optical birefringence and dichroism measurements, neutron and X-ray scattering, and most recently, nuclear magnetic resonance.

An overview of the NMR methods will be given, along with some examples of flow measurement in different deformation geometries. Velocity imaging has proven useful in elucidating tubeless siphon flow, the "spurt effect", shear banding, fracture, yield stress phenomena, polymer demixing and shear-induced polymer chain alignment while spectroscopy is answering new questions about molecular organisation and ordering.

Already Rheo-NMR has thrown up some interesting effects. These include anomalous polymer deformation under shear, dynamics of shear-induced isotropic to nematic phase transitions in wormlike micelles, and correlations between stress fluctuations, shear banding fluctuations, and fluctuations in the orientational order of surfactant molecules.


Paul Callaghan was born in Wanganui, New Zealand and took his first degree in Physics at Victoria University of Wellington. He then did a DPhil degree at Oxford University, working in low temperature physics. On his return to New Zealand in 1974 he took up a lecturing position at Massey University where he began researching the applications of magnetic resonance to the study of soft matter. He was made Professor of Physics in 1984, and in 2001 was appointed Alan MacDiarmid Professor of Physical Sciences at Victoria University of Wellington. He also heads the multi-university MacDiarmid Institute for Advanced Materials and Nanotechnology. Paul is Past President of the Academy Council of the Royal Society of New Zealand. He has published around 200 articles in scientific journals as well as a book on magnetic resonance. In 2001 he became the 36th New Zealander to be made a Fellow of the Royal Society of London.