A recent development in the field of rheology is a mechanism developed by a team of researchers at the University of Washington which produces the same effect as surfactants but without actual surfactants needing to be added to a substance. (A surfactant is the chemical found in soap that allows the soap to clean out oil and grease in water.) The new technology, called a microfluidics device, shoves molecules through slits one-tenth the width of a human hair which causes the molecules--in this case, water with detergent and salt--to deform and become significantly more viscous, with added elasticity.
(Note: This is a for-profit company website. I'm linking to it because it explains rheology; I cannot speak for the company itself or its products.)
What's the strangest substance you can think of? Do you use (or consume) any non-Newtonian fluids?
-----The Golden Eagle