Saturday, 6 April 2013

Surface Science in my refrigerator...soon

As a taxpayer you may think that you are wasting money on research at publicly funded Universities that you may never see in your lifetime, occasionally you are correct.  However, sometimes the research can go from lab testing to your home (or more specifically your kitchen) very quickly.

If you live in the Western world likely you have eaten ketchup.  Americans consume around 36 million tons of ketchup annually (ca 2008 chachacha).  The inventors of ketchup probably did not care too much about its fluidic properties.  The problem with ketchup is that it is a thixotropic fluid.  This means that under normal conditions it has a thick or viscous property but when the ketchup bottle is shaken or stressed it has a shear thinning property.  Many thixotropic fluids take a finite time to obtain equilibrium viscosity.  With ketchup the gel viscous state returns almost instantly.  Ketchup has another characterization calls a pseudoplastic fluid.  This is likely why designing a new kind of bottle was innovative.  

Originally, ketchup was in glass bottles and for anybody that grew up in that era it was always an interesting (and possibly slightly messy affair) to get the ketchup out.  With the advent of plastic ketchup bottles it allowed ketchup to be squeezed out.  Following this ketchup manufacturers  created bottles that can be set with the lid facing downwards so the ketchup settles at the top of the bottle.  With these bottles there is always some ketchup left these kinds of bottles and the bottles do not look so nice.

A designer and a scientist made a bottle and immediately found a purpose for ketchup.  The researchers at MIT introduced the LiquidGlide Ketchup bottle.  It has a coating that is composed of a porous solid layer that bonds to the surface of the bottle.  Another layer impregnated in this provides lubrication.  Varying the structure or materials used in the coatings, it can be tailor-made to any purpose and any level of lubrication be it for ketchup or other non-newtonian fluids.  The most interesting thing about this bottle is that some of the outer materials are edible.  In case you have a friend that wants to scratch off the surface and eat it.

'Sometimes the best inventions address persistent problems that people have kind of just given up on.'  That is why these researchers were a nominee for 2013 Design of the Year award and that they are on display at the Design Museum in London.  Yes, all for understanding some physicochemical properties ketchup and making a hydrophobic bottle.  Surface tension and viscosity have no clear correlation and in the case of ketchup flowing surface tension should be negligible.  However, in the glass bottle since it is superhydrophobic the surface tension effects on the surface of the ketchup are important in order for the MIT designed ketchup bottle to work.