Science is fun and cool.

On the whole, I like my job. Sure I b!tch a lot about undergraduate students and the fact that they can't follow the simplest of instructions or break everything they go near but on the whole my job is pretty good.

And days like today show just how interesting science can be. Today, the students are looking at Rheology. One of the compounds they make is called Carbomer 940. At a concentration of 1% in water it forms a fairly fluid gel (like runny hair gel). The students make a 0.2% solution (which is nearly as fluid as water) and measure its viscosity. This comes out to be very, very low (close to water). Then they add a 2.0% (0.5M) Sodium Hydroxide solution (otherwise known as Caustic Soda). This causes the pH of the solution to increase (become more alkaline). The effect on the gel is dramatic. It goes from being very fluid to being a thick gel in a matter of seconds. The mechanism behind this is that the Carbomer is tightly coiled at very low and very high pH levels and as such is quite liquid. At a neutral pH the carbomer molecule uncoils, making it very thick. The students continue to increase the pH until the solution is quite alkaline and see that the gel goes very thick at neutral pH and then becomes fluid again. Its very, very cool to watch as the change is so dramatic.

Another compound they work with is Methylcellulose. It’s weird stuff. It’s dispersible only in hot water but only soluble in cold water (I'm not sure why). So to make the solution, you need to have very hot water and disperse the powder in it. It will not dissolve, despite the high temperature. You then add ice cold water and you notice that the solution goes from a cloudy fluid to a thick, clear gel in a matter of seconds. And it’s fun stuff. Completely non-toxic (it’s edible), it’s the classic goo. It’s actually the stuff they use in movies for goo and saliva special effects. Ever seen Aliens? Remember the saliva that dripped menacingly from the aliens' jaws? Methylcellulose goo. The goo the Gremlin's had dripping off them when they came out of their cocoons? Methylcellulose. A guy in Scandinavia once tried to make ice-cream that stayed solid at room temperature and he used methylcellulose as the base. It worked apart from one fatal flaw: it tasted terrible.

Science is fun.