Welcome to Lecture Hall E for our pre-post-pandemic video extravaganza, where
we will make nylon 66 out of hexamethyldiamine and adipoyl chloride! This little guy is a 6-carbon
chain, with two amine groups at the ends, and this one is a 6-carbon chain with two carboxyl chloride
groups at the end. This is about a 1-percent solution in in cyclohexane, and this is a
1-percent solution in about one-half molar sodium hydroxide. So the base keeps this dissolved,
and the non-polar solvent keeps this dissolved. One of the things this allows us to do
is to layer these two solutions. If we were to start with just the hexamethylenediamene
and the adipoyl chloride, they would react instantly as pure chemicals, and...it
wouldn't be pretty—there would be a lot of heat, and...you
wouldn't get good mixing. By diluting these compounds into solution we're able to
take a fairly small amount of the active ingredients in a fairly large amount
of solution. Because this is water and this is a hydrocarbon,
the water is denser than the hydrocarbon and so we can float the hydrocarbon on top of the water.
And so what you see here, as I add the cyclohexane with the adipoyl chloride to this mixture, is that
there's this sort of cloudy formation, and that cloudy formation is a condensation
product where the acid chloride of the adipoyl chloride meets up with the amine
of the hexamethylenediamene and forms a bond. So what we can do is I can reach in,
and pinch that layer and pull it up, because it's a solid—this is nylon 66—and
as I pull it up you can see that I'm pulling the skin that forms, and as I
expose the fresh solution (remember there's a layer of water and a layer of hydrocarbon)...as
I expose that interface by pulling away the nylon product, new nylon forms, and
it's connected to the old nylon. So what I get by pulling it up slowly is a continuous thread. And
if I pull quickly, I get a thin thread; if I pull more slowly,
the reaction is happening
in a slightly thicker layer, so I get a thicker thread. So, there's a thread of
nylon 66, it's pretty contaminated with water and cyclohexane and un-reacted monomers.
When nylon was discovered...the reaction was
instantaneously recognized as a great polymer, but it took them many years to get to the point
where they could take this product and turn it into a useable plastic, as useable polymer.