Things at the nanoscale are a little different. Think about your room at home. If you dont work at putting stuff away, things become a mess. At the nanoscale sometimes things arrange themselves without you having to do anything. This is a process called self-assembly. Molecules sometimes self-assemble, like soap forming a bubble when you blow air through a soapy loop. The soap molecules spontaneously form a bubble because they interact in a special way when they are around a lot of air and little bit of water. Soap bubbles are made from micelles. These molecules form a thin layer that then becomes a ball. So at the nanoscale, molecules sometimes self-assemble but only when the environment is also right.
Scientists use this idea of self-assembly to help make nanoscale devices. One type of molecule that can self assemble is called an alkane thiol. There is a sulfur (thiol) group on one end and a long hydrophobic tail on the other. Having a hydrophobic tail means that the tail part of the molecule doesn’t like water. When a solution of these molecules are squirted on to gold, they self-assemble to form a thin layer. This is because the sulfur group is attracted to the gold and the hydrophobic tails pack together to push away the water in the solution. When they are done self-assembling, the layer is only one molecule deep. It is called a self-assembled monolayer. If we use a very powerful microscope we can see a self-assembled monolayer.
How can we see how this self-assembly process works? One way is through simulations, like the one shown on the right. Powerful computer simulations can calculate all the forces that make molecules self assemble, and show the assembly process in slow motion. The molecules move around in the solution, and over time, they become attracted to the surface and spontaneously organize into a self-assembled monolayer.
Image Source: +Plus Magazine