Using scientific methods to find ways to create new materials with desirable properties. There is a great deal of overlap between materials science and
chemical engineering when undertaking the synthesis of a new material.
Kevlar, the infamous bullet proof fabric, is synthesized in
a process with many steps including solution spinning from sulfuric acid. The removal of the sulfuric acid during subsequent steps adds a great deal of cost to the synthesis of this useful material.
Polycarbonate can be produced by a reaction of Bisphenol-A and the highly toxic gas Phosgene, but needless to say the EPA and OSHA would have something to say about this. For that reason, less toxic but more expensive proprietary starting materials must be used.
Nylon-6 is produced by heating caprolactam. There are many other varieties of nylon, including nylon-6,6, which is produced industrially by the mixture of two "nylon salts".
Beta Carbon Nitride is a ceramic material that has been predicted by theorists to be nearly as hard or harder than diamonds, but it has never been successfully produced in a laboratory.
Carbon fibers, which are used as a reinforcement in composites, are produced by heating polyacrylonitrile fibers in a nitrogen atmosphere. Removal of trace amounts of metals from the PAN fibers before they are heated makes the resulting carbon fibers much stronger.
The production cost of a material is determined by the cost of the starting materials, the number of steps required in the process of synthesizing it, the amount of energy consumed while producing it, and the cost of any waste disposal associated with the process.
While some methods of synthesis work well in the lab, they do not always scale up as easily.