Given the number of possible combinations of atoms and the ways they can be dimensionally
arranged there appears to be an almost infinite number of ways to form polymers, but there are
additional difficulties because the arrangement must yield a useful product. In a way, this is
similar to the problem of “How many ways are there to knot a tie?”. Two mathematical physicists
at Cambridge (UK) used topological (and geometric) knot theory and statistical mechanics to find
that there are in fact 85 ways to knot a tie. Their research found all the knots currently in use and
also discovered another nine new knots that matched the aesthetic criteria1. We have been
wearing ties for hundreds of years and yet this vital piece of research was only conducted in 1999.
The polymer chemists were a little faster in attempting to develop useful polymers from the basic
structure, and Carothers carried out some of the first work in the development of nylon in the
1930s. This basic research continued, and in the 1970s, Rose and his team at ICI began
constructing polymers almost from the first reported principles. Their work was based on
previously successful materials such as the polysulfones, and one of their first products was the
aromatic polyether ketone family.
PTFE has relatively lower wear resistance. Under compression or in situations where rubbing or abrasion can occur, it can produce wear particles. These can result in a chronic inflammatory reaction, an undesirable outcome. For a given application, the biomaterials engineer must consider many aspects of the physical and biological properties of the materials. Thus, although PTFE is highly inert in the body, if applied in the wrong circumstances (for example, a device that is under compression or exposed to wear) it may lead to a reaction that no longer qualifies as “biocompatible.”