What are polymers and why are they interesting?

The word comes from the greek polumeres, which means `having many parts'. Polymers are large molecules consisting of repeated chemical units (`mers') joined together, usually in a line, like beads on a string. Each `mer' is typically made up of more than 5 and less than 500 atoms; the word `polymer' is applied when you have more than about 50 `mers' stuck together. Most of the plastics that make up the pieces of junk that fill our lives are made of polymers.

Historically, polymers have mostly been used to make solid plastics where the chains virtually don't move. But nowadays people dream of new applications of polymer liquids where fluctuations (Brownian motion) and interactions (the sticking together or association of different types of molecules) can play a more important role. Many of the most important research problems involve polymers free to fluctuate about in a small-molecule solvent. Naturally, the most important solvent is also the hardest one to understand: water. An important area of research is the modification of the properties of surfaces using thin polymer coatings.

The sky is the limit for these wet technologies: living organisms are mainly composed of polymerized amino acids (proteins) nucleic acids (RNA and DNA), and other biopolymers. The most powerful computers - our brains - are mostly just polymer glorp soaking in salty water!

Last modified: May 23, 1994

John Marko, marko@msc.cornell.edu