Polymers are a type of synthetic macromolecule, in contrast with natural macromolecules such as proteins and polynucleotides. They are characterized by a large molecular weight and consist of repeating structural units, termed monomers, connected by chemical bonds. In general, their properties differ markedly from the corresponding monomers which they consist of. These properties may result in strong and/or durable materials that have many applications.
In the 24th century there are several different words used to describe such large molecules: biopolymer, tri-polymer and polymer. Although they all have the same basic characteristics, they are created differently and for different reasons.
Polymers were, among other things, used to make plexiglass in the 20th century on Earth. To withstand a pressure of 18,000 cubic feet of water, a piece of plexiglass at 60 by 10 feet needed to be six inches thick. To hold the same amount of water, only a thickness of one inch was needed with a piece of transparent aluminum. Montgomery Scott explained how to make this to Doctor Nichols of the Plexicorp cooperation. (Star Trek IV: The Voyage Home)
A biopolymer is an organic form of polymer. The 247th element known to the Federation was present in a polymer residue as a byproduct of the decomposition process after a Vhnori died. (VOY: "Emanations")
Tri-polymers can be used to create tripolymer plasma. This plasma would have less energy than plasma from a Federation Intrepid-class warp engine. The Pralor and Cravic used it in their chromodynamic power modules, which in turn powered the Automated Personnel Units. (VOY: "Prototype")
Enzymes could be made out of tripolymer. A Delta Quadrant merchant named Bathar of Hodos once sold a so-called anti-aging process formula to Neelix which used tripolymer enzymes. It turned out the formula was better suited to make shoe polish. (VOY: "Memorial")
Data's artificial body frame had approximately six kilograms of non-conductive tripolymer composites. It was capable of withstanding at least half a million amps, although this was no guarantee that Data would survive such a massive current. Fortunately, his safeguards protected him when he tried to disrupt a high energy arc using his body. (TNG: "The Most Toys", "Disaster")
Geordi La Forge compared replicated pasta al Fiorella with a liquid polymer after receiving a plate from the replimat on Deep Space 9. Although Worf ate his and found it delicious, La Forge thought the replicator was malfunctioning. (TNG: "Birthright, Part I")