Polymer
A polymer is a very large molecule made up of many identical small building blocks connected into a long chain. Plastic, rubber, nylon, and also proteins or starch are polymers.
All substances consist of molecules, meaning small groups of atoms. In a polymer, a great many identical building blocks are linked together into a long chain. A single such building block is called a monomer, and a polymer can consist of thousands of them. You can picture it like a string of pearls: individual pearls are unremarkable, but the long chain has entirely new properties. This is exactly where the toughness, stretchiness, or moldability of plastic and rubber comes from. Polymers are formed not only in factories but also in nature, for example as cellulose in wood.
Why chains of molecules changed industry
About a hundred years ago, materials were quite limited: wood, metal, glass, stone, leather. Polymers added a material whose properties can be specifically adjusted. Depending on the building blocks and chain length, the result can be as hard as a helmet or as soft as a rubber band. It can also be cast into molds and produced cheaply in large quantities.
That is why polymers are found almost everywhere today. Cables are insulated with them, aircraft are made lighter through plastic parts, and medical implants are made of them. Paints, adhesives, and packaging films are also polymers. In chip manufacturing, special light-sensitive polymers are needed to transfer fine structures onto silicon wafers.
The downside is durability. Many plastics take centuries to break down in the environment. A common misconception is that polymer is simply another word for plastic. Plastic is only one group of synthetic polymers, while DNA and proteins in the body are also polymers.
How monomers become a chain
The decisive step is called polymerization. In this process, bonds in the small building blocks open up, and these link together with one another. This often requires heat, pressure, or a catalyst, meaning a substance that speeds up the reaction without being consumed itself. This is how the gas ethylene becomes polyethylene, the material used in many shopping bags.
How the chains arrange themselves relative to one another determines the properties. If they lie jumbled and disordered, the material tends to be soft and flexible. If many chains lie parallel and tightly packed, it becomes firmer and stiffer. If the chains are additionally cross-linked with one another, a network forms that no longer melts. This is exactly what happens during the vulcanization of rubber for car tires.
You can also mix different monomers to combine properties. Such mixed chains are called copolymers. In addition, plasticizers, dyes, or glass fibers are blended in. This turns a basic substance into an entire family of materials.
Polymers in the news and in everyday life
In everyday life, you can recognize them by the abbreviations on packaging. PET stands for the plastic used in beverage bottles, PVC for pipes and window frames, PP for yogurt cups. Clothing made of polyester or fleece also consists of polymer fibers. The casing of a mobile phone and the coating of a frying pan belong to this group as well.
In business news, polymers usually come up in connection with the chemical industry. Companies like BASF or Dow earn money from producing them, and prices are strongly tied to the price of oil, since petroleum is the most important raw material. New rules against single-use plastic or debates about microplastics directly affect this industry. Research into biodegradable polymers and better recycling is therefore heavily promoted.
They also play a role in the world of technology. Batteries use polymers as electrolytes or as a separator layer between the poles, 3D printers process plastic filaments, and flexible displays sit on polymer films. Anyone who can place this term will understand such news much more quickly.