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Physical
Polymers and Plastics
Polymers are materials made of huge molecules built from repeating units, and plastics are moldable synthetic materials made mainly of polymers.
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The idea
A polymer is a substance made of very large molecules, called macromolecules, that are built from many repeating small units called monomers. The chemical process that links monomers together is called polymerization. Because their molecules are so large, polymers can be tough and highly elastic. Some polymers are natural: DNA, proteins and the rubber in latex are all polymers. Others, such as polystyrene, are synthetic.
Plastics are synthetic or semisynthetic materials made mainly of polymers. Their defining property, plasticity, means they can be molded, extruded or pressed into many solid shapes. They are also light, durable, flexible, resistant to chemicals and cheap to make. Most plastics are made from natural gas and petroleum, though a growing minority, such as polylactic acid, come from renewable resources.
The main uses of plastic include packaging and building construction. An estimated 9.2 billion metric tons of plastic were made between 1950 and 2017. Plastics break down very slowly in nature, and only a small share of discarded plastic has ever been recycled. Much of the rest ends up in landfills or as pollution, including tiny pieces called microplastics.
Check yourself
Question 1 of 2
What was the first fully synthetic plastic?
Composition
what it's made of
- Monomers — The small molecules that link together, over and over, to build a polymer.
- Macromolecules — The very large molecules, made of many repeating subunits, that make up a polymer.
- Polymerization — The process that joins many monomers into a polymer.
- Natural polymers — Polymers made by living things, such as DNA, proteins and latex rubber.
- Synthetic plastics — Moldable materials made mainly of polymers, such as polyethylene and PVC.
Connection
how it relates
Under Materials
Change
how and why it evolves
- Past
- Bakelite, the first fully synthetic plastic, was invented in 1907 by Leo Baekeland. Since the early 20th century, plastics have spread into medical devices, building materials, packaging and much more.
- Now
- Preliminary figures show that over 400 million metric tons of plastic were produced worldwide in 2023 alone.
- Next
- If current trends in demand continue, yearly plastic production is projected to exceed 1.3 billion tons by 2060. Better recycling and more plastics from renewable resources could ease the pollution problem, though by how much is uncertain.