Polymer

Some things are made of long chains.

These chains are very big. They are made of many small pieces joined together. This joining is called polymerization.

Many things in nature use these chains. Wood and silk are made this way. Even the DNA in your body is a chain.

People can make these chains too. We use them to make plastic. Some plastics are used for things like foam. These chains can be very strong or stretchy. They are all around us!

A polymer is a very large molecule. It is made of many small pieces joined together. We call these small pieces monomers.

Making these chains is a way called polymerization. In this way, monomers link up to form a long chain or a web.

Some polymers are natural. You can find them in silk, wool, and wood. Even the DNA in your body is a natural polymer.

Other polymers are synthetic. This means people make them in a lab. We use them to make many plastics. For example, polystyrene is used to make foam.

Polymers can be different shapes. Some are straight lines. Others have branches that stick out like tree limbs.

These shapes change how the material feels. Some polymers are very tough. Others are very stretchy, like rubber. They are used in almost everything we use every day.

A polymer is a special kind of material made of huge molecules. These molecules are called macromolecules because they are so large. They are built from many small, repeating parts called monomers.

Because these chains are so long, they have unique physical properties. They can be very tough or very stretchy. Some polymers are even elastic, which means they can snap back after being pulled. These materials are everywhere in our world, from the air to the deep sea.

Making these large molecules is a way of working called polymerization. During this process, many monomers link together to form a long chain or a network.

There are two main ways this happens in a lab. In chain polymerization, monomers are added to the chain one at a time. One example is making polystyrene. In step-growth polymerization, smaller chains can actually combine with each other directly.

Sometimes, small pieces are lost during this link-up, like when making PET polyester. This leaves behind a repeat unit that stays in the chain.

People have been using certain polymers for a very long time. Natural polymers like wool, silk, and amber have been used for centuries.

The word "polymer" was first used in 1833 by a scientist named Jöns Jacob Berzelius. His definition was a bit different from how we use it today. Later, in 1920, Hermann Staudinger proposed the modern idea of polymers. He suggested they were structures held together by strong chemical bonds. He spent ten years finding proof for this important idea.

There are many different kinds of polymers in the world. Natural ones include cellulose, which makes up wood and paper.

In space, scientists found a polymer called hemoglycin in meteorites. Synthetic polymers are man-made and are used for many things. In 2015, people made more than 330 million tons of these materials. Some common ones include polyethylene and polypropylene. Others include nylon and silicone, which is used in Silly Putty.

Polymers can take many different shapes and structures. A polymer made of only one type of monomer is a homopolymer.

If it uses two or more different types, it is called a copolymer. Some can be straight lines, while others have branches sticking out.

These shapes change how the material behaves. Some chains are so organized they form crystals. Others are messy and called amorphous. These tiny shapes determine if a material is hard or soft.

A polymer is a substance made of very large molecules called macromolecules. These massive structures are built from many repeating subunits called monomers.

Because of their enormous molecular mass, polymers possess unique physical properties. They often show great toughness, high elasticity, or viscoelasticity. They can form organized semicrystalline structures or messy, disordered amorphous structures. Polymers are essential to both the natural world and modern technology. They exist as both natural biopolymers and man-made synthetic materials.

Creating these large molecules requires a process called polymerization. This process combines small monomers into long chains or networks through covalent chemical bonds. In chain polymerization, monomers are added to a growing chain one at a time. An example of this is the radical polymerization of styrene. In step-growth polymerization, smaller chains can combine directly with one another. This method includes polycondensation, where a small molecule is lost during each step. For instance, making PET polyester involves losing two water molecules during the reaction.

Polymers are categorized by their composition into homopolymers and copolymers. A homopolymer consists of only one type of repeating unit. Polystyrene is a common homopolymer made of styrene-based units.

A copolymer contains two or more different types of repeat units. If a polymer has three different types, it is called a terpolymer. For example, styrene-butadiene rubber is a random copolymer. These different combinations allow scientists to create materials with specific, custom properties.

The history of polymer science involves a shift in how we understand molecules. The term "polymer" was coined in 1833 by Jöns Jacob Berzelius. His original definition focused on substances with related molecular formulae. However, the modern concept emerged much later in 1920. Hermann Staudinger proposed that polymers were large structures held by covalent bonds. He spent the next decade gathering experimental evidence to prove this hypothesis. His work laid the foundation for the modern field of polymer science.

Natural polymers, or biopolymers, are fundamental to all life on Earth. There are three main classes: polysaccharides, polypeptides, and polynucleotides.

In living cells, enzymes manage the synthesis of these molecules. For example, DNA polymerase catalyzes the formation of DNA. Proteins are also polymeric, built from amino acids through transcription and translation. Other natural examples include cellulose in wood, silk, and natural rubber. Even in space, polymers exist, such as the amino acid polymer hemoglycin found in meteorites.

Synthetic polymers are man-made materials used in massive quantities. In 2015, the world produced more than 330 million tons of these polymers. Common examples include polyethylene, polypropylene, and polyvinyl chloride. Many of these use a backbone of carbon atoms. However, other elements like silicon can form polymers like silicone.

Humans also modify natural polymers to create new products. Heating natural rubber with sulfur creates vulcanized rubber. Reacting cellulose with nitric acid produces nitrocellulose.

The physical behavior of a polymer depends on its microscopic structure. Polymers can be linear, meaning they consist of a single unbranched chain.

They can also be branched, with side chains extending from the main backbone.

Some polymers feature cross-linking, where chains are tied together. Wide-meshed cross-linking often creates elastomers, while close-meshed links create hard thermosets.

These structural details determine if a material is a flexible plastic or a rigid solid.