Poly(methyl methacrylate)

This clear plastic is called acrylic.

It looks like glass. But it is much lighter. It is also very strong.

Because it is tough, it does not shatter easily. It breaks into large, dull pieces instead.

In the past, soldiers used it for plane windows. They even used it for knife handles. They put small photos inside them.

Today, we use it for many things. It can even be colorful!

Acrylic is a clear plastic. Its real name is poly(methyl methacrylate).

Many people call it PMMA. It is made from small parts called monomers.

This plastic is very useful. It is strong and tough. It is also very light. In fact, it is about half the weight of glass.

Acrylic lets in a lot of light. It lets in 92% of visible light. This makes it great for windows. During World War II, pilots used it for plane windscreens.

It does not shatter like glass. Instead, it breaks into large, dull pieces. This can help keep people safe. Some people use it to make jewelry or art.

Scientists can change the plastic to make it better. They add other things to make it harder to scratch. They can also add dyes to give it color. This helps it work for many different jobs.

Poly(methyl methacrylate), or PMMA, is a clear and strong material.

Many people simply call it acrylic or acrylic glass. It is a synthetic polymer, which is a type of plastic made by humans. This material is very useful because it is lightweight and tough. It is often used as a replacement for glass. It can be made into thin sheets or thick blocks.

Making this plastic involves a way it works called polymerization.

It starts with small parts called monomers. One specific monomer is called methyl methacrylate. Scientists can make PMMA through different methods like bulk polymerization or emulsion polymerization. Some high-quality sheets are made by cell casting. This is where the liquid monomer and the hardening steps happen at the same time. This method creates very strong and clear pieces.

People have been studying these chemicals for a long time. Chemists first created acrylic acid in 1843. Later, they made methacrylic acid in 1865. In 1928, several different chemists began developing the final plastic. These scientists included William R. Conn, Otto Röhm, and Walter Bauer. The German company Röhm & Haas AG first sold it in 1933 under the name Plexiglas. At the same time, British chemists Rowland Hill and John Crawford made a version called Perspex.

PMMA has many interesting facts and numbers. It is about half as heavy as real glass. Its density is between 1.17 and 1.20 grams per cubic centimeter. This plastic is very good at letting in light. It allows up to 92% of visible light to pass through it. During World War II, it was used for submarine periscopes and aircraft parts. Soldiers even used scraps to make "Sweetheart Grips" for knives. They put small photos inside the clear handles.

You can see this material in many places today. It is used to make parts for watches, like the Omega brand.

It is also used in large items like the pressure sphere for the bathyscaphe Trieste.

You might see it in aquarium tanks or even in colorful jewelry. Because it is easy to shape, it works well for art and home design. It is a part of our world that we often look right through.

Poly(methyl methacrylate), often called PMMA, is a synthetic polymer.

It is a clear, transparent thermoplastic used widely in engineering. Many people know it by common names like acrylic or acrylic glass. It also has many famous trade names. Some of these include Plexiglas, Perspex, and Lucite. Because it is a non-crystalline vitreous substance, it is sometimes technically classified as a type of glass. This material is highly valued because it serves as a lightweight and shatter-resistant alternative to traditional glass.

To understand how PMMA is made, we must look at the process of polymerization.

The process begins with small molecules called monomers. In this case, the specific monomer is methyl methacrylate. Scientists use different methods to turn these monomers into long polymer chains. They might use emulsion polymerization, solution polymerization, or bulk polymerization. One high-quality method is cell casting. In cell casting, the polymerization and the molding steps happen at the same time. This creates sheets with a very high molecular mass. These cast sheets are stronger than those made through other molding processes.

PMMA can be modified to change how it behaves. Pure PMMA is rarely sold as a finished product because it is not optimized for most jobs. Instead, manufacturers add different substances to create specific properties. For example, they might add acrylate comonomers to help the plastic handle heat during processing. They may add butyl acrylate to improve the impact strength of the material. To make the plastic work better in high-temperature lighting, they add methacrylic acid. This increases the glass transition temperature, which is the temperature where the material softens. Other additives like plasticizers can make the plastic easier to process or more flexible.

The history of this material spans many decades of chemical discovery. Chemists first created acrylic acid in 1843. They formulated methacrylic acid in 1865. By 1928, several chemists were working to develop the final polymer. These scientists included William R. Conn, Otto Röhm, and Walter Bauer. In 1933, the German company Röhm & Haas AG brought Plexiglas to the market. Around the same time, British chemists Rowland Hill and John Crawford at ICI developed Perspex. In the United States, the company E.I. du Pont de Nemours & Company introduced Lucite. These developments changed how we use transparent materials in industry.

PMMA has very specific physical properties that make it useful. It is much lighter than glass. Its density is between 1.17 and 1.20 g/cm, which is about half the density of glass. This makes it an excellent choice for lightweight applications. PMMA is also very clear. It transmits up to 92% of visible light. It also has a refractive index of 1.4905 at 589.3nm. This means it reflects about 4% of light from each surface. During World War II, its strength and clarity were vital. It was used for aircraft windscreens, gun turrets, and submarine periscopes. Soldiers even used scraps to make "Sweetheart Grips" for knives by placing photos inside the handles.

Today, we see PMMA in many surprising places. It is used in high-end items like Omega watches, known as Hesalite. It is strong enough to be used in the pressure sphere of the bathyscaphe Trieste. You can find it in consumer goods like colorful jewelry or even high-heeled footwear. It is also used in large aquarium tanks. Because it can be laser cut, it is often used to make very intricate and beautiful designs. However, cutting it with a laser can create internal stress. This means the plastic must undergo a process called annealing to stay stable.

PMMA relates to many different fields of science and industry. It is an important topic in polymer science because of its stability. While it can swell in organic solvents, its environmental stability is better than plastics like polystyrene. This makes it a top choice for outdoor use. Scientists also study ways to recycle it. One method uses heat to trigger the polymer to disassemble back into monomers. Another method uses a chlorinated solvent and ultraviolet light to break the polymer down. These processes allow us to recover up to 98% of the material for reuse.