Poly(methyl methacrylate)

Paul Hockey

Poly(methyl methacrylate), which lazy scientists call PMMA, is a clear plastic, used as a shatterproof replacement for glass. The clear barrier at the ice rink which keeps hockey pucks from flying in the faces of hockey fans is made of PMMA. The chemical company Rohm and Haas makes windows out of it and calls it Plexiglas®. Ineos Acrylics also makes it and calls it Lucite. Lucite is used to make the surfaces of hot tubs, sinks, one-piece bathtub/shower units, among other things.

When it comes to making windows, PMMA has another advantage over glass. PMMA is more transparent than glass. When glass windows are made too thick, they become difficult to see through. But PMMA windows can be made as much as 13 inches (33 cm) thick, and they're still perfectly transparent. This makes PMMA a wonderful material for making large aquariums, with windows which must be thick in order to contain the high pressure of millions of gallons of water. In fact, the largest single window in the world, an observation window at California's Monterrey Bay Aquarium, is made of one big piece of PMMA which is 54 feet long, 18 feet high, and 13 inches thick (16.6 m long, 5.5 m high, and 33 cm thick).

PMMA is also found in paint. The painting on your right, Acrylic Elf, was painted by Pete Halverson with acrylic paints. Acrylic "latex" paints often contain PMMA suspended in water.

But PMMA is more than just plastic and paint. Often lubricating oils and hydraulic fluids tend to get really thick and even gummy when they get really cold. This is a real pain when you're trying to operate heavy construction equipment in really cold weather. But when a little bit PMMA is dissolved in these fluids it keeps them from getting thick in the cold, and machines can be operated down to -100 oC (-150 oF), that is, presuming the rest of the machine can take that kind of cold!

As you can see from the picture, the structure of methyl methacrylate kind of looks like Massachusetts. But Massachusetts doesn't polymerize, because there's only one. Here's a better, 3-D look at the monomer methyl methacrylate:

methylmethacrylate polymethylmethacrylate

PMMA is a member of a family of polymers which chemists call acrylates, but the rest of the world calls acrylics.

Another polymer used as an unbreakable glass substitute is polycarbonate. But PMMA is cheaper!

Other polymers used as plastics include:

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