You and I are surrounded by an amazing class of chemicals called polymers. Chances are the clothes you have on are a mixture of polyester and cotton, called permanent press. It's the most popular fabric in the world because it has the comfort of cotton but without all the wrinkles. Trust me, you have no idea how neat this is. When your grandparents were kids all they had was cotton and wool. Wool was warm, but boy did it itch! You might use if for a sweater or even a heavy shirt; but no way were you going to use it for your underwear. Cotton was comfortable, but if you didn't iron it first you looked like a walking, crumpled newspaper. So grandma spent a big part of her day ironing the clothes, table clothes, and bed sheets. (Why would anyone bother to iron bed sheets? I have no idea. After all, most of us plan to have our eyes closed when we're in bed and who cares about wrinkles we can't see. But believe me, Mom used to iron all of our sheets!) So now you have more time to play Nintendo or chat on the net instead of doing chores like ironing clothes. What is this amazing permanent press stuff? It's a blend of a natural polymer, cotton, with a man-made polymer called polyester.
So what's this "polymer" thing I keep talking about? Polymers are extremely large molecules (I know you remember what a molecule is, your science teacher said you've already covered that) made by linking one or more small, chemical units together, over and over. Polymers can have millions or even billions of these units all chained together. Have you ever tied two rubber bands together? It's easy! Just poke one rubber band through the middle of another, and then loop it back through itself to make a simple knot. Now do it over and over to make a long chain. Do it thousands or even millions of times and you've got a model of a polymer.
Like I said, we're surrounded by this stuff. Take milk jugs for instance. Chances are you buy your milk in a plastic jug made of polyethylene. And chances are that when you bought that milk the check-out person put it in a plastic bag, also made of polyethylene. Notice how much weight you can hold with a thin sheet of this modern plastic. That bag weighs almost nothing, yet it will hold one or even two gallons of milk! How did they live without this stuff back in the stone ages, like when your mom and dad were kids? Believe it or not, milk used to come in glass jugs. You couldn't buy anything larger than a half-gallon, because with the jug and all it weighed a ton and would jerk your arm right out of its socket. And, of course, there was always the problem of what happened when you dropped it-little glass fragments everywhere and a big pool of milk on the floor!
So with all these miracle polymers of our modern age, care to guess which is the strongest of all? It's been around for ages and it's definitely not man-made. It's spider silk! All the brains in the world have failed to come up with anything stronger, pound for pound, than the silky stuff that spiders spin their webs from. Who cares, you ask. I'll tell you who cares! Right this minute the U.S. military is looking at making lighter, tougher bulletproof vests and other personal armor out of the stuff. Of course, getting enough spider webs to make a bulletproof vest is no small feat; so some pretty clever scientists have transferred the spider silk gene to goats. Milk the goat, extract the spider silk from the milk, and start spinning the lightest, strongest fiber known to man. How strong? "A silk cable as thick as your thumb would be able to haul down a jet fighter," according to a Canadian company that is developing the technology. So move over, Spider Man, the U.S. Marines are on the way, complete with spider web suits.
Cool Stuff You Can Do
Get an adult to help you with this; and find a place where you can make a mess without causing a lot of trouble. You'll need a disposable cup, some Borax detergent additive, and some Elmers glue (the white stuff for gluing papers works just fine).
In the disposal cup, mix approximately 1 tablespoon of Borax into 2 tablespoons of water. If you don't have any Borax, liquid starch will work as a substitute for the Borax. Squeeze some Elmer's glue into the Borax solution. Now use a popsicle stick to stir the mixture. You can also use your hands to work the putty into a ball. Or, if you want to be neat, pour the goop into a plastic bag, seal it shut, and then knead the bag by hand until it becomes rubbery. And there you have it-your very own recipe for play putty!
