Hobbies And Interests
Carbon Double Bonds
If a monomer has a carbon double bond, it can form a polymer by breaking the double bond and forming a single bond with another monomer. Imagine you and a dance partner, each representing a carbon atom, are holding both hands. You each have hydrogen atoms attached to each foot, as do other pairs of dancers around the room. If you and your partner let go of one of your hands, you now each have a free hand to extend to one of the other monomers (dancing couples). Since all of them have a double bond -- the two people are holding both hands -- they can take your hand by simply letting go of one of them. If a group of people all do this, you'll end up with a long chain of people. You'll be holding on to one person with each hand, and there could be hundreds of people in this chain. Where before you had many couples waltzing, now you have a line dance.
Vinyl Chloride
A monomer of vinyl chloride has a pair of carbons double-bonded together. Carbon number one makes its two remaining bonds with hydrogen. Carbon number two is bonded to an atom of hydrogen and an atom of chlorine. If a large number of these molecules come together, they can link up by breaking their double carbon bonds and reforming single bonds between the monomers. There will be a string of carbon atoms together. A carbon, bonded to two hydrogens, is attached to a carbon, bonded to a hydrogen and a chlorine, attached to a carbon, bonded to two hydrogens, attached to another carbon, bonded to a hydrogen and a chlorine and so forth.
Condensation Polymers
Monomers can attach together even without breaking double carbon bonds. Monomers with -OH groups -- an oxygen atom attached to a carbon with one of its two bonds and to a hydrogen with its other bond -- can form polymers when the OH groups react with each other. Suppose you have a monomer with two OH groups, HO-R-OH, where R represents a number of carbons and their associated bonds with other atoms that do not take part in the reaction. HO-R-OH meets another HO -R-OH. The OH from the first monomer combines with the H from the second to form water. The first group lost its OH group, so now it has a carbon that needs to form a bond. The second lost the hydrogen from its OH group, so now it has an oxygen, which needs to bond to something. They get together. Now you have HO-R-O-R-OH. This dimer still has an OH group on either end. It can continue to form bonds with other molecules that also have -OH groups, so that you have a long chain of monomers, linked together through oxygen, which forms two bonds. This is an example of condensation polymerization.
Glucose
Glucose, nature's most simple sugar, has two -OH groups. Glucose monomers can attach together via condensation polymerization. One polymer of glucose is starch. Another is cellulose. Three-dimensional models are helpful in visualizing the difference between the two. Glucose is based on a carbon ring, and when two glucose monomers attach through an oxygen, which forms bonds at an angle, there are two different ways the two glucose molecules can line up. The rings can be coplaner, in which case you have starch. Think of a bunch of rings in a row attached by upside-down V-shaped elbows. Alternatively, as is the case with cellulose, the rings can be arranged in what looks like a staircase. Think of a bunch of rings arranged in an ascending fashion connected by right-side-up V-shaped elbows. In both of these cases, a large number of monomers are attached together to form a polymer. The orientation of the monomers with respect to each other gives the two different polymers very different qualities.