Isoprene

Rubber, the simplest natural polymer known to man, has shaped and still shapes the world we live in today, in both positive and negative ways.  Rubber components for machines, such as belts, gaskets, joints, valves, o-rings, washers, tires, and seals have allowed for major developments in transportation and the indusrial world.  Mechanization of agriculture has allowed the growth of cities and has changed our society from a rural to an urban one. Though rubber has fueled the mechanization of the world, its negative effects can still be seen.  In tropical rainforests such as the Amazon and the Congo, where rubber can be tapped from natural sources, members of the wealthy class (mostly whites) had once exerted power over members of the lower class, forcing them to extract rubber from these sources, in a system of indebted bondage close to that of slavery.  Once rubber could be produced synthetically, however, these rubber barons went out of business, but the effects of the shameful treatment of the indigenous populations of these regions still lasts in the the form of ethnic and political strife.

Natural rubber is a polymer of the molecule isoprene, which has the following chemical structure:

When polymerized, the double bonds become single and the bond between the two center carbons becomes double.  The CH2 group of one molecule bonds with the CH2 group of another.  If the two CH2 groups of the isoprene molecules are on the same side of the carbon double bond, it is a cis polymer.  If they are on opposite sides of the carbon double bond, as in the illustration above, it will produce a trans polymer.  The cis arrangement is what natural rubber is made out of, giving it its elastic properties, where the trans arrangement causes less elasticity, and can be found in products such as golf balls.  Both of these molecules have shaped history, however, in both developmental and detrimental ways, and will continue to do so, as it will also likely shape our exploration of the future, as it is an essential component of space stations, space suits, rockets, and shuttles.