Isoprene

          Only in the cast century and a half has rubber become a necessity in society, but how would be life without the rubber products that we use in our daily life. The discovery of rubber is without a doubt an important discovery since it is a component in the most various objects affecting life in various ways.

            Natural rubber, a polymer of the molecule isoprene, was long known in 1600 and 1200 B.C. At this time this natural rubber was used for decorative and practical purposes, and balls made of this material could jump really high. However this rubber latex substance was not very practical since it would become sticky and smelly in hot weather, while during winters it would turn hard and fragile. It was during 1835that it was found that natural rubber was composed of repeating units of isoprene that when bond together to form the polymer chain, cis double bonds meaning that the  two CH2 groups in each isoprene unit are on the same side of the double bond. This cis structure originated is what gives the elasticity to rubber and in natural cases where isoprene forms with a trans arrangement substances named, gutta-percha and balata are originated being totally different from rubber in the aspect that when exposed to air they become hard right away. The only time they wouldn’t become hard was when it was under water, reason behind its uses as underwater products. Later they would also be used in other things like catheters, forceps, fillings for cavities and even in golf balls.

             A rubber fever hit when its waterproof quality was discovered however the previous flaws made its demand decrease and started the search for methods to fix these flaws and give more consistency to the rubber. Charles Goodyear was the one that finally discovered the way to make the rubber not chance in the hot weather. He accidently found that there was some potential in the mixture of rubber, sulfur and heat, and after five years he was able to produce rubber that was consistently tough, elastic and stable in hot and cold weather. The way for the ideal rubber was finally found. At the time Goodyear had no idea of how this substances reacted to produce the desired rubber, but nowadays it is known that this phenomenon happens thanks to the cross linkages between the rubber molecules. With the heat provided, the sulfur molecules would serve as links and hold the rubber molecules chains in position, process named vulcanization.

            Another characteristic behavior of rubber is its ability to stretch, which is also due to its chemical structure, more specifically the cis arrangement. With this arrangement the rubber molecules can’t lie close together, as in a trans arrangement, and cannot produce effective cross-links between the chains, making possible for the aligned molecules to slip past each other when the substance is under some kind of pressure, giving elasticity to the rubber. As for trans, the molecules fit close together and the effective cross-links stop the molecules from slipping past each other, making it hard to stretch. With the vulcanization and addition of enough cross linkage it decreases the elasticity still maintaining some of it, and different amounts of sulfur will originate different types of rubber some harder than others depending on the amount of sulfur and cross linkage that it will eventually create.

             With the discovery of the stabilized rubber, its demand had a great increase, and the producers of rubber became very wealthy in the following years using the Amazon natives as workers in a system that was very similar to slavery.  The demand for rubber was so great and had such potential to bring profit, that Europeans took the seeds from the tree which produced rubber and started to plant them in Asia. Thousands of immigrants were sent to these plantations of natural rubber in Malaya and Ceylon. Misery also came from this frenetic rubber production, since certain villages were forced to abandon their lifes and work in the rubber plantations where barbaric punishments took place. The uses and demand for rubber increased in such a way that even with innumerous plantations the supply could not satisfy the need and the need of rubber by the United States during World War II stimulates the discovery of a synthetic rubber since this was a material that had also become indispensable for the nations development and growth of the industrial and transportation sectors. However the production of synthetic rubber was harder than it seemed since it was really hard to control the formation of cis and trans double bonds, and ironically, it was Germany that create the technology to create the rubber substitutes. During the World War I Germany had developed the substance styrene butadiene rubber, a polystyrene made of styrene and butadiene which had the properties as natural rubber and could be vulcanized with sulfur. This method eventually reached America and there was again a huge production of rubber substitutes, with even new ones being originated. However only in 1953 the methods to synthesize natural rubber were found this being a revolutionary discovery which would give the ability to precisely control the properties of the polymers produced.

           As the authors demonstrate the reader in the book, rubber as had innumerous effects in the world. The demand for rubber has created one of the many examples of the over exploration of resources and destruction of the environment. The thirst for natural rubber has induced nations to brutally colonize others and shamefully take over the lands of others. Rubber induced migrations and was vital for the mechanization of the industry which could only be possible with rubber. Even today, rubber is important, products all around us that are indispensable are made of rubber, so even though we are not exploring land and people, isoprene is still important being part of our daily life.