Isoprene
Rubber is a
natural polymer that is ubiquitously applied to various machinery and
industrially produced and manufactured products such as elastic bands and car
tires. Rubber consists of repeating units of one type of monomer, isoprene, or
C5H8. Isoprene is the smallest natural monomer component
and could undergo polymerization reactions to form rubber with either the cis
configuration or the trans configuration. The cis isomer of isoprene is
responsible for the elasticity of the rubber and for the desired properties of
rubber. The cis isomer involves the hydrogen atom at the top and the trans
isomer involves the hydrogen atom at the bottom of the molecular structure; the
two double bonds present in the molecular structure of isoprene locks the
attached components in position and do not permit a rotational symmetry to
other, giving rise to the possibility of diasteriomers. The polymerization of
cis isoprene and trans isoprene produces polymers with different properties.
Rubber with the cis configurations is elastic and rubber with the trans
configurations is brittle, non-elastic, and lacks flexibility. The two
substances, balata and gutta-percha obtained from the latex of the Sapotaceae
family contain the trans isoprene polymer naturally and have been applied to
fill in cavities and for dental applications. Golf balls constructed form the
trans isoprene rubber became brittle and hard over time and eventually broke
apart into pieces while being hit with the club. The unprocessed cis isoprene
polymer also interfered with golf games because in humid or hot conditions, the
golf ball would become sticky and disintegrate. The first use of rubber
involved forming decorations and other products rubber has been found in
Central and South America and in Mesopotamia
between 1600 and 1200 B.C. During hot weathers, the rubber became sticky and
smelly and became hard and brittle during the European weathers; the results
trace to the fact that vulcanization of rubber has not occurred and the
technological advancements were not available during that epoch or period of
time. Treatment with sulfur and heat causes rubber to be resistant to hot and
cold temperatures. Various experiments with rubber have occurred during the
eighteenth and nineteenth centuries, including the production of nitrated
rubber and rubber treated with naphtha (a waste product from the local gas
works), and sulfur-treated rubber as erasers, raincoats, and other materials.
Goodyear, a chemist, in 1839, accidently poured a trace of rubber on sulfur on
a heated stove and noticed the formation of a mass with potentially applicable
and desirable properties for the production of a variety of materials and
appliances. The sulfur-treated tuber is strong, tough, elastic to a certain
extent (depending on the percentage composition of sulfur), resistant to
various solvents, and resistant to hot and cold temperatures the rubber that
Goodyear has accidently synthesized has been patented and produced on a large
industrial scale to make floors, ships, car springs, rubber banknotes, sails,
jewelry, and other materials. However, since Goodyear is not very financially
capable and orientated, has been incarcerated because he did not pay his bills
during a technicality during the vulcanization process, which involves the
polymerization of cis isoprene and treating it with sulfur and heat to
stabilize it. Heat catalyzes the formation of the cross-linkages and sulfur
actually forms the cross-linkages between the rubber molecules and anchors the
long chains into place; cross-linking strengthens the molecule, but decreases
its elasticity. The elastic properties of cis isoprene links to its molecular
structure, which involves the coiled chains slipping and sliding past on
another when tension is applied and restoring their coils when the force of
tension subsides; the cis isoprene polymer or rubber is a flexible elastomer
and the formation of disulfide bonds aids in the stability and flexibility of
the rubber molecules, yet suppresses the elasticity of the molecules. The
elastic forms of rubber contained approximately 1 to 3 percent sulfur and the
non-elastic rubber contains 3 to 10 percent sulfur and this type of rubber is
applied to produce car tires. The vulcanization process discovered by Goodyear
impacted civilization and technological advancements significantly. The rubber
monopoly in the Amazon area has generated huge profits and produced significant
amounts of rubber through cultivation and arduous labor; however the Castilla
tree, which is used to isolate and produce natural rubber was about to face
extinction due to the depletion of the resource and constant cutting down of
those trees to obtain the resource that had a very high demand. Leopold, a
member of the rubber trade, established a regime in central Africa
and enslaved many people to cultivate, isolate, and produce natural rubber;
however the conditions were very harsh and inhumane at the plantations and the
selected land to cultivate rubber. despite the humanitarian protest, other
corporations forced many other people into labor to produce rubber on a large
scale. Since the demand for natural rubber has been so high, resources were
being depleted rapidly and a majority of rubber had to be cultivated and
produced in other areas of the world such as southeast Asia because the supply
of natural rubber from the Amazon area has been insufficient and negligible. The
polymerization of isoprene has also been unsuccessful because certain enzymes
in the plant species control the polymerization of isoprene to form rubber with
the cis configurations; however industrial isoprene polymerization to lead to
the production of mixtures containing cis isoprene and trans isoprene polymers
of rubber, which would not be very applicable. The growing gum industry in the United States
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