Silk and Nylon

Silk and Nylon

 

Silk, is a common material that is used to produce clothing. Silk is a protein or a polypeptide, which means that silk is a polymer of repeating units that happen to be amino acids. An amino acid contains two functional groups; one end of the molecule contains an amine group (NH₂) and a carboxyl group (COOH) at the other end of the molecule. Peptide or amide bonds are established through the covalent bonding between the amino acids (the monomers) to form a polypeptide. A hydroxyl is removed from the carboxyl group of one amino acid and a hydrogen atom is removed from the amine group of the other amino acid through a condensation reaction, thus the two molecules fuse at their functional groups and a small molecule, water, is produced. In the endomembrane system within a living cell, ribosomes synthesize polypeptides by reading the sequence of nucleic acids on the messenger RNA and the converting it to its corresponding amino acid sequence of a protein, with the assistance of transfer RNA. Energy is used through the hydrolysis of ATP to form the peptide bonds between the amino acids. Amino acids also contain an R group, which can have twenty-two possible combinations; the R group is responsible for the properties and characteristics of the amino acid and influences its polarity, pH, structural configurations, and chemical behavior. The three amino acids, glycine, alanine, and serine, have the simplest R groups and are the amino acids that make up silk. Approximately 85% of silk is composed of these three amino acids. Silk is composed of the same types of monomers, except the amino acids are different because of the R group; without the R group, amino acids would be identical. The particular sequence of amino acids is responsible for the properties, structure, and function of the polypeptide; for example, the peptide hormone, insulin, has a function of stimulating sugar metabolism and increasing the permeability of various cells to glucose so that they could obtain a source of energy through the oxidation of glucose. The polypeptide chain of silk has a zig-zag structure with a parallel chain running in the opposite direction, forming cross linkages with the other chain. This type of arrangement forms a pleaded sheet structure, which is responsible for the properties of silk; the smoothness, sheen, and strength. The pleaded sheet structure is formed because the R groups of each amino acid is relatively of the same size and the polypeptide chains fit tightly together; the R groups face upward and facilitate room for the polypeptide chains to be right beside each other at a very small distance. Not all types of silk contain the small R group pleaded sheet structures; the irregularities of certain silk molecules could break down reflected light and produce flashes and brightness. Silk molecules that contain a combination of other amino acids contain certain amino acids that could react with dye molecules and form clothing and fabric of varying colors and designs. Silk has been used during ancient times, especially in China. The Chinese emperor Huang-ti found out that silk has been produced to form a cocoon by the silkworm moth. To obtain the silk, the cocoons were heated and boiled to dissolve the sticky secretion to hold silk threads together; the cultivation of silkworms has spread rapidly in China and the silk trade began during 200 A.D, when shipments of silk arrived at different parts of the world, such as Japan. The industry of silk trade also developed in Italy and throughout the Mediterranean. The production of silk-based products, such as luxury clothing and the silk exports to other parts of the world induced economic growth and financial stability, which contributed significantly to the Renaissance Movement. During the early twentieth century, the United States has been one of the largest producers and manufacturers of silk products in the world. Attempts to produce synthetic forms of silk by Hilaire de Chardonnet were unsuccessful yet the silk that has been synthesized resembled and mimicked the properties of silk, however had certain unique properties of its own; the silk was lustrous and soft, but flammable and explosive because the artificial silk because the silk has been spun from a solution of nitrocellulose; the explosiveness of a substance depends of the degree of nitration of the molecules. Certain incidents have occurred after the Chardonnet silk has been manufactured during 1891, which lead to the discontinued usage of the product. During 1901, in England, Charles cross and Edward Bevan produced viscose, which is a viscous substance that regenerated cellulose when placed in an acid bath to form the viscose silk. This process has been used by the Du Pont Corporation; the demand for silk-based products, including clothing, has been very high and significant profit margins were generated from the manufacture of silk fibers, particularly the viscose silk. The viscose silk, however does not contain the pleaded sheet structure and is based on cellulose, which absorbs moisture and water and causes it to sag, unlike the regular silk. However, in order to sell much larger amounts of silk on an industrial scale, artificial forms of the product should be derived because the abundance of the natural and original form of silk is limited. During 1938, a non-cellulose-based nylon has been synthesized by an organic chemist hired by the Du Pont Fibersilk Company. The polyamide, nylon 66, has been synthesized after a series of attempts to synthesize “artificial silk” with a greater amount of desirable properties and a lower amount of non-desirable properties such as melting in hot water. Nylon is a polyamide that contains amide linkages, just like silk, yet it is composed of two alternating monomers; adipic acid (HOOC-(CH₂)₄-COOH) and 1,6-diamonoheaxane (H₂N-(CH₂)₆-NH₂). Through a condensation polymerization reaction, the addition of each monomer in an alternating manner occurs to form a very long nylon chain. Carothers’s nylon is known as nylon 66 because each monomer in the polyamide chain contains six carbon atoms. Nylon has been manufactured in large quantities and many nylon-based products were produced such as tire cords, mosquito netting, and military items. Wallace Carother, however ingested a vial dose of cyanide during the Great Depression in 1937 and did not notice that nylon, his product, has been applied to form a large amount of items and would be used by almost everybody. Personally, I think that the author’s argument makes sense because the influence of each polymer, silk and nylon, on society and the development of cities and economies have been described. Large profit margins, fortunes, economic growth, the growth and development of cities and the industry, ubiquitous applications, and a significant change and movement in society and technology have occurred because of these two polymers, silk and nylon that have been synthesized by a few people, but have influenced millions of other people who would use the products and manufacture the products based on silk and nylon. In conclusion, the two polymers, silk and nylon, that have been synthesized, discovered, and contributed to economic growth and prosperity through trade, exportation, and manufacturing are now been used by almost everybody in the form of clothing or products found at home. New synthetic polymers are being manufactured and synthesized to produce a variety of items such as clothing and certain products made of plastic such as water bottles are being reused, molded, and processed to form different products such as sweaters due to technological advancements, yet the idea of experimental design, monopoly, synthesis, and derivation remain and are carried from ancient times.

In silk molecules that differ from the original silk molecule that contain the pleaded sheet structure, certain amino acids react with dye molecules to form silk products such as clothing or these types of products to be applied at home. A different dye molecule is used to produce a silk product with a different colour.