Silk and Nylon

Silk and Nylon

     Silk has always been regarded as a fabric for the wealthy, and it is considered irreplaceable. The desirable properties of silk- its warmth in cold weather and coolness in warm weather, its ability to take dyes so well, its smooth feel, and its luster- are all results of its chemical structure. The chemical structure of silk ultimately led to new trade routes between the East and the rest of the world.

     There is a legend that around 2640 B.C., Princess Hsi-ling-shih found that a thread of silk could be unwound from an insect cocoon that fell into her tea. It is unknown whether this story is true, however silk production did begin in China with the cultivation of the silkworm. The silkworm is a small gray worm that only feeds on the leaves of mulberry trees. The silkworm moth can lay approximately 500 eggs in a five-day period, and then it dies. A single gram of these eggs can produce over a thousand silkworms, which together produce around 200 grams of raw silk. The worm spends several days spinning its cocoon with a long, continuous strand of silk that comes from its jaw. It creates a dense cocoon, and gradually changes into a chrysalis. To extract the silk, the cocoon is heated to kill the chrysalis inside, and then submerged in boiling water to dissolve the secretion that holds the threads together. The silk is unwound from the cocoon and wound onto reels, with a thread length ranging from 400 to over 3,000 yards. 

      Although trade routes known as the Silk Road were opened throughout central Asia, China kept silk production details secret. Silk trade had a slow spread, but regular shipments were arriving in the West by 1 B.C.. The Chinese desperately wanted to maintain their silk monopoly, so they created new laws. Any attempt to smuggle silkworms, silkworm eggs, or white mulberry seeds out of China was punishable by death. According to legend, in the year 522, two monks managed to smuggle silkworm eggs and mulberry seeds in hollowed-out canes, opening silk production to the West. By the 14th century, silk production became a major industry in Italy, which became one of the financial bases of the Renaissance movement. There were various attempts to produce silk in North America, but they were commercially unsuccessful. However, the United States became one of the largest silk manufacturers in the world in the 20th century.
     Silk is a protein, which is made of amino acids. The three main amino acids found in silk are glycine, alanine, and serine, which have the smallest side groups of all the amino acids. Together, these amino acids consitute 85% of silk's structure. The very small side groups of these amino acids contribute to the smooth texture of silk. Silk is a polymer in which the constituent amino acids have varying side groups. Amino acids are linked by peptide bonds between the carbon of one amino acid and the nitrogen of the other amino acid. An estimated 80-85% of the amino acids in silk form a repeating pattern of glycine-serine-glycine-alanine-glycine-alanine. A pleated sheet structure formed by adjacent chains of amino acids accounts for the smoothness as well as the luster of silk. The amino acids that are not part of the pleated sheet structure are responsible for the brightness or "sparkle" of silk and its ability to easily absorb dyes.

     Silk is difficult to replicate due to all of its properties, however many attempts to produce a synthetic version were made beginning in the late 19th century. Although silk is a fairly simple molecule, it is chemically challenging to attach the amino acids in the combinations that occur in natural silk. In the late 1870s, while pursuing photography, French count Hilaire de Chardonnet found that spilled collodion (nitrocellulose material that coats photographic plates) stuck to a sticky mass. Chardonnet was able to pull long, silk-like threads from this mass. He had spent a lot of time studying the silkworm and the way it spins its silk fiber. Chardonnet tried forcing collodion through tiny holes, producing the first reasonable facsimile of silk fiber.
     Although the words synthetic and artificial are often used interchangeably, they have different meanings. Synthetic means that a product is man-made through chemical reactions. Artificial means that a compound has a different chemical structure than another compound, but it has properties that can mimic its role. Chardonnet actually produced artificial silk, even though it was synthetically made. This Chardonnet silk was soft and had luster, but it was also highly flammable. This silk was spun from nitocellulose, which is explosive. Chardonnet began manufacturing this material in 1891, but its flammable nature led to its downfall. Several incidents with the fabric caused the Chardonnet factory to be shut down. However, Chardonnet continued his production of artificial silk with a denitrating agent that made the fabric safer and only about as flammable as cotton. In 1901, Charles Cross and Edward Bevan produced viscose. The name was derived from the high viscosity of the substance. Viscose liquid forced through a spinnerette and into an acid bath produced viscose silk. This process was used by the American Viscose Company and the Du Pont Fibersilk Company (later becoming the Du Pont Corporation). By 1938, approximately 300 million pounds of viscose silk were produced each year. The viscose process is still used today to produce rayons- artificial forms of silk with threads composed of cellulose.
     In 1938, an organic chemist hired by the Du Pont Fibersilk Company created nylon, which was not cellulose based. In the 1920s, Wallace Carothers, an organic chemist from Harvard University who was 31 years old, was given the opportunity to do an independent study for Du Pont on a virtually unlimited budget. Carothers made the decision to work with polymers. At the time, it was unclear what the structure of polymers actually was. One theory was that they were groups of molecules grouped together (colloids). Another theory, proposed by Hermann Staudinger, was that polymers were very large molecules. Within a year of working, Carothers produced a polyester molecule that had an atomic weight larger than 5,000. He later increased the weight to 12,000, providing more support for the giant molecule theory. Staudinger won the Nobel Prize in chemistry for this theory in 1935.
     For four years, Carothers and his colleagues created different types of polymers and studied their properties, until they finally produced nylon. This fabric is man-made and is the most similar to silk in its properties, worthy of being called "artificial silk". Nylon is a polyamide, having the same amide linkages as silk. However, the monomer units are different. Rather than having an acid and amine on each end like silk does, nylon has units with either two acids or two amines. Nylon was used for the first time as toothbrush bristles in 1938. A year later (1939) nylon stockings were brought onto the market. It proved to be an excellent material for stockings because it did not sag or wrinkle, and it was far cheaper than silk. Only a year after being introduced, approximately 64 million pairs of "nylons" were sold.

                         

     Nylon's properties allowed it to find uses in other products, including fishing nets and lines, surgical sutures, strings for tennis and badminton rackets, and coating for electrical wires. During World War II, Du Pont shifted its focus to military-related products. Main uses of nylon became tire cords, mosquito netting, ropes, weather balloons, and parachute shrouds. After the war, civilian products were made again. In the 1950s, silk was commonly used for skiwear, clothing, sails, furnishings, and carpets. Nylon was also able to be molded and known as the "engineering plastic" because it was strong enough to be a replacement for metal. In 1953, over 10 million pounds of nylon were produced for that single purpose. Wallace Carothers became depressed and committed suicide in 1937. He swallowed a vile of cyanide, and never lived to see the success of his polymer. 

BOOM!

Nitro Compounds

     Explosive molecules have varying structures, but most of them commonly contain a nitro group. NO2 has created the ability to literally move mountains, and has made it easier to wage war. Gunpowder (or black powder) was the first explosive mixture to be invented. It was used during ancient times in India, China, and Arabia. Gunpowder was originally used in fireworks and firecrackers, but by the the eleventh century, it was used to launch flaming arrows. The reactants in the reaction of gunpowder are all solid, but eight molecules of gaseous products form. It is these hot, expanding gases that propel a bullet or a cannonball.
     The firelock was the first firearm, produced sometime between 1300 and 1325. It was a tube of iron that was loaded with gunpowder and ignited by inserting a heated wire. As more advanced firearms were produced, different rates of gunpowder were needed. The finer the powder was, the faster it would burn. This made it possible to create the powder necessary for various applications. The water used for manufacturing was often supplied from the urine of mill workers.
     The force behind explosives is the rapid expansion of gases in reactions. The shock wave resulting from the rapid volume increase determines the destructive power of the explosion. Since explosions give off a lot of heat, these reactions are known to be highly exothermic. In nitro compounds' explosive reactions, an extremely stable N2 molecule forms (the stability comes from the triple bond between the two nitrogen atoms). The number of nitro groups attached to a nitrated molecule determines how explosive the molecule is. Nitrotoluene has one nitro group and dinitrotoluene has two, however they do not have the same power as trinitrotoluene (TNT).
     Italian chemist Ascanio Sobrero created nitroglycerin, another explosive nitro molecule. Sobrero tasted the compound (this practice was common at the time), and noted that "a trace placed on the tongue but not swallowed gives rise to a most pulsating, violent headache, accompanied by great weakness of the limbs". Later, nitroglycerin became used for treatment of angina pectoris, a heart disease. Nitroglycerin in the body releases nitric oxide, which dilates blood vessels. For angina sufferers, this dilation allows adequate blood flow, relieving angina pain.
     Alfred Nobel had an idea to employ an explosion of a tiny amount of gunpowder to detonate a much larger explosion of nitroglycerin. His idea worked, and is still used in the mining and construction industries to this day. Nobel was able to produce desired explosions, but faced the issue of preventing undesired ones. He searched for ways to stabilize nitroglycerin, and solidification was an obvious method. Nobel began experimenting by mixing the oily nitroglycerin liquid with neutral solids. He found that kieselguhr (a fine, natural, siliceous material) could soak up the nitroglycerin while remaining porous. The kieselguhr diluted the nitroglycerin, and separation of the nitroglycerin particles slowed their decomposition. The explosions were now controllable. Nobel named his mixture dynamite, and by 1867, Nobel and Company began shipping dynamite, and the family fortune was assured. Nobel died alone at his home in Italy in 1896, and his wealthy estate was left for providing yearly prizes for research in chemistry, physics, medicine, peace, and literature (the Nobel Prize).

     Dynamite could not be used as an ammunition propellant, and military leaders were looking for something more powerful than gunpowder. Nitrocellulose (guncotton) or nitrocellulose mixed with nitroglycerin have been used as "smokeless powder" and remain the basis of firearm explosives. TNT was well suited for munitions because it wasn't acidic, it had a low melting point (it could easily be melted and poured into bombs and shells), and it could penetrate armor. Ammonium nitrate can be a safe explosive when handled properly, but it is responsible for disasters caused by improper safety procedures or bombings by terrorist organizations. Pentaerythritoltetranitrate (PETN) is also a common explosives choice among terrorists. This is because PETN can mix with rubber to form a plastic explosive, which can be molded into any shape. It is easily detonated, very powerful, and it has little odors, making it difficult for trained dogs to detect.
     Explosive nitro compounds have made major impacts in terrorism and war, but they have impacted the world in other ways too. The compounds have been used for mining, building canal tunnels, building railway tunnels, and removing dangerous rock obstacles. Explosives have changed civilization. Whether they are used for destruction, or for construction, explosives have a major role in civilization. They have improved firearms and other explosive-based weapons used in war. Not to mention, the discovery of dynamite eventually created the Nobel Prize, which is considered a very remarkable award to receive.

Sugar and Cellulose

Glucose

     Glucose is a major component of sugar, which is formally called sucrose. The glucose molecule is relatively small, containing six carbon atoms, six oxygen, and twelve hydrogen atoms. Sugarcane is thought to have originated in the South Pacific or southern India. It was used in medicine to enhance taste, bind drugs, and even as a medicine itself. Sugar became readily available in Europe in the fifteenth century, but at a high cost. Within a century, sugar became the most preferred sweetener, and it eventually became used for preservation- jams, jellies, and marmalades became common. In the 1790s, sugar became a staple food in chocolate, tea, coffee, and sweet treats. The world's sugar production increased by 700 percent from 1900 to 1964.
     Sugar played a huge role in shaping the world we live in today. It sparked the start of the slave trade, and profit from the sugar trade caused economic growth in Europe. When explorers in the New World began cultivating sugar, there was an increased demand for workers. They looked toward Africa to supply these workers, entering America into the slave trade. There were other industries that relied on slaves, but sugar was the major one. It has been estimated that two-thirds of African slaves worked on sugar plantations.
     Glucose is a simple sugar, or monosaccharide, and the most simple one too. Its structure can be drawn as a straight chain, called the Fischer projection formula. It is named after German chemist Emil Fischer, who discovered the structure of glucose in 1891. In 1902, Fischer received the Nobel Prize in chemistry for his work with sugars. We now know that sugars typically occur in a cyclic structure called the Haworth formula. The ring structure is named after British chemist Norman Haworth, who received the 1937 Nobel Prize for his work on vitamin C and carbohydrates. Glucose is the fuel for the brains of healthy mammals.

     Sugars are so appealing to humans because they are sweet. Sweetness is one of the major tastes, and it typically means that a food is good to eat. The strongest sensors for sweetness are in the front tip of the tongue. The A-H,B model suggests that the arrangement of atoms in a molecule determines the sweetness.

     Without sugar, the slave trade would not have reached the magnitude that it did. Sugar continues to have a major impact on the world today. It is widely used in drinks and foods, and sweet treats are very popular during holidays and among children.

Cellulose
     Cotton was another crop that depended upon slave labor. The fruit of a cotton plant is called a boll. It's a pod that contains cotton fibers and oily seeds. Cotton had to be imported to Britain and other countries in the north because it requires long hot summers to grow. Lancashire, England became the center for the cotton manufacturing industry because the dampness made it easier for the fibers to stick together, reducing the breaking of fibers in production, reducing production costs.
    England imported 2.5 million pounds of raw cotton in 1760. Within 80 years, the country's production rates were at 140 times this amount. The harsh work requirements for cotton factories resulted in poor living conditions in England. Several families were crammed into a cold, damp, and dirty building, and another family lived in the cellar. Not even half of the children born in these conditions lived past the age of 5. This concerned authorities because the children wouldn't live to work in the factories. Children that worked in the factory were often beaten to keep them awake for the long hours of the workday. When English legislation banned the slave trade in 1807, industrialists imported slave-grown cotton from the southern part of America. Raw cotton was Britain's major import between 1825 and 1873. However, during WWI the raw cotton supplies were cut off, so cotton processing decreased.

     Cotton contains over 90 percent cellulose, which is a polymer of glucose. These polymers, also called polysaccharides, are classified based on their function in a cell. Cellulose is a structural polysaccharide, meaning it provides support for an organism. Structural polysaccharides contain beta-glucose units, which have an OH group on the first carbon, above the glucose ring.The structure of cellulose makes cotton a very desirable fabric. Cellulose forms long chains that pack tightly together in side by side bundles. The bundles twist together to form fibers that can be seen with the naked eye. The OH groups on the outside of the bundles allow cotton to absorb water, accounting for its ability to "wick" moisture from the body while sweating.

     Cellulose in the cotton form was responsible for both the Industrial Revolution and the American Civil War. Cotton caused the urbanization and industrialization in England. It also was a major cause of slavery in America, which was an important issue in the Civil War. Nitrocellulose (guncotton), discovered by Friedrich Schönbein, was one of the first organic explosive molecules made by man. This discovery led to other industries that were based on nitrated forms of cellulose: explosives, photography, and movies. Cellulose played a major role in shaping the world we live in today.

Scurvy

Ascorbic Acid

     The Age of Discovery almost reached its end due to a lack of ascorbic acid. The lack of vitamin C causes scurvy- an ancient disease with symptoms that include exhaustion, swelling of arms/legs, diarrhea, bruising, foul breath, and many others. Depression is also a symptom and appears at an early stage, but it's unknown whether it is a result of the disease or a reaction to the other symptoms. Scurvy became common at sea during the fourteenth and fifteenth centuries, when ship advancements (such as more efficient sales) were made. Due to the long, overseas voyages, sailors relied heavily on preserved foods. The crowded conditions on the ships mixed with the large number of men in the crew led to increased illness while out at sea. Respiratory conditions and infectious diseases were common.
     The food the sailors were eating did nothing to help with the disease issue. It was very difficult to keep food dry and mold-free aboard the wooden ships, and due to poor ventilation, the inside of the ships were very humid. A typical meal for sailors included salted beef or pork, and hardtack. Hardtack was used as a bread substitute, because it was fairly resistant to mildew. It was a mixture of flour and water without salt, and it was baked to such a hardness that it was very difficult to bite into, but it would remain edible for years. There was also a major fear of having a fire. Since the ships were made of wood, it was very difficult to have a fire. The only time fire was allowed was in calm weather, and it had to be in the galley. If the weather got rough, fires were extinguished until the storm passed. Due to these extreme requirements, sailors weren't often able to cook their food. Items such as butter, beer, bread, vinegar, dried peas, and cheese were often brought on board for the journey, but they quickly went bad. They also didn't provide vitamin C, so it could be easy to see scurvy in a short period of time.
     Remedies for scurvy were known at the time, but they were largely ignored. The Chinese grew fresh ginger on their ships as early as the fifth century. Many other countries in southeast Asia knew that fresh fruits and vegetables could help with the symptoms of scurvy, In 1601, a small fleet of four ships under the command of Captain James Lancaster collected oranges and lemons from Madagascar. Lancaster carried bottled lemon juice on his ship, and anyone with signs of scurvy was given three teaspoons of the lemon juice every morning. Upon arrival, none of the men on Lancaster's ship had scurvy, but the tolls on the other three ships were high. A quarter of the men in the entire fleet died from scurvy, but none of them were from Lancaster's ship. In 1747, Scottish naval surgeon James Lind performed an experiment on twelve crew members who had scurvy. He gave them each the same diet, but different supplements- each pair received either cider, vinegar, sulfuric acid, sea water, a mixture including nutmeg and mustard seed (as well as garlic, cream of tartar, gum myrrh, and barley water), or lemons and oranges. The results of the experiment showed that the orange and lemon provided the fastest cure. James Cook from the British Royal Navy was the first captain to make sure his crew was scurvy-free. He was very adamant about having good diet and hygiene. He can be associated with discovering antiscorbutics, but his high standards of health and cleanliness kept a low mortality rate among his crew. He was awarded the Copley gold medal for showing that scurvy can be prevented while out at sea. Cook never lost a man to scurvy.

The Fall of Napoleon's Army and the Effect of Spices on Exploration

   Napoleon's Buttons was written by Penny Le Couteur and Jay Burreson, and explains 17 groups of molecules that have had major impacts in history. From sugars to silk, dyes, caffeine, salt, etc., this book describes the history of the molecules and the effects they've had since discovery.

Introduction

  Napoleon's army, once 600,000 strong, dwindled down to less than 10,000 men within 6 months from June to December 1812. The French troops were not dressed nor were they properly equipped to survive the bitter cold of the Russian winter. Napoleon and the remaining troops retreated from Moscow. What happened to Napoleon's army that led to this retreat? As people say, "all for the want of a button". The downfall of this great army was quite possibly caused by... a button. The buttons used by the army were made of tin, which does not remain strong in cold temperatures. When the soldiers entered the bitter temperatures in Russia, their tin buttons slowly began disintegrating, leaving the soldiers to hold their garments together or find other materials to keep themselves warm. The problem, known as "Tin disease", was well known in Europe for many centuries. It is left for us to wonder- what would have happened if Napoleon's soldiers did not lose their buttons? 

   

Peppers, Nutmeg, and Cloves

   Pepper originated in India, from the Piper nigrum vine, and is the most commonly used spice. The vine can grow up to twenty feet, and produce up to ten kilograms of spice every season. The majority of pepper sold is black pepper, which is produced from the unripe pepper berries through fungal fermentation, but other forms of the spice can also be used. White pepper is formed from the ripe berry after it is skinned and dried, and is the second most used form of pepper. Green pepper is made by pickling the green berries in brine as they just start to ripen. Peppercorn found in other colors is often artificially dyed, or made from other berries.

   In the fifth century B.C., the Greeks used pepper as an antidote to poison, not for cooking/spice purposes. The Romans on the other hand, often used pepper and other spices to enhance their food. Spices, especially pepper, were used as preservatives in addition to improving the flavor of food. Since the sixth century A.D., merchants in Venice had created a huge market with salt, and later gained markets with pepper (people began to see pepper as irreplaceable due to its abilities). The demand for pepper led people to search for new sea routes to India, which would help kick off the Age of Discovery. Vasco da Gama reached India in 1948, then later returned with weapons to take over the pepper industry. Spain was also looking into pepper, which ultimately led Christopher Columbus to America. He was trying to find a shorter route to India to allow Spain to enter the spice trade. 

   The hot sensation we experience when eating pepper is caused by piperine. It is not a taste, but a response to the chemical stimulus by pain nerves. It is not fully understood how this works, but it is believed that the structure of the piperine molecule allows it to attach to proteins on the end of pain nerves, causing the proteins to change shape and send signals to the brain. When Columbus traveled to Haiti, he found the chili pepper and brought it back to Spain, even though it wasn't like the pepper he knew. Chili peppers, unlike peppercorn, grow on many species of the Capsicum genus (peppercorn is a single species). The chili pepper is believed to have originated in Mexico, and have been used for over 9,000 years. The compound responsible for the flavor of chili peppers is called capsaicin, which has a similar structure to that of piperine. These "hot" molecules increase the production of saliva in our mouths, which help with digestion. After eating spicy foods, the body releases endorphins as a response to pain.

   Nutmeg and cloves originated in the Spice Islands (Moluccas), and were much rarer than pepper. The people who lived on the islands where the spices could be found began harvesting them for trade. In 1512, Alfonso de Albuquerque, governor of Portuguese India, established direct trade with the Moluccas. Spain also wanted to get involved in the trade. In 1518, Ferdinand Magellan convinced the Spanish rulers that a westward route to the Spice Islands was not only possible, but shorter (sounds a lot like Columbus!). Magellan and his crew faced a treacherous journey, and Magellan was killed by natives on the island of Mactan. He never made it to the Moluccas, however his crew and ships continued on to Ternate, where the cloves were. Three years after departure, the eighteen survivors arrived back in Spain with 26 tons of spices on the last remaining ship- the Victoria. 

   Cloves and nutmeg come from different families and different island groups, and they each have their own distinctive odors. However, they have extremely similar aromatic molecules. Eugenol, found in the oil of cloves, and isoeugenol, found in the oil of nutmeg, have only one difference- the location of a double bond in the molecule. Piperine, capsaicin, eugenol, and isoeugenol are produced by the plants as a natural pesticide to protect themselves. Cloves were used to sweeten the breath of courtiers in the Chinese imperial court, while the oil was used to treat toothaches. Nutmeg has been used to treat stomach pain and rheumatism in China, as well as dysentery and cholic in southeast Asia. In Europe, it was used to protect against the Black Death. Eating nutmegs has been known to cause sickness, hallucinations, and even death.

   Due to the invention of refrigeration, spices are not as important for preservation. They are no longer major exports, and the conflicts and exploration caused by spices is in the past. We still enjoy spices in our food, but they are no longer at the peak they reached a few centuries ago.