Updated July 21, 2017 Show By John Brennan
Synthetic polymers are an integral part of the modern world. They make your life easier and more convenient in hundreds of different ways -- but that doesn't necessarily mean synthetic polymers are free from disadvantages. The raw materials used to produce them are not limitless, and the way you dispose of them can also lead to environmental problems.
Synthetic polymers are an incredibly versatile group of compounds -- so versatile, in fact, you can find them in all sorts of unexpected places. The methyl 2-cyanopropenoate in your superglue polymerizes to make a tough, solid film; RTV silicone hardens when dried to make gaskets for use in cars. The nylon in stockings and ropes, the polyesters in clothes, the polyethylene in shopping bags, the PVC in plumbing and the rubber in your car tires are just a few more examples of synthetic polymers in your everyday life.
Society uses synthetic polymers because many of them have highly desirable properties: strength, flexibility, resistivity, chemical inertness and so forth. Take, for example, acrylonitrile/butadiene/styrene (ABS) copolymer -- a synthetic polymer -- which is strong and hard and yet flexible as well. ABS is found in objects as diverse as car bumpers and camera cases. Or take polystyrene, which is easily molded to make items like plastic forks. Polystyrene foam, better known as Styrofoam, is a fantastic thermal insulator popular as beverage containers used in restaurants.
Currently synthetic polymers are manufactured from hydrocarbons derived from crude oil, especially substances like ethylene and 1,3-butadiene. The supply of oil, however, is far from limitless. According to the New York Times, in March 2011, economists at the major international bank HSBC warned that less than 50 years' supply of oil is left, given current rates of consumption (assuming major undiscovered reserves do not exist). Consuming crude oil to make synthetic polymers takes another bite out of the already limited amount remaining, and once these dwindling supplies run out, the world will need new sources of industrial starting materials to make these synthetic polymers.
Many synthetic polymers' most desirable feature is their chemical inertness -- their resistance to various kinds of chemical degradation. This same property, however, also means they last a long time once they are thrown away. According to a 2007 article in Slate, scientists estimate that a single plastic bag could take as much as 500 years to break down. If items made of these sturdy synthetic polymers are thrown away as litter, they can also find their way into the local environment as well.
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From the stone age to the age of computers, a significant development is self-evident in the materials that make our daily life comfortable. One of these revolutionary materials in the modern world is polymers. It is a material containing large molecules made by bonding (chemically linking) a series of building blocks called monomers. Polymers are present in almost every aspect of modern-day lives because of their vast spectrum of properties. Natural polymers like wool, cotton, and silk are present in our society long before the notion itself. The first synthetic polymer was invented in 1869 by John Wesley Hyatt, who made the first substitute for ivory billiard balls. It was not until 1907 when polymers entered the industrial sector with the invention of Bakelite, the first fully synthetic plastic, containing zero naturally occurring molecules. These inventions later emerged as a field of macromolecular chemistry, a field closely associated with the name of Herman Staudinger, who received the Nobel Prize in 1953 for first proposing the idea of polymerization (a process of reacting monomer molecules together in a chemical reaction to form polymer chains). Since then, there have been several developments in the synthesis of various polymers, contributing to six more Nobel prizes associated with the field of polymeric sciences. Let’s take a look at some of the most commonly used polymers in everyday life. 1. PolyethylenePolyethylene, also known as polythene, is one of the most prominent plastic polymers, accounting for 34% of the total plastic market in the world. It is a lightweight and durable thermoplastic with a crystalline structure and the general chemical formula ({C}_{2}{H}_{4})_{n}. It has several excellent physical properties such as high ductility, high impact strength, and very great chemical resistance. Although there are different types of polyethylene classified by their density and branching, the most common types that we encounter in our daily life are:
2. PolyesterPolyester is the class of polymers comprising an ester group in the monomer subunit. In daily life, it is most commonly referred to as a form of fiber called Polyethylene terephthalate (PET). Polyester can be both an amorphous and a semi-crystalline polymer, depending on its production and thermal history. Polyester fibers are often mixed with natural fibers to create a fabric with aggregate properties. As compared to natural fibers, polyester fibers have superior water, wind, and environmental resistance. Moreover, Its hydrophobic property makes it ideal for garments and jackets that are to be used in wet or damp environments by coating the fabric with a water-resistant finish intensifies this effect. Besides clothing and fabric, PET is also used as a substrate in solar cells, a waterproof barrier for cables, and also as an oxygen barrier for type IV composite high-pressure gas cylinders. 3. AcrylicsAcrylics, also known as acrylate polymers, are a group of polymers prepared from acrylate monomer ({CH}_{2}{=}{CHCOO}^{-}). These materials are commonly known for their transparency, resistance to breakage, and elasticity. These properties make acrylic extensively useful for applications requiring high transparency and impact resistance. Some of the common uses include acrylic nails, acrylic paint, security barriers, LCD screens, and acrylic home decors. Another acrylic includes cyanoacrylate resins, made into fast-acting adhesives, such as superglue, pressure-sensitive adhesive, etc. Poly-2-hydroxyethyl methacrylate, abbreviated poly HEMA, is acrylic used in the medical sector to make contact lenses. 4. Polyvinyl Chloride (PVC)Polyvinyl Chloride (PVC or Vinyl) is a high-strength thermoplastic material that comes in two basic forms, rigid and flexible. It is produced by the polymerization of vinyl chloride monomer. It’s a white, brittle solid that comes in powder or granule form. PVC has replaced several conventional building materials such as wood, metal, concrete, rubber, ceramics, and others in a variety of applications due to its versatile properties such as lightweight, durability, low cost, and ease of processing. PVC pipes have replaced the metal pipes used for household distribution of water, thereby reducing the risk of contamination via corrosion. It is commonly used as an insulating cover for electricity wires network throughout the house. PVC is used in the manufacturing of sliding doors and window frames that are extremely durable, affordable, and help conserve energy when heating and cooling homes. In fact, vinyl windows have three times the heat insulation of aluminum windows. It also plays a critical safety role in dispensing life-saving medicine through IV bags and medical tubing. Almost one-third of plastic-based medical materials are made from PVC. 5. Polypropylene (PP)Polypropylene ({C}_{3}{H}_{6})_{n} is one of the most versatile and cost-effective thermoplastic polymers in all plastics. It is a rigid and partially-crystalline polymer produced via chain-growth polymerization of propene (or propylene) monomer. It has several properties that make it a better choice of plastic than polyethylene, e.g., higher melting point makes it employable in the manufacture of microwave-safe containers, and higher resistance to cracking and stress, even when flexed, makes it less vulnerable to daily wear and tear. Polypropylene’s characteristics make it ideal for tough and robust products ranging from protective car bumpers to life-saving medical tools and cold-weather gear for soldiers. Moreover, it can also be engineered into a wide range of packaging that helps protect products we rely on every day, from medicine to yogurt and baby food. A large volume of PP is utilized in the fabric industries. PP fiber is utilized in a host of applications including slit-film, tape, strapping, bulk continuous filament, staple fibers, spun bond, and continuous filament. For marine applications, PP ropes and twines are used as they are very strong and moisture resistant. 6. RubberRubber is an elastomer, i.e., a polymer that is primarily characterized by its ability to regain its original shape after being deformed. There are many different kinds of rubber, but they all fall into two broad types: natural rubber and synthetic rubber. Natural rubber is harvested mainly in the form of the latex from the rubber tree (Hevea brasiliensis) or other plants. In chemical terms, it is a polymer of isoprene, also known as 2-methylbuta-1,3-diene, with the chemical formula ({C}_{5}{H}_{8})_{n}. Synthetic rubbers are made in chemical plants using petrochemicals as their starting point. One of the most commonly known synthetic rubber is neoprene, chemically known as polychloroprene, made by reacting together acetylene and hydrochloric acid. Neoprene has good chemical stability and maintains elasticity over a wide temperature range, which makes it a preferred material for the manufacturing of wetsuits, wrist and orthopedic knee braces, surgical gloves, laptop sleeves, mousepads, and gaskets. Another popular family of synthetic rubbers is styrene-butadiene rubber (SBR), which is derived from the copolymerization of two monomers: styrene and 1,3-Butadiene. This rubber is widely used for the manufacturing of tires all around the world. 7. TeflonMany of us come across this material when we make our food on a non-stick pan. Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene and is known by its common brand name Teflon. It is one of the most slippery man-made materials. Apart from its use in the kitchen, PTFE is used as a cost-effective solution for industries ranging from oil & gas, chemical processing, industrial to electrical/electronic and construction sector because of its extensive properties such as exceptional heat and chemical resistance, good electrical insulating power in hot and wet environments, low dielectric constant, strong anti-adhesion, flexibility, and low water absorption. These properties make Teflon employable in several automotive parts such as gaskets, valve stem seals, shaft seals, linings for fuel hoses, power steering, transmission, etc. In the chemical industry, it can be used as coatings for heat exchangers, pumps, diaphragms, impellers, tanks, reaction vessels, autoclaves, containers, etc. Due to its electrical properties, it is widely used in insulation, flexible printed circuit boards, semiconductor parts, etc. 8. NylonMost of us are familiar with the term ‘nylon’ as a superstrong silky fiber that is generally found in umbrellas, socks, and ropes. In chemistry, nylon is a generic designation for a class of polyamides (polymers with repeating monomer units linked by amide bonds). Nylons are generally produced by reacting difunctional monomers containing equal parts of amine and carboxylic acid so that amides are formed at both ends of each monomer. There are different types of nylon depending on the nature of the monomer units. Two of the most commonly used nylons are:
9. SiliconeSilicone, also known as polysiloxane, is a high-performance elastomer made of polymerized siloxanes (chains made of alternating silicon and oxygen atoms). By varying the lengths, side groups, and crosslinking of −Si−O− chain, silicones can be synthesized with a wide variety of properties and compositions. These properties range from high-temperature performance to durability, excellent electrical insulation properties as well as varying transparency. With these unique characteristics, silicone rubber is widely used in industries such as aerospace, automotive, construction, medical, electricity, food processing, etc. For instance, sealants and adhesives made of silicone are used to seal and protect doors, windows, wings, and electrical components in the aviation and construction sectors. Due to their non-toxic properties, silicones are often used in the medical sector for implants and drug delivery systems. Advances in silicone technology enable today’s exterior paints and coatings to last longer and stand up to the sunlight and pollution. Paints made with silicones offer exceptional adhesion, pigment dispersion, and chemical, weather, and stain resistance 10. HydrogelA hydrogel is a three-dimensional (3D) network of hydrophilic polymers that can absorb and hold a substantial amount of water while maintaining the structure due to the chemical or physical cross-linking of individual polymer chains. Physical crosslinks consist of hydrogen bonds, hydrophobic interactions, and chain entanglements, whereas chemical cross-linkage involves covalent bonds between polymer strands. The polymers used to create hydrogels usually have monomers containing hydrophilic groups such as –{NH}_{2}, –{COOH}, –{OH}, –{CONH}_{2}, –{CONH}, and –{SO}_{3}{H}, which is why they are so efficient in absorbing water. Hydrogels appear in various everyday products such as hair gel, toothpaste, and cosmetics. Some superabsorbent hydrogels are acrylate-based materials, which are mainly used to absorb fluids in disposable diapers. The high-porosity structure of hydrogels allows drugs to be loaded and then released, making long-term transdermal drug delivery easier and allowing for a controlled drug delivery system. Another important use of hydrogels in the medical sector involves tissue engineering (a set of methods that can replace or repair damaged or diseased tissues with natural, synthetic, or semisynthetic tissue mimics). Both synthetic and naturally derived materials can be used to form hydrogels for tissue engineering scaffolds. Prev Article Next Article |