Polymer is the substance composed of large complex molecules formed by joining together smaller sub-units into long chains. The process by which monomers are combined to form polymer is called polymerization. We can read the mechanism of polymerization here. Depending on the molecule, a polymer may consist of several hundreds or even thousands of monomers. Because of their size, polymers are also referred to as macromolecule.
Polymer may be divided into two broad categories, naturally occurring and synthetic molecules. The natural polymers include carbohydrates, lipids, proteins, and nucleic acid.
Natural polymer
The monomer carbohydrate is called a monosaccharide, the polymer is polysaccharide. Examples of monosaccharide include glucose and fructose, which are simple sugar. Polymers of glucose include starch and cellulose, the fiber component of all plant structure. Cotton is an example of a naturally occurring polysaccharide.
Lipids include fats, waxes, oils, and steroid molecules such as cholesterol and some of the sex hormones. Some of the most common lipids are triglycerides, the monomers of which are fatty acids. Fatty acids are a type of hydrocarbon, a long linked chain of carbon atoms with attached hydrogen, with a carboxyl group (COOH) at the end. The identity of the lipid depends on the number of carbon in each of its fatty acids and whether or not the chain is saturated (linked exclusively by single bounds).
All of the previous mentioned polymers contain only elements carbon, hydrogen, and oxygen. The more complex polymers, such as proteins and nucleic acids, incorporate other elements, such as nitrogen, sulfur, and phosphorus, as well.
The basic monomer of protein is the amino acid, of which there are 20 different types. All amino acids share the common feature of amino group (NH2), as well as carboxyl group. The amino acids are linked to form a polypeptides chain. Proteins include a vast number of types of molecules, including hormones, enzymes, and muscle tissue. Wool and silk are protein polymers.
Synthetic polymers
Many of the synthetic polymers are various types of plastics and textiles, formed from repeated units of small hydrocarbons and amides (subunits containing nitrogen). Examples include Teflon, Plexiglas, Lucite, Polyurethane foam, Nylon and Polyester.
Synthetics are formed by addition reactions, which involve simply adding together monomer that automatically connect to each other, or by condensation reaction, in which a molecule of water or alcohol must first be removed in order to allow the formation of bond between the individual monomers.
Regardless of a polymer’s type or category, all of them have certain characteristics and behavior in common. At high temperature, a polymer is often a viscous liquid in which the molecular chains have mobility relative to each other. At lower temperature, some regions within the polymer may form regular crystalline structures. Alternatively, at very low temperatures, the molecular chains may freeze in an irregular pattern.
Polymer may be divided into two broad categories, naturally occurring and synthetic molecules. The natural polymers include carbohydrates, lipids, proteins, and nucleic acid.
Natural polymer
The monomer carbohydrate is called a monosaccharide, the polymer is polysaccharide. Examples of monosaccharide include glucose and fructose, which are simple sugar. Polymers of glucose include starch and cellulose, the fiber component of all plant structure. Cotton is an example of a naturally occurring polysaccharide.
Lipids include fats, waxes, oils, and steroid molecules such as cholesterol and some of the sex hormones. Some of the most common lipids are triglycerides, the monomers of which are fatty acids. Fatty acids are a type of hydrocarbon, a long linked chain of carbon atoms with attached hydrogen, with a carboxyl group (COOH) at the end. The identity of the lipid depends on the number of carbon in each of its fatty acids and whether or not the chain is saturated (linked exclusively by single bounds).
All of the previous mentioned polymers contain only elements carbon, hydrogen, and oxygen. The more complex polymers, such as proteins and nucleic acids, incorporate other elements, such as nitrogen, sulfur, and phosphorus, as well.
The basic monomer of protein is the amino acid, of which there are 20 different types. All amino acids share the common feature of amino group (NH2), as well as carboxyl group. The amino acids are linked to form a polypeptides chain. Proteins include a vast number of types of molecules, including hormones, enzymes, and muscle tissue. Wool and silk are protein polymers.
Synthetic polymers
Many of the synthetic polymers are various types of plastics and textiles, formed from repeated units of small hydrocarbons and amides (subunits containing nitrogen). Examples include Teflon, Plexiglas, Lucite, Polyurethane foam, Nylon and Polyester.
Synthetics are formed by addition reactions, which involve simply adding together monomer that automatically connect to each other, or by condensation reaction, in which a molecule of water or alcohol must first be removed in order to allow the formation of bond between the individual monomers.
Regardless of a polymer’s type or category, all of them have certain characteristics and behavior in common. At high temperature, a polymer is often a viscous liquid in which the molecular chains have mobility relative to each other. At lower temperature, some regions within the polymer may form regular crystalline structures. Alternatively, at very low temperatures, the molecular chains may freeze in an irregular pattern.
loading...
0 Response to "Understanding Polymers"
Post a Comment