Mindblown: a blog about philosophy.

Synthetic polymers are produced in different types of reactions. Many simple hydrocarbons, such as ethylene and propylene, can be transformed into polymers by adding one monomer after another to the growing chain. Polyethylene, composed of repeating ethylene monomers, is an addition polymer. It may have as many as 10,000 monomers joined in long coiled chains. Polyethylene is crystalline, translucent, and thermoplastic—i.e., it softens…

Organic polymers play a crucial role in living things, providing basic structural materials and participating in vital life processes. For example, the solid parts of all plants are made up of polymers. These include cellulose, lignin, and various resins. Cellulose is a polysaccharide, a polymer that is composed of sugar molecules. Lignin consists of a complicated three-dimensional network of polymers. Wood resins…

The word polymer designates an unspecified number of monomer units. When the number of monomers is very large, the compound is sometimes called a high polymer. Polymers are not restricted to monomers of the same chemical composition or molecular weight and structure. Some natural polymers are composed of one kind of monomer. Most natural and synthetic polymers, however, are made up of two or more…

Natural polymers include proteins, which are polymers of amino acids, and nucleic acids, which are polymers of nucleotides—complex molecules composed of nitrogen-containing bases, sugars, and phosphoric acid. Starches, an important source of food energy derived from plants, are natural polymers composed of glucose.

Organic polymers play a crucial role in living things, providing basic structural materials and participating in vital life processes. For example, the solid parts of all plants are composed of polymers. These include cellulose, lignin, and various resins.

A polymer is any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, which are multiples of simpler chemical units called monomers. Polymers make up many of the materials in living organisms and are the basis of many minerals and man-made materials.

Boride, any of a class of hard substances in which boron is chemically combined with various metals (see boron).

Antifreeze, any substance that lowers the freezing point of water, protecting a system from the ill effects of ice formation. Antifreezes, such as ethylene glycol or propylene glycol, commonly added to water in automobile cooling systems prevent damage to radiators. Additives to prevent freezing of water in gasoline (e.g., Drygas) usually contain methanol or isopropanol. Organisms that must survive freezing temperatures use various chemicals to inhibit ice crystal formation in their cells and tissues: glycerol or dimethyl…

Silica, compound of the two most abundant elements in Earth’s crust, silicon and oxygen, SiO2. The mass of Earth’s crust is 59 percent silica, the main constituent of more than 95 percent of the known rocks. Silica has three main crystalline varieties: quartz (by far the most abundant), tridymite, and cristobalite. Other varieties include coesite, keatite, and lechatelierite. Silica sand is used in buildings and roads in the form of portland cement, concrete, and mortar, as…

chemical compound Nitrate, any member of either of two classes of compounds derived from nitric acid, HNO3. The salts of nitric acid are ionic compounds containing the nitrate ion, NO–3, and a positive ion, such as NH4+ in ammonium nitrate. Esters of nitric acid are covalent compounds having the structure R―O―NO2, in which R represents an organic combining group, such as…