What are Polymers? (Что такое полимеры?) - страница 3

Полимер – это высокомолекулярное соединение (вещество с большой молекулярной массой от нескольких тысяч до нескольких миллионов), в котором атомы, соединенные химическими связями, образуют линейные или разветвленные цепи, а также пространственные трехмерные структуры. Часто в его строении можно выделить мономер – повторяющийся структурный фрагмент, включающий несколько атомов. Полимер образуется из мономеров в результате полимеризации. К полимерам относятся многочисленные природные соединения: белки, нуклеиновые кислоты, полисахариды, каучук и другие органические вещества. В большинстве случаев понятие относят к органическим соединениям, однако существует и множество неорганических полимеров.

Большое число полимеров получают синтетическим путем на основе простейших соединений элементов природного происхождения путём реакций полимеризации, поликонденсации и химических превращений.

Polymer is the term used to describe large molecules consisting of repeating structural units, or monomers, connected by covalent chemical bonds. The term is derived from the Greek words: «polys» meaning «many», and «meros» meaning «parts». A key feature that distinguishes polymers from other molecules is the repetition of many identical, similar, or complementary molecular subunits in these chains. These subunits, the monomers, are small molecules of low-to-moderate molecular mass, and are linked to each other during a chemical reaction called polymerization. Although most polymers are organic, with carbon-based monomers, there are also inorganic polymers; for example, the silicones, with a backbone of alternating silicon and oxygen atoms.

A polymer is a large molecule constructed from many smaller structural units called monomers joined together by covalent bonds. Polymers have existed in natural form since life began and those such as DNA, RNA, proteins and polysaccharides are some of the most important macromolecules found in plant and animal life. From the earliest times, the man has used many of these polymers as materials for providing clothing, decoration, tools, weapons and other requirements. However, the origins of today’s polymer industry commonly are accepted as being in the nineteenth century when important discoveries were made concerning to the modification of certain natural polymers, as cellulose. The use of synthetic and natural polymers as stabilizers for colloid systems (sols, dispersions, microemulsions, etc.) is becoming more important everyday in contemporary life. Polymer additives can be applied in preconcentrations and dehydration of suspensions in mineral processing, purification of wastewater and even in nutritional and pharmaceutical emulsions being their importance related to the characteristics of the process and the properties that they show.