Heteropolymer, repeating unit

A polymer is a long-chain molecule which consists of many smaller molecules (monomers) linked together by covalent bonds. In a homopolymer all the monomer repeating units are the same, whereas in a heteropolymer there can be two or more different repeating units, according to ordered or random patterns (Figure 6.7). 

The following simple scheme distinguishes between homopolymers, in which all the repeat units are the same, and copolymers (or heteropolymers) of two types, in which two (or sometimes more) repeat units are involved. 

Common structures of heteropolymers with two types of repeat units... 

These polymers have more than one type of repeating unit in their structure. They are also known as heteropolymers. Examples are poly(ethylene-co-propylene), poly (styrene-co-butadiene) and poly (acrylonitrile-... 

Block copolymer. A block copolymer denotes a heteropolymer having a great regularity of structure with large repeating unit containing dozens of monomers. 

In all of the examples considered so far, it has been assumed that each repeating unit is identical. Polymers built up in this way are called homopolymers. However, in many macromolecules there are sequences or blocks of repeating units. These are termed heteropolymers. Important examples of sequenced heteropolymers are biological polymers like DNA, which is built from a sequence of four repeating... 

Initially, the protein-like HP sequences were generated in [18] for the lattice chains of N = 512 monomeric units (statistical segments), using for simulations a Monte Carlo method and the lattice bond-fluctuation model [34], When the chain is a random (quasirandom) heteropolymer, an average over many different sequence distributions must be carried out explicitly to produce the final properties. Therefore, the sequence design scheme was repeated many times, and the results were averaged over different initial configurations. 

Polymers are a class of molecules characterized by their high molar masses, which range from the thousands to the hundreds of thousands, and by the presence of simple repeating structural units called monomers. Because of their large size, polymers are often referred to as macromolecules. A polymer comprised of a single recurring monomer, M, is termed a homopolymer, whereas one containing at least two structurally distinct monomeric units, and M2, distributed at random in the molecule is called a heteropolymer or copolymer. These two classes of macromolecules are represented by 1 and 2, respectively. 

Other important polyamides include Cyanophycin from Cyanobacteria and -poly-L-lysine from Streptomyces albulus. The former is a repeating heteropolymer comprised of dipeptide units of aspartate and arginine, whereas the latter is a homopolymer with lysine as the main component. Cyanophycin is used as a water softener and dispersant, whereas e-poly-L-lysine is used as a food [133] preservative as well as an adsorbent [131]. 

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