Copolymer

Copolymers (schematic representation)
Random copolymer
Gradient copolymer
Alternating copolymer
Block copolymer
Graft copolymer

Copolymers are polymers that are composed of two or more different types of monomer . This is the opposite of homopolymers .

Classification

Copolymers can be divided into five classes, as illustrated by a binary copolymer made up of two different comonomers A and B :

Statistical copolymers, in which the distribution of the two monomers in the chain follows a statistical distribution. If the ratio of the monomers in a section corresponds to the molar ratio, one speaks of a random distribution (English random copolymer) (- AA B A BBB A B AA BBB A BB A B A B -).
Gradient copolymers which in principle are similar to random copolymers, but in which the proportion of one monomer increases and the other decreases over the course of the chain (- AAAAAA B AA BB AA B A BBB AA BBBBBB -).
Alternating copolymers in which the two monomers alternate (- A B A B A B A B A B A B A B A B A B A B -).
Block copolymers and segment copolymers consisting of longer sequences or blocks of each monomer (- AAAAAAAAA BBBBBBBBBBBB -). Depending on the number of blocks, one also speaks of diblock copolymers, triblock copolymers, etc. The number of monomers per block is generally a maximum of ten units.
Graft copolymers, in which blocks of one monomer are grafted onto the backbone of another monomer.

Copolymers that consist of three different monomers are called terpolymers (-ABCABCABCABCABCABC-). This group of copolymers can also be divided into the classes listed above.

Interaction parameters in copolymer blends are shown with the Schubert plot .

Examples

Acrylonitrile butadiene styrene copolymer (ABS)
Styrene-acrylonitrile copolymer (SAN)
Poloxamers
Butyl rubber

Biopolymers

In addition to the copolymers (this term indicates the type and method of synthesis), which are designed and synthesized process-technically for intended applications, there are a large number of naturally selected biopolymers , which can in principle be referred to as copolymers, but which are usually referred to with the term heteropolymers (indicates the composition). Biological synthesis mechanisms for polymers follow different catalytic principles than those of chemical-synthetic polymer chemistry. Examples are proteins , deoxyribonucleic acid (DNA) and cellulose ; Overview .

literature

JMG Cowie: Chemistry and Physics of Synthetic Polymers. 2 Ed., Vieweg, 1991, p. 4f.

Web links

Commons : Copolymers - Collection of images, videos, and audio files

Glossary in Chemgapedia

Individual evidence

↑ Entry on copolymer . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.C01335 Version: 2.3.3 ..
^ ^A ^b ^c ^d Joachim Buddrus: Fundamentals of Organic Chemistry , Walter de Gruyter Verlag, Berlin, 4th edition, 2011, p. 899, ISBN 978-3-11-024894-4 .
Jump up ↑ JMG Cowie, Valeria Arrigh, Polymers: Chemistry and Physics of Modern Materials , CRC Press, Boca Raton, 2007, p. 148. Google Books
↑ ^a ^b M. D. Lechner, K. Gehrke and EH Nordmeier: Makromolekulare Chemie , 5th edition, Springer-Verlag, 2014, p. 133, ISBN 978-3-6424-1769-6 .

[1] Entry on copolymer . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.C01335 Version: 2.3.3 ..

[Buddrus-2] A ^b ^c ^d Joachim Buddrus: Fundamentals of Organic Chemistry , Walter de Gruyter Verlag, Berlin, 4th edition, 2011, p. 899, ISBN 978-3-11-024894-4 .

[3] Jump up ↑ JMG Cowie, Valeria Arrigh, Polymers: Chemistry and Physics of Modern Materials , CRC Press, Boca Raton, 2007, p. 148. Google Books

[Lechner-4] M. D. Lechner, K. Gehrke and EH Nordmeier: Makromolekulare Chemie , 5th edition, Springer-Verlag, 2014, p. 133, ISBN 978-3-6424-1769-6 .