From Big Medical Encyclopedia

COPOLYMERIZATION — a kind of polymerization, at a cut monomers not of one, but several types participate in the reaction of linkage of molecules of monomer leading to formation of macromolecules. As a result of S. polymers, macromolecules are formed to-rykh are formed of two and more types of constitutional structural repeating units. On the basis of S. synthesis of many biologically important macromolecules — proteins, nucleinic to - t, and also synthetic fibers, important for the national economy is carried out (see. High-molecular compounds ).

By means of S. by the corresponding selection of initial monomers, their ratio and S.'s conditions receive the substances combining various valuable properties of separate polymers. E.g., synthetic rubber is S.'s product of monomers of butadiene and styrene; for giving to synthetic acrylic fibers of colourability they are copolymerized about vinyl amines etc.

One of main types of S. is radical S. when in a macromolecule of initial polymer under the influence of physical factors (e.g., ionizing radiation, Uv-radiation, etc.) there are active centers — free radicals (see. Radicals free ), capable to initiate an inoculation to polymer in these points of any monomer. The possibility of accession («inoculation») on such mechanism of synthetic polymer side chains on such biopolymers as cellulose, gelatin, starch, etc. is shown. It is shown also that introduction in nontoxic concentration to living cell of water-soluble monomer of a vinyl row acryle of amide is followed by its S. with biopolymers of a cell on condition of initiation of this reaction by the radicals arising in a cell in the course of its life activity is normal also at pathology. The amount of the monomer polymerized and connected by a cell can be found by means of various methods — weight, radiometric, gistoavtoradiografiya (see the Autoradiography, Isotopes, Radiometry).

Radical S.'s method is applied to intravital detection of free radicals in zooblasts and plants. With its help participation of free radicals in processes of muscular contraction, carrying out rhythmic excitement in the isolated nerve fibrils is shown, the kinetics of development of free radical processes in various fabrics after radiation of animals is investigated by ionizing radiation, at carcinogenesis, etc. In a number of experiments instructions on the fact that radical S.'s method can be used not only for detection of free radicals, but also as method of controlling with a tumor were received. In particular, in experiences on cells of an angiosarcoma of the person, on mice with transplantirovanny sarcoma, on vegetable objects it was shown that introduction to cells of the monomer capable to radical G. with biopolymers of a cell, has antineoplastic effect.

See also Polymerization .

Bibliography: Kozlov Yu. P. Grafting as a method of a research of free radicals in biological systems, M., 1970. See also bibliogr. to St. Polymerization .

G.E. Fedorov.