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Copolymerization for Windows. Software modeling tool for the prediction of chemical structure, molecular inhomogeneity and some service properties of products of multicomponent free-radical copolymerization.

A. S. Yakovlev and S. I. Kuchanov ( kuchanov-AT-polly-DOT-phys-DOT-msu-DOT-su.gif )
Polymer Modeling Group, Keldysh Institute of Applied Mathematics, 4 Miusskaya sq., Moscow 125047, Russia.

Multicomponent Polymer Systems are of great scientific and industrial importance. These systems are often intended to meet the requirements of a familiar application more cheaply or more effectively. On the other hand, some of them provide novel combinations of properties opening up new applications. Pronounced tendency of today's polymer industry is the employment of the blends of traditional polymers rather than the synthesis of entirely new polymers on the basis of unknown monomers. Not less prospective fashion of designing multicomponent systems with prescribed set of properties is the method of multicomponent copolymerization of traditional monomers. By varying their number, chemical nature and initial stoichiometric composition it is possible to synthesize a great diversity of different copolymers exhibiting desired physico-chemical and mechanical properties.

One of serious difficulties hampering the realization of this idea in practice is connected with tremendous amount of routine experimental work aimed at the search of optimum conditions of the synthesis of the wanted products. It is a common knowledge that even from the same monomers by merely changing their proportion and the processes conditions it is possible to obtain copolymers of different composition and chemical structure markedly varying in their properties. Establishing the dependence of these latter on initial monomer mixture composition and their conversion by direct exhaustive search within the whole range of compositions is rather time consuming experimental undertaking even for any three-component copolymer. As for the copolymers with larger number of components this task turns out virtually impossible to realize. On the other hand, the larger is the number of the components in a system the more ample are the prospects of imparting to the products obtained wide range of desired properties. It comes as no surprise therefore that the method of mathematical modeling is of particular importance here since it enables one, escaping arduous routine experimental work to establish, rapidly and reliably, quantitative correlations between the conditions of the synthesis of a multicomponent copolymer and its performance properties.

We have developed corresponding user-friendly computer program permitting one to find statistical characteristics of chemical structure of the products of free-radical copolymerization of up to six monomers at their arbitrary initial composition and conversion. Essentially, the only thing supposed to be known in order to obtain such an information are the reactivity ratios whose values are available in literature for many hundreds of particular systems.

With "Copolymerization for Windows" a user is able to answer the question about the region of compositions and conversions of monomers where multicomponent copolymers will be transparent and homogeneous. To this end it is necessary along with the reactivities to know only the Flory-Huggins parameters characterizing physical interactions between pairs of monomer units of different types in homopolymers and alternating binary copolymers. Many of these thermodynamic parameters can be obtained from literature or calculated using well-known algorithms put forward by Bizzerano and van Krevelen. Another property of multicomponent copolymers of utmost importance which is possible to predict by means of our program in hand is their thermostability. This software allows the calculation of the glass transition temperature of radical copolymerization products of up to six monomers, given the glass transition temperatures of corresponding homopolymers and alternating binary copolymers. In order to find these parameters the recourse can be also made to the structure-additive Bizzerano or van Krevelen algorithms.

The Demo Version of the program "Copolymerization for Windows" can be found in the Internet at: http://www.copolymerization.da.ru.