химический каталог




Компьютерное материаловедение полимеров

Автор А.А.Аскадский, В.И.Кондращенко

s in computer-aided synthesis of polymers the fragment method has been proposed; then a computer designs a repeating unit of the polymer of those fragments. A part of the 194 fragments calculated in[17] is shown in Table 54, the possibility of their mutual connection being given by a matrix on page 400. This approach was later improved in the basic fragment method when computer-aided synthesis of polymers is performed from smaller basic fragments than die above-discussed fragments wliich cannot be "comminuted" in principle. The list of basic fragments for computer-aided synthesis of polymers is given in Table 55, the matrix of their combinations along 20 different end marks being shown on page 401. In Fig. 105 a combinatory tree is presented illustrating the design of a recurrent polymer repeating unit of three basic fragments with different end marks. A computer program based on the use of liny basic fragments permits to calculate and "synthesize" polymers of the following classes: 1. Polyolefins, vinyl polymers, etc. 2. Polyethers and polyeUterketones. 3. Polyesters. 4. Polyamides. 5. Polysul-fones, polyethersulfones. 6 Polyimides. 7. Polyoxadiazoles. 8. Polybeimmidazoles. 9. Polysulphides. 10. Organosilicon polymers. 11. Polycarbonates. If necessary the number of polymer classes can be enlarged. For this purpose it is necessary to introduce the group which defines belonging of polymers to a selected class into the database For instance, urethane group being introduced into the database allows to calculate properties of polyurethanes and to perforin computer-aided synthesis of polyuretlianes with the preset properties.

The capacities of the chemical fragment method, are, nevertheless, limited to solution of the above-mentioned problems only for polymers whose basic fragments are contained in a computer database. This disadvantage is eliminated in the method of structural formulas of chemical compounds, when chemical structure of a polymer is "composed" not of blank fragments, but of individual atoms. In this case chemical structure of a repeating unit is composed on the display screen in the form of a structural formula of a chemical compound, just like a chemist draws it on paper. This allows to perform molecular design of a polymer, varying its chemical stmcture, introducing various atoms and atomic groups and to obtain physical characteristics of a substance being synthesized from the very beginning.

This program allows to calculate the following properties of polymers, copolymers and polymer networks:

1. Molar volume. 2. Temperature dependence of molar volume. 3. Van-der-Waals volume. 4. Density. 5. Temperature dependence of density. 6. Variation of volume in a given temperature range. 7. Coefficient of thermal expansion in glassy state. 8. Coefficient of thennal expansion in rubbery state. 9. Glass transition temperature. 10. Melting point. 11. Temperature of onset of intense thermal degradation. 12. Solubility parameter. 13. Oxygen permeabilily. 14. Nitrogen permeability. 15. C02-permeability. 16. Cohesion energy. 17. Share of dispersion interaction in cohesion energy 18. Ratio of dipole-dipole interaction in cohesion energy. 19. Ratio of H-bonds in cohesion energy. 20. Surface tension. 21. Interface tension at boundary between polymer and solvent. 22. Interface tension at boundary between polymer-1 and polymer-2. 23. Prediction of solubility of polymers in organic solvents. 24. Pre516

Summary

diction of compatibility between polymers. 25. Molar heat capacity in glassy state. 26. Molar heat capacity in rubbery state. 27 Specific heat capacity in glassy state. 28. Specific heat capacity in rubbery state. 29 Jump of heat capacity at transition of polymer from glassy state to rubbery state. 30. Refractive index. 31. Temperature dependence of refractive index. 32. Molar refraction. 33. Stress-optical coefficient. 34. Energy of intermolecular interaction. 35. Energy of dispersion interaction. 36. Energy of dipole-dipole interaction and H-bonds. 37. Ratio of dispersion interaction in total energy of intermolecular interaction. 38. Ratio of dipole-dipole interaction and H-bonds in total energy of intermolecular interaction. 39. Activation energy of gamma-transition. 40. Dielectric constant. 41. Polarizability. 42. Degree of polymerization for rubbery state occurrence. 43. Molecular mass of polymer for rubbery state occurrence. 44. Rubber elasticity modulus in field of plateau for linear polymers. 45. Equilibrium modulus of rubber elasticity for polymer networks. 46. Temperature of transition of polymer in viscous-flow state versus molecular mass. 47. Solubility of poly mer versus molecular mass 48. Solubility of polymer versus degree of orientation. 49. Calculation of properties of copolymers depending on their composition. 50. Properties of polymers versus degree of their crystallinity.

For low molecular liquids the program envisages calculation of the following properties:

1. Molecular mass

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