Application of the Methods of Molecular Distribution to Solutions of Large Molecules
- 1 March 1946
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 14 (3), 164-179
- https://doi.org/10.1063/1.1724116
Abstract
The equations for the thermodynamic potentials of the solvent in solutions of ordinary organic molecules are extended to solutions of large molecules by methods using continuous molecular distribution functions. Particular attention is given to the coefficient, A2, of the second term in the expansion of the osmotic pressure in terms of the concentration, since this coefficient has a simple molecular meaning and is sufficient to describe the deviation of the system from ideality at low concentrations. A2 is calculated by direct integration for two rigid shapes, the sphere and the long thin rod. A general expression is then developed for A2 for flexible chain molecules in terms of the interactions of the segments of the chains. In favorable cases it is found possible to relate A2 for a chain molecule to the solution properties of its small molecule homologues by an equation very similar to those developed by Flory, Huggins, and Miller. In general, however, interactions that depend both on the local structure and also on the over‐all shape of the chain molecules seriously modify such a relationship. The nature of these interactions, including the effects of branching and of limited flexibility, is discussed. It is also shown that higher coefficients in the expansion of the osmotic pressure in terms of concentration can be treated in a similar way. Comparison with experimental data confirms the general predictions of the theory both for proteins and chain polymers.Keywords
This publication has 20 references indexed in Scilit:
- The Thermodynamics of High-Polymer Solutions: I. The Free Energy of Mixing of Solvents and Polymers of Heterogeneous DistributionThe Journal of Chemical Physics, 1945
- The free energies of solutions of single and multiple moleculesTransactions of the Faraday Society, 1944
- Comparative Osmotic and Viscosity Measurements with Polystyrene FractionsJournal of the American Chemical Society, 1943
- The Vapour-Pressure Equations of Solutions and the Osmotic Pressure of RubberMathematical Proceedings of the Cambridge Philosophical Society, 1943
- Theory of Solutions of High Polymers1Journal of the American Chemical Society, 1942
- THERMODYNAMIC PROPERTIES OF SOLUTIONS OF LONG‐CHAIN COMPOUNDSAnnals of the New York Academy of Sciences, 1942
- The interaction between rubber and liquids. 1. A thermodynamical study of the system rubber-benzeneTransactions of the Faraday Society, 1942
- Propriétés des polymères en solution. XII. Energie libre et chaleur de dilution. Système caoutchouc‐toluèneHelvetica Chimica Acta, 1940
- Über die Gestalt fadenförmiger Moleküle in LösungenColloid and Polymer Science, 1934
- A theory of partial osmotic pressures and membrane equilibria, with special reference to the application of Dalton's Law to hæmoglobin solutions in the presence of saltsProceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 1928