Correlation between shape and size of linear polymer chains

The correlation between shape (measured by the asphericity parameter A) and size (measured by the square end-to-end distance R-2 or the square radius of gyration S-2) is investigated using a Monte Carlo technique for linear c hains random grown on the three-choice tetrahedral lattice. A positive corr elation is found, indicating that a chain conformation of small size is usu ally more spherical than that of large size. Moreover, the correlation coef ficients C-AR2 and C-A.S2 are chain length dependent; they decrease with in creasing chain length n. The asphericity parameter (A) is dependent on the bond energy epsilon and can be expressed as (A) = alpha + beta exp(epsilon) for not very short chain (n greater than or equal to 400), The value a is nearly independent of n while beta decreases with n, The result can be expl ained by the correlation between shape and size, (C) 2001 Elsevier Science Ltd. All rights reserved.