Long Range Bond-Bond Correlations in Dense Polymer Solutions

Abstract

The scaling of the bond-bond correlation function $C(s)$ along linear polymer chains is investigated with respect to the curvilinear distance, $s$, along the flexible chain and the monomer density, $\ddot{I}$, via Monte Carlo and molecular dynamics simulations. % Surprisingly, the correlations in dense three dimensional solutions are found to decay with a power law $C(s)\sim s^{-\ddot{I}‰}$ with $\ddot{I}‰=3/2$ and the exponential behavior commonly assumed is clearly ruled out for long chains. % In semidilute solutions, the density dependent scaling of $C(s)\approx g^{-\ddot{I}{‰}_0}(s/g{)}^{-\ddot{I}‰}$ with $\ddot{I}{‰}_0=2-2\hat{I}½=0.824$ ($\hat{I}½=0.588$ being Flory's exponent) is set by the number of monomers $g(\ddot{I})$ contained in an excluded volume blob of size $\hat{I}¾$. % Our computational findings compare well with simple scaling arguments and perturbation calculation. The power-law behavior is due to self-interactions of chains on distances $s\gg g$ caused by the connectivity of chains and the incompressibility of the melt. %

4 pages, 4 figures