About the experimental determination of the persistence length of wormlike chains of polystyrene

This article describes a fitting method allowing to determine the persistence length of a wormlike Kratky-Porod chain. The form factor of a flexible polymer chain is measured by means of a scattering technique. Its theoretical expression is composed of the exact calculations of des Cloiseaux for an infinite chain and of the approximated function of Sharp and Bloomfield valid for a finite chain. Two examples of the determination of b illustrate this method : one describes a polyion in a semi dilute solution without salt, the other a polystyrene chain in its melt.