THE DYNAMIC STRUCTURE FACTOR OF A STAR POLYMER IN A CONCENTRATED-SOLUTION

To describe the dynamics of very long linear polymers in concentrated solutions, de Gennes introduced the reptation concept, where it is assumed that the dominant motion of a given polymer, confined to a tube by neighboring polymers, is along the axis of the tube. This model and its refinements have led to many successful predictions about the mechanical properties of polymeric systems. For the star polymer, which consists of many linear 'arms', each attached to a common point, reptation is strongly suppressed due to the presence of the star centre. A complete description of star dynamics should also allow for motion of the branch point: however, far stars with more than three arms it is believed that such a mechanism is negligible during the time taken for an arm to fully relax.