Structure and dynamics of star polymers.

The structural and dynamical properties of an 18-arm poly(isoprene) star polymer (Mnarm=7360 g mol−1) are investigated by experiment and theory. Light scattering techniques reveal the existence of static and dynamic long range correlations (ξ ≈ 100 nm) above the overlap concentration c*, which are an indication for a structural glass transition at higher concentrations. Combining statistical-mechanical theories and small angle neutron scattering (SANS), it is shown that the effective pair potential between star polymers is exponentially decaying for large distances and crosses over, at a density-dependent corona diameter, to an ultra-soft logarithmic repulsion for small distances. Finally, neutron spin echo spectroscopy (NSE) is used to investigate the influence of interstar entanglements on the internal dynamics of the star polymer. Hence, star polymers can actually be viewed as hybrids between polymer-like entities and colloidal particles establishing an important link between these different domains of physics. [ABSTRACT FROM AUTHOR]