Static and dynamic structure factors for star polymers in .theta. conditions

The static and dynamic structure factors for star polymers in θ solutions are derived for semiflexible models and the partially stretched (PS) arm model. The PS model for the static structure factor is found to be in fairly good agreement with SANS experiments with exclusion of the high-a region, where only a qualitative agreement is obtained. The nonpreaveraged first cumulant for the PS model reproduces fairly well the peculiar effects found by neutron spin-echo experiments even though those experiments were carried out in good solvents. The effects of preaveraging and screening of the hydrodynamic interaction are considered. Results for the full dynamic structure factor are presented only in the preaveraging approximation