Synthesis and Linear Viscoelasticity of PolystyreneStars with a Polyketone Core.

Wereport on a novel synthetic route to synthesize relatively largequantities of polystyrene (PS) star polymers with targeted arm functionalityand molar mass and their rheological properties in the molten state.The synthetic route involves grafting styrene monomers onto a modified(aliphatic, alternating) polyketone backbone with a specific numberof initiating grafting sites using controlled atom transfer radicalpolymerization (ATRP). Several polyketone precursors were used. Thisresulted in a large array of star polystyrenes with nonspherical coresand varying average arm length and number of arms. Their linear viscoelasticitywas investigated and discussed in the context of the known responseof anionically synthesized stars. Using a powerful characterizationtoolbox, including state-of-the-art interaction chromatography, rheometry,and tube modeling via the branch-on-branch (BoB) algorithm, we haveassessed the viscoelasticity of these star polymers quantitatively.In particular, we have demonstrated a variability in molecular structure,which differs substantially from their anionically synthesized counterparts.Hence, whereas this new family of star polymers is not recommendedfor fundamental studies of polymer physics such as the molecular originof relaxation mechanisms without prior extensive fractionation, theycould be used in studies of mixtures as well as industrially relevantprocessing operations that require large amounts of polymeric stars. [ABSTRACT FROM AUTHOR]