Surface aggregation structure of (linear polystyrene / hyperbranched polystyrene) blend films

Aggregation structure of (linear polystyrene / hyperbranched polystyrene) blend films was examined by dynamic secondary ion mass spectroscopy (DSIMS) and neutron reflectivity (NR). Two types of monodisperse hyperbranched polystyrenes (HB-PS) with longer and shorter branches were synthesized combing cationic and anionic polymerizations. Total molecular mass for the both was fixed to be 1M. Deuterated polystyrene (dPS) with molecular weight of 1M was used as a linear component. DSIMS and NR measurements revealed that HB-PS are preferentially segregated at both surface and substrate interface. Interestingly, to what extent HB-PS exists at the surface and interface was dependent on the architecture of HB-PS. This might be explained in terms of number density of chain ends and distorted chain conformation. The above results were in good accordance with a prediction based on simulation using a self-consistent filed theory. Finally, it was concluded that surface aggregation states, resulting in surface physical properties, of conventional polymers would be regulated by an addition of a little amount of hyperbranched component.