Blends of Linear and Branched Polymers for Useful Materials

摘要

The aim is to study the use of molecules of novel architecture for tailoring the surface properties of blends. Key to this work is understanding the bulk miscibility of blends of linear and branched molecules and characterizing the surface segregation that occurs in such blends. The thermodynamic interaction between two polymers due only to the effect of regular branching has been measured for polystyrene blends of linear and star polymers as well as for one blend of a comb polymer with linear chains. Blends of star and linear polybutadiene have been investigated as well. The bulk interaction grows in size with the number of arms in the star. The interaction for the comb/ linear blend is a order of magnitude larger than for a star/linear blend in which the star has the same number of arms as the comb. Segregation of the star to both interfaces of a film is observed for the polystyrene blends. For polybutadiene blends the isotopic effect is so strong that for small numbers of arms the isotopic effect dominates. The collective dynamics of two star polybutadienes are seen to be identical to those of linear analogs when the arms have lengths many times the entanglement length.