Surface Segregation in Blends of Chains with Two Architectures

Blends of chains of two architectures, e.g. linear chains with pom-pom branched polymers, present opportunities for tailoring bulk rheology and surface character of the blends. Pom-pom chains contain a central linear portion between two junction points from which multiple arms extend. We have studied the effect of varying the relative length of the central linear portion of the pom-pom chain on the size of a single chain and on the bulk and surface thermodynamics of blends of the pom-pom chains with linear analogs. The strength of segregation to the surface and substrate interface of a blend film is seen with neutron reflectivity and surface enhanced Raman spectroscopy to depend on the relative length of the central linear portion of the pom-pom. Comparison will be made to a linear response theory that considers the number and type of chain ends and junction points.