Linear Melt Rheology of Pom-Pom Polystyrenes with Unentangled Branches

Abstract

We measured the linear viscoelastic properties of a series of polystyrene melts with pom-pom architecture consisting of backbones ranging from marginally to well-entangled (of molecular weight Mb), endgrafted with q unentangled branches (Mbr) per backbone end. In this case, the branches relax very fast and act primarily as solvents for the backbone. Using a time-marching tube-based model, we showed that, in such a case only, the pom-pom polymer is equivalent to a blend of long (ML Mb + 2Mbr) and short (MS Mbr) linear chains with respective proportion (Mb + 2Mbr)/2(q - 1)Mbr