Effect of Star Structure Versus Linear Polymers on Structure and Shear Rheology

The research focuses on developing a star-shaped polymer with a poly(divinylbenzene) nucleus and poly(styrene) arms through ATRP polymerization. The rheology of linear and star polymers with narrow molecular weight distributions was compared with commercially available high molecular weight PS. The polymers containing DOA plasticizer were subjected to rheology experiments at 25°C at varying shear rates. The entangled and randomly oriented polymer chains dispersed during flow, increasing free space and reducing molecular interactions. At elevated shear rates, the polymers achieved the infinite shear viscosity plateau (η∞). The shear rate-independent behavior of the commercially used linear PS mixture containing DOA was observed. In contrast, star polymers exhibited a smaller hydrodynamic volume and gyration radius, leading to a lower viscosity.