Molecular dynamics study of slip at the interface between immiscible polymers - art. no. 021801

Nonequilibrium molecular dynamics simulations were used to study the struct ural properties and viscous response of interfaces in binary blends of symm etric polymers. The polymers were made immiscible by increasing the repulsi on between unlike species. As the repulsion increased, the interface narrow ed, and the fraction of chain ends in the interfacial region increased. The viscosity in the interfacial region eta (1) was lower than the bulk viscos ity, leading to an effective slip boundary condition at the interface. As t he degree of immiscibility increased, the interfacial viscosity decreased, and the slip length increased. When the radius of gyration of the chains wa s much larger than the interfacial width, eta (1) was independent of chain length. As predicted by de Gennes and co-workers, eta (1) corresponds to th e bulk viscosity of chains whose radius of gyration is proportional to the width of the interfacial region.