Sizes and Second Virial Coefficients of Miktoarm Star Polymers

Abstract

An off-lattice bead model with a hard-sphere potential between interacting units has been used to characterize the sizes and second virial coefficients of miktoarm star polymers AxBy using Monte Carlo simulations. These stars are composed of f = x + y branches. Each arm contains NA units of type A or NB of type B. The number of units in each arm is determined by the total number of units N, and the compositional fraction, ΦB = yNB/N. We assume that each one of two types of units can be immersed in a good solvent (which we associate with repulsive interactions between the corresponding chain units AA or BB) or in a ϑ solvent (in which case,we do not consider interaction between these units). Repulsive interactions are always used between polymer units of different types (AB). The numerical sizes and second virial coefficients are analyzed in terms of some ratios. These ratios are obtained with the values of the miktoarms and those of linear diblock copolymers with the same compositional fraction. We also a...