Extreme Deflection of Phase Boundaries and Chain Bridging in A(BA′)<sub><i>n</i></sub> Miktoarm Star Polymers
Joshua Lequieu, Trenton Koeper, Kris T. Delaney, Glenn H. Fredrickson
Abstract
In this study, we use self-consistent field theory to demonstrate that the A(BA′)n miktoarm architecture can strongly deflect order–order phase boundaries to large volume fractions fA. The A(BA′)n architecture achieves this strong deflection by combining the effects of miktoarm frustration and block bidispersity and is shown to stabilize discrete spheres and cylinders of the A block up to values of fA = 0.58 and fA = 0.78, respectively. We next analyze the prevalence of chain bridging νB in both neat miktoarm melts and in homopolymer blends that form the fluctuation-stabilized “bricks and mortar” phase. These calculations demonstrate that high νB and fA can both be simultaneously achieved with highly asymmetric miktoarm stars, a property especially useful for the design of tough thermoplastic elastomers. Finally, we show that these miktoarms exhibit large windows of phase space where the σ and A15 Frank–Kasper phases are stable.