Segmental relaxation behavior of polystyrene chains in the cores of collapsed dry micelles tethered on the micelle film surface by a poly(acrylic acid) corona

Abstract

We present an experimental investigation of the segmental relaxation behavior of polystyrene (PS) chains that are confined in a micellar core tethered by a poly(acrylic acid) (PAA) block corona on the dry film surface, along with various core density and molecular weight of PS block from below to well above the entanglement molecular weight. The results show that the onset temperature of PS chain rearrangement (T^onset), which was much lower than the T^bulk_g of the corresponding PS block and higher than T^film_g of ultrathin PS films with corresponding thickness and molecular weights, generally increases with increasing density of the micelle core. It was found that the difference in ΔT^onset with increasing relative density ρ/ρ_min obtained from PS₁₅₄-b-PAA₄₉ and PS₂₇₈-b-PAA₄₇ micelles was large, while these from PS₂₇₈-b-PAA₄₇ and PS₄₀₄-b-PAA₆₃ was negligible, suggesting that entanglement has considerable influence on the density dependence of the T^onset of PS chains under confinement in the micelle core on the film surface.