Morphological evolution of self‐assembled PS‐g‐PA6 graft copolymer via in situ polymerization

Abstract

AbstractThe self‐assembly behaviors of polystyrene graft polyamide‐6 (PS‐g‐PA6) copolymer obtained through incorporation of PA6 and PS segments with exact lengths via in situ polymerization were studied in this work. Copolymers were obtained via the bulk polymerization induced self‐assembly process without any external template or stabilizer. The morphological characteristics of PS‐g‐PA6 copolymer were probed using SEM and TEM techniques. Particular attention was paid to changing the PS‐g‐PA6 morphology from a simple nanospherical to the combined nano/microspherical phase structure by varying the [PA6]/[PS] mass ratio. At a [PA6]/[PS] mass ratio of 80:20, PS‐g‐PA6 copolymer revealed a specific phase structure, where the PS backbones formed a continuous phase and the PA6 side chains ensured the microspheres with dispersed nano‐scale inclusions. The grain diameter of a dispersed PA6 sphere phase was found to be about 75 nm. When the PS backbone mass ratio decreased to 10 wt%, the copolymer structure was self‐assembled into the 1–3 μm large microspheres with uniformly distributed nanospherical particles. A further decrease in the PS backbone content to 5 wt% led to the failure of phase inversion in the copolymers. The main feature of this project is that the structure of the main chain and branch chain of PS‐g‐PA6 copolymer can be reversed. The branched chain forms spherical phase and the main chain forms continuous phase structure. The strategy was proved to be effective to obtain the novel structure of graft copolymer.