Planet‐Like Nanostructures Formed by an ABC Triblock Terpolymer


A novel planet-like nanostructure formed by an asymmetric polystyrene-block-polyisoprene-block-poly(methyl methacrylate) (SIM) triblock terpolymer is presented, where polystyrene (PS) forms spherical microdomains, covered by polyisoprene (PI) rings/helices/polar caps and poly(methyl methacrylate) (PMMA) forms the matrix. The new nanostructure is the result of a thermally induced morphological transition of a kinetically trapped helical nanostructure by thermal annealing above its glass transition temperature. This new nanostructure is observed when the triblock terpolymer solution is cast from chloroform (CHCl3). When cast from tetrahydrofuran (THF) or toluene, mainly cylindrical and to a lesser extent spherical microdomains are observed. This is caused by a selectivity of the CHCl3 for the PS and PMMA microdomains. The SIM triblock terpolymer is synthesized by anionic polymerization, and the morphology is characterized by transmission electron microscopy, atomic force microscopy, and small angle X-ray scattering.
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