Spiral hierarchical superstructures were found in the self-assembly of chiral block copolymers (BCPs*) composed of a chiral poly(l-lactide) (PLLA) and an achiral polystyrene (PS) as major and minor blocks, respectively. The PLLA helical chain with semiflexible rod-like character as compared to the random coil of PS results in self-assembly with a conformational asymmetry effect overwhelming the compositional one. Consequently, instead of the forming PS cylinder microdomains in the PLLA matrix, a smectic liquid-crystal-like bilayer sandwiched with PLLA and PS microdomains will be formed. Owing to twisting and bending due to the chiral cholesteric liquid-crystal-like force field combined with steric hindrance at the chiral interface, the forming bilayers (twisted ribbon) will develop into either a concentric lamellar texture from scrolling or roll-cake textures from spiraling. This study might bring a concept for the formation of spiral hierarchical superstructures from self-assembled bilayers for device application.

中文翻译：

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自组装手性嵌段共聚物扭曲带的螺旋分层超结构

在由手性聚（l-丙交酯）（PLLA）和非手性聚苯乙烯（PS）分别作为主要和次要嵌段。与 PS 的随机线圈相比，具有半柔性棒状特征的 PLLA 螺旋链导致自组装，其构象不对称效应压倒了组合链。因此，代替在 PLLA 基质中形成 PS 圆柱微区，将形成夹有 PLLA 和 PS 微区的近晶型液晶双层。由于手性胆甾型液晶样力场与手性界面处的空间位阻相结合而产生的扭曲和弯曲，形成的双层（扭曲带）将通过滚动发展成同心层状结构或螺旋状形成卷饼结构.