Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, Carl-Benz-Strasse 199, 47057 Duisburg, Germany.
J Am Chem Soc. 2020 Jun 24;142(25):10989-10995. doi: 10.1021/jacs.0c02009. Epub 2020 Jun 10.
Polymer hexosomes are block copolymer solution morphologies that adopt an internal structure composed of an inverse hexagonal (H) phase. To date, most polymer hexosomes are reportedly rotationally symmetric solid structures that possess a common feature where hexagonally ordered inverted cylinders rotate along a central axis of symmetry to form circular hoops. Here, we report on the formation of polymer hexosomes whose inverted cylinders orient in an unusual manner, forming hoops that are noncircular. For topological reasons, this led to the generation of four defects in the resulting hexosome structure. We find that these defect-bearing hexosomes are hollow, thereby resembling polymer vesicles or polymersomes with an inverse hexagonal cylindrical morphology in the shell. The topological defects of these so-called "vesicular hexosomes" are enticing as they could serve as a platform to spatially anchor targeting ligands or biomolecules on the surface, while the hollow cylindrical shell and the vesicular lumen could spatially accommodate cargoes within the different domains. We propose that these vesicular hexosomes do not form via a conventional nucleation-growth self-assembly pathway, but rather via a two-step process involving first liquid-liquid phase separation followed by polymer microphase separation.
聚合物六方体是嵌段共聚物溶液形态，采用由反六方（H）相组成的内部结构。迄今为止，据报道大多数聚合物六方体是旋转对称的固体结构，具有一个共同的特征，即六边形有序的倒置圆柱沿对称轴旋转以形成圆形箍。在这里，我们报告了聚合物六方体的形成，其倒置圆柱以不寻常的方式取向，形成非圆形的箍。由于拓扑原因，这导致了所得六方体结构中产生了四个缺陷。我们发现这些带有缺陷的六方体是中空的，因此类似于具有反向六方柱状形态的聚合物囊泡或聚合物囊泡。这些所谓的“囊泡六方体”的拓扑缺陷很有吸引力，因为它们可以作为平台，将靶向配体或生物分子空间固定在表面上，而中空的圆柱壳和囊泡腔可以在不同的区域内空间容纳货物。我们提出，这些囊泡六方体不是通过常规的成核-生长自组装途径形成的，而是通过涉及首先液-液相分离然后聚合物微相分离的两步过程形成的。
