Although polymeric single crystals fabricated from self‐assembly of block copolymers are reported, preparation of single crystals with different aspect ratios still remains a major challenge. In this work, a facile way is demonstrated to prepare poly(ε‐caprolactone) based single crystals with tunable aspect ratios through simple counterion exchange on the basis of the Hofmeister series. Briefly, after ion exchange from Brˉ (an ion‐containing triblock copolymer, poly(ethylene oxide)‐b‐poly(ε‐caprolactone)‐b‐poly(quaternized 2‐(dimethylamino)ethyl methacrylate)/ethyl bromide (PEO‐b‐PCL‐b‐qPDM‐Br)) to more hydrophobic anions, Iˉ, SCNˉ, PF₆ˉ and OTfˉ, respectively, morphological transitions from spheres to wormlike micelles and sphere to 2D platelet structure with an increasing aspect ratio are observed. The morphological transition depends on the essential hydrophilicity of the qPDM‐X segment and increasing crystallinity of the PCL core caused by ion exchange. These findings provide a facile approach to the preparation of polymeric single crystals with tunable aspect ratios.

中文翻译：

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基于Hofmeister系列的抗衡离子交换介导的不同纵横比的聚（ε-己内酯）单晶

尽管报道了由嵌段共聚物自组装制备的聚合物单晶，但制备具有不同长径比的单晶仍然是一项重大挑战。在这项工作中，展示了一种简便的方法，可以在Hofmeister系列的基础上通过简单的抗衡离子交换来制备具有可调长宽比的聚（ε-己内酯）基单晶。简言之，将来自BR（离子交换含离子的三嵌段共聚物，聚（环氧乙烷）后- b -聚（ε -己内酯） - b -聚（季铵化的2-（二甲基氨基）乙基甲基丙烯酸酯）/乙基溴（PEO- b ‐ PCL‐ b ‐ q PDM‐Br））生成更多疏水性阴离子Iˉ，SCNˉ，PF ₆ˉ和OTfˉ分别观察到了从球形到蠕虫状胶束的形态转变以及从球形到二维血小板结构的高宽比变化。形态转变取决于q PDM-X段的基本亲水性和由离子交换引起的PCL核心结晶度的增加。这些发现为制备具有可调长宽比的聚合物单晶提供了一种简便的方法。