Cocontinuous polymeric nanostructures have garnered significant interest due to their ability to combine different properties of two separate polymer domains. Randomly linked copolymer networks have proven to be especially robust for formation of disordered cocontinuous phases across wide composition ranges (≈30 wt % or more). While theoretical treatments of microphase-separated networks have focused primarily on the role of random elastic forces imposed on the self-assembled nanostructures by virtue of the network architecture, experimental studies seeking to disentangle these contributions from other potential effects, such as dispersity in preferred interfacial curvatures, have been scarce. To provide insight into this matter, we here study the self-assembly of randomly linked star copolymers (RSCs), constructed by linking premade polymer arms of polystyrene (PS) and poly(d,l-lactide) (PLA) using 3, 4, and 6-functional connectors. This architecture yields similar distributions of preferred curvature as networks made using corresponding difunctional strands, but lacks the elastic forces imposed by a network architecture. Gravimetry and small-angle X-ray scattering, coupled with scanning electron microscopy, were performed to identify the percolation of PS/PLA RSCs. Remarkably, the 4-arm RSC system exhibited a disordered cocontinuous window of ≈25 wt %, indicating that dispersity in preferred curvature can in some cases be sufficient to robustly drive formation of this morphology. However, the other RSC architectures showed smaller cocontinuous ranges, which we interpret in terms of the influence of homopolymer stars in the 3-arm case and the narrower distribution of preferred interfacial curvatures in the 6-arm case. Finally, thin layers of interconnected porous PS were achieved by solution-processing, suggesting that RSCs have the potential to serve as a robust and easily processable cocontinuous polymeric nanomaterials in both bulk and membrane geometries.

中文翻译：

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通过随机连接的星形共聚物形成无序共连续相


共连续聚合物纳米结构因其能够结合两个独立聚合物结构域的不同特性而引起了人们的极大兴趣。随机连接的共聚物网络已被证明在较宽的成分范围（≈30 wt % 或更高）中形成无序共连续相特别可靠。虽然微相分离网络的理论处理主要集中在通过网络架构施加在自组装纳米结构上的随机弹性力的作用上，但试图将这些贡献与其他潜在影响（例如优选界面曲率的分散性）分开的实验研究一直很少。为了深入了解这个问题，我们在这里研究了随机连接的星形共聚物 （RSC） 的自组装，通过使用 3、4 和 6 功能连接器连接聚苯乙烯 （PS） 和聚（d，l-丙交酯）（PLA） 的预制聚合物臂来构建。这种架构产生的优选曲率分布与使用相应的双功能链构建的网络相似，但缺乏网络架构施加的弹性力。进行重力测定和小角 X 射线散射，结合扫描电子显微镜，以鉴定 PS/PLA RSC 的渗流。值得注意的是，4 臂 RSC 系统表现出 ≈25 wt % 的无序共连续窗口，表明在某些情况下优选曲率的分散性足以稳健地驱动这种形态的形成。然而，其他 RSC 结构显示出较小的共连续范围，我们根据 3 臂情况下均聚物星的影响和 6 臂情况下优选界面曲率的较窄分布来解释。 最后，通过固溶处理实现了互连多孔 PS 的薄层，这表明 RSC 有可能在块状和膜几何形状中用作坚固且易于加工的共连续聚合物纳米材料。