Nanoparticle-Stabilized Perforated Lamellar Morphology in Block Copolymer/Quantum Dot Hybrids

We report on the surprising observation of a unique perforated lamellar (PL) morphology in a mixture of an asymmetric polystyrene-block-poly­(4-vinylpyridine) (PS-b-P4VP) block copolymer and CdSe–CdS quantum dots (QDs). The PL morphology formed by the PS-b-P4VP/CdSe–CdS composites consisted of alternating layers of PS and P4VP, where the layer formed by the minority PS block contained cylindrical perforations of the majority P4VP block. Most interestingly, the CdSe–CdS QDs were localized exclusively in the P4VP perforations. The swelling of the bulk samples in a P4VP selective solvent also allowed the isolation of the perforated PS nanosheets, with QDs localized in the perforations, which further provided strong evidence for the formation of the unique PL morphology. The observed PL morphology was, plausibly, energetically stabilized because of the localization of QDs within the P4VP perforations, which allowed for the conformational entropy minimization of the majority P4VP block. The present work reveals possibilities for the discovery of novel hierarchical structures in block copolymer/nanoparticle composite systems and also provides new opportunities for the application of such materials in nanotechnology.