Noncovalent Synthesis of Topological Heterostructures Using a Site-Selective Electrostatic Co-Assembly Strategy

Heterostructured nanomaterials composed of heterogeneous zones with dramatically different chemical and/or physical properties have attracted significant attention. However, achieving controllable synthesis of heterostructures integrated with segments of different stiffness and morphologies has been highly challenging, limiting their applications. Herein, a site-selective electrostatic co-assembly strategy was developed to rationally fabricate topological heterostructures (THSs) containing rigid and flexible segments with different chemical compositions and morphologies. Cationic organometallic complexes have been employed to prepare 1D crystalline supramolecular polymers (SPs), followed by electrostatic co-assembly with oppositely charged block copolymers (BCPs) of poly(ethylene glycol)-block-poly(acrylic acid). It has been found that the BCPs could interact and co-assemble with the complexes in SPs in situ at some specific sites bearing positively charged groups to form nanofiber-like moieties. The co-assembled nanofibers are connected to the intact parts of SPs, resulting in THSs composed of nanofibers and intact parts of SPs. The position of the defect sites on SPs and the dimension of SPs could be finely regulated by performing thermal annealing and/or sonication treatments, further enriching the architectures of the co-assembled THSs. This study unveils new topologies that exhibit enhanced higher-order structural complexity in the realm of supramolecular nanostructures, enabling the exploration of their properties and applications.