Synthesis of Double-Shelled Hollow Inorganic Nanospheres through Block Copolymer-Metal Coordination and Atomic Layer Deposition

Abstract

Double-shelled hollow (DSH) structures with varied inorganic compositions are confirmed to have improved performances in diverse applications, especially in lithium ion battery. However, it is still of great challenge to obtain these complex nanostructures with traditional hard templates and solution-based route. Here we report an innovative pathway for the preparation of the DSH nanospheres based on block copolymer self-assembly, metal–ligand coordination and atomic layer deposition. Polymeric composite micelles derived from amphiphilic block copolymers and ferric ions were prepared with heating-enabled micellization and metal–ligand coordination. The DSH nanospheres with Fe2O3 stands inner and TiO2 outer the structures can be obtained with atomic layer deposition of a thin layer of TiO2 followed with calcination in air. The coordination was carried out at room temperature and the deposition was performed at the low temperature of 80 °C, thus providing a feasible fabrication strategy for DSH structures without destruction of the templates. The cavity and the outer layer of the structures can also be simply tuned with the utilized block copolymers and the deposition cycles. These DSH inorganic nanospheres are expected to find vital applications in battery, catalysis, sensing and drug delivery, etc.

Periodic arrays of structurally complex oxide nanoshells and their use as substrate-confined nanoreactors

“…Apart from a nanostructure coating technology, there exists an emergent set of synthesis techniques that realize nanomaterials by using either the ALD-deposited layer or an adjacent material as a sacrificial entity. The preparation of (i) free-standing ALD layers through the dissolution of a sacrificial substrate, 8 (ii) the high-temperature desorption of Cu from Al 2 O 3 -coated Cu nanowires, 36 (iii) the coating of electrospun fibers, 7 carbon nanocoils, 37 polymeric structures, 38,39 or cellulose 40 followed by the removal of the core material through calcination, and (iv) the application of a conformal etch-resistant layer to a nanostructured template (e.g., anodic aluminum oxide, metal organic frameworks) followed by the removal of the template in a liquid etchant, 10 all provide conceptually straightforward examples of this strategy. The formation of sub-10 nm air-filled plasmonic nanogaps with tunable widths have relied upon the use of a sacrificial ALDdeposited oxide that first defines a dielectric-filled nanogap between adjacent metal structures, after which it is removed with a selective etch.…”

Self-Assembly of Block Copolymers

“…Nina Yan et al use spherical micelles of polystyrene-block-poly(4-vinylpyridine) with a PS core to first bind iron ions in the P4VP shell, which was then followed by atomic vapor deposition of titania. A final calcination step removes all organic components and transformed the iron ions of the inner shell into iron oxide, leading to inorganic hollow double-shell nanospheres [23]. A similar approach is demonstrated on vapor-annealed thin films of a PS-b-PEO diblock copolymer by Jin Xu et al [24], where the cylindrical PEO domains are loaded with iron and cobalt ions, followed by an oxidative and thermal treatment to yield regularly arranged, ferrimagnetic cobalt ferrite nanodots with suitable transition temperature to superparamagnetic nanodots, making them interesting candidates for memory storage applications.…”