Programmable Self-Assembly from Two-Dimensional Nanosheets to Spiral, Twisted and Branched Nanostructures

Area of Science:

• Materials Science
• Nanotechnology
• Crystallography

Background:

• Hierarchical self-assembly of nanomaterials is crucial for fabricating functional materials.
• Programmable design of self-assembled nanostructures remains a significant challenge.

Purpose of the Study:

• To develop a programmable self-assembly strategy for customizing nanomaterial structures.
• To investigate the formation mechanisms of various hierarchical nanostructures.

Main Methods:

• Two-dimensional (2D) calcium ion (Ca) assembled F127 nanosheets (Ca-F127 NSs) were used as a base material.
• Techniques including Wide-angle X-ray Scattering (WAXS), X-ray Absorption Spectroscopy (XAS), Selected Area Electron Diffraction (SAED), and Cryo-Electron Microscopy (Cryo-EM) were employed.
• Programmable transformations were applied to create spiral, branched, and twisted nanostructures.

Main Results:

• The strategy successfully transformed 2D Ca-F127 NSs into diverse hierarchical structures: spiral (S-Ca-F127 NSs), branched (B-Ca-F127 NSs), branched-spiral (B-S-Ca-F127 NSs), and twisted-branched (T-Ca-F127 NBs).
• All structures maintained the orthorhombic phase and Ca-O octahedral coordination.
• Eshelby twist and oriented epitaxial growth were identified as key mechanisms, with spiral structures forming via screw dislocation growth.

Conclusions:

• The programmable self-assembly strategy offers precise control over nanomaterial hierarchical structures.
• Understanding and recombining formation mechanisms, such as epitaxial growth along screw dislocations, allows for the creation of complex, custom nanostructures.