A top‐down lithographic patterning and deposition process is reported for producing nanoparticles (NPs) with well‐defined sizes, shapes, and compositions that are often not accessible by wet‐chemical synthetic methods. These NPs are ligated and harvested from the substrate surface to prepare colloidal NP dispersions. Using a template‐assisted assembly technique, fabricated NPs are driven by capillary forces to assemble into size‐ and shape‐engineered templates and organize into open or close‐packed multi‐NP structures or NP metamolecules. The sizes and shapes of the NPs and of the templates control the NP number, coordination, interparticle gap size, disorder, and location of defects such as voids in the NP metamolecules. The plasmonic resonances of polygonal‐shaped Au NPs are exploited to correlate the structure and optical properties of assembled NP metamolecules. Comparing open and close‐packed architectures highlights that introduction of a center NP to form close‐packed assemblies supports collective interactions, altering magnetic optical modes and multipolar interactions in Fano resonances. Decreasing the distance between NPs strengthens the plasmonic coupling, and the structural symmetries of the NP metamolecules determine the orientation‐dependent scattering response.
Patterning of nanoparticles (NPs) via photochemical reduction within thermally responsive hydrogel films is demonstrated as a versatile platform for programming light‐driven shape morphing and materials assembly. Responsive hydrogel disks, containing patterned metal NPs, form characteristic wrinkled structures when illuminated at an air/water interface. The resulting distortion of the three‐phase (air/water/hydrogel) contact lines induces capillary interactions between two or more disks, which are either attractive or repulsive depending on the selected pattern of light. By programming the shapes of the NP‐rich regions, as well as of the hydrogel objects themselves, the number and location of attractive interactions are specified, and the assembly geometry is controlled. Remarkably, appropriately patterned illumination enables sustained rotation and motion of the hydrogel disks. Overall, these results offer insight into a wide variety of shape‐programmable materials and capillary assemblies, simply by controlling the NP patterns and illumination of these soft materials.
more » « less- NSF-PAR ID:
- 10460186
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 31
- Issue:
- 27
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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