Dissipative self‐assembly of colloidal nanoparticles offers the prospect of creating reconfigurable artificial materials and systems, yet the phenomenon only occurs far from thermodynamic equilibrium. Therefore, it is usually difficult to predict and control. Here, a dissipative colloidal solution system, where anisotropic chains with different interparticle separations in two perpendicular directions transiently arise among largely disordered silver nanoparticles illuminated by a laser beam, is reported. The optical field creates a nonequilibrium dissipative state, where a disorder‐to‐order transition occurs driven by anisotropic electrodynamic interactions coupled with electrostatic interactions. Investigation of the temporal dynamics and spatial arrangements of the nanoparticle system shows that the optical binding strength and entropy of the system are two crucial parameters for the formation of the anisotropic chains and responsible for adaptive behaviors, such as self‐replication of dimer units. Formation of anisotropic nanoparticle chains is also observed among colloidal nanoparticles made from other metal (e.g., Au), polymer (e.g., polystyrene), ceramic (e.g., CeO2), and hybrid materials (e.g., SiO2@Au core–shell), suggesting that light‐driven self‐organization will provide a wide range of opportunities to discover new dissipative structures under thermal fluctuations and build novel anisotropic materials with nanoscale order.
This content will become publicly available on June 21, 2024
Magnetic field enabled in situ control over the structure and dynamics of colloids interacting via SALR potentials
Colloidal suspensions are an ideal model for studying crystallization, nucleation, and glass transition mechanisms, due to the precise control of interparticle interactions by changing the shape, charge, or volume fraction of particles. However, these tuning parameters offer insufficient active control over interparticle interactions and reconfigurability of assembled structures. Dynamic control over the interparticle interactions can be obtained through the application of external magnetic fields that are contactless and chemically inert. In this work, we demonstrate the dual nature of magnetic nanoparticle dispersions to program interactions between suspended nonmagnetic microspheres using an external magnetic field. The nanoparticle dispersion simultaneously behaves as a continuous magnetic medium at the microscale and a discrete medium composed of individual particles at the nanoscale. This enables control over a depletion attractive potential and the introduction of a magnetic repulsive potential, allowing a reversible transition of colloidal structures within a rich phase diagram by applying an external magnetic field. Active control over competing interactions allows us to create a model system encompassing a range of states, from large fractal clusters to low-density Wigner glass states. Monitoring the dynamics of colloidal particles reveals dynamic heterogeneity and a marked slowdown associated with approaching the Wigner glass state.
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- Award ID(s):
- 2038305
- NSF-PAR ID:
- 10480185
- Publisher / Repository:
- RSC
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 19
- Issue:
- 24
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 4439 to 4448
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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