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Anomalous Anisotropic Nanoparticle Aggregation in Cu2(OH)3Br Gels.
Tyler M Fears1, Joshua A Hammons1, Swanee J Shin1
1Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|June 10, 2020
Summary
Researchers observed anisotropic aggregation in copper hydroxybromide aerogels, revealing insights into nanoparticle assembly. This finding challenges traditional models of inorganic sol-gel chemistry and offers new perspectives on aerogel structure control.
Area of Science:
- Materials Science
- Nanotechnology
- Chemistry
Background:
- Aerogels possess unique properties due to their nanoscale structure, crucial for applications requiring low density and high surface area.
- Controlling the nanoporous network structure is essential for tailoring aerogel macroscopic properties.
Purpose of the Study:
- To investigate nanoparticle aggregation during the in situ formation of copper hydroxybromide (Cu2(OH)3Br) aerogels.
- To understand the mechanisms governing the structure formation in inorganic aerogels.
Main Methods:
- Utilized time-resolved small-angle X-ray scattering (SAXS) to monitor nanoparticle aggregation.
- Employed epoxide-assisted gelation to form Cu2(OH)3Br aerogels.
Main Results:
- Observed anomalous anisotropic aggregation, attributed to the intrinsic molecular structure of Cu2(OH)3Br nanoparticles.
- Identified rapid nucleation of primary particles (~1.5 nm) forming unbranched, chain-like aggregates, deviating from typical mass-fractal models.
- Found primary particle size and aggregate structure to be independent of concentration, while aggregation rates and gelation times were concentration-dependent.
Conclusions:
- The findings suggest independent processes for particle formation chemistry and aggregation physics in these aerogels.
- The observed anisotropic aggregation mechanism may be applicable to other inorganic aerogels, providing broader insights into their formation.
- This study offers a fundamental departure from traditional inorganic sol-gel chemistry models.
