How can nanoparticle size determine the structure of nanocomposite supramolecules?

Le Ma, Ting Xu, and their colleagues at the University of California – Berkeley, Berkeley Lab, and MIT published work using the Hummingbird Scientific tomography sample holder to perform 3D electron tomography on co-assembled nanoparticles (NP) and a block copolymer (BCP) nanostructured matrix. The team combined elastic high angle annular dark field (HAADF) electron tomography with dissipative particle dynamics (DPD) simulations to characterize the and identify the mechanism underlying the 3D superstructure of the nanocomposite.

Characterization of train track (a-d) and simple hexagon (e-h) multicomponent nanocomposite morphologies. (a,b,e,f) TEM images, scale bars: a, e, 200 nm, b, f, 100 nm; (c,g) 3-D tomography; (d,h) three slides of reconstruction results. i) TEM image showing the coexistence of the two structures, scale bar: 200 nm. NP size distribution of the j) train track phase and k) simple hexagon phase. Copyright © 2022 American Chemical Society

The phase behavior of the BCP/NP blend is closely related to the relative length scale between the NP size and the microdomain of the soft matrix, separating into two distinct phases with different nanostructures based on only a few nanometers size difference. Tomographic reconstructions reveal that in the highly mobile multicomponent blend, a symmetry-broken “train track” phase forms out of the self-sorting of particles equal in size to the microdomain of the BCP. Larger NPs sort into a symmetric “simple hexagon” structure. This self-sorting is indicative of the strong self-regulatory behavior of the multicomponent system, demonstrating the possibility of nanocomposite microstructural control based on NP size.

Reference: Le Ma, Hejin Huang Peter Ercius, Alfredo Alexander-Katz, Ting Xu, ACS Nano 16 (6) 9368–9377 (2022) DOI: 10.1021/acsnano.2c02179

Full paper Copyright © 2022 American Chemical Society

 

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