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Self-Assembly of Colloidal Nanomaterials towards Multi-Functional Supraparticles

By: Minghan Hu
From: Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich
At: Online - Zoom (https://videoconf-colibri.zoom.us/j/83206120575)
[2021-12-02]

Assembly of nanoparticles can have collective properties that are different to those displayed by individual nanoparticles and bulk materials. The property of nanoparticles and the interaction between assembled nanoparticles determine the ultimate function and property of assembled materials. In this talk, two types of colloidal nanomaterials, superparamagnetic nanoparticles and polymeric nanocapsules, are used as building blocks to produce multi-functional supraparticles through evaporation guided assembly.[1, 2] First, superparamagnetic nanoparticles are used as building blocks to produce supraparticles with anisotropic shapes. By tuning the concentration of ferrofluid droplets and controlling the magnetic field, barrel-like, cone-like, and two-tower-like supraparticles are obtained. These assembled supraparticles preserve the superparamagnetism of the original nanoparticles. Moreover, the ferrofluid suspension can be used as the driving force to template the assembly of other nanoparticles to fabricate functional anisotropic binary supraparticles. Thus, this flexible fabrication process offers the possibility to create anisotropic and magneto-responsive supraparticles with various materials. The magnetic and anisotropic nature of the resulting supraparticles is harnessed to prepare magnetic microswimmers. [3] Unlike the solid nanoparticles, nanocapsules are the vesicular systems that can entrap sensitive substrates within a solid shell and prevent damage from the adverse environment. The entrapped cargoes can be further released on demand through diffusion the nanocapsules shells. We use similar assembly strategy to produce controlled assemblies of polymeric nanocapsules, called supracapsules. After assembly, the resulting supracapsules also preserve the functions presented in the nanocapsules. Interestingly, the supracapsules have unique release kinetics compared to single nanocapsules. The release profile of encapsulated cargos in supracapsules can be further programmed by the supracapsules’ diameter. We envision that this novel assembly strategy will pave the way for the realization of new suprastructured assemblies with many exciting emerging properties, which could find applications in a wide range of fields [4].

References:

[1] S. Wooh, H. Huesmann, M.N. Tahir, M. Paven, K. Wichmann, D. Vollmer, W. Tremel, P. Papadopoulos, H.J. Butt, Synthesis of mesoporous supraparticles on superamphiphobic surfaces, Adv. Mater. 27(45) (2015) 7338-7343. 

[2] N. Vogel, S. Utech, G.T. England, T. Shirman, K.R. Phillips, N. Koay, I.B. Burgess, M. Kolle, D.A. Weitz, J. Aizenberg, Color from hierarchy: diverse optical properties of micron-sized spherical colloidal assemblies, Proc. Natl. Acad. Sci. U.S.A. 112(35) (2015) 10845-10850. 

[3] M. Hu, H.J. Butt, K. Landfester, M.B. Bannwarth, S. Wooh, H. Thérien-Aubin, Shaping the assembly of superparamagnetic nanoparticles, ACS Nano 13(3) (2019) 3015-3022. 

[4] M. Hu, N. Reichholf, Y. Xia, L. Alvarez, X. Cao, S. Ma, A. J. deMello, L. Isa, Microfluidic assembly of nanocapsules towards multifunctional supracapsules, submitted.