Spontaneous symmetry breaking: formation of Janus micelles

Ilja K. Voets (Corresponding author), Remco Fokkink, Thomas Hellweg, Stephen M. King, Pieter de Waard, Arie De Keizer, Martien A. Cohen Stuart

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68 Citations (Scopus)

Abstract

We describe the preparation and solution properties of Janus micelles, i.e., non-centrosymmetric nanoparticles with compartmentalized shells, via co-assembly of two fully water-soluble block copolymers. They consist of a mixed core of poly(N-methyl-2-vinyl pyridinium iodide) (P2MVP) and poly(acrylic acid) (PAA), and a shell segregated into two sides, consisting of poly(ethylene oxide) (PEO) or poly(acryl amide) PAAm. These Janus particles form spontaneously and reversibly, i.e., association, dissocation, and reassociation can be carefully controlled via parameters, such as polymer mixing fraction, solution pH, and ionic strength. Dynamic (polarized and depolarized) and static light scattering, cryogenic transmission electron microscopy, small angle neutron and X-ray scattering, and two-dimensional nuclear magnetic resonance spectroscopy are used to monitor the micelle formation and to characterize the micellar structure. The Janus particles were found to be ellipsoidal, with a cigar-like overall shape and a disc-like core. This peculiar morphology is driven by the delicate interplay between two opposing forces: an attraction between the oppositely charged core blocks and a subtle repulsion between the water-soluble, neutral corona blocks.

Original languageEnglish
Pages (from-to)999-1005
Number of pages7
JournalSoft Matter
Volume5
Issue number5
DOIs
Publication statusPublished - 5 Mar 2009
Externally publishedYes

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    Voets, I. K., Fokkink, R., Hellweg, T., King, S. M., de Waard, P., De Keizer, A., & Cohen Stuart, M. A. (2009). Spontaneous symmetry breaking: formation of Janus micelles. Soft Matter, 5(5), 999-1005. https://doi.org/10.1039/b812793j