Jump to main content
Jump to site search

The phase diagram of colloidal silica–PNIPAm core–shell nanogels

Author affiliations


We study the structure and dynamics of aqueous dispersions of densely packed core–shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell as a function of temperature and concentration. With small angle X-ray scattering (SAXS) and X-ray photon correlation spectroscopy (XPCS) we shed light on the structural and dynamical changes of the thermo-responsive colloidal nanogel during its volume phase transition at a lower critical solution temperature (LCST) of 32 °C. A transition of the dynamics and its distinct dependency on the particle number concentration could be determined by analysing the intensity autocorrelation function while the structural transition remains concentration independent. We found the dynamics of a jammed system beyond a critical concentration. In addition, by variation of the PNIPAm shell size we tuned both the effective volume fraction and the underlying nature of the dynamics in the system. With our results we can present a full phase diagram of a PNIPAm core–shell system that spans from diluted suspensions, where the system behaves like a liquid, to an effective volume fraction of more than ninety percent where after exceeding a critical concentration the system undergoes a temperature-induced transition from a liquid towards a colloidal gel.

Graphical abstract: The phase diagram of colloidal silica–PNIPAm core–shell nanogels

Back to tab navigation

Supplementary files

Publication details

The article was received on 17 Sep 2019, accepted on 23 Nov 2019 and first published on 25 Nov 2019

Article type: Paper
DOI: 10.1039/C9SM01884K
Soft Matter, 2020, Advance Article

  •   Request permissions

    The phase diagram of colloidal silica–PNIPAm core–shell nanogels

    L. Frenzel, F. Lehmkühler, M. Koof, I. Lokteva and G. Grübel, Soft Matter, 2020, Advance Article , DOI: 10.1039/C9SM01884K

Search articles by author