Jump to main content
Jump to site search

Issue 15, 2012
Previous Article Next Article

Structure and rheology of nanoparticlepolymer suspensions

Author affiliations

Abstract

Structure and rheology of oligomer-tethered nanoparticles suspended in low molecular weight polymeric host are investigated at various particle sizes and loadings. Strong curvature effects introduced by the small size of the nanoparticle cores are found to be important for understanding both the phase stability and rheology of the materials. Small angle X-ray scattering (SAXS) and transmission electron microscopy measurements indicate that PEG–SiO2/PEG suspensions are more stable against phase separation and aggregation than expected from theory for interacting brushes. SAXS and rheology measurements also reveal that at high particle loadings, the stabilizing oligomer brush is significantly compressed and produces jamming in the suspensions. The jamming transition is accompanied by what appears to be a unique evolution in the transient suspension rheology, along with large increments in the zero-shear, Newtonian viscosity. The linear and nonlinear flow responses of the jammed suspensions are discussed in the framework of the Soft Glassy Rheology (SGR) model, which is shown to predict many features that are consistent with experimental observations, including a two-step relaxation following flow cessation and a facile method for determining the shear-thinning coefficient from linear viscoelastic measurements. Finally, we show that the small sizes of the particles have a significant effect on inter-particle interactions and rheology, leading to stronger deviations from expectations based on planar brushes and hard-sphere suspension theories. In particular, we find that in the high volume fraction limit, tethered nanoparticles interact in their host polymer through short-range forces, which are more analogous to those between soft particles than between spherical polymer brushes.

Graphical abstract: Structure and rheology of nanoparticle–polymer suspensions

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 Oct 2011, accepted on 13 Dec 2011 and first published on 11 Jan 2012


Article type: Paper
DOI: 10.1039/C2SM06889C
Citation: Soft Matter, 2012,8, 4097-4108
  •   Request permissions

    Structure and rheology of nanoparticlepolymer suspensions

    S. Srivastava, J. H. Shin and L. A. Archer, Soft Matter, 2012, 8, 4097
    DOI: 10.1039/C2SM06889C

Search articles by author

Spotlight

Advertisements