https://doi.org/10.1007/s100510050830
Rheology of nanosized hairy grain suspensions
1
Rhône-Poulenc Recherche, 52 rue de la Haie-Coq, 93308 Aubervilliers Cedex, France
2
FAST (UMR 7608 du CNRS) , Université Paris-Sud, 91405 Orsay Cedex, France
3
Institut Curie (UMR 168 du CNRS) , Section de Recherche,
11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France
4
Laboratoire Léon Brillouin, CNRS-CEA, Centre d'Études Nucléaires de Saclay,
91191 Gif-sur-Yvette Cedex, France
Corresponding author: a auroy@curie.fr
Received:
23
March
1998
Published online: 15 July 1999
Suspensions of nanosized hairy grains have been prepared by grafting long
polydimethylsiloxane chains (molecular weight 
) onto silica particles
(radius 
), dispersed into a good solvent of PDMS. Depending
on the particle volume fraction, different rheological behaviors are observed.
In the very dilute regime, the suspensions are perfectly stable and the particles
behave almost as hard spheres: flow penetration inside the corona is then very weak.
When the particle volume fraction goes to the close packing volume fraction, the
suspension viscosity does not diverge as for hard spheres due to the increase of
flow penetration inside the corona and to corona entanglements. The particles have then the
same behavior as polymer stars having an intermediate number of arms (
).
Finally, in the concentrated regime (
), the suspensions form
irreversible gels. We shown that this unexpected gelation phenomenon is related to the
presence of the silica cores: grafted PDMS chains can adsorb onto different particles
and form irreversible bonds between the cores. The viscosity and elastic modulus
evolutions during gelation are well described by the scalar percolation model of
sol-gel transition.
PACS: 82.70.Dd – Colloids / 61.41.+e – Polymers, elastomers, and plastics / 81.05.Qk – Reinforced polymers and polymer-based composites
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999
