Mechanism of aggregate formation in simplified industrial silica styrene–butadiene nanocomposites: effect of chain mass and grafting on rheology and structure

Guilhem Baeza (1, 2) , Anne-Caroline Genix (1, 3) , Christophe Degrandcourt (4) , Jérémie Gummel (5) , Marc Couty (4) , Julian Oberdisse (1, 2)

1 L2C - Laboratoire Charles Coulomb
2 Matière Molle
3 Physique des Verres
4 Centre de Technologie de Ladoux
5 ESRF - European Synchrotron Radiation Facility

The formation of aggregates in simplified industrial styrene–butadiene nanocomposites with silica filler hasbeen studied using a recent model based on a combination of electron microscopy, computer simulations,and small-angle X-ray scattering. The influence of the chain mass (40 to 280 kg/mol, PI < 1.1), which setsthe linear rheology of the samples, was investigated for a low (9.5 vol%) and high (19 vol%) silica volumefraction. 50% of the chains bear a single graftable end-group, and it is shown that the (chain-massdependent) grafting density is the structure-determining parameter. A model unifying all available dataon this system is proposed and used to determine a critical aggregate grafting density. The latter is foundto be closely related to the mushroom-to-brush transition of the grafted layer. To our best knowledge,this is the first comprehensive evidence for the control of the complex nanoparticle aggregate structurein nanocomposites of industrial relevance by the physical parameters of the grafted layer.

Domaines: Matière Molle [cond-mat.soft]

Guilhem Baeza, Anne-Caroline Genix, Christophe Degrandcourt, Jérémie Gummel, Marc Couty, et al.. Mechanism of aggregate formation in simplified industrial silica styrene–butadiene nanocomposites: effect of chain mass and grafting on rheology and structure. Soft Matter, 2014, 10, pp.6686-6695. ⟨10.1039/c4sm01095g⟩. ⟨hal-01110034⟩