Interplay between polymer chain conformation and nanoparticle assembly in model industrial silica/rubber nanocomposites

Adrien Bouty, Laurent Petitjean, Julien Chatard, Rachid Matmour, Christophe Degrandcourt, Ralf Schweins, Florian Meneau, Pawel Kwasniewski, François Boué, Marc Couty and Jacques Jestin, Faraday Discuss., 2016,186, 325.

We report a complete study of the interplay between polymer chain conformations and NP assemblies in model industrial SBR/silica nanocomposites. By mixing d and h chains, we applied the ZAC method with SANS that enables the extraction of the polymer chain form factor while matching the silica filler contribution. SAXS/TEM permits characterization of the NP assembly as a function of NP loading and dispersing agent, coating and coupling additives. NPs form individual clusters at low loading that can connect to form a continuous network at high silica loading. Using RPA analysis, we show that the radius of gyration of the polymer chain remains unchanged – compared to the pure polymer – within a range of 5% whatever the crosslinking, the degree of confinement induced by NP loading and the degree of interaction between NP and polymer balanced by the nature (coating or coupling) and the amount of the dispersing additives. The extra scattering at low Q, that does not influenced the Rg determination, can be attributed to NP clusters whose neutron contrast is enhanced from ZAC conditions by trapped h/d chains due to random chain adsorption at the surface of the NPs. Under stretching, the NP acts as an additional cross-linked junction preventing the chain relaxations that are deformed at a larger amplitude than the pure polymer.

A. Menelle, dépêche du 03/06/2016