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Entrapped Styrene Butadiene Polymer Chains by Sol–Gel-Derived Silica Nanoparticles with Hierarchical Raspberry Structures
journal contribution
posted on 2018-01-19, 00:00 authored by Sankar
Raman Vaikuntam, Klaus Werner Stöckelhuber, Eshwaran Subramani Bhagavatheswaran, Sven Wießner, Ulrich Scheler, Kay Saalwächter, Petr Formanek, Gert Heinrich, Amit DasA sol–gel
transformation of liquid silica precursor to solid
silica particles was carried out in a one-pot synthesis way, where
a solution of styrene butadiene elastomer was present. The composites,
thus produced, offered remarkable improvements of mechanical and dynamic
mechanical performances compared to precipitated silica. The morphological
analysis reveals that the alkoxy-based silica particles resemble a
raspberry structure when the synthesis of the silica was carried out
in the presence of polymer molecules and represent a much more open
silica-network structure. However, in the absence of the polymer,
the morphology of the silica particles is found to be different. It
is envisaged that the special morphology of the in situ synthesized
silica particles contributes to the superior reinforcement effects,
which are associated with a strong silica–rubber interaction
by rubber chains trapped inside the raspberry-like silica aggregates.
Therefore, the interfaces are characterized in detail by low-field
solid-state 1H NMR spectroscopy, 29Si solid-state
NMR spectroscopy, and energy-dispersive X-ray spectroscopy. Low-field 1H NMR-based double-quantum experiments provide a quantitative
information about the cross-link density of the silica-filled rubber
composites and about the influence of silane coupling agent on the
chemical cross-link density of the network and correlates well with
equilibrium swelling measurements. The special microstructure of the
alkoxy-based silica was found to be associated with the interaction
between alkoxy-based silica and rubber chains as a consequence of
particle growth in the presence of rubber chains.
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alkoxy-based silicaenergy-dispersive X-ray spectroscopyHierarchical Raspberry Structuresalkoxy-based silica particleschemical cross-link densitysilica-filled rubber composites1 H NMR spectroscopysilica particlesstyrene butadiene elastomerLow-field 1 H NMR-based double-quantum experimentsEntrapped Styrene Butadiene Polymer Chainsraspberry-like silica aggregatesrubber chainsone-pot synthesis way
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