Particle-induced bridging in immiscible polymer blends |
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Authors: | Prachi Thareja Sachin Velankar |
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Institution: | (1) Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA |
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Abstract: | Pickering emulsions are emulsions whose drops are stabilized against coalescence by particles adsorbed at their interface.
Recent research on oil/water/particle systems shows that particles can sometimes adsorb at two oil/water interfaces. Such “bridging particles” can glue together drops of oil in water or vice versa. We hypothesize that
the same effect should apply in immiscible polymer blends with droplet-matrix morphologies, viz., added particles should glue
together drops and give rise to particle-bridged drop clusters. We test this hypothesis in PIB-in-PDMS blends PIB, poly(isobutylene);
PDMS, poly(dimethylsiloxane)] with fumed silica particles. Direct visualization shows that the particles can indeed induce
clustering of the drops, and the blends appear to show gel-like behavior. Such gel-like behavior is confirmed by dynamic oscillatory
experiments. However, we are unable to conclusively attribute the gel-like behavior to droplet clustering: Association of
the fumed silica particles in the bulk, which itself causes gel-like behavior, confounds the results and prevents clear analysis
of the gluing effect of the particles. We conclude that PIB/PDMS/fumed silica is not a good model system, for studying particle-containing
polymer blends. We instead propose that spherical monodisperse silica particles can offer a far more convenient model system,
and provide direct visual evidence of gluing of PIB drops in a PDMS matrix. |
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Keywords: | Spherical monodisperse silica particles Drop clustering PIB PDMS Fumed silica |
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