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Interactions, Structure, and Dynamics of Polymer-Tethered Nanoparticle Blends
Akanksha Agrawal1, Brandon M Wenning1, Snehashis Choudhury1
1Robert Frederick Smith School of Chemical and Biomolecular Engineering and ‡Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 2, 2016
Summary
Blending hairy silica nanoparticles with poly(ethylene glycol) (PEG) and poly(methyl methacrylate) (PMMA) enhances particle correlations and jamming. This creates entangled-polymer-like properties, even in low molecular weight polymers.
Area of Science:
- Materials Science
- Colloid Science
- Polymer Science
Background:
- Hairy silica nanoparticles are functionalized with polymers like poly(ethylene glycol) (PEG) and poly(methyl methacrylate) (PMMA).
- Self-suspended nanoparticle suspensions exhibit entropic attractions due to polymer chain crowding.
Purpose of the Study:
- To investigate the structure, jamming, and dynamics of blends of PEG- and PMMA-grafted silica nanoparticles.
- To understand how enthalpic and entropic attractions influence nanoparticle blend behavior.
Main Methods:
- Synthesis of hairy silica nanoparticles grafted with PEG and PMMA.
- Rheological measurements to assess soft glassy behavior and jamming.
- Small-angle X-ray scattering (SAXS) for structural analysis.
- Density functional theory (DFT) for theoretical analysis.
- Analysis of heat of mixing to quantify enthalpic interactions.
Main Results:
- Favorable enthalpic attraction between PEG and PMMA chains augments entropic attractions, enhancing particle correlations and jamming.
- Nanoparticle blends exhibit soft glassy rheological behavior with maxima in energy dissipation and elastic modulus at symmetry.
- Addition of PMMA to PEG suspensions increases corona chain stretching, interdigitation, and slows polymer relaxation.
- Strong enthalpic attraction leads to entangled-polymer-like properties in polymers below typical entanglement molecular weights.
Conclusions:
- Enthalpic and entropic forces synergistically enhance particle interactions and jamming in hairy nanoparticle blends.
- These blends display unique rheological properties, mimicking entangled polymer systems.
- The findings offer insights into designing advanced soft materials with tunable properties.
