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Detecting bound polymer layers in attractive polymer-nanoparticle hybrids.
Hamed Emamy1, Francis W Starr, Sanat K Kumar
1Department of Chemical Engineering, Columbia University, New York, New York 10027, USA. sk2794@columbia.edu.
Nanoscale
|September 3, 2021
Summary
Mobile polymer-nanoparticle (NP) systems show a bound polymer layer whose signature disappears with NP motion. This polymer layer
Area of Science:
- Polymer physics
- Soft matter physics
- Nanotechnology
Background:
- Strong polymer-nanoparticle (NP) attractions form a bound polymer layer at the NP interface.
- This phenomenon is analogous to polymer films near attractive substrates.
- Previous simulations focused on fixed NPs, limiting understanding of NP mobility effects.
Purpose of the Study:
- To investigate how nanoparticle (NP) mobility influences the dynamic signature of the bound polymer layer.
- To explore alternative methods for observing the bound layer's dynamics in mobile NP systems.
Main Methods:
- Molecular dynamics simulations of mobile polymer-nanoparticle systems.
- Analysis of the intermediate scattering function to probe polymer dynamics.
- Investigation of nanoparticle diffusivity as a proxy for bound layer dynamics.
Main Results:
- For mobile NPs, the bound polymer layer's dynamic signature is masked by NP motion.
- The bound layer's relaxation signature is lost in the intermediate scattering function for small, mobile NPs.
- The signature of the bound polymer layer can be recovered by measuring NP diffusivity, which is affected by the bound layer's mass.
Conclusions:
- Nanoparticle (NP) mobility significantly impacts the observed dynamics of the bound polymer layer.
- Changes in NP diffusivity provide a measurable signature of the bound polymer layer, even for mobile NPs.
- This finding reconciles simulation results with experimental observations of NP diffusivity in polymer-NP systems.
