Anisotropic Polymer Conformations in Aligned SWCNT/PS Nanocomposites
Wei-Shao Tung1, Russell J Composto1, Nigel Clarke2
1Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia 19104-6272, United States.
ACS Macro Letters
|May 21, 2022
Summary
Aligned single-walled carbon nanotubes (SWCNTs) in polymer nanocomposites cause anisotropic polymer chain conformations. Increased SWCNT concentration leads to larger polymer radii of gyration, especially perpendicular to alignment, impacting material properties.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Previously, polymer radii of gyration in isotropic SWCNT/polymer nanocomposites increased with SWCNT concentration.
- Polymer chain conformations in nanocomposites are influenced by nanoparticle dispersion and alignment.
Purpose of the Study:
- To investigate the effect of aligned single-walled carbon nanotubes (SWCNTs) on polymer chain conformations in nanocomposites.
- To understand how SWCNT alignment and concentration influence polymer radii of gyration and mesh size.
Main Methods:
- Melt fiber spinning was used to align SWCNTs within polymer nanocomposites.
- Small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) were employed to analyze polymer chain conformations and SWCNT mesh sizes.
Main Results:
- Aligned SWCNT meshes exhibited smaller mesh sizes perpendicular to the alignment direction compared to the parallel direction.
- The polymer radius of gyration perpendicular to SWCNT alignment (Rgper) increased more significantly than the parallel radius (Rgpar) with increasing SWCNT concentration.
- The extent of polymer conformation anisotropy increased with SWCNT concentration.
Conclusions:
- Aligned SWCNTs induce anisotropic polymer conformations, with larger radii of gyration perpendicular to alignment when SWCNT mesh size is smaller than the unperturbed polymer radius of gyration.
- This anisotropic polymer conformation has significant implications for entanglement density, polymer dynamics, and the mechanical properties of nanocomposites.
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