Tailoring nanorod alignment in a polymer matrix by elongational flow under confinement: simulation, experiments, and...

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Controlling nanorod dispersion and orientation in polymer matrices is crucial for advanced material properties.
• Elongational flow offers unique advantages over shear flow for aligning nanostructures.

Purpose of the Study:

• To investigate the influence of elongational flow and confinement on nanorod configuration in polymer melts.
• To optimize nanorod alignment in polymer nanofibers for enhanced sensing performance.

Main Methods:

• Coarse-grained molecular dynamics (CGMD) simulations of nanorod behavior in polymer melts under planar elongational flow.
• Electrospinning of gold (Au) nanorods within polyvinyl alcohol (PVA) matrices, including coaxial electrospinning.
• Transmission Electron Microscopy (TEM) for structural analysis.
• Surface-enhanced Raman spectroscopy (SERS) for sensing evaluation.

Main Results:

• Elongational flow promotes superior nanorod dispersion and orientation compared to shear flow.
• Simulations predicted and experiments confirmed that increasing nanorod aspect ratio and polymer chain length enhances alignment.
• Coaxial electrospinning successfully localized Au nanorods in the sheath layer, achieving better surface alignment.
• Au nanorod-PVA fibers produced via coaxial electrospinning exhibited significantly higher SERS signal intensity.

Conclusions:

• Extensional flow and coaxial electrospinning are effective strategies for directing nanorod orientation and dispersion in polymer fibers.
• Optimized nanorod configuration in polymer matrices leads to substantially improved sensing performance in SERS applications.