Structural analyses of blended Nafion/PVDF electrospun nanofibers

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Immiscible polymer blends often phase-separate during processing.
• Electrospinning offers a method to control nanoscale morphology.
• Understanding polymer-polymer interactions is crucial for developing advanced materials.

Purpose of the Study:

• To characterize a novel polymer blend of polyvinylidene fluoride (PVDF) and Nafion prepared by electrospinning.
• To investigate the unique nanofiber morphology and physicochemical properties of the blend.
• To explore the concept of "reciprocal templating" in creating nanostructured polymer materials.

Main Methods:

• Electrospinning of PVDF (10 wt%) and Nafion (90 wt%) to form nanofibers.
• Characterization of nanofiber morphology using electron microscopy.
• Analysis of physicochemical properties, including thermal behavior and water uptake.
• Investigation of polymer chain interactions and conformational changes.

Main Results:

• A unique internal nanofiber morphology with phase-separated Nafion and PVDF fibrils (2-7 nm) aligned along the fiber axis (∼500 nm).
• PVDF imparts conformational constraints on Nafion's PTFE backbone, increasing its 21 helical conformation.
• Dipole-dipole interactions stabilize the β-phase polymorph of PVDF at elevated temperatures.
• The composite mats and membranes exhibit properties not seen in pure polymers.

Conclusions:

• Electrospinning creates a novel nanostructured morphology in immiscible PVDF/Nafion blends.
• "Reciprocal templating" between PVDF and Nafion alters their individual properties, leading to enhanced material characteristics.
• This method provides a new pathway for fabricating advanced, multi-component polymer materials with tunable properties.