Reversible mechanical actuation of elastomeric nanopores.

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Physics

Background:

• Nanopores are crucial for various applications, including filtration, sensing, and energy conversion.
• Controlling nanopore size dynamically is essential for advanced material functionalities.

Purpose of the Study:

• To characterize the mechanical resizing of individual nanopores in a thermoplastic polyurethane elastomer.
• To investigate the relationship between elastomer extension and nanopore radius.
• To explore the potential for tunable nanopore devices.

Main Methods:

• Mechanical stretching and relaxation of thermoplastic polyurethane elastomer specimens.
• Electrophoretic current measurements to estimate nanopore radius.
• Optical microscopy to relate macroscopic extension to local radial strain.
• Scanning electron microscopy and atomic force microscopy for surface analysis.

Main Results:

• Conical nanopores with dimensions in the tens to hundreds of nanometers were characterized.
• Nanopore radius was reversibly actuated over an order of magnitude by elastomer deformation.
• Within a working range, current was proportional to extension to the power of a constant (n=0.9-2.3).
• Super-affine scaling of the effective pore radius was observed.

Conclusions:

• Mechanical deformation of thermoplastic polyurethane elastomers provides a viable method for dynamic nanopore size control.
• The observed super-affine scaling suggests complex local strain effects around the nanopores.
• This work opens avenues for developing reconfigurable nanoporous materials.