Nanoscale Rheology: Dynamic Mechanical Analysis over a Broad and Continuous Frequency Range Using Photothermal...

Area of Science:

• Materials Science
• Polymer Physics
• Nanotechnology

Background:

• Polymeric materials are essential in diverse industries, with mechanical properties dictating their function.
• Understanding nanoscale viscoelasticity is key for accurate material modeling and simulations.
• Current methods for nanoscale rheology are limited in frequency range and scope.

Purpose of the Study:

• To develop and validate a novel atomic force microscopy (AFM) method for quantifying nanoscale viscoelastic properties.
• To measure the loss tangent, storage modulus, and loss modulus of polymers at the nanoscale.
• To extend the frequency range of AFM-based viscoelastic measurements.

Main Methods:

• Photothermal actuation of an AFM cantilever to probe viscoelasticity.
• Validation using styrene-butadiene rubber (SBR).
• Integration with amplitude modulation-frequency modulation (AM-FM) AFM for broader frequency coverage.

Main Results:

• The developed AFM method successfully quantifies nanoscale viscoelasticity.
• Measurements were performed over a continuous frequency range of 0.2–20,200 Hz.
• The technique synergizes with existing AFM methods for comprehensive characterization.

Conclusions:

• A novel AFM method enables precise nanoscale viscoelastic characterization of polymers.
• This technique expands the capabilities for studying time-dependent material properties.
• The method is applicable to polymers, soft matter, and biological materials.