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Nanometer-scale flow of molten polyethylene from a heated atomic force microscope tip
Jonathan R Felts1, Suhas Somnath, Randy H Ewoldt
1Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
Nanotechnology
|May 4, 2012
Summary
Molten polymer flow during nanolithography is driven by capillary forces, not shear. Temperature-dependent viscosity and thermal Marangoni forces control polymer mass flow rate for nanostructure fabrication.
Area of Science:
- Materials Science
- Nanotechnology
- Surface Science
Background:
- Atomic Force Microscope (AFM) cantilevers enable precise nanoscale manipulation.
- Thermal Dip-Pen Nanolithography (tDPN) utilizes heated AFM tips for material deposition.
- Understanding polymer flow at the nanoscale is crucial for advanced nanofabrication.
Purpose of the Study:
- To investigate the fundamental mechanisms governing nanometer-scale molten polymer flow from a heated AFM tip.
- To determine the key driving forces and parameters influencing polymer deposition during tDPN.
- To elucidate the role of thermal effects and material properties on nanostructure formation.
Main Methods:
- Utilized a heated AFM cantilever tip for tDPN experiments.
- Controlled cantilever and substrate temperatures (100-260°C).
- Varied tip movement speed (0.5-2.0 µm s⁻¹) and heating duration (0.1-100 s).
Main Results:
- Polymer flow is primarily governed by surface capillary forces, not tip-substrate shear.
- Polymer mass flow rate is significantly influenced by temperature-dependent viscosity.
- Thermal Marangoni forces and non-equilibrium wetting dynamics at the solidification front dictate polymer flow.
Conclusions:
- Capillary forces are the dominant factor in nanoscale polymer transport during tDPN.
- Polymer viscosity and thermal gradients are critical parameters for controlling nanostructure dimensions.
- The study provides insights into the physics of nanoscale material transport for advanced nanofabrication techniques.
