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Measuring the Elastic Modulus of Thin Polymer Sheets by Elastocapillary Bending.
Jinhye Bae1, Tetsu Ouchi1, Ryan C Hayward1
1Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.
ACS Applied Materials & Interfaces
|July 3, 2015
Summary
A new method uses liquid interfaces to measure the elastic modulus of thin films. This technique accurately characterizes a wide range of materials, including soft hydrogels and stiff polymers, in various environments.
Area of Science:
- Materials Science
- Polymer Science
- Surface Science
Background:
- Measuring the elastic modulus of thin films is crucial for understanding material properties.
- Existing methods often face limitations with soft, thin, or liquid-immersed samples.
Purpose of the Study:
- To introduce a simple and broadly applicable technique for measuring the elastic modulus of thin elastic sheets.
- To demonstrate the method's utility across a wide range of materials and environments.
Main Methods:
- Utilizing the balance between bending and surface energies at liquid/liquid or liquid/air interfaces.
- Characterizing materials with elastic moduli from kilopascals to gigapascals.
- Applying the technique to soft hydrogel layers and stiff glassy polymer films in vapor and liquid environments.
Main Results:
- Successfully measured the elastic modulus of diverse materials, including photo-cross-linkable polyelectrolyte hydrogel sheets.
- Demonstrated good agreement between experimental results and predicted scalings with cross-link density.
- Validated the method's independence from contact angle under specific wetting conditions.
Conclusions:
- The described interface bending technique offers a versatile and accessible approach for elastic modulus characterization.
- The method is particularly advantageous for soft materials, sub-millimeter thin sheets, and samples in liquid media.
- This technique simplifies material characterization by requiring only surface tension and sheet thickness measurements.
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