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Measuring Molecular Diffusion Through Thin Polymer Films with Dual-Band Plasmonic Antennas
Hao Chen1, Gaurav Singhal1, Frank Neubrech2,3
1Department of Material Science and Engineering, Materials Research Laboratory, and Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States.
A new Surface-Enhanced Infrared Absorption (SEIRA) method offers precise molecular transport characterization in polymers. This technique enhances detection sensitivity and spatial resolution for analyzing diffusion in thin polymer films.
Area of Science:
- Polymer Science
- Analytical Chemistry
- Materials Science
Background:
- Characterizing molecular transport in polymers is crucial for industries like pharmaceuticals and packaging.
- Existing methods lack the necessary spatial resolution and sensitivity for complex environments.
- A need exists for a quantitative method with high temporal and spatial resolution.
Purpose of the Study:
- To develop a general and quantitative method for molecular transport characterization in polymers.
- To leverage Surface-Enhanced Infrared Absorption (SEIRA) for enhanced sensitivity and localized detection.
- To enable diffusion measurements in thin polymer films and complex mixtures.
Main Methods:
- Utilized plasmonic nanoantenna-based Surface-Enhanced Infrared Absorption (SEIRA).
- Achieved enhanced infrared absorbance sensitivity within 50 nm of nanoantennas.
- Compared SEIRA with a commercial attenuated total internal reflection (ATR) system.
Main Results:
- SEIRA enhanced the limit of detection at least 13-fold compared to ATR.
- The detection volume was approximately 15 times thinner than ATR, ideal for diffusion measurements.
- Determined diffusion coefficients and solubility of various molecules (vitamin C, ethanol, sugars, water) in polymer films.
Conclusions:
- SEIRA provides a powerful, localized method for quantitative molecular transport analysis in polymers.
- The technique is effective for thin films and complex sample matrices.
- This advancement benefits pharmaceutical, textile, and food packaging industries.
