A new approach to sample preparation free micro ATR FTIR chemical imaging of polymer laminates

Significance of the Topic

The analysis of polymer laminates by micro ATR FTIR often demands laborious resin embedding, cutting, and polishing to achieve good crystal contact. Simplifying this workflow can improve throughput and reduce contamination risks in industries such as packaging, food, and pharmaceuticals.

Study Objectives and Overview

This work introduces an ultralow pressure micro ATR FTIR chemical imaging approach using Agilent’s Live ATR imaging mode. The aim is to eliminate structural support and sample pre-treatment, enabling direct “as-is” analysis of delicate polymer laminate cross-sections and thin adhesive layers.

Methodology and Instrumentation

• Sample: Cross-section of a sausage wrapper polymer laminate (~55 µm total thickness) comprising polyethylene, nylon, and polyurethane tie layers.
• Instrumentation: Agilent Cary 670 FTIR spectrometer with Cary 620 FTIR microscope, 64×64 MCT focal plane array detector, germanium micro ATR crystal.
• Acquisition settings: 4 cm⁻¹ spectral resolution, 64 scans (~2 min), pixel size of 1.1 µm.
• Live ATR Imaging: Real-time 2D chemical contrast monitoring to identify the precise moment of sample-crystal contact under minimal pressure.

Main Results and Discussion

The Live ATR mode enables visualization of initial contact and progressive pressure application, allowing direct analysis of unsupported cross-sections. Chemical imaging resolved polymer layers of 11–20 µm thickness and two polyurethane adhesives of only 2–3 µm and 5–6 µm. Spatial resolution improved fourfold compared to transmission FTIR, with clear spectral differentiation of each layer.

Benefits and Practical Applications

• Rapid preparation: Complete workflow from raw sample to data in minutes without resin embedding.
• Non-destructive analysis: Ultralow pressure prevents sample deformation, preserving integrity for further testing.
• High spatial resolution: 1.1 µm pixel size enables detection of ultrathin adhesive layers.

Future Trends and Opportunities

Future developments could integrate automated stage control for high-throughput mapping and extend Live ATR imaging to in situ studies under variable temperature, humidity, or mechanical stress. Application to complex multilayer composites and real-time quality control in manufacturing lines represents promising avenues.

Conclusion

Agilent’s Live ATR imaging method revolutionizes micro ATR FTIR chemical imaging of polymer laminates by removing the need for extensive sample preparation. It offers rapid, non-destructive, high-resolution chemical mapping of ultrathin layers, addressing key challenges in materials testing and quality assurance.

Reference

Mustafa Kansiz et al., A new approach to sample preparation free micro ATR FTIR chemical imaging of polymer laminates, Agilent Technologies Application Note, 2011.