Cellulose nanomaterial metrology: microscopy measurements

Area of Science:

• Materials Science
• Nanotechnology

Background:

• Cellulose nanomaterials (CNMs) are versatile and widely applied.
• Accurate characterization is essential for quality control, differentiating materials, application development, and regulatory compliance.

Purpose of the Study:

• To review recent microscopy measurements for cellulose nanocrystals, individual cellulose nanofibrils, and cellulose nanofibrils.
• To focus on studies with metrological rigor and compare microscopy results with routine quality control methods.

Main Methods:

• Review of recent studies employing atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
• Emphasis on metrological rigor in measurements, rather than qualitative assessments.
• Comparison of microscopy data with other routine quality control measurement methods.

Main Results:

• Microscopy studies with metrological detail enable comparison and differentiation of various CNMs.
• Challenges in measuring particle size and morphology include agglomeration, low contrast, and complex nanofibril structures.
• Some studies successfully provide insights into fundamental material properties, such as chirality.

Conclusions:

• Detailed microscopy protocols yield accurate and reliable results for CNM characterization.
• These rigorous measurements aid material production, regulatory compliance, and validation of routine methods.
• Despite advancements, challenges remain in definitively concluding size differences for all CNMs.