Particle Size Distributions for Cellulose Nanocrystals Measured by Transmission Electron Microscopy: An...

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Accurate particle size measurement of cellulose nanocrystals (CNCs) is crucial for reproducible manufacturing and reliable application performance.
• Challenges in CNC size characterization include broad size distributions, irregular shapes, and aggregation, necessitating standardized measurement protocols.

Purpose of the Study:

• To evaluate and compare transmission electron microscopy (TEM) protocols for image acquisition and analysis of CNCs across multiple laboratories.
• To identify key factors contributing to variability in CNC size measurements.

Main Methods:

• An interlaboratory comparison (ILC) involving 10 laboratories with varying expertise in imaging CNCs.
• Standardized CNC samples and detailed data acquisition/analysis protocols were provided to all participants.
• Image analysis utilized skew normal distribution fitting to accommodate data variability, with consensus values derived from interlaboratory variation modeling.

Main Results:

• Consensus CNC size distributions were established: mean length 95.8 nm (SD 38.2 nm, shape 6.3 nm) and mean width 7.7 nm (SD 2.2 nm, shape 2.9 nm).
• Variations in measured CNC widths were linked to differences in imaging resolution between laboratories.
• Discrepancies in measured length and width were primarily attributed to the selection of individual CNCs for analysis and variations in CNC agglomeration and staining.

Conclusions:

• The study highlights the significant impact of individual CNC selection and sample preparation (agglomeration, staining) on measurement outcomes.
• Differences in imaging resolution also contribute to variability, particularly in width measurements.
• Standardization of imaging and analysis protocols is essential for improving the reproducibility of CNC size characterization.