3D Analysis of Ordered Porous Polymeric Particles using Complementary Electron Microscopy Methods

Area of Science:

• Materials Science
• Nanotechnology
• Biomaterials

Background:

• Highly porous particles with internal triply periodic minimal surfaces are promising for protein sorption.
• Visualizing their complex internal morphology requires advanced 3D imaging techniques beyond 2D projections.

Purpose of the Study:

• To investigate the application of advanced electron microscopy methods for 3D imaging of porous particles.
• To compare the capabilities of transmission electron microscopy (TEM) tomography, focused ion beam (FIB)-SEM, and serial block face (SBF)-SEM for reconstructing complex morphologies.

Main Methods:

• Transmission electron microscopy (TEM) tomography
• Focused ion beam (FIB) scanning electron microscopy (SEM)
• Serial block face (SBF) scanning electron microscopy (SEM)

Main Results:

• TEM tomography offers high resolution (<1 nm) but limited volume (2.5 μm³).
• FIB-SEM and SBF-SEM allow in situ sectioning and larger imaging volumes.
• SBF-SEM was particularly effective for visualizing block copolymer particles (32-54 nm nanopores) with a 20 μm³ sampling volume, demonstrating its utility for synthetic polymers.

Conclusions:

• Advanced 3D electron microscopy techniques are essential for characterizing complex porous materials.
• SBF-SEM is a powerful tool for imaging nanoporous synthetic polymers, previously underutilized in this field.
• These methods enable detailed structural analysis crucial for applications like protein sorption.