In Situ Ptychographic X-ray CT of Fully Hydrated Polyamide Membranes

This collaboration between KAUST and the Brazilian Center for Research in Energy and Materials (CNPEM) resulted in the development of a high-resolution 3D imaging methodology that allows 3D nanoscale imaging of soft matter in situ. Unlike traditional techniques that require vacuum or sample modifications – which can distort structures and sample physicochemical properties - this method captures the structure directly in water (without vitrification/freezing). The methodology was used to capture the structure of thin film composite polyamide membrane (typically used for water purification) directly in its hydrated state – close to operational conditions. The sample did not have to be modified with typical heavy-metal stains or separated from the polysulfone, which allows preservation of the membrane’s native state. Using the developed approach led to observations of substantial swelling and structural changes of the polyamide membrane with artificial water channels, providing new insights that can guide the design of more efficient water purification materials. This novel method and observations based on in situ ptychographic x-ray computed tomography using a synchrotron source are presented in the recently published article in Langmuir (details below). The method has a huge potential to be applied to the study of soft matter in hydrated environments in its native state, ranging from polymers to biological samples.

In Situ Ptychographic X-ray Computed Tomography of Fully Hydrated Polyamide Membranes. Radosław Górecki, Ronell Sicat, Carla Cristina Polo, Tiago Araujo Kalile, Maria Di Vincenzo, Florian Meneau, and Suzana P. Nunes. Langmuir Article. DOI: 10.1021/acs.langmuir.5c04933.

This figure from the paper shows the whole workflow including ptychographic x-ray computed tomography (PXCT), reconstruction, segmentation, and analysis.

KVL's visualization scientist Ronell Sicat provided support in setting up the ptychographic and tomographic reconstruction workflows in the Ibex cluster (maintained by the KAUST Supercomputing Core Lab). He also worked closely with the domain experts in pre-processing, segmentation, analysis, and visualization of the reconstructed 3D image stacks using Avizo software.