Imaging internal flows in a drying sessile polymer dispersion drop using Spectral Radar Optical Coherence Tomography (SR-OCT)

In this work, we present the visualization of the internal flows in a drying sessile polymer dispersion drop on hydrophilic and hydrophobic surfaces with Spectral Radar Optical Coherence Tomography (SR-OCT). We have found that surface features such as the initial contact angle and pinning of the contact line, play a crucial role on the flow direction and final shape of the dried drop. Moreover, imaging through selection of vertical slices using optical coherence tomography offers a feasible alternative compared to imaging through selection of narrow horizontal slices using confocal microscopy for turbid, barely transparent fluids.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (238 K)Download as PowerPoint slideHighlights► SR-OCT visualization of the internal flows in a drop on hydrophilic and hydrophobic surfaces. ► Initial CA and pinning of the CL, play a crucial role on the flow direction and final shape. ► The particles in the drop flow outwards on hydrophilic surface and inwards on hydrophobic surface.