Sulphated cellulose nanocrystals (CNCs) have the ability to self-assemble in suspension above a critical concentration into chiral nematic structures due to the helicoidal orientation of the CNCs that can lead to iridescent/birefringent films when dried. Critical concentration conditions can be reach during evaporation of dilute CNCs suspension droplets since drying induces concentration of CNCs at the edge of the sessile droplet to form a ring-like solid deposit. This process, also termed coffee ring effect, is due to faster evaporation rate at the pinned three-phase contact line than in the center of the droplet. This inhomogeneous evaporation results on fluid flow from the interior of the drop to the contact line to compensate the loss of solvent carrying the particles and accumulates them on its perimeter to form coffee ring.<br/>One strategy to inhibit coffee ring formation is to increase the viscosity of the suspension by the addition of polymers for instance. We investigate the effect of viscosity during drying by focusing on the mixture of CNCs and wheat arabinoxylan (AX). Drying CNCs/AX droplets results in the formation of maltese cross due to gel formation. Recovery of coffee ring can be achieved thank to the hydrolysis of AX by xylanase that breaks the gel structure. The work presented reports the description and the modelling of the drying process in presence and absence of polymer and open the way to fast, easy to handle and efficient enzymatic activity detection method.<br/>

Control of coffee ring formation during CNCs droplet drying by polymer addition: Application to enzymatic activity detection

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.