Stabilization of two-phase octanol/water flows inside poly(dimethylsiloxane) microchannels using polymer coatings

Abstract

In this paper we present our first results on the realization of stable water/octanol, two-phase flows inside poly(dimethylsiloxane) (PDMS) microchannels. Native PDMS microchannels were coated with high molecular weight polymers to change the surface properties of the microchannels and thus stabilize the laminar flow profile. The polymers poly(2-hydroxyethyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(ethylene glycol), and poly(vinyl alcohol) were assessed for their quality as stabilization coatings after deposition from flowing and stationary solutions. Additionally, the influence of coating the microchannels homogeneously with a single kind of polymer or heterogeneously with two different polymers was investigated. From the experimental observations, it can be concluded that homogeneous polymer coatings with poly(2-hydroxyethyl methacrylate) and poly(vinyl pyrrolidone) led to the effective stabilization of laminar water/octanol flows. Furthermore, heterogeneous coatings led to two-phase flows which had a better-defined and more stable interface over long distances (i.e., 40-mm-long microchannels). Finally, the partitioning of fuchsin dye in the coated microchannels was demonstrated, establishing the feasibility of the use of the polymer-coated PDMS microchannels for determination of logP values in laminar octanol/water flows.

Microfluidic biochip for the perifusion of precision‐cut rat liver slices for metabolism and toxicology studies

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Multiple flow profiles for two-phase flow in single microfluidic channels through site-selective channel coating

“…Previously we reported the stabilization of 1-octanol : water sideby-side streams in microchannels in poly(dimethylsiloxane) (PDMS) chips through physisorption of high-molecular-weight polymers to the channel's surface. 19 For 1-octanol : water systems, native PDMS 21 exhibits slug-flow behaviour, 19 which improves extraction, but renders separation of slugs into separate channel streams challenging. In our approach, heterogeneous coating with two different polymer solutions, PVP (30 kDa) and pHEMA (1 MDa), provides for a stable side-byside flow and effective separation of the two solvent streams.…”

Microflow Systems for Chemical Synthesis and Analysis: Approaches to Full Integration of Chemical Process

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