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

Area of Science:

• Materials Science
• Chemical Engineering
• Microfluidics

Background:

• Poly(dimethylsiloxane) (PDMS) microchannels are widely used in microfluidics.
• Achieving stable two-phase flows within these channels is crucial for various applications.
• Surface modification of PDMS is necessary to control interfacial properties and flow stability.

Purpose of the Study:

• To investigate the stabilization of water/octanol two-phase flows in PDMS microchannels.
• To evaluate the efficacy of different polymer coatings for surface modification.
• To explore homogeneous versus heterogeneous coating strategies for flow stabilization.

Main Methods:

• PDMS microchannels were coated with various high molecular weight polymers: poly(2-hydroxyethyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(ethylene glycol), and poly(vinyl alcohol).
• Coatings were applied from both flowing and stationary solutions.
• Homogeneous (single polymer) and heterogeneous (two polymers) coating configurations were tested.

Main Results:

• Homogeneous coatings with poly(2-hydroxyethyl methacrylate) and poly(vinyl pyrrolidone) effectively stabilized laminar water/octanol flows.
• Heterogeneous coatings resulted in more stable and well-defined interfaces over longer microchannel distances (40 mm).
• Fuchsin dye partitioning demonstrated the potential for logP value determination in coated microchannels.

Conclusions:

• Polymer coatings significantly enhance the stability of two-phase flows in PDMS microchannels.
• Both homogeneous and heterogeneous coating approaches offer distinct advantages for flow control.
• The developed polymer-coated PDMS microchannels are suitable for applications such as logP determination in microfluidic systems.