Electrohydrodynamic effect on phase separation morphology in polymer blend films.

Area of Science:

• Materials Science
• Polymer Science
• Fluid Dynamics

Background:

• Polymer blend films are crucial in various applications.
• Controlling domain structure in polymer blends is challenging.
• Solvent evaporation is a common method for film preparation.

Purpose of the Study:

• To investigate the effect of electrohydrodynamic (EHD) convection on the domain structure of polystyrene (PS)/polyvinyl acetate (PVA) blend films.
• To demonstrate the feasibility of using EHD convection for mixing and morphology control in polymer blend films.
• To understand the mechanism behind pattern formation in PS/PVA blend films.

Main Methods:

• Preparation of PS/PVA blend films using solvent evaporation.
• Application of a DC electric field to polymer solutions on a patterned electrode substrate.
• Observation and analysis of EHD convection patterns and resulting film morphology.
• Control experiments using a SiO2-coated substrate to rule out wetting/dewetting effects.

Main Results:

• Well-defined EHD convection structures were formed in the polymer solutions.
• Regular patterns were observed in the PS/PVA blend films.
• PVA-rich domains were confined within the patterned electrodes at appropriate electric voltages.
• The observed morphology was confirmed to be independent of substrate wetting/dewetting effects.

Conclusions:

• Electrohydrodynamic (EHD) convection is a viable method for controlling domain structure in polymer blend films.
• EHD-induced convection offers a novel approach for mixing and morphology control in polymer blends.
• The patterned electrode setup allows for precise control over the formation of regular structures in PS/PVA films.