Creating controlled thickness gradients in polymer thin films via flowcoating.

Area of Science:

• Materials Science
• Fluid Dynamics
• Polymer Science

Background:

• Flowcoating is a widely used method for producing thin polymer films (5-200 nm) on substrates.
• Substrate acceleration during flowcoating generates thickness gradients, beneficial for high-throughput applications.

Purpose of the Study:

• To compare experimental polymer film thickness profiles with a Landau-Levich model.
• To identify critical experimental parameters influencing film thickness in flowcoating.

Main Methods:

• Experimental flowcoating of polymer films with varying substrate acceleration.
• Comparison of experimental thickness profiles with a first-principles Landau-Levich model.
• Analysis of parameters including capillary number and static meniscus radius.

Main Results:

• Excellent quantitative agreement was observed between experimental data and the Landau-Levich model.
• Key parameters governing film thickness were identified as capillary number and meniscus radius.
• Meniscus radius is determined by blade angle, gap height, fluid volume, and contact angles.

Conclusions:

• The Landau-Levich model provides a reliable framework for understanding and controlling flowcoating parameters.
• This model enables precise control over polymer thin film thickness profiles for diverse applications.
• The study offers a design approach for achieving desired film thicknesses in flowcoating processes.