Permeability- and Surface-Energy-Tunable Polyurethane Acrylate Molds for Capillary Force Lithography

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Capillary-force lithography (CFL) is a technique for micro- and nanopatterning.
• The performance of CFL relies heavily on mold properties like surface energy and gas permeability.
• Simultaneously controlling these two properties in traditional CFL molds is challenging.

Purpose of the Study:

• To introduce a novel polyurethane acrylate (PUA) based mold material, termed "capillary-force material" (CFM), for CFL.
• To demonstrate that the surface energy and gas permeability of CFM molds can be precisely modulated.
• To overcome geometric limitations in nanopatterning, especially on curved surfaces.

Main Methods:

• Developed CFM molds with controllable cross-linking degrees.
• Investigated the relationship between cross-linking density, surface energy, and air permeability.
• Evaluated the performance of CFM molds for patterning at different functionalities and on various substrates.

Main Results:

• Increased cross-linking density in CFM molds led to decreased surface energy and air permeability.
• High functionality CFM molds enabled fine and rapid patterning due to high capillary rise and stiffness.
• Low functionality CFM molds facilitated conformal contact and patterning on curved surfaces.

Conclusions:

• The developed CFM molds offer tunable interfacial properties for enhanced CFL.
• This approach allows for precise control over patterning resolution and adaptability.
• CFMs significantly expand the scope of CFL for sub-100 nm and curved-surface nanopatterning.