Tailored topography: a novel fabrication technique using an elasticity gradient

Area of Science:

• Materials Science
• Surface Engineering
• Polymer Science

Background:

• Creating surfaces with controlled topography is crucial for advanced applications.
• Poly(dimethyl)siloxane (PDMS) is a versatile polymer, but controlling its surface properties, like elasticity, remains a challenge.
• Tailoring surface topography can influence material properties such as wettability and adhesion.

Purpose of the Study:

• To present a facile methodology for creating wrinkled surfaces with tailored topography.
• To exploit the dependency of PDMS elasticity on curing temperature to create an elasticity gradient.
• To investigate the control over surface pattern dimensions and wettability.

Main Methods:

• A novel setup was used to create a temperature gradient across PDMS during curing, influencing its elasticity.
• The PDMS substrate with an elasticity gradient was stretched and treated with oxygen plasma.
• Time-dependent temperature distributions were measured, and the physics of PDMS elasticity dependence on curing temperature was analyzed.

Main Results:

• An ordered wrinkled surface with continuously varying wavelength and amplitude was obtained upon relaxation of the plasma-treated PDMS.
• The hydrophobicity recovery of the plasma-oxidized PDMS with varying elasticity was studied.
• Wavelength and amplitude of the wrinkled patterns were controlled by parameters like pre-strain, plasma power, and heater temperature.

Conclusions:

• The spatial distribution of topography and hydrophobicity collectively determine the substrate's wettability.
• Gradient surfaces with controlled substructure dimensions exhibit tunable wetting characteristics.
• This method offers potential applications in droplet manipulation, cell adhesion, and diffraction gratings.