Surface Functionalization of 4D Printed Substrates Using Polymeric and Metallic Wrinkles.

Area of Science:

• Materials Science
• Surface Engineering
• Biomimetics

Background:

• Wrinkle topographies offer versatile, biomimetic surface functionalization.
• Fabricating wrinkles often relies on thin-film mechanical instability on deforming substrates.
• Previous work was limited to simple geometries, necessitating methods for complex substrates.

Purpose of the Study:

• To develop a strategy for generating wrinkle topographies on arbitrarily complex 3D substrates.
• To combine 4D printing of shape-memory polymers (SMPs) with thin films for topographic functionalization.
• To investigate the influence of printing parameters and film properties on wrinkle characteristics.

Main Methods:

• Utilized 4D printing of SMPs integrated with polymeric and metallic thin films.
• Fabricated complex shape-changing substrates and parts with surface wrinkles.
• Characterized wrinkle topography and its effect on nuclear alignment using SEM, AFM, and fluorescent imaging.

Main Results:

• Increased nozzle temperature led to greater wrinkle wavelength but reduced strain trapping and nuclear alignment.
• Increasing thin film thickness also resulted in increased wrinkle wavelength.
• Demonstrated fiber-level topographic functionalization on complex 3D printed parts.

Conclusions:

• 4D printing of SMPs and thin films provides a novel approach for creating complex wrinkle topographies on 3D structures.
• Printing parameters like nozzle temperature and film thickness significantly influence wrinkle characteristics.
• This technique holds potential for advanced surface functionalization in diverse applications.