Unique aspects of a shape memory polymer as the substrate for surface wrinkling

Area of Science:

• Materials Science
• Polymer Science
• Thin Film Mechanics

Background:

• Traditional bilayer wrinkle systems utilize soft elastomers as substrates.
• Shape memory polymers (SMPs) present a novel alternative due to their unique thermomechanical properties.
• SMPs transition from rigid at room temperature to a low modulus state upon heating.

Purpose of the Study:

• To investigate the use of shape memory polymers as substrates for thin film wrinkling.
• To explore the creation of both reversible and irreversible wrinkles and associated diffraction colors.
• To understand the mechanics of wrinkle formation on SMP substrates and compare them to elastomer systems.

Main Methods:

• Fabrication of bilayer systems using metallic thin films on shape memory polymer substrates.
• Systematic investigation of experimental parameters influencing wrinkle formation (wavelength, amplitude).
• Analysis of wrinkle reversibility and crack-free formation conditions.

Main Results:

• Demonstrated feasibility of creating both reversible and irreversible wrinkles on a single SMP substrate.
• Identified experimental conditions for producing crack-free wrinkles.
• Observed deviations in wrinkle mechanics compared to established theories for elastomer substrates.

Conclusions:

• Shape memory polymers are viable and unique substrates for thin film wrinkling applications.
• The thermomechanical properties of SMPs lead to distinct wrinkle mechanics.
• New theoretical models are required to accurately describe wrinkling phenomena on SMP substrates, considering plastic deformation of thin films.