4 research outputs found
Switchable Micropatterned Surface Topographies Mediated by Reversible Shape Memory
Reversibly switching topography on
micrometer length scales greatly expands the functionality of stimuli-responsive
substrates. Here we report the first usage of reversible shape memory
for the actuation of two-way transitions between microscopically patterned
substrates, resulting in corresponding modulations of the wetting
properties. Reversible switching of the surface topography is achieved
through partial melting and recrystallization of a semi-crystalline
polyester embossed with microscopic features. This behavior is monitored
with atomic force microscopy (AFM) and contact angle measurements.
We demonstrate that the magnitude of the contact angle variations
depends on the embossment pattern
Dynamic Optical Gratings Accessed by Reversible Shape Memory
Shape memory polymers (SMPs) have
been shown to accurately replicate photonic structures that produce
tunable optical responses, but in practice, these responses are limited
by the irreversibility of conventional shape memory processes. Here,
we report the intensity modulation of a diffraction grating utilizing
two-way reversible shape changes. Reversible shifting of the grating
height was accomplished through partial melting and recrystallization
of semicrystalline poly(octylene adipate). The concurrent variations
of the grating shape and diffraction intensity were monitored via
atomic force microscopy and first order diffraction measurements,
respectively. A maximum reversibility of the diffraction intensity
of 36% was repeatable over multiple cycles. To that end, the reversible
shape memory process is shown to broaden the functionality of SMP-based
optical devices
Shapeshifting: Reversible Shape Memory in Semicrystalline Elastomers
We present a general strategy for
enabling reversible shape transformation
in semicrystalline shape memory (SM) materials, which integrates three
different SM behaviors: conventional one-way SM, two-way reversible
SM, and one-way reversible SM. While two-way reversible shape memory
(RSM) is observed upon heating and cooling cycles, the one-way RSM
occurs upon heating only. Shape reversibility is achieved through
partial melting of a crystalline scaffold which secures memory of
a temporary shape by leaving a latent template for recrystallization.
This behavior is neither mechanically nor structurally constrained,
thereby allowing for multiple switching between encoded shapes without
applying any external force, which was demonstrated for different
shapes including hairpin, coil, origami, and a robotic gripper. Fraction
of reversible strain increases with cross-linking density, reaching
a maximum of <i>ca</i>. 70%, and then decreases at higher
cross-linking densities. This behavior has been shown to correlate
with efficiency of securing the temporary shape
Shapeshifting: Reversible Shape Memory in Semicrystalline Elastomers
We present a general strategy for
enabling reversible shape transformation
in semicrystalline shape memory (SM) materials, which integrates three
different SM behaviors: conventional one-way SM, two-way reversible
SM, and one-way reversible SM. While two-way reversible shape memory
(RSM) is observed upon heating and cooling cycles, the one-way RSM
occurs upon heating only. Shape reversibility is achieved through
partial melting of a crystalline scaffold which secures memory of
a temporary shape by leaving a latent template for recrystallization.
This behavior is neither mechanically nor structurally constrained,
thereby allowing for multiple switching between encoded shapes without
applying any external force, which was demonstrated for different
shapes including hairpin, coil, origami, and a robotic gripper. Fraction
of reversible strain increases with cross-linking density, reaching
a maximum of <i>ca</i>. 70%, and then decreases at higher
cross-linking densities. This behavior has been shown to correlate
with efficiency of securing the temporary shape