3 research outputs found
Reversible Sliding in Networks of Nanowires
This
work demonstrates that metal nanowires in a percolating network can
reversibly slide across one another. Reversible sliding allows networks
of metal nanowires to maintain electrical contact while being stretched
to strains greater than the fracture strain for individual nanowires.
This phenomenon was demonstrated by using networks of nanowires as
compliant electrodes for a dielectric elastomer actuator. Reversible
nanowire sliding enabled actuation to a maximum area strain of 200%
and repetitive cycling of the actuator to an area strain of 25% over
150 times. During actuation, the transmittance of the network increased
4.5 times, from 13% to 58%. Compared to carbon-based compliant electrodes,
networks of metal nanowires can actuate across a broader range of
optical transmittance. The widely tunable transmittance of nanowire-based
actuators allows for their use as a light valve
Dynamic surface deformation of silicone elastomers for management of marine biofouling: laboratory and field studies using pneumatic actuation
<div><p>Many strategies have been developed to improve the fouling release (FR) performance of silicone coatings. However, biofilms inevitably build on these surfaces over time. Previous studies have shown that intentional deformation of silicone elastomers can be employed to detach biofouling species. In this study, inspired by the methods used in soft-robotic systems, controlled deformation of silicone elastomers <i>via</i> pneumatic actuation was employed to detach adherent biofilms. Using programmed surface deformation, it was possible to release > 90% of biofilm from surfaces in both laboratory and field environments. A higher substratum strain was required to remove biofilms accumulated in the field environment as compared with laboratory-grown biofilms. Further, the study indicated that substratum modulus influences the strain needed to de-bond biofilms. Surface deformation-based approaches have potential for use in the management of biofouling in a number of technological areas, including in niche applications where pneumatic actuation of surface deformation is feasible.</p></div
Mechanochemical Activation of Covalent Bonds in Polymers with Full and Repeatable Macroscopic Shape Recovery
Covalent
mechanochemistry within bulk polymers typically occurs
with irreversible deformation of the parent material. Here we show
that embedding mechanophores into an elastomeric poly(dimethylsiloxane)
(PDMS) network allows for covalent bond activation under macroscopically
reversible deformations. Using the colorimetric mechanophore spiropyran,
we show that bond activation can be repeated over multiple cycles
of tensile elongation with full shape recovery. Further, localized
compression can be used to pattern strain-induced chemistry. The platform
enables the reversibility of a secondary strain-induced color change
to be characterized. We also observe mechanical acceleration of a
flex-activated retro-Diels–Alder reaction, allowing a chemical
signal to be released in response to a fully reversible deformation