Dataset Information

Self-Healing and Shape Memory Effects in Gold Microparticles through the Defects-Mediated Diffusion.

ABSTRACT: Some metal alloys subjected to irreversible plastic deformation can repair the inflicted damage and/or recover their original shape upon heating. The conventional shape memory effect in metallic alloys relies on collective, or "military" phase transformations. This work demonstrates a new and fundamentally different type of self-healing and shape memory in single crystalline faceted nano and microparticles of pure gold, which are plastically deformed with an atomic force microscope tip. It is shown that annealing of the deformed particles at elevated temperatures leads to nearly full recovery of their initial asymmetric polyhedral shape, which does not correspond to global energy minimum shape. The atomistic molecular dynamic simulations demonstrate that the shape recovery of the particles is controlled by the self-diffusion of gold atoms along the terrace ledges formed during the particles indentation. This ledge-guided diffusion leads to shape recovery by the irreversible diffusion process. A semiquantitative model of healing developed in this work demonstrates a good agreement with the experimental data.

SUBMITTER: Kovalenko O

PROVIDER: S-EPMC5566342 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Publications

Self-Healing and Shape Memory Effects in Gold Microparticles through the Defects-Mediated Diffusion.

Kovalenko Oleg O Brandl Christian C Klinger Leonid L Rabkin Eugen E

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 20170707 8

Some metal alloys subjected to irreversible plastic deformation can repair the inflicted damage and/or recover their original shape upon heating. The conventional shape memory effect in metallic alloys relies on collective, or "military" phase transformations. This work demonstrates a new and fundamentally different type of self-healing and shape memory in single crystalline faceted nano and microparticles of pure gold, which are plastically deformed with an atomic force microscope tip. It is sh ...[more]

PMID: 28852628

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Project description:Photoresponsive nucleic acid-based carboxymethyl cellulose (CMC) hydrogels are synthesized, and their application as shape-memory and self-healing functional matrices are discussed. One system involves the preparation of a carboxymethyl cellulose hydrogel crosslinked by self-complementary nucleic acid duplexes and by photoresponsive trans-azobenzene/?-cyclodextrin (?-CD) supramolecular complexes. Photoisomerization of the trans-azobenzene to the cis-azobenzene results in a hydrogel exhibiting lower stiffness due to the separation of the azobenzene/?-CD bridging units. The hydrogel is switched between high and low stiffness states by the cyclic and reversible light-induced isomerization of the azobenzene units between the trans and cis states. The light-controlled stiffness properties of the hydrogel are used to develop a shape-memory hydrogel, where the duplex bridging units act as permanent memory in the quasi-liquid shapeless state of the hydrogel. A second system in the study is a carboxymethyl cellulose hydrogel crosslinked by the K+-stabilized G-quadruplex bridging units and by trans-azobenzene/?-CD complexes. The resulting hydrogel includes dual-trigger functionalities, where the trans-azobenzene/?-CD complexes can be reversibly formed and dissociated through the trans and cis photoisomerization of the azobenzene units, and the K+-stabilized G-quadruplexes can be reversibly dissociated and reformed in the presence of 18-crown-6-ether/K+-ions. The signal-responsive crosslinked hydrogel reveals controlled stiffness properties, where the hydrogel crosslinked by the trans-azobenzene/?-CD and K+-ion-stabilized G-quadruplex reveals high stiffness and the hydrogel crosslinked only by the K+-ion-stabilized G-quadruplexes or only by the trans-azobenzene/?-CD complexes reveals low stiffness properties. The controlled stiffness properties of the hydrogel are used to develop shape-memory hydrogels, where the trans-azobenzene/?-CD complexes or the K+-ion-stabilized G-quadruplexes act as permanent memories in the shapeless and quasi-liquid states of the hydrogels. In addition, the hydrogel that includes two types of stimuli-responsive crosslinking units is used as a self-healing matrix, where each of the triggers guides the self-healing processes.

Dataset Information

Self-Healing and Shape Memory Effects in Gold Microparticles through the Defects-Mediated Diffusion.

Publications

Self-Healing and Shape Memory Effects in Gold Microparticles through the Defects-Mediated Diffusion.

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