Light‐Induced Shape Morphing of Liquid Metal Nanodroplets Enabled by Polydopamine Coating

Abstract

Shape morphing nanosystems have recently attracted much attention and a number of applications are developed, spanning from autonomous robotics to drug delivery. However, the fabrication of such nanosystems remains at an early stage owing to limited choices of strategies and materials. This work reports a facile method to fabricate liquid metal (LM) nanodroplets by sonication of bulk LM in an aqueous dopamine hydrochloride solution and their application in light‐induced shape morphing at the nanoscale. In this method, dopamine acts as a surfactant, which stabilizes the LM nanodroplets dispersion during the sonication, and results in downsizing of the nanodroplets. Furthermore, by adding 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol to the suspension, self‐polymerization of dopamine molecules occurs, resulting in the formation of polydopamine (PDA)‐coated LM nanodroplets. Owing to the high photothermal conversion of the PDA, PDA‐coated LM nanodroplets are transformed from spherical shapes to ellipsoids by NIR laser irradiation. This study paves a simple and reliable pathway for the preparation of functional LM nanodroplets and their application as shape‐morphing nanosystems.

Liquid Metal–Based Soft Microfluidics

“…In contrast, nanosized droplets are often synthesized by sonication while the droplets minuscule droplets are stabilized by their oxide skin and surfactants. The size of the LM NPs can be efficiently adjusted, from microscale to nanoscale, by controlling the balance between the dissecting and coalescence of the micro‐/nanoscale LM droplets, power of the sonication, sonication time and so forth . Notably, the oxide skin is of pivotal importance for the generation of nanodroplets, as fast coalescence commences when the oxide skin is absent.…”

“…The size of the LM NPs can be efficiently adjusted, from microscale to nanoscale, by controlling the balance between the dissecting and coalescence of the micro-/nanoscale LM droplets, power of the sonication, sonication time and so forth. [50,52] Notably, the oxide skin is of pivotal importance for the generation of nanodroplets, as fast coalescence commences when the oxide skin is absent. Yan et al [51] recently developed a novel highly stable LM nanodroplets by the surface-initiated atom transfer radical polymerization (ATRP) of poly(methyl methacrylate) (PMMA), poly(n-butyl acrylate) (PBMA), poly(2-dimethylamino)ethyl methacrylate) (PDMAEMA), and poly(n-butyl acrylate-block-methyl methacrylate) (PBA-b-PMMA).…”

Near‐Infrared Photodriven Self‐Sustained Oscillation of Liquid‐Crystalline Network Film with Predesignated Polydopamine Coating

“…[ 26–29 ] Interestingly, it was found that the PDA nanospheres and coatings can act as effective photothermal materials showing strong absorption at NIR region with high photostability, [ 30,31 ] which makes the PDA polymer a promising candidate in multiple applications like photothermal therapeutic agent for cancer therapy, [ 30,32 ] fabrication of the programmable shape‐memory materials, [ 31,33 ] and shape‐morphing of liquid metals. [ 34 ] Based on the versatile PDA coating, herein, a NIR‐responsive polymeric oscillator was judiciously designed and fabricated by selectively depositing a PDA layer on the splay‐aligned LCN films. As schematically illustrated in Figure a, when the PDA‐coated region was irradiated by NIR light, the film bent due to the photothermal effect of PDA coating, leading the blank edge block the light.…”

High Resolution Soft and Stretchable Circuits with PVA/Liquid‐Metal Mediated Printing

“…To be suitable for inkjet printing, low viscosity EGaIn nanoparticle (EGaInNP) inks were synthesized in a water or ethanol carrier. [ 41,42 ] Promising results are obtained in terms of the synthesis of stable EGaInNP inks [ 52,53,54 ] and gallium oxide nanostructures. [ 55 ] Nevertheless, one major drawback is the need for a posterior sintering step to rupture the nanometer‐thick (≈0.5–3 nm) semi‐conductor oxide shell around the particles by mechanical pressure [ 56 ] or a UV laser beam.…”