This study introduces a novel 2D colloid surfactant system that exhibits catalytic activity at the interface of a reactant‐containing water‐in‐oil Pickering emulsion microreactor. To this end, amphiphilic nanoplatelets (ANPLs) are fabricated with hydrophobic poly (n‐butyl methacrylate) brushes on one face, and hydrophilic poly (2‐aminoethyl methacrylate) brushes on the other face via surface‐induced activators regenerated by electron transfer atom transfer radical polymerization (SI‐ARGET ATRP) on zirconium hydrogen phosphate (ZrHP) nanoplatelets. Subsequently, in situ reduction of metal precursors on the primary amine reaction sites on the hydrophilic face of ANPLs is conducted, thus enabling the production of ANPL catalysts (ANPLcat): ANPLAg, ANPLPd, and ANPLAu. Owing to the platelet geometry and catalytic functionalization, the ANPLcat demonstrates excellent ability to stabilize the Pickering emulsion reactant drops, while exhibiting its own catalytic activity at the interface. It is demonstrated that this ANPLcat system has a high catalytic activity that requires a short reduction reaction time with the speed of which is 750% higher compared with the spherical colloidal surfactant catalyst. In addition, ANPLcat is easily recoverable and recyclable. These results highlight that the ANPLcat‐based emulsion microreactor system is expected to be widely applied as a high‐performance catalyst for various organic chemical reactions.
Rapid industrial growth has severely impacted ecosystems and aggravated economic and health risks to society. Monitoring of ecosystems is fundamental to our understanding of how ecosystem change impacts resources and is critical for developing data-based sustainability. Thus, the design and development of optimized sensors for ecosystem monitoring have received increasing attention.This review provides a comprehensive overview of systematic sensor design strategies for ecosystem monitoring from the material level to the form factor level. We discuss the fundamental transducing mechanisms of a representative sensor system including optical, electrical, and electrochemical sensors. We then review the sensor interfacing strategy for achieving stable and real-time monitoring of environmental biochemical factors from air, water, soil, and living organisms. Finally, we provide a summary of the current performance and prospects of this state-of-the-art sensor technology and an outlook on opportunities for possible future research directions in this emerging field.
A new type of colloidal surfactant that not only has a nanoscale platelet geometry, but can also induce complementary face-to-face interactions among Pickering emulsion droplets is introduced.
A platform
is introduced for bilayered coacervation of oppositely
charged nanoplatelets (NPLs) at the oil–water interface. To
this end, we synthesized two types of zirconium hydrogen phosphate
(ZrHP) NPLs, cationically charged NPLs (CNPLs), and anionically charged
NPLs (ANPLs) by conducting surface-initiated atom transfer radical
polymerization. Taking advantage of the platelet geometry and controlled
wettability, we demonstrated that ANPLs and CNPLs coacervate themselves
to form a bilayered NPL membrane at the interface, which was directly
confirmed by confocal laser scanning microscopy. Via theoretical consideration
using the hit-and-miss Monte Carlo method, we determined that electrostatic
attraction-driven coacervation of ANPLs and CNPLs at the interface
shows a minimum attachment energy of ∼ −106
k
BT, which is comparable to the cases
where NPLs charged with the same type of ions are attached. Finally,
this unique and novel interfacial coacervation behavior allowed us
to develop a pH-responsive smart Pickering emulsion system.
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