Anomalous Structural Transformation of Cu(I) Clusters into Multifunctional CuAg Nanoclusters.

We report an anomalous structural transformation of a Cu(I) cluster into two different types of copper-silver (CuAg) alloy nanoclusters. Different from previous reports, we demonstrate that under specifically designed reaction conditions, the Ag-doping could induce a substantial growth of the starting Cu15 and a Ag13Cu20 nanocluster was obtained via the unexpected insertion of an Ag13 kernel inside the Cu(I)-S shell. Ag13Cu20 demonstrates high activity to initiate the photopolymerization of previously hard-to-print inorganic polymers in 3D laser microprinting. Interestingly, a slight modification of the reaction condition leads to the formation of another Ag18-xCuxS (8≤x) nanocluster templated by a central S2- anion, which possesses a unique electronic structure compared to conventional template-free CuAg nanoclusters. Overall, this work unveils the intriguing doping chemistry of Cu clusters, as well as their capability to create different types of alloy nanoclusters with previously unobtainable structures and multifunctionality.

Mechanical Performance of Copper-Nanocluster-Polymer Nanolattices.

A type of copper-nanocluster-polymer composites is reported and showcased that their 3D nanolattices exhibit a superior combination of high strength, toughness, deformability, resilience, and damage-tolerance. Notably, the strength and toughness of ultralight copper-nanocluster-polymer nanolattices in some cases surpass current best performers, including alumina, nickel, and other ceramic or metallic lattices at low densities. Additionally, copper-nanocluster-polymer nanolattices are super-resilient, crack-resistant, and one-step printed under ambient condition which can be easily integrated into sophisticated microsystems as highly effective internal protectors. The findings suggest that, unlike traditional nanocomposites, the laser-induced interface and the high fraction of ultrasmall Cu15 nanoclusters as crosslinking junctions contribute to the marked nonlinear elasticity of copper-nanocluster-polymer network, which synergizes with the lattice-topology effect and culminates in the exceptional mechanical performance.

PVA/ChCl Deep Eutectic Polymer Blends for Transparent Strain Sensors with Antifreeze, Flexible, and Recyclable Properties.

Wearable elastic electronic devices have attracted tremendous attention due to their monitoring capabilities for human motion detection. In this work, a hydrogen bond acceptor quaternary ammonium salt, choline chloride (ChCl), has been used to fabricate deep eutectic polymer (DEP) blends with polyvinyl alcohol (PVA). The miscibility, molecular interaction, and physical properties of PVA/ChCl DEP blends were investigated systematically. It is demonstrated that the deep eutectic of PVA/ChCl can be obtained by simple solution blending, and the melting points of both PVA and ChCl are reduced respectively due to the strong hydrogen bond between PVA and ChCl. Due to the elasticity of the PVA/ChCl elastomer and the response of ChCl ions to temperature and humidity, the fabricated sensor showed stable and repeatable resistance changes upon strain, temperature, and humidity variations. We hypothesize that the DEP blend system has potential applications in functional composites and the final PVA/ChCl elastomer composites exhibited high transparent, antifreeze, and recyclable capability, which may be promising for applications in soft/flexible devices.