Self‐Assembled Ag‐MXA Superclusters with Structure‐Dependent Mechanical Properties

Abstract

The low elastic modulus and time-consuming formation process represent the major challenges that impede the penetration of nanoparticle superstructures into daily life applications. As observed in the molecular or atomic crystals, more effective interactions between adjacent nanoparticles would introduce beneficial features to assemblies enabling optimized mechanical properties. Here, a straightforward synthetic strategy is showed that allows fast and scalable fabrication of 2D Ag-mercaptoalkyl acid superclusters of either hexagonal or lamellar topology. Remarkably, these ordered superstructures exhibit a structure-dependent elastic modulus which is subject to the tether length of straight-chain mercaptoalkyl acids or the ratio between silver and tether molecules. These superclusters are plastic and moldable against arbitrarily shaped masters of macroscopic dimensions, thereby opening a wealth of possibilities to develop more nanocrystals with practically useful nanoscopic properties.

Survey on the Mechanical Properties of Lamellar Ag‐MXA Supercluster Architectures

“…Both calculated analyses and experimental data show that the Ag‐MPA/K superclusters have the highest E r and the alkaline treated Ag‐MPA/M superclusters exhibit higher E r than Ag‐MPA assembly without insertion of alkaline cations. The mechanical properties of the Ag‐MXA and Ag‐MPA/M superclusters are exhibited in Figure c with other synthetic and natural materials . The mechanical properties of the ionic bond enhanced Ag‐MPA/M supercluster pellets are on a par with partially synthetic and natural polymers.…”

“…Ordered supercluster architectures can be constructed under the guidance of Israelachvili theory . A straightforward synthetic strategy was adopted to allow fast and scalable fabrication of Ag‐MXA supercluster architectures . The creation of intermolecular hydrogen‐bond interactions serve as a thermodynamic driving force to induce the ordered assembly of lamellar superstructures.…”

“…The E r values of the three Ag‐MXA superclusters almost all gradually increase along with the increased impaction pressures. It suggested that the lamellar superclusters with a flatter morphology as shown in Figure a could help to distribute stress evenly, which significantly increases the E r in comparison with the Ag‐MXA supercluster pallets prepared under low compaction pressures . However, Ag‐MPA pellets contribute to superior tolerance to the external pressure compared with the other two.…”

“…Noncovalent bonds including hydrogen bonds, π‐π stacking, ionic bonds (electrostatic interactions), hydrophobic interactions, van der Waals interactions, and metal‐coordination bonds drive the self‐assembly and govern the structural conformation . In our previous work, we have assembled straight‐chain mercaptoalkyl acids (MXAs, including 3‐mercaptopropionic acid, MPA; 6‐mercaptohexanoic acid, MHA; and 11‐mercaptoundecane acid, MUA) through grafting on silver clusters using intermolecular hydrogen bonds as the driving force to construct the anisotropic lamellar superstructures . The hydrogen‐bond network dominates the assembled structure of Ag‐MXA supercluster architectures and further induces the structure‐dependent mechanical properties.…”

“…[8] In our previous work, we have assembled straight-chain mercaptoalkyl acids (MXAs, including 3mercaptopropionica cid, MPA; 6-mercaptohexanoic acid, MHA; and 11-mercaptoundecane acid, MUA) through grafting on silver clusters using intermolecularh ydrogen bonds as the drivingf orce to construct the anisotropic lamellar superstructures. [9] The hydrogen-bond network dominates the assembled structure of Ag-MXAs upercluster architectures and further induces the structure-dependent mechanical properties. However,t he understanding of the structure-dependent mechanical properties based on other noncovalent bond supporting frameworks still lack detailed experimental investigations.…”