Polymer-metal hybrid structures have attracted significant attention recently due to their advantage of great weight reduction and excellent integrated physical/chemical properties. However, due to great physicochemical differences between polymers and metals, obtaining an interface with high bonding strength is a challenge, which makes it critically important to clarify the underlying bonding mechanisms. In the present research, we focused on revealing the underlying bonding mechanisms of a laminated Cr-coated steel-ethylene acrylic acid (EAA) strip prepared by hot roll bonding from the microscale to the molecular scale with experimental evidence. The microscale mechanical interlocking was analyzed and proven by scanning white light interferometry and scanning electron microscopy (SEM) by means of observing the surface and cross-sectional morphologies. Additionally, interfacial phases and chemical compositions were analyzed by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). More directly and effectively, the interface was successfully exposed for X-ray photoelectron spectroscopy (XPS) analysis. Combined with time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and depth profiling analysis, the formation of -(O═)C-O-Cr and -C-(O-Cr)2 covalent bonds through chemical reactions at the interface between -COOH and Cr2O3 was verified. Based on these characterization results, interfacial bonding mechanisms for the laminated Cr-coated steel-EAA strip were clearly identified to be chemical bonding and micromechanical interlocking, along with hydrogen bonding, which were all demonstrated with solid experimental evidence. In addition, 3D-render view and cross-section images of typical ion fragments at the interface were used to reveal the interfacial structure more comprehensively. The contributions of hydrogen bonds and covalent bonds to the interface were evaluated and compared for the first time. This study provides both methodological and theoretical guidance for investigating and understanding interfacial bonding formation in polymer-metal hybrid structures.

Chemical Reaction and Bonding Mechanism at the Polymer-Metal Interface.

Polyphenylene sulfide (PPS) and copper (Cu) were selected as candidate materials for modeling a nano-injection molding process. Four nanopit shapes (rectangular, cylindrical, pyramidal and conical)...

MD simulation analysis of the anchoring behavior of injection-molded nanopits on polyphenylene sulfide/Cu interface

Electrides are a unique class of electron-rich materials where excess electrons are localized in interstitial lattice sites as anions, leading to a range of unique properties and applications. While hundreds of electrides have been discovered in recent years, magnetic electrides have received limited attention, with few investigations into their fundamental physics and practical applications. In this work, 51 magnetic electrides (12 antiferromagnetic, 13 ferromagnetic, and 26 interstitial-magnetic) were identified using high-throughput computational screening methods and the latest Materials Project database. Based on their compositions, these magnetic electrides can be classified as magnetic semiconductors, metals, or half-metals, each with unique topological states and excellent catalytic performance for N2 fixation due to their low work functions and excess electrons. The novel properties of magnetic electrides suggest potential applications in spintronics, topological electronics, electron emission, and as high-performance catalysts. This work marks the beginning of a new era in the identification, investigation, and practical applications of magnetic electrides.

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Magnetic Electrides: High-Throughput Material Screening, Intriguing Properties, and Applications.

Catalytic N2 activation and reduction for ammonia synthesis has been subject of intense research interest. Cluster-modified catalysts have been proposed as promising candidates for nitrogen activation due to the featured active sites and maximized synergistic effect. However, the nature of metal clusters itself has not been fully unveiled. Herein, we report a systematic investigation of N2 activation and reduction on three-atom metal clusters (M3) of all the 20 transition metals in the third and fourth periods of elements. We evaluate the catalysis of these M3 clusters by taking into consideration three critical processes, namely, N2 dissociation, hydrogenation, and NH3 desorption. The TMI series of the M3 clusters (Group 3B–5B metals) are found to support N2 dissociation spontaneously, in contrast to the TMII and TMIII clusters (i.e., Groups 6B–8B and 1B–2B). Based on the three criteria, Y3, Sc3, Zr3, and Nb3 are identified as eligible candidates for ammonia synthesis. These clusters show preferable hollow-site N2 adsorption and strong orbital hybridization, with electronic backdonation from the metal d orbitals to both π* and π/σ orbitals of N2. Further studies on ammonia synthesis have been conducted by applying Y3 and Nb3 clusters supported on graphene (Y3/G and Nb3/G), illustrating superior activity and potential application of such M3 clusters. This work validates the three-atom cluster catalysis and guides the design of efficient catalysts for N2 fixation. 

On the Nature of Three-Atom Metal Cluster Catalysis for N2 Reduction to Ammonia

Nano-injection molding has been widely used in polymer-metal integrated structures. This study aimed to investigate the joining strength and bonding mechanism between polymer-metal interfaces, as well as the interfacial interactions and joining properties with molecular dynamics methods. Besides, six polymer-aluminum interface systems in 5.4 × 5.4 × 12.5 nm cuboids composed of aluminum, polymer, and vacuum layers (from bottom to top) were constructed. The joining strength and flow behavior were explored by calculating the interfacial energy, filling rate, gyration radius, and pullout force. The effects of nano-cavity shape and non-bonding interaction strength on the separation process were analyzed. The simulation results demonstrated that during the filling process, the polymer molecular chains slipped and flowed along the inner wall of the nano-cavity, and the filling behavior depended largely on the fluidity and filling rate of the polymer. During the separation process, the polymer chains close to the aluminum matrix were stretched, the polymer chains far from the interface were relatively stable, and residual polymer molecular chains were observed near the interface. The interface joining primarily contributed to the interaction energy. Additionally, the formed mechanical interlocking effect further enhanced the joining strength when the nano-cavity was in a “T” shape, providing a reference value for the nano-injection time and dwell time. 

Molecular dynamics simulation study of the joining strength of different polymer‐aluminum heterointerfaces in nano‐injection molding

Intermetallic electrides have recently shown their priority as catalyst components in ammonia synthesis and CO2 activation. However, their function mechanism has been elusive since its inception, which hinders the further development of such catalysts. In this work, ternary intermetallic electrides La-TM-Si (TM = Co, Fe, and Mn) were synthesized as hosts of ruthenium (Ru) particles for ammonia synthesis catalysis. Although they have the same crystal structure and possess low work functions commonly, the promotion effects on Ru particles rather differ from each other. The catalytic activity follows the sequence of Ru/LaCoSi > Ru/LaFeSi > Ru/LaMnSi. Furthermore, Ru/LaCoSi exhibits much better catalytic durability than the other two. A combination of experiments and first-principles calculations shows that apparent N2 activation energy on each catalyst is much lower than that over conventional Ru-based catalysts, which suggests that N2 dissociation can be conspicuously promoted by the concerted actions of the specific electronic structure and atomic configuration of intermetallic electride-supported catalysts. The NHx formations proceeded on La are energetically favored, which makes it possible to bypass the scaling relations based on only Ru as the active site. The rate-determining step of Ru/La-TM-Si was identified to be NH2 formation. The transition metal (TM) in La-TM-Si electrides has a significant influence on the metal-support interaction of Ru and La-TM-Si. These findings provide a guide for the development of new and effective catalyst hosts for ammonia synthesis and other hydrogenation reactions.

Unique Catalytic Mechanism for Ru-Loaded Ternary Intermetallic Electrides for Ammonia Synthesis.

Study on the interfacial interactions and adhesion behaviors of various polymer‐metal interfaces in nano molding

Self-assembly and drug release mechanisms of mechano-responsive and antibacterial F127-Rif hydrogels

Carbon dots electrochemically prepared from dopamine and epigallocatechin gallate for hypochlorite detection with high selectivity via a dynamic quenching mechanism.

Hongchen Li

Papers

Unique Catalytic Mechanism for Ru-Loaded Ternary Intermetallic Electrides for Ammonia Synthesis.

Study on the interfacial interactions and adhesion behaviors of various polymer‐metal interfaces in nano molding

MD simulation analysis of the anchoring behavior of injection-molded nanopits on polyphenylene sulfide/Cu interface

Self-assembly and drug release mechanisms of mechano-responsive and antibacterial F127-Rif hydrogels

Carbon dots electrochemically prepared from dopamine and epigallocatechin gallate for hypochlorite detection with high selectivity via a dynamic quenching mechanism.