Nanocomposite Structure Research Articles

Titanium carbide (Ti3C2Tx) decorated molybdenum diselenide (MoSe2) nanoflower composite enhanced photo-electrocatalytic activity in hydrogen evolution

Two-dimensional titanium carbides (Ti3C2Tx) are part of the novel family of transition metal carbides/nitrides known as MXenes, which exhibit a broad range of photo-electrocatalytic applications. In this study, we present a facile hydrothermal synthesis method for Ti3C2Tx decorated on molybdenum diselenide (MoSe2) nanoflower composites, serving as an enhanced catalyst for hydrogen (H2) evolution. Ti3C2Tx, acting as a 2D conductive substrate, facilitates electron transfer, preventing MoSe2 agglomeration, while MoSe2 offers abundant active sites. The characterizations of surface analysis, optical properties, morphological nanostructure, and elemental composition performance of Ti3C2Tx nanosheets, MoSe2 nanoflowers, and Ti3C2Tx/MoSe2 nanoflower composites was conducted using FTIR, XRD, UV–Visible spectroscopy, SEM, EDS Mapping, TEM, and XPS techniques. The catalyst with optimal performance, the Ti3C2Tx/MoSe2 nanoflower composite demonstrates excellent functional properties in the H2 evolution, showing a lower overpotential of 135 mV and smaller Tafel slope of 72 mV/dec at 10 mA/cm2 compared to Ti3C2Tx nanosheets and MoSe2 nanoflowers. The Ti3C2Tx/MoSe2 nanoflower composite forms heterojunctions to inhibit the rapid recombination rate of photo-induced electrons and holes. In comparison to MoSe2 nanoflowers and Ti3C2Tx catalysts (where Tx = F, and O surface terminations), the optimized Ti3C2Tx/MoSe2 nanoflower composite exhibits significantly enhanced photocatalytic activity in H2 production, with a H2 production rate of 2146 μmolg−1h−1 superior than the Ti3C2Tx nanosheets (1367 μmolg−1h−1) and MoSe2 nanoflowers (986 μmolg−1h−1), respectively. Through this design, effective separation of photogenerated charge carriers is achieved, improving the activity of photocatalytic H2 production and demonstrating the promise of the cocatalyst strategy for photocatalysis.

Comprehensive characterization of a Mn0.1Mg0.9Fe2O4/CeO2/MgFe2O4 nanocomposite for high-performance supercapacitor applications

Metal oxide nanocomposites have grown in popularity in the field of electrochemical devices due to their numerous advantages, such as a large active surface area and high chemical stability. However, it is crucial to emphasize that the structural properties of these metal oxide nanocomposites are crucial in molding their electrochemical performance. Using solvothermal reflux and auto-combustion techniques (Mn0.1Mg0.9Fe2O4/CeO2/MgFe2O4) comprising Mn0.1Mg0.9Fe2O4, CeO2, and MgFe2O4 was successfully produced. This nanocomposite was used to construct high-performance electrochemical energy storage devices, notably battery-type applications. This nanocomposite crystal structure, morphology, and elemental composition were thoroughly examined. The electrochemical performance of the synthesized nanocomposite was examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using a 6 M KOH electrolyte solution to acquire a thorough grasp of its properties. When tested at a current density of 1 A/g, the composite electrode demonstrated an impressive specific capacity (Cs) of 368.7 C/g. Even after 5000 charge-discharge cycles, the Mn0.1Mg0.9Fe2O4/CeO2/MgFe2O4 nanocomposite electrode retained 93 % of its capacity retention. These findings definitively establish the Mn0.1Mg0.9Fe2O4/CeO2/MgFe2O4 nanocomposite as a top choice for energy storage systems.

An effective route to the additive manufacturing of a mechanically gradient supramolecular polymer nanocomposite structure

3D Printing techniques are additive methods of fabricating parts directly from computer-aided designs. Whilst the clearest benefit is the realisation of geometrical freedom, multi-material printing allows the introduction of compositional variation and highly tailored product functionality. The paper reports a proof-of-concept additive manufacturing study to deposit a supramolecular polymer and a complementary organic filler to form composites with gradient composition to enable spatial distribution of mechanical properties and functionality by tuning the number of supramolecular interactions. We use a dual-feed extrusion 3D printing process, with feed stocks based on the supramolecular polymer and its organic composite, delivered at ratios predetermined. This allows for production of a graded specimen with varying filler concentration that dictates the mechanical properties. The printed specimen was inspected under dynamic load in a tensile test using digital image correlation to produce full-field deformation maps, which showed clear differences in deformation in regions with varying compositions, corresponding to the designed-in variations. This approach affords a novel method for printing material with graded mechanical properties which are not currently commercially available or easily accessible, however, the method can potentially be directly translated to the generation of biomaterial-based composites featuring gradients of mechanical properties.

High-efficiency photocatalytic degradation of Rhodamine B and tetracycline by Z-scheme nanostructured Ag/Ag3PO4/Ti3+-TiO2 mesocrystals heterojunctions under visible light

This paper discusses the photocatalytic properties of Ag/Ag3PO4/Ti3+-TiO2 composites. The nanostructured composites were synthesized by gas-phase hydrolysis, precipitation, and photoreduction methods. The photocatalytic performance of the photocatalysts was evaluated by degrading RhB and TC under visible light. The degradation efficiency of AT4 for RhB and TC reached 99.9 % and 78.2 % under visible light irradiation for 20 min and 2.5 min, respectively. The superior performance of AT4 is facilitated by the combined influence of the heterojunction and the SPR. The free radical capture test proved that h+ and •O2− were the major reactive groups, and in conjunction with UV–vis DRS curves and Mott-Schottky curves, a probable reaction mechanism was proposed.

Preparation and Characterization of Conductive/Self-Healing Resin Nanocomposites Based on Tetrafunctional Furan-Functionalized Aniline Trimer Modified Graphene.

The nanocomposites with reversible cross-linking covalent bonds were prepared by reacting furfurylamine (FA)-modified diglycidyl ether of bisphenol A (DGEBA) and furfuryl-functionalized aniline trimer-modified graphene (TFAT-G) with bismaleimide (BMI) via the Diels-Alder (DA) reaction. The successful synthesis of the TFAT modifier is confirmed by nuclear magnetic resonance (NMR) hydrogen spectroscopy and IR spectroscopy tests. The structure and properties of TFAT-G epoxy nanocomposites are characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), tensile, and resistivity. The results show that TFAT-G was uniformly dispersed in the resin, and 1 wt% TFAT-G composites increased to 233% for tensile strength, 63% for elongation at break, 66% for modulus, and 7.8 °C for Tg. In addition, the addition of unmodified graphene degrades the mechanical properties of the composite. Overall, the graphene/self-healing resin nanocomposites have both good self-healing function and electrical conductivity by adding 1 wt% modified graphene; this allows for the maintenance of the original 83% strength and 89% electrical conductivity after one cycle of heating repair.

Construction and Tribological Performance of Ag Nanowire-Dotted 2D Ni-BDC Nanocomposites in Oil.

The collaborative lubrication effect based on different lubricating nanostructures could not only overcome the respective drawbacks of different nanostructures as nanoadditives but also comprehensively improve friction performance. For this, we first developed a novel collaborative lubrication nanostructure based on Ag nanowires (NWs) and two-dimensional (2D) Ni-BDC nanosheets (Ag NWs/2D Ni-BDC) by the in situ chemical reduction strategy. The structural characterizations corroborated that Ag NWs with a width of approximately 20-30 nm grew on the surface of 2D Ni-BDC nanosheets, which presented the chemical interface between both. As the nanoadditive applied in oils, the tribological finding confirmed that the Ag NWs/2D Ni-BDC enabled the friction coefficient and wear scar diameter to reduce by 38 and 37% at 0.04 wt % additive content, respectively. The worn surface was characterized by a series of analytical techniques, which basically revealed the friction-reducing and antiwear mechanism based on the layered structure and self-repair effect. Consequently, the nanocomposite structure incorporating the nanowire and 2D nanosheets should be taken into account as a new potential lubricating material.

Designing B–C3N4/Bi2WO6 to construct a Z-type hybrid heterostructure for efficient degradation of antibiotics

Constructing nanocomposite structures with good charge transfer pathways is an effective way to obtain high-efficiency photocatalysts. Therefore, we prepared a Z-scheme heterojunction B–C3N4/Bi2WO6 composite material by combining 2D B–C3N4 nanosheets and 2D Bi2WO6 nanosheets. The composite catalyst exhibited significant multi-purpose photocatalytic activity against the antibiotics. When the Bi2WO6 proportion was 100 % (The proportion of Bi2WO6 to B–C3N4 is 1:1), the degradation efficiency of TC-HCl reached 85.7 % within 90 min, demonstrating the best photocatalytic performance. UV–vis showed that the visible light response range of the photocatalytic material shifted to the infrared region, possibly due to the construction of a Z-type heterojunction. The PL results showed that the electron-hole recombination rate of B–C3N4 is lower than that of g-C3N4 due to B-doping. Doped heterostructures can effectively enhance the performance of photocatalytic materials and offer a novel approach to pollutant degradation.

WO3 Nanostructures Modified with Carbon and Sulfur Used as Anode for Li-Ion Batteries

Nowadays, energy problems have become one of the biggest challenges in our society and they have drawn worldwide attention. Rechargeable lithium-ion batteries (LiBs) are a good option thanks to their potential applications as power sources for electric vehicles and mobile devices due to their high energy density and good cycle stability. Much effort has recently been devoted to find alternative anode materials and replace graphite in LiBs, like transition metal oxides that are currently being investigated (1).Specifically, tungsten oxide (WO3) has attracted much interest as an anode due to its excellent properties: high electronic conductivity (10–10−6 s cm−1), high intrinsic density (>7 g cm−3), small radius, and correct crystalline phase for rapid ion insertion and superior electrochemical performance (2).In this research, the effects of the morphology and composition of WO3 nanostructures on the charge/discharge behavior for Li-ion batteries are methodically examined.On the one hand, a simple method is used to synthesize crystalline WO3 nanostructures, with a well-defined morphology by means of an electrochemical procedure known as electrochemical adodization. Then, an annealing treatment at 600◦C in air environment for 4 h was carried out. In the second electrode synthesized, a carbon layer was uniformly deposited on WO3 nanostructures to obtain a WO3/C electrode. Finally, WO3/WS2 electrodes were prepared by means of in situ sulfurization of WO3 one-step solid-state synthesis using tungsten trioxide (WO3) and thiourea as precursor material.The different electrodes synthesized have been morphologically characterized by using X-ray photoelectron spectroscopy, X-ray diffraction analysis, transmission electron microscopy, Raman spectra, and field-emission scanning electron microscopy.The performance of the nanostructures applied as anodes for energy storage in Li-ion batteries and their specific capacity was evaluated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Charge-Discharge curves. Among all the synthesized samples, WO3/C nanostructures reveal the best performance as they exhibit the greatest discharge capacity and cycle performance (820 mA h g−1). Acknowledgments Authors would like to express their gratitude to AEI (PID2019-105844RB-I00/ AEI/10.13039/501100011033) for the financial support. M. Cifre-Herrando thank Ministerio de Universidades for the concession of the pre-doctoral grant (FPU19/02466). G. Roselló-Márquez also thanks the UPV for the concession of a post-doctoral grant (PAID-10-21) and for the grant to promote postdoctoral research at the UPV (PAID.-PD-22). Finally, project co-funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044) is acknowledged. References Li P, Li X, Zhao Z, Wang M, Fox T, Zhang Q, et al. Correlations among structure, composition and electrochemical performances of WO3 anode materials for lithium ion batteries. Electrochim Acta. 2016;192:148–57. 2. Lian C, Xiao X, Chen Z, Liu Y, Zhao E, Wang D, et al. Preparation of hexagonal ultrathin WO3 nano-ribbons and their electrochemical performance as an anode material in lithium ion batteries. Nano Res. 2016;9(2):435–41.

Synthesis, Characterization, and Wear Behavior of W-DLC Films Deposited on Si Substrates

Tungsten (W) reinforced diamond-like carbon (DLC) nanocomposite thin films were deposited on silicon substrates by magnetron sputtering in a CH4/Ar discharge. The W content of the films was varied by varying the W target power (20, 40, 60, 80, and 100 W). The evolution of the W-DLC nanocomposites was studied by high-resolution transmission electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, 3D optical profilometry and Raman spectroscopy. Increasing the W target power resulted in an almost liner increase in the W content, reduced the hardness and the sp3/sp2 ratio in the films, while it increased the surface roughness and promoted formation of WC nanoparticles. Tribological properties were studied by conducting sliding reciprocating testing. Wear tracks were analyzed with Raman spectroscopy and 3D optical profilometry. Increasing the W content in the films (increasing target power) resulted in a reduction of both, the friction coefficient and wear rate. The film deposited at 80 W target power (~8 at. % W) exhibited the lowest friction coefficient (0.15) and wear rate (6x10-7 mm3N-1m-1). The observed low friction and wear rate were attributed to the particular nanocomposite structure of the films involving a fine distribution of WC nanoparticles surrounded by a sp2 dominant carbon network. The present W-DLC nanocomposite films offer a highly desirable combination of low friction and low wear rate.

Confining Co1.11Te2 nanoparticles within mesoporous hollow carbon combination sphere for fast and ultralong sodium storage

Co1.11Te2 nanoparticles are in-situ uniformly grown within mesoporous hollow carbon combination sphere (MHCCS@Co1.11Te2) using a hard-template and spray drying process, solution impregnation and pyrolysis tellurization. Material characterizations reveal that Co1.11Te2, with a diameter of ∼ 20 nm, is attached to the internal walls of the unit spheres or embedded in the mesopore shells of the unit spheres, presenting a distinctive “ships-in-combination-bottles” nanoencapsulation structure. In sodium-ion half-cells, MHCCS@Co1.11Te2 exhibits excellent cycling stability, achieving reversible capacities of 257 mAh/g at 0.5 A/g after 250 cycles, 235 mAh/g at 1.0 A/g after 300 cycles and 161 mAh/g at 10.0 A/g after 1900 cycles. Electrochemical kinetic analyses and ex-situ characterizations reveal rapid electron/Na+ transport kinetics, prominent surface pseudocapacitive behavior, robust nanocomposite structure, and multi-step conversion reactions of sodium polytellurides. In sodium-ion full-cells, MHCCS@Co1.11Te2 still demonstrates stable cycling performance at 1.0 and 5.0 A/g and excellent rate capability. The superior electrochemical performance is associated with the nanoencapsulation structure based on mesoporous hollow carbon combination spheres, which promotes electron conduction and Na+ transport. The space-confined effect maintains the high electrochemical activity and cycling stability of Co1.11Te2.

Carbon nanotube reinforced LDPE/SAN thermoplastic nanocomposites: thermo-mechanical and electromagnetic interference shielding properties

A prevalent area of research is the development of structural polymer composites with diverse functions. An ingenious material solution is two-phased nanocomposites with distinctive structural and electrical characteristics. This study produced a nanocomposite structure with carbon nanotube-reinforced low-density polyethylene (LDPE) and styrene acrylonitrile (SAN) as a thermoplastic matrix. The injection molding method was used in the production of nanocomposites. Thermo-dynamic and electromagnetic shielding properties of the nanocomposites were investigated. As the LDPE/MWCNT ratio added to pure SAN increased, the storage modulus decreased as expected, and the storage modulus for the MB50 sample was determined as 1.24 GPa with a 50% decrease. The percolation threshold for the two-phase thermoplastic composite was obtained for the MB50 sample containing 10 wt% carbon nanotubes. In addition, the MB75 sample containing 15 wt% carbon nanotubes reached an EMSE value of 37 dB.

Influence of alkaline sources for the electrochemical performance of NiCo layered double hydroxide nanostructures

The morphology and composition of nanostructures play important role in their electrochemical properties. Herein, NiCo layered double hydroxide (LDH) nanostructures were prepared by hydrothermal method with NaOH, urea and ammonia as alkaline sources, respectively. The types of alkaline can affect the morphology of the obtained NiCo LDH nanostructures. Compared with the NaOH as alkaline source, NiCo LDHs with urea and ammonia as alkaline sources exhibit obvious nanoflower structure. And the electrode corresponding to ammonia has the highest specific capacity (1498.98 F/g) at a current density of 1 A/g. And the dosage of ammonia was also influenced the composition of the obtained NiCo LDH nanostructures. Moderate ammonia dosage (0.9 mL) would ensure the purity of NiCo LDH, and achieve high specific capacity and high retention rate (82.9 %) at high current density (10 A/g). These obtained results can provide a new idea and sight for the promotion of the related electrochemical devices based on NiCo LDH materials.

Photocatalytic activity of colloidal Bi–Si-based nanoparticles prepared by laser synthesis in liquid

A combination of laser ablation and laser irradiation by focused laser beam in liquid is used to prepare the Bi- and Si-based nanocolloids in water in a Bi:Si molar ratio of 12:1. The composition, structure, morphology, and optical properties of the obtained nanostructures are studied. The synthesized composite nanostructures are shown to consist mainly of bismuth oxycarbonate Bi2(CO3)O2 and bismuth silicate Bi12SiO20. The materials are tested in the decomposition of the model dye rhodamine B, including the stability of the catalyst and the opportunity of its regeneration by laser irradiation as well as in phenol decomposition when excited by LED with a wavelength of 375 nm. The opportunity to use the Bi–Si-based colloidal nanostructures for the selective photooxidation of 5-(hydroxymethyl)furfural is considered.

A theoretical modelling of strengthening mechanism in graphene-metal nanolayered composites

Graphene-metal nanolayered composites (GMNCs) are a new generation of nano-structural composites characterized by a very high density of graphene reinforced interfaces (GRI) between metal nanolayers. Compared to traditional graphene flake reinforced composites, GMNCs have much higher strength, toughness and ductility due to the excellent ability of GRI on constraining dislocation motion and crack propagation. Despite numerous experimental and numerical studies on the mechanical behavior of GMNCs, the underlying strengthening mechanism is still not fully understood due to the absence of appropriate theoretical model. This paper proposes a continuum mechanics based theoretical model to explain the strengthening mechanism in GMNCs. In this model, the metal matrix and the GRI are simulated as homogenous elastic medium of infinite extend and inextensible thin membrane of zero thickness, respectively. Using the theoretical model, two boundary value problems namely (i) A circular prismatic dislocation loop approaching to the GRI and (ii) A mixed mode I/II penny-shaped crack near the GRI are formulated to reveal the two key strengthening mechanism: dislocation blocking and crack shielding, respectively. The two problems are solved analytically by the Generalized Kelvin's Solution (GKS) based method for 3D elasticity and Fredholm integral integration technique. Exact closed form solution for the Peach-Koehler (P-K) force on the dislocation loop is obtained. An efficient numerical scheme is developed to solve the Fredholm integral integration for the crack problem with very high accuracy. It is shown that our theoretical model can well capture and explain the strengthening mechanism observed in experiments. Moreover, the dominant role of Poisson's ratio on the strengthening efficiency is also revealed by our model. This finding implies the exciting possibility that the strength of GMNCs can be tailored by controlling the Poisson's ratio of the metal matrix. The present theoretical modeling can provide valuable insights into the mechanics-based design of GMNCs.

Interface engineering in ZnO/CdO hybrid nanocomposites to enhanced resistive switching memory for neuromorphic computing

Resistive random-access memory (RRAMs) has attracted significant interest for their potential applications in embedded storage and neuromorphic computing. Materials based on metal chalcogenides have emerged as promising candidates for the fulfilment of these requirements. Due to its ability to manipulate electronic states and control trap states through controlled compositional dynamics, metal chalcogenide RRAM has excellent non-volatile resistive memory properties. In the present we have synthesized ZnO-CdO hybrid nanocomposite by using hydrothermal method as an active layer. The Ag/C15ZO/Pt hybrid nanocomposite structure memristors showed electrical properties similar to biological synapses. The device exhibited remarkably stable resistive switching properties that have a low SET/RESET (0.41/−0.2) voltage, a high RON/OFF ratio of approximately 105, a high retention stability, excellent endurance reliability up to 104 cycles and multilevel device storage performance by controlling the compliance current. Furthermore, they exhibited an impressive performance in terms of emulating biological synaptic functions, which include long-term potentiation (LTP), long-term depression (LTD), and paired-pulse facilitation (PPF), via the continuous modulation of conductance. The hybrid nanocomposite memristors notably achieved an impressive recognition accuracy of up to 92.6 % for handwritten digit recognition under artificial neural network (ANN). This study shows that hybrid-nanocomposite memristor performance could lead to efficient future neuromorphic architectures.

A novel nickel-doped photoactive nanocomposite materials for the application of wastewater treatment

We have reported an efficient and novel nanocomposite structure of nickel (0.5 %, 1.0 %, 1.5 %, 2.0 % and 2.5 %) doped Fe3O4@rGO which is prepared by a simple chemical co-precipitation technique for degradation of methylene blue. In the current study, reduced graphene oxide (rGO) is chosen as the electron mediator for NiFe3O4/rGO nanocomposite catalyst to construct a binary photocatalytic system. The analysis of structural and optical properties supports their nano size, formation of nanocomposite material, doping of nickel ions into the characteristic inverse spinel cubic structure of Fe3O4 and the existence of synergistic effect between NiFe3O4 and rGO. Methylene blue was considered as a model dye during the investigation of the Photocatalytic activity of NiFe3O4/rGO. From the kinetic measurements, the reaction rate was predicted to play a key role in the process of degradation. This discussion also highlights the absorption peak extension towards the visible region and the energy band gap value decreases with increasing the nickel dopant concentration in novel NiFe3O4/rGO nanocomposite material. Transition metal doping significantly enhances the degradation efficiency and reduces the recombination rate of charge carriers which makes the NiFe3O4/rGO nanocomposite material a potential candidate for the degradation of methylene blue from wastewater. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe3O4 photocatalyst, and the highest photodegradation of 96.3 % MB within 30 min irradiation under visible light was shown by the 2.0 % of nickel-doped Fe3O4@rGO. In addition, the study examined the photodegradation process and photocatalytic reaction kinetics of MB.

A novel facile synthesis of metal nitride@metal oxide (BN/Gd2O3) nanocomposite and their antibacterial and anticancer activities

In this study, a novel core/shell nanocomposite structure (h-BN@Gd2O3 NCs) was created for the first time by combining hexagonal boron nitride (h-BN) with doped gadolinium oxide (Gd2O3) using different laser pulse numbers, i.e., 150, 338, and 772 pulses. We employed various analytical techniques, including mapping analysis, FE-SEM, EDS, HRTEM, SAED, XRD, zeta potential analysis, DLS, FTIR, Raman spectroscopy, and PL measurements, to characterize the synthesized h-BN, c-Gd2O3, and h-BN@Gd2O3 NCs (338 pulses). XRD results indicated hexagonal and cubic crystal structures for BN and Gd2O3, respectively, while EDS confirmed their chemical composition and elemental mapping. Chemical bonds between B–N–Gd, B–N–O, and Gd–O bands at 412, 455, 474, and 520 cm−1 were identified by FTIR analysis. The antimicrobial and anticancer activities of these NCs using agar well diffusion and MTT assays. They exhibited potent antibacterial properties against both Gram-positive and Gram-negative pathogens. Furthermore, NCs have reduced the proliferation of cancerous cells, i.e., human colon adenocarcinoma cells (HT-29) and human breast cancer cells (MCF-7), while not affecting the proliferation of the normal breast cell line (MCF-10). The anticancer efficacy of NCs was validated by the AO/EtBr assay, which confirmed apoptotic cell death. Blood compatibility on human erythrocytes was also confirmed by hemolytic and in vitro toxicity assessments. The compiled results of the study proposed these nanoparticles could be used as a promising drug delivery system and potentially in healthcare applications.

Synthesis PEO/PS/PMMA/Se as new nanocomposite with porous morphology

Novel nanocomposite structure has been made from physical mixing of polymer blend consist PMMA, PEO and PS filled with selenium nanoparticles. The nanocomposite had been deposited on glass slide by drop casting to form a thin film. This film was examined by required instrument like FESEM, XRD, EDS and UV-Vis to show the main physical properties of it. The XRD results were reflected the crystallinity nature of selenium NPs. SEM result shows the porosity nature of prepared film , where the pore size ranging from nano to micro size on all the surface of film. Also the indirect and direct bandgaps estimated and presented and equal to 3.77 and 4 eV.

Freezing of water confined between calcium-silicate-hydrate layers: a coarse-grained molecular dynamics study

Freezing of water has a direct impact on the durability of cementitious materials, which include porous binding phases, like calcium-silicate-hydrate (CSH). Molecular dynamics (MD) simulations can capture behaviors of the water freezing in the pores and may give rise to insightful observations. In this work, the monoatomic water (mW) model and all-atom CSH model are combined to study low-temperature behavior of water molecules restricted within CSH layers. The developed model features good accuracy and accelerated computational rate, and is employed to study how ultra-confined water in CSH phases (≤6 nm) freezes. The threshold width of CSH gap that allows the stable existence of ice is 1.5 ± 0.1 nm. A non-icing layer with an average thickness of ∼0.65 nm exists ambient to CSH surface. The main factor affecting the melting point of confined water is the size of the confined space rather than the water filling fraction. The Gibbs-Thomson model is utilized to describe the relationship between the melting temperature and the width of the confined CSH layers. The utilization of this modeling technique presents a novel approach to replicate the freezing process of nanostructures in cementitious composites subjected to low-temperature erosion.

Hierarchically Structured Nanocomposites via Mixed-Graft Block Copolymer Templating: Achieving Controlled Nanostructure and Functionality.

Integrating inorganic and polymerized organic functionalities to create composite materials presents an efficient strategy for the discovery and fabrication of multifunctional materials. The characteristics of these composites go beyond a simple sum of individual component properties; they are profoundly influenced by the spatial arrangement of these components and the resulting homo-/hetero-interactions. In this work, we develop a facile and highly adaptable approach for crafting nanostructured polymer-inorganic composites, leveraging hierarchically assembling mixed-graft block copolymers (mGBCPs) as templates. These mGBCPs, composed of diverse polymeric side chains that are covalently tethered with a defined sequence to a linear backbone polymer, self-assemble into ordered hierarchical structures with independently tuned nano- and mesoscale lattice features. Through the coassembly of mGBCPs with diversely sized inorganic fillers such as metal ions (ca. 0.1 nm), metal oxide clusters (0.5-2 nm), and metallic nanoparticles (>2 nm), we create three-dimensional filler arrays with controlled interfiller separation and arrangement. Multiple types of inorganic fillers are simultaneously integrated into the mGBCP matrix by introducing orthogonal interactions between distinct fillers and mGBCP side chains. This results in nanocomposites where each type of filler is selectively segregated into specific nanodomains with matrix-defined orientations. The developed coassembly strategy offers a versatile and scalable pathway for hierarchically structured nanocomposites, unlocking new possibilities for advanced materials in the fields of optoelectronics, sensing, and catalysis.