Dense Interface Research Articles

Development, characterization, and applications of multi-material stereolithography bioprinting

As a 3D bioprinting technique, hydrogel stereolithography has historically been limited in its ability to capture the spatial heterogeneity that permeates mammalian tissues and dictates structure–function relationships. This limitation stems directly from the difficulty of preventing unwanted material mixing when switching between different liquid bioinks. Accordingly, we present the development, characterization, and application of a multi-material stereolithography bioprinter that provides controlled material selection, yields precise regional feature alignment, and minimizes bioink mixing. Fluorescent tracers were first used to highlight the broad design freedoms afforded by this fabrication strategy, complemented by morphometric image analysis to validate architectural fidelity. To evaluate the bioactivity of printed gels, 344SQ lung adenocarcinoma cells were printed in a 3D core/shell architecture. These cells exhibited native phenotypic behavior as evidenced by apparent proliferation and formation of spherical multicellular aggregates. Cells were also printed as pre-formed multicellular aggregates, which appropriately developed invasive protrusions in response to hTGF-β1. Finally, we constructed a simplified model of intratumoral heterogeneity with two separate sub-populations of 344SQ cells, which together grew over 14 days to form a dense regional interface. Together, these studies highlight the potential of multi-material stereolithography to probe heterotypic interactions between distinct cell types in tissue-specific microenvironments.

Enhanced functional properties of CeO2 modified graphene/epoxy nanocomposite coating through interface engineering

This paper reports significant enhancement of corrosion resistance and electrical properties of waterborne epoxy coatings through additions of ceria modified graphene. Results showed that ceria particles were uniformly distributed and covalently bonded onto the surface of graphene. A dense interface layer was formed between the ceria modified graphene and epoxy matrix by aliphatic ether bonds. The composite coating with a modified graphene content of 0.5 wt% exhibited the best corrosion resistance with the highest impedance modulus (e.g., 103 Ω cm2 for the damaged coating) and the lowest corrosion rate (e.g., 0.002 mm/year). The excellent corrosion resistance of the composite coating is related to the barrier effect of graphene and the inhibition effect of ceria on metal corrosion. Moreover, the coating showed a low percolation threshold of 0.231 vol% and its electrical conductivity reached 10−5 S/m when the content of modified graphene was 0.5 wt%.

Phosphorus‐Containing C12H27O4P as Functional Electrolyte Additives for High‐Voltage LiNi0.5Mn1.5O4/Graphite Li‐Ion Batteries with Excellent Electrochemical Performance

AbstractAs the most promising cathode material in new energy resources, LiNi0.5Mn1.5O4 (LNMO) are widely researched due to its high platform, low cost, and environment‐friendliness, when they are assembled with graphite into battery which can lead to a faster capacity decay because of unstable solid–liquid interface. This work is devoted to stabilize electrolyte and protect interface of LNMO/graphite full battery by adding multifunctional additive, tributyl phosphate (TBP). Theory calculation which exhibits disconnection of TBP can participate in the reaction to form a uniform and dense cathode electrolyte interface film (8–10 nm) and solid electrolyte interface film around 15 nm on both electrodes, more importantly, the existence of phosphoric acid functional group can hinder the attack of hydrofluoric acid and protect electrode film. Besides, comparing with its homolog, the high‐voltage LiNi0.5Mn1.5O4/graphite battery with 1% TBP shows a preponderant discharged capacity retention of 77.8% after 150 cycles, while the blank is only 66%, this work provides a direction for electrolyte additives’ selection at high voltage and has far‐reaching significance for the application of phosphate ester materials.

Polyvinyl Alcohol/Graphene Oxide Interlayer for Enhancing Adhesive Performance of HA Coating on C/C Composites Prepared by Hydrothermal Electrodeposition/Hydrothermal Treatment.

Hydroxyapatite (HA) coatings directly deposited by hydrothermal electrochemical technology (HET) onto carbon/carbon (C/C) composites exhibited a catastrophic failure occurring at the interface of the HA and C/C. To overcome this problem, a polyvinyl alcohol (PVA)/graphene oxide (GO) interlayer (P/G interlayer) was applied on the (NH4)2S2O8-pretreated C/C substrate (named P/G-C/C) by using a dipping method. Subsequently, a calcium phosphate coating was deposited on P/G-C/C, shortened as M-P/G-C/C, by HET, and then converted into HA coating (abbreviated as HA-P/G-C/C) through posthydrothermal treatment. For comparison, HA coating was prepared onto C/C without a P/G interlayer through the same process, which was denoted as HA-C/C. The composition, microstructure, and morphology of the samples were characterized by X-ray diffractometry (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), Raman spectra, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The adhesive performance of the coatings on C/C was measured by a scratch test. Finally, an in vitro bioactivity of the coatings was evaluated in a simulated body fluid solution at 37 °C. Results showed no apparent differences in the morphology and phase of the posttreated coatings, both of which are composed of a dense structure containing needle-like HA crystals. However, the HA-P/G-C/C sample possessed a higher Ca/P ratio and denser interface, thereby exhibiting higher adhesive performance and better bioactivity. The adhesive strength of the HA-P/G coating was observed at a critical load of 41.04 N, which increased by 29.3% relative to the HA coating. Moreover, the failure site was on the HA-P/G coating rather than at the interface. The enhanced adhesive performance was ascribed to the PVA/GO-repairing pits on C/C and PVA and GO toughening effects on the HA coating. In vitro and in vivo tests revealed no statistical significance for the two HA-coated C/C samples, although the HA-P/G coating exhibited better bioactivity, inducing the growth of bonelike apatite than the HA coating.

(Invited) Wetting Mechanism of Molten Lithium on Garnet-Type Solid Electrolytes

Garnet-type solid electrolytes are one of key materials towards oxide-based all-solid-state batteries. Their superb electrochemical stability against lithium metal have driven ambition to employ lithium metal as large-capacity anode. However, poor contact between the garnet-type solid electrolytes and lithium metal causes large area specific resistance on lithium plating/stripping reaction, which is supposed to be one of reasons of lithium growth through the solid electrolytes. To achieve good contact, various processes have been proposed: polishing, vacuum deposition and/or interface layers.[1] Wetting the surface of garnet-type solid electrolytes with molten lithium is a simple but certain process to form dense interface between Li and garnet-type solid electrolyte. In this work, we report a mechanism of wetting of molten lithium on the garnet-type solid electrolytes. X-ray photoelectron spectroscopy of surface and interface of garnet-type solid electrolytes indicated a three-step wetting mechanism: (1) formation of Li2CO3 on garnet-type solid electrolytes, (2) reduction of Li2CO3 to form C by molten lithium, and (3) wetting of molten lithium on carbon formed on the solid electrolyte. Lithium ions are inserted to the carbon layer, which play a role of mixed ionic and electronic conductor. This mechanism can also explain the novel short-circuit mechanism without current.

Construction of p-n type heterojunction for effective photo-generated electron separation and visible light hydrogen evolution

With the development of research on the photocatalytic water splitting and hydrogen (H2) precipitation, cobalt ferrite and molybdate have begun to appear as catalysts for the study of photocatalytic hydrogen precipitation. In this paper, the p-n heterojunction CoFe2O4/NiMoO4 (CFO/NMO) is prepared by hydrothermal method. The constructed p-n type (type Ⅱ) heterojunction CFO/NMO has the highest hydrogen evolution (Eosin Y as a sensitizer), which is 7.39 times and 1.95 times that of elemental CFO and NMO, respectively. After the CFO and NMO form a heterojunction, a built-in electric field is formed inside to effectively separate the photogenerated carriers. At the same time, the dense interface of the heterojunction also promotes the transfer of photogenerated carriers and promotes the reduction of H+ protons on this catalyst surface. In short, this work provides more possibilities for the field of photocatalytic hydrogen evolution from molybdate and cobalt ferrite compounds.

Fiber cement boards modified with styrene-acrylic copolymer: An approach to address dimensional stability and cellulose fiber preservation

The performance of polymers such as acrylics, styrene-acrylics, styrene-butadiene, ethylene vinyl acetate, type added in cementitious composites are well reported in the literature to boost properties in the fresh mortar stage as workability, anti-bleeding, and hard stage as deformation, adhesion strength, crack bridging, cohesion, durability and reduced water uptake. Polymer treatment was performed in fiber cement boards by adding 5% w/w (dry basis) of styrene-acrylic copolymer aiming to investigate the impact on the mechanical and physical properties at initial curing period (28 days) and after the 200 soak and drying ageing cycles. Dimensional stability at 28 days and the cellulose fiber/cement interface transition zone were assessed by scanning electron microscopy combined with dispersive energy X-ray spectroscopy (EDS). These experiments confirmed that the water absorption value in polymer modified cement boards was reduced by 50% after the ageing cycles when compared to the unmodified boards. Additionally, improvements on board’s rigidity with reduction of modulus of elasticity (MOE) values up to 40% and 15% reduction of board shrinkage was noticed, enhancing boards dimensional stability and preventing fibers from the mineralization process by keeping the cellulose fiber adhered on the cementitious matrix, providing a dense and cohesive fiber-cement interface transition zone after the ageing cycles. This achievement can open important fields of application for the reinforcement of flat panels.

Integration of Ultrananocrystalline Diamond (UNCD)-Coatings on Chemical-Mechanical Surface Nano-structured (CMNS) Titanium-Based Dental Implants

This paper focuses on describing the integration of ultrananocrystalline diamond (UNCD) coating on pure titanium-based dental implants (DIs) integrated with the surface pre-treatment by chemical-mechanical nano-structuring (CMNS) process. The combination of the UNCD coating with the CMNS metal surface treatment provides a transformational process to produce a new generation of metallic implants. CMNS promotes a uniform and dense titanium oxide interface and UNCD enables higher resistance to chemical-induced corrosion by oral fluids and enhanced bone attachment due to superior bone cell growth on C atoms (element of life in human DNA and cell). The main focus of the presented research is to establish the preliminary studies on the integration of the UNCD coating process on CMNS treated dental implants to promote corrosion resistance and biocompatibility. It is demonstrated that the CMNS process in the presence of an oxidizer (1M to be optimal) induces a tailored interface to promote UNCD coating capability through effective interface passivation leading to uniform surface coverage. The final implant product is observed to have improved corrosion potential and enhanced hydrophobicity indicating better biocompatibility providing the basis for a new generation of superior DIs. The findings can further be extended to the hip, knee, and other orthopedic metallic implants, which require major performance improvements, particularly in reducing or eliminating in-vivo body fluid-induced chemical corrosion.

A dynamic view of DNA structure within the nucleosome: Biological implications

Most of eukaryotic cellular DNA is packed in nucleosome core particles (NCPs), in which the DNA (DNANCP) is wrapped around histones. The influence of this organization on the intrinsic local dynamics of DNA is largely unknown, in particular because capturing such information from experiments remains notoriously challenging. Given the importance of dynamical properties in DNA functions, we addressed this issue using CHARMM36 MD simulations of a nucleosome containing the NCP positioning 601 sequence and four related free dodecamers. Comparison between DNANCP and free DNA reveals a limited impact of the dense DNA-histone interface on correlated motions of dinucleotide constituents and on fluctuations of inter base pair parameters. A characteristic feature intimately associated with the DNANCP super-helical path is a set of structural periodicities that includes a marked alternation of regions enriched in backbone BI and BII conformers. This observation led to uncover a convincing correspondence between the sequence effect on BI/BII propensities in both DNANCP and free DNA, strengthening the idea that the histone preference for particular DNA sequences relies on those intrinsic structural properties.These results offer for the first time a detailed view of the DNA dynamical behavior within NCP. They show in particular that the DNANCP dynamics is substantial enough to preserve the ability to structurally adjust to external proteins, for instance remodelers. Also, fresh structural arguments highlight the relevance of relationships between DNA sequence and structural properties for NCP formation. Overall, our work offers a more rational framework to approach the functional, biological roles of NCP.

Imidazolium-based ionic liquids as electrolyte additives for high-voltage Li-ion batteries

Functionalized ionic liquid 1-cyanopropy-1-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide (CPMIMTFSI) was synthesized as an electrolyte additive for high-voltage Li-ion batteries to improve the voltage resistance of carbonate-based electrolytes. The electrochemical behavior of LiNi0.5Mn1.5O4/Li cells was studied by charge–discharge testing, electrochemical impedance spectroscopy, and cyclic voltammetry. The surface morphology of LiNi0.5Mn1.5O4 cathodes was studied by scanning electron microscopy (SEM), and the results showed that when 15 vol% CPMIMTFSI was added to the ethylene carbonate (EC)/dimethyl carbonate (DMC) electrolyte, the highest discharge capacity of LiNi0.5Mn1.5O4/Li cells was 133.09 mAh g−1 at 0.2 C, which changed to 109.91 mAh g−1 at a high rate of 5 C. This value was 92.6% higher than that in EC/DMC electrolyte at 5 C. In addition, the discharge capacity retention rate of LiNi0.5Mn1.5O4/Li cell with 15 vol% CPMIMTFSI reached 95% after 50 cycles at 0.2 C, which was nearly 10% higher than that with EC/DMC electrolyte. The results of SEM and X-ray photoelectron spectroscopy showed that a uniform and dense electrolyte interface film was attached to the surface of LiNi0.5Mn1.5O4 cathode after adding CPMIMTFSI to the carbonate-based electrolyte.

Comparison of different turbulence models in predicting cohesive fluid mud gravity current propagation

A numerical study of propagation of cohesive fluid mud gravity currents in the form of lock-exchange was done using the OpenFOAM open source toolbox. An Eulerian approach solution for three separate phases was developed by incorporating a rheological model to predict the front position of cohesive fluid mud gravity currents. The model also simulates features in the complete movement phases including slumping, self-similar, and viscous in which the dynamics of propagation are affected by the balance of viscous and buoyancy forces, and the inertia force is negligible. The influence of using different turbulence models containing sub-grid scale (SGS), modified SGS, detached eddy simulation (DES), delayed-detached eddy simulation (DDES), Launder-R eece-Rodi (LRR), and k-ɛ models on the accuracy of simulation results was evaluated by comparing with available experimental data. The results show that the selection of the proper turbulence model is one of the most important issues for this type of the numerical modeling. The more efficient turbulence model was suggested and tabulated for each stage of propagation and different selected concentrations of 1,045, 1,140, and 1,214 g/L. Although different turbulence models (except k-ɛ) lead to front propagation dynamic simulation results that are in good agreement with the experimental measurements in the early stage of propagation for low concentrations, only DES, SGS, and modified SGS are able to capture the Kelvin-Helmholtz instability vortex shapes at the dense fluid interface, which is the main characteristic of the gravity current through the slumping phase. The calculated accuracies of SGS and modified SGS in predicting gravity current propagation for the both self-similar and viscous phases also are slightly better than DES, DDES, and LRR model results. The results of this study confirmed the performance and efficiency of the modified SGS model in which the interaction coefficients between phases are calibrated for the numerical modeling of fluid mud gravity current propagation.

High-performance Cr2AlC MAX phase coatings: Oxidation mechanisms in the 900–1100°C temperature range

Dense and predominantly single-phase Cr2AlC MAX phase coatings without columnar structure were fabricated using an easy combined arc/sputtering deposition method followed by annealing. Isothermal oxidation of coatings was conducted under flowing air for 40 h at 900−1100 °C. Although the results revealed that the oxide scale showed strong dependence upon oxidation temperature, the coated samples remained intact even after oxidation at 1100 °C. Such excellent resistance to oxidation resulted in the parabolic kinetics exhibiting two stages. This was attributed to the formation of a dense and continuous Al2O3 interface layer and a (Cr, Al)2O3 outermost layer.

High signal-to-noise ratio for high-impedance-loaded nano-photodetector toward attojoule optical reception

We demonstrate a high signal-to-noise ratio (SNR) for a photonic-crystal nanophotodetector (PD). The ultralow-capacitance nano-PD can be terminated with a load resistor with a resistance as high as 59 kΩ for efficient light-to-voltage conversion, and its strong thermal-noise suppression leads to an SNR that is 30 dB higher than that of the conventional p-i-n PD terminated with a 50-Ω load. The noise equivalent power is only 500 fW/√Hz, while a gigahertz-level bandwidth can be maintained when considering that the PD capacitance is only 1 fF. Theoretically, this allows optical reception at less than 100 aJ to obtain a bit error rate of 10–9. The resistor-loaded nano-PD requires a small electrical biasing energy comparable to the optical energy, which is remarkably energy saving compared with avalanche PDs or other PDs integrated with amplifiers. Such a receiver promises a dense optical interface with CMOS electronics in photonic networking and processing chips.

Theoretical considerations on cavity diameters and penetration depths of concrete materials generated by shaped charge jets using the targets response modes described by a modified HJC model

The traditional dynamic cavity expansion theory generally deals with the problem of penetrator penetration into targets at lower velocity, which is considered that the materials near the penetrator/target interface are in the plastic state. For shaped charge jets penetration, the concrete materials in a certain distance away from the jet/target interface are in the fluid state. Thus, the radial stress at the cavity surface derived from the dynamic cavity expansion theory cannot be directly applied as the target resistance. The current paper aims to establish a theoretical model for shaped charge jets penetration into concrete targets based on the cavity expansion idea, assuming that the cavity expansion stress is the stress at the flow/fully dense interface. Firstly, the hydrostatic pressure-volume strain relationship described by the HJC concrete constitutive model was analyzed; result indicated that four response regions were produced when concrete subjected to load: the elastic region, the cracked region, the plastic-like (the “plastic” behavior of concrete is named as “plastic-like” since the behavior has nothing to do with the dislocation movement of metals that reflects the plastic behavior) transitional region and the fully dense region. The HJC yield surface equation was then modified by discussing the elastic-cracked-transitional-fully dense response in front of the flow/fully dense interface. With the changing particle velocity at the flow/fully dense interface, it showed that another three response modes were produced in front of the flow/fully dense interface, i.e., the elastic-transitional-fully dense response, the elastic-fully dense response, and the fully dense response. The applications of the equations of state in different response modes were analyzed. Secondly, the calculation model of the radial stress at the flow/fully dense interface was proposed based on the modified HJC model. Thirdly, the shaped charge jets penetration theories were analyzed. In the end, the depth of penetration (DOP) experiments for three different shaped charges into C200 reactive powder concrete (RPC) targets were carried out to verify the theoretical model. Results showed that the cavity diameters and penetration depths predicted by the elastic-cracked-transitional-fully dense response, the elastic-transitional-fully dense response and the elastic-fully dense response exhibited good agreement with the experimental data, whereas that by the fully dense response existed relatively large errors comparing with the other three response modes.

W/TaC/SiC sandwich stack for high temperature applications

High-temperature stability of the tungsten/tantalum carbide/silicon carbide (W/TaC/SiC) system was examined and compared to the tungsten/silicon carbide (W/SiC) system. Interfacial reactions, surface morphology, and roughness evolutions on thermal annealing at 1000 °C were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). For the W/SiC system, WC, W2C and W5Si3 phases were observed due to severe chemical reaction after 24 h annealing, which led to an inhomogeneous surface structure with several large craters and small pores, thereby increasing surface roughness greatly. On the other hand, there was no tungsten silicide and/or carbide formation upon annealing with a TaC diffusion barrier. The surface structure remained nearly unchanged, and small changes in surface roughness with annealing time, which could be due to the growth of W grains, were noted. Furthermore, both the as-deposited and the 24 h annealed W/TaC/SiC samples presented an excellent interfacial bonding with a dense uniform interface. The results indicate that TaC is a promising diffusion barrier in the W/SiC system for high temperature applications.

Tendon-to-Bone Healing in a Rat Extra-articular Bone Tunnel Model: A Comparison of Fresh Autologous Bone Marrow and Bone Marrow–Derived Mesenchymal Stem Cells

Background: Despite widespread acceptance of fresh autologous bone marrow (BM) for use in clinical practice, limited information exists to analyze if tendon-to-bone healing could be accelerated with local use of fresh autologous BM. Purpose: To investigate the effect of fresh autologous BM on tendon-to-bone healing with a novel rat model. Study Design: Controlled laboratory study. Methods: An extra-articular bone tunnel was created and filled with an autologous tendon graft in skeletally mature Sprague-Dawley rats (N = 60). They were then randomly divided into 3 groups: BM group (injection of fresh autologous BM into the tendon-bone interface, n = 20), BM-derived mesenchymal stem cell (BMSC) group (injection of allogenic cultured BMSCs, n = 20), and the control group (tendon-bone interface without injection of BM or BMSCs, n = 20). Biomechanical, histological, and immunohistochemical analyses were performed at 2 and 6 weeks after surgery. Results: The BM group showed a relatively well-organized and dense connective tissue interface with better orientation of collagen fibers as compared with the BMSC group. At 2 weeks, the tendon-bone interface tissue thickness of the BMSC group was 140 ± 25 μm (mean ± SEM), which was significantly greater than the BM group (58 ± 15 μm). The BM group showed fewer M1 macrophages at the tendon-bone interface at 2 and 6 weeks (P < .001). In contrast, there were more M2 macrophages at the interface in the BM group 2 and 6 weeks postoperatively when compared with controls and the BMSC group (P < .001). Biomechanical tests revealed significantly higher stiffness in the BM group versus the control and BMSC groups at 2 and 6 weeks after surgery (P < .05). Load to failure showed similar trends to stiffness. Conclusion: These findings indicate that local delivery of fresh autologous BM enhances tendon-to-bone healing better than the alternative treatments in this study. This effect may be partially due to the observed modulation of inflammatory processes, especially in M2 macrophage polarization. Clinical Relevance: Fresh autologous BM could be a treatment option for this disorder.

Preparation and Ablation Performance of BN Fiber Fabrics Reinforced Nitrides Composites

High-performance three-dimensional boron nitride fiber reinforced silicon nitride (BNf/Si3N4) composites were prepared by the infiltration and pyrolysis (PIP) process using BN fiber fabrics as the reinforcing body and excellent nitride organic precursor (Perhydropolysilazane, PHPS) as the Impregnated liquid. The ablation resistance of the composite was evaluated by plasma jet ablation test in air. The results show that a uniform and dense interface layer is formed on the fiber surface, with thickness is about 100 nm, and the XRD test shows that it is hexagonal BN (h-BN). The density of the composite reaches more than 1.72 g·cm-3 and the bending strength is more than 80 MPa. Under the condition of plasma jet ablation test at 2000 °C / 200 s, the mass ablation rate is 3.32 × 10-4 g/s, the linear ablation rate is 4.78 × 10-3 mm/s. The prepared materials have excellent resistance to high temperature ablation, and are expected to be used in the field of high temperature microwave transparent such as high mach missile radome, antenna window and so on.

Fabrication and Thermoelectric Properties of n-Type CoSb2.85Te0.15 Using Selective Laser Melting.

We report a nonequilibrium fabrication method of n-type CoSb2.85Te0.15 skutterudites using selective laser melting (SLM) technology. A powder of CoSb2.85Te0.15 was prepared by self-propagating high-temperature synthesis (SHS) and served as the raw material for the SLM process. The effect of SLM processing parameters such as the laser power and scanning speed on the quality of the forming CoSb2.85Te0.15 thin layers was systematically analyzed, and the optimal processing window for SLM was determined. A brief postannealing at 450 °C for 4 h, following the SLM process, has resulted in a phase-pure CoSb2.85Te0.15 bulk material deposited on a Ti substrate. The Seebeck coefficient of the annealed SLM prepared bulk material is close to that of the sample prepared by the traditional sintering method, and its maximum ZT value reached 0.56 at 823 K. Moreover, a Ti-Co-Sb ternary compound transition layer of about 70 μm in thickness was found at a dense interface between CoSb2.85Te0.15 and the Ti substrate. The contact resistivity was measured as 37.1 μΩcm2. The results demonstrate that SLM, coupled with postannealing, can be used for fabrication of incongruently melting skutterudite compounds on heterogeneous substrates. This lays an important foundation for the follow-up research utilizing energy efficient SHS and SLM processes in rapid printing of thermoelectric modules.

The investigation on the mechanism of the increased decay time in red SrS:Eu2+,Dy3+ phosphor

In this manuscript, a stick-like SrS:0.03Eu3+,0.03Dy3+ microstructure with about 20–30 μm in width and several hundred μm in length was fabricated utilizing a post-annealing hydrothermal method, in which the size of the structure is modulated by the surfactants used while formation of the precursor. The stick like microstructure shows very long decay time compare to that obtained by the traditional high temperature method at the same condition for about 6 times. A “bridge-transmission” mechanism to explain the long phosphorescence phenomenon, including two factors mainly the homogenously incorporation of Eu and Dy elements into the crystal lattice by hydrothermal co-deposition method, and the dense interface among crystalline grains due to the shrinkage of the structure while annealing.

Nano-Silica Sol-Gel and Carbon Nanotube Coupling Effect on the Performance of Cement-Based Materials.

Carbon nanotubes (CNTs) have shown promise for improving the mechanical performance of cement composites through crack-bridging and frictional pull-out. The interactive behaviors between CNTs and cement matrix act are crucial in optimizing the reinforcement of CNTs in cement composites. This study investigates the effects of nano-silica (NS) sol-gel on the interactive behaviors of CNTs and the cement matrix through a series of experiments and analyses. UV-visible spectrometer results show that CNTs are well-dispersed in suspension and the addition of NS has a negligible effect on the stability of CNT dispersion. Calorimetry tests and dynamic mechanical analysis demonstrate the nucleation and frictional performance of CNTs in cement matrix, respectively. The paper shows that the physical adsorption of NS on the CNT surface could result in the acceleration of cement hydration. Morphology observation confirms that a denser interface between CNTs and cement hydrates is formed. Finally, the improved interaction between CNTs and cement hydrates leads to a substantial increase in friction between CNTs and the cement matrix under periodic loading. NS may act as an ideal admixture for improving both the interactive behaviors between CNTs and cement matrix and the damping properties of cement composite.