Micro-nano Hybrid Research Articles

Synergistic enhancement of modulus and ductility in Mg matrix composites: A new strategy for GNPs&MgOnp and SiCp hybrid reinforcement

SiC particles (SiCp) reinforced magnesium matrix composites (MMCs) exhibit elevated specific stiffness. However, the non-uniform distribution of SiCp and the interfacial cracking between the SiCp and Mg matrix compromise the ductility. This paper presents a novel approach to enhance the modulus and ductility of the MMCs by utilizing in-situ synthesized graphene nanoplatelets (GNPs) and MgO nanoparticles (MgOnp). The in-situ reaction of GNPs and MgOnp (GNPs&MgOnp) conducted at a high temperature (720 °C) demonstrates an improvement in the local agglomeration of SiCp compared to the conventional semi-solid temperature (590 °C). Moreover, the GNPs&MgOnp optimized interfacial structure and transferred the load during plastic deformation, inhibiting stress concentration and crack propagation at the interface of SiCp. The ductility and modulus are enhanced by approximately 70 % and 10 % compared to SiCp/Mg-6Zn composites, demonstrating the effectiveness of the strategy employing micro-nano hybrid reinforcement and synergistic enhancement of ductility and modulus.

Effect of micro-nano hybrid SiCp on microstructure and mechanical properties of 7075Al alloy

In this study, micro-nano hybrid SiCp/7075Al composites were successfully prepared for the first time by ultrasonic-assisted semi-solid stirring casting method. The effects of micro-nano hybrid SiCp on the microstructure and mechanical properties of 7075 Al were studied. The results show that the distribution of SiCnp and micron SiCp in the microstructure was uniform. During the extrusion process, most of the micron SiCp were subjected to significant load and broken, which increased the contact area with the matrix and promoted the interface bonding. In addition, the enhanced interfacial interaction promoted the formation of MgAl2O4 phase, which significantly improved the mechanical properties. SiCnp not only had a significant effect on grain refinement, but also promoted the enrichment of Cu, accelerated the formation of GP zone, and promoted the formation of more nano-MgZn2 precipitates. The yield strength and the elastic modulus of micro-nano hybrid SiCp/7075 Al composites reached 450 MPa and 94 GPa, respectively. The synergistic effect of SiCnp and micron SiCp could produce composite strengthening effects such as load transfer strengthening, thermal mismatch strengthening and Orowan strengthening. Moreover, a large number of dislocation pile-ups were observed near the interface between micron and nano SiCp and Al matrix. This leaded to a higher work hardening rate of the composites as the particle content increases. The higher work hardening rate enhanced the strain hardening ability of the material during plastic deformation, thereby significantly improving the tensile strength and elongation of the material.

One-step hybridization of silane hydrolysis and silica mineralization for enhanced superhydrophobic coating on cement-based materials

The complex and demanding marine environment poses significant challenges for concrete coatings. Despite the exceptional properties, superhydrophobic coatings have encountered limitations such as complex preparation processes and limited structural stability, thus impeding their widespread application. In this study, we employed molecular monomers to simultaneously conduct in-situ silica mineralization and silane hydrolysis reactions on mortar substrate. The mineralized product, nano-silica, effectively fills microcracks and pores, serving as an internal reinforcing agent. Simultaneously, the silica is utilized to construct a robust and dense micro-nano hybrid structure. The results in the preparation of a silica mineralized layer with exceptional mechanical strength on the surface. The in-situ hydrolysis of silane introduces a low surface energy for hydrophobic modification, leading to the formation of a stable superhydrophobic coating with a contact angle of 157°. Mineralized structure and hydrophobic surface offer both internal and external protective effects. This one-step approach promotes the complete hybridization of hydrophobic silane groups with the three-dimensional silica matrix. During the in-situ reaction process, the hydrolyzed silane molecules bond with the surface of silica microspheres, significantly enhancing the integrity and stability of the coating structure. Notably, even after multiple cycles of peeling and abrasion, the coating surface maintains its hydrophobic properties, further emphasizing its durability. The results demonstrate that this coating enhances both the structural and chemical performance of cement-based materials, paving the way for the expanded application and development of superhydrophobic coatings in the marine concrete industry.

Fabrication and characterization of graphene oxide (GO)-modified micro-nano composite magnetic microspheres

Addressing the contradiction between the magneto-rheological properties and dispersion stability of MRFs poses a significant challenge in the preparation process. This paper proposes a micro-nano composite material design scheme using graphene oxide as a grafting agent to encapsulate nanoscale magnetite (Fe3O4) particles onto the surface of carbonyl iron powders. The prepared micro-nano composite magnetic microspheres achieve a reduction in density for enhanced stability while ensuring no compromise in magnetic performance. The effectiveness of the preparation process is ensured through the analysis of the microscopic morphology, crystal structure, and elemental characteristics of all process products using Field Emission Scanning Electron Microscopy (FE-SEM), powder X-ray diffraction (XRD), Raman Spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR). To obtain MRFs more suitable for magneto-rheological damper applications, this study synthesized micro-nano composite MRFs with different base liquids and varying volume fractions. The stability and magneto-rheological properties of each sample were analyzed through visual techniques and rheological testing platforms. The results indicated that micro-nano composite MRFs based on 40% to 50% silicone oil exhibit superior stability in various aspects, including sedimentation stability, redispersion stability, and temperature stability. Additionally, the micro-nano composite MRFs demonstrated significantly enhanced magnetic performance compared to pure micrometer-sized, pure nanometer-sized, and micro-nano hybrid MRFs.

Fabrication of Al/Au hybrid SERS substrate using laser engraving for rapid detection of melamine and its analogues by hand-held Raman spectrometer

Surface-enhanced Raman spectroscopy (SERS), combined with a handheld Raman spectrometer, was utilized for the rapid and highly sensitive detection of melamine and its analogues. The investigation focused on the hybrid micro-nano structures of SERS-active substrates, fabricated by laser engraving aluminum (Al) sheets and depositing gold (Au) nanoparticles using magnetron sputtering. The laser engraving frequency was varied to get optimum SERS substrate. The fabricated SERS substrates were tested with rhodamine 6G (R6G) to optimize the Raman signal and subsequently detect melamine and its analogues viz., cyanuric acid, ammeline, ammelide in milk samples. The results demonstrated that a laser frequency of 20 kHz was the optimal condition for fabricating a micro-nano Al template with a depth of 61.21 μm, providing the highest Raman signal for R6G. The limit of detection (LOD) for melamine in mild acid solution and milk samples were determined to be 1x10-5 M and 1x10-4 M, respectively. The laser-engraved Al sheet technique offers a cost-effective approach for SERS substrate fabrication. The integration of the Al/Au hybrid SERS substrate with a hand-held Raman spectrometer demonstrates significant potential for detecting melamine and its analogues in realistic environments.

Robust micro-nano hybrid aerogel derived from waste resources for thermal management and high-efficiency adsorption

Ultra-low density nanoaerogels as the lightest solid material have aroused extensive attention. However, lacking crack extension resistance limited their further development and application. Here, aramid and cellulose wastes were recycled to prepare high value-added nanofibers, which were further self-assembled to construct multilfunctional hybrid aerogels. In-situ growth of zeolitic imidazolate frameworks-8 (ZIF-8) on the cellulose nanofiber (CNF) created a robust skeleton. Flexible aramid nanofibers (ANF), as burgeoning building blocks were employed to inlay into the microscopic skeleton structure for establishing micro-nano double networks. Benefiting from the existence of multiscale networks, the maximum value in the compressive stress of S0, S1, S2 and S3 increased from 2.74 to 4.63, 5.19 and 6.61 MPa, respectively.Meanwhile, ANF-ZIF-8-CNF hybrid aerogels exhibited low thermal conductivity of 3.58–3.97 × 10-2 W/(m⋅K). The significant increase in the specific surface area (481.46 m2/g) endowed hybrid aerogels with high adsorption abilities for nitrogen (280.83 cm3/g), prussian blue (34.12 mg⋅g−1), rhodamine B (37.30 mg⋅g−1), DMF (25.13 g⋅g−1) and DMSO (15.48 g⋅g−1), respectively. This multiscale structural engineering strategy opens an avenue toward to upcycle waste resources into the next-generation high-performance nanoaerogels, showing huge application potential in thermal management, air purification and sewage treatment.

Bi-path color tunable plasmonic micro-nano hybrid structures for encrypted printing.

Colored information is crucial for humans to perceive the world. Plasmonic spectra modulation can serve as an effective means to create different colors. Although several solutions for plasmonic color-printing have been proposed, further information encryption has not received any attention. Herein, we exhibit a fine color modulation strategy to construct noble-metal-based micro-nano hybrid structures in the bi-path of photo-thermal deformation and liquid-phase-chemical reaction. Ag/Ta2O5 bi-layer films are ablated at the center of the machined lines of nanosecond pulsed laser, while silver nanoparticles are formed in other regions by thermal radiation of the infrared laser, which can be further dissolved and shape-modulated in KCl solution under different periods. The variation of size and spacing of nano-Ag particles results in a precise shift of plasmonic spectra in visible region. Colored information can be hidden by adjusting the scan number and the energy density during laser processing, and will emerge after the subsequent chemical dissolution reactions. The bi-path color adjustment strategy is easy to operate and can play a role in key information protection and color image switching.

Construction of micro-nano hybrid structure based on carbon nanotube whisker and alumina for thermally conductive yet electrically insulating silicone rubber composites

High-performance electronics urgently need more effective thermally conductive rubber composites to solve interfacial heat transfer problems in the thermal management systems. Tiny amounts nanocarbon materials (NCM) can significantly improve the thermal conductivity of conventional ceramic-filled rubber composites, but the volume exclusion effect of micrometer ceramic fillers makes NCM highly susceptible to the formation of the conductive pathways, which inevitably leads to the substantial decrease in the volume resistivity of the materials, posing a safety hazard, such as short circuits, to electronic devices. Here, we report an electrostatic self-assembly method to prepare CNW@n-Al2O3 hybrids by loading nano-alumina (n-Al2O3) onto carbon nanotube whiskers (CNW) and co-filling them with micrometer alumina (m-Al2O3) to silicone rubber, constructing a micro-nano-multi-level hybrid network structure, which can fully utilize the high thermal conductivity while shielding the electrical conductivity of CNW. The resulting composite filled with 2 phr of CNW@n-Al2O3 exhibits a significantly enhanced thermal conductivity of 1.137 W/(m·K) and a high volume resistance of 1.323 × 109 Ω cm, and is proved to be used as an excellent thermal interface material to assist the heat dissipation of the microelectronic chip. This study provides a facile and effective strategy for the design of thermally conductive yet electrically insulating rubber composites filled with CNW, which shows a bright application prospect in the thermal management of high-performance electronic devices.

PH-controlled construction of 2D and 3D micro-nano hybrid carbon architectures with fluorescence/phosphorescence dual-mode emission for white-emitting diodes

Developing nanocarbon-based white-emitting diodes (WLEDs) with high energy conversion efficiency is still extremely challenging due to the issue of Kasha's rule and serious self-aggregation caused luminescent quenching of nanocarbon in a solid-state. Herein, the synergistic strategy of framework and intercalator between nanosheets and carbon dots (CDs) was adopted. Three novel 2D nanosheets, 3D nanoflowers and 3D parasa consocia-like micro-nano carbon architectures decorated with dispersive CDs were successfully fabricated through one-step hydrothermal reaction at different pH medium. The pH-regulated mechanisms of morphology and structure, via degree modulation of condensation and carbonization, were further proposed. All samples exhibited bright white emission, derived from fluorescence/phosphorescence dual-mode emission. The hybrid emission made sufficient utilization of single and triplet excitons with the quantum yield of 16%–30%. The superior white light with CIE coordinates of (0.331,0.334) was recorded for neutral sample (p-CNDs-N), ascribed to the multiple energy level transitions from polydisperse luminescence centers. The luminous efficiency was remarkably improved in HCl (p-CNDs-H) and NaOH treated samples (p-CNDs-OH), resulting from inner carbonization, external cross-linked network and the passivation of surface defect sites. This is the first example for pH-controlled fabrication of multi-dimension hybrid nanocarbon structures and pH-controlled fluorescence/phosphorescence dual-mode emission for highly efficient carbon-based WLEDs.

Synergistic effect of drug/antibiotic-impregnated micro/nanohybrid mesoporous bioactive glass/calcium phosphate composite bone cement on antibacterial and osteoconductive activities

Calcium phosphate bone cements (CPC) can be used in minimally invasive surgery because of their injectability, and they can also be used to repair small and irregular bone defects. This study aimed to release the antibiotic gentamicin sulfate (Genta) to reduce tissue inflammation and prevent infection in the early stages of bone recovery. Subsequently, the sustained release of the bone-promoting drug ferulic acid (FA) mimicked the response of osteoprogenitor D1 cells interaction, thereby accelerating the healing process of the overall bone repair. Accordingly, the different particle properties of micro-nano hybrid mesoporous bioactive glass (MBG), namely, micro-sized MBG (mMBG) and nano-sized MBG (nMBG), were explored separately to generate different dose releases in MBG/CPC composite bone cement. Results show that nMBG had better sustained-release ability than mMBG when impregnated with the same dose. When 10 wt% of mMBG hybrid nMBG and composite CPC were used, the amount of MBG slightly shortened the working/setting time and lowered the strength but did not hinder the biocompatibility, injectability, anti-disintegration, and phase transformation of the composite bone cement. Furthermore, compared with 2.5wt%Genta@mMBG/7.5 wt% FA@nMBG/CPC, 5wt.%Genta@mMBG/5wt.%FA@nMBG/CPC exhibited better antibacterial activity, better compressive strength, stronger mineralization of osteoprogenitor cell, and similar 14-day slow-release trend of FA. The MBG/CPC composite bone cement developed can be used in clinical surgery to achieve the synergistic sustained release of antibacterial and osteoconductive activities.

Biologically enhanced 3D printed micro-nano hybrid scaffolds doped with abalone shell for bone regeneration

Biologically enhanced 3D printed micro-nano hybrid scaffolds doped with abalone shell for bone regeneration

Comparative study of pool boiling heat transfer on different subtractive surfaces

• The subtractive micro-nano structured surfaces based on sandblasting were prepared. • The structured surface facilitates heat transfer depends on synergistic benefit of the influencing factors. • The characteristic parameters of the micro-nano surface have been quantitatively analyzed. • The visualization study has been carried out on the micro-nano structured surface. The preparation of stable surfaces to improve the heat transfer performance can make the equipment operate safely and bring significant economic benefits. Using sandblasting and ultrasonic wet etching techniques, copper surfaces were subtracted to prepare the microscale structures (MS) and nanoscale structures (NS) in this study. Then, these two special subtractive structures were composited together to form a hybrid micro-nano structured (HMS) surface. Nucleate pool boiling experiments were carried out on the prepared surfaces with different structures at atmospheric pressure. The effect of surface modification on key parameters such as critical heat flux (CHF) and heat transfer coefficient (HTC) were investigated. Through the quantitative analysis of roughness, surface area ratio and apparent contact angle, potential mechanisms affecting nucleate boiling were explored. Meanwhile, the surfaces were visualized and their enhancement mechanisms were analyzed from the perspective of bubble dynamics. The results show that compared with the smooth plain (SP) surface, the CHFs on NS surface, MS surface and HMS surface are improved by 22.8%, 48.2% and 33.8%, respectively. The maximum HTCs are improved by 42.9%, 83.7% and 77.6%, respectively. However, the boiling heat transfer performance of HMS surface is not improved compared with MS surface. According to the characterization results, this is the result of the combined effect of roughness, surface area ratio and wettability.

Experimental research on static and dynamic magnetic powder sealing used by micro-nano composite magnetic particles

The focus of the paper is the experimental study of static and dynamic magnetic powder sealing by preparing micro-nano hybrid magnetic powders with different proportions. The magnetization curves of the magnetic powders are measured, and the formula for calculating saturation magnetization of mixed magnetic particles is fitted. In the static seal test, the maximum pressure resistances of magnetic powders are studied. It can be concluded that the nanoparticles can achieve a stable pressure resistance under low pressure and the micron particles have higher pressure resistance, but there is a small amount of leakage due to the microcavities between particles. The nanoparticles are introduced into the micron particles’ microcavities to form a hybrid magnetic powder, which significantly improves the pressure resistance. The microstructure models of magnetic powders in the sealing gap are proposed based on the static pressure curves. However, in the dynamic magnetic powder seal test, its pressure characteristic curve is different from that of the magnetic fluid seal. The relationship between the pressure resistance and the rotational speed of the shaft is studied. It is concluded that different microstructures’ fracture and recombination abilities under shear stress and external magnetic field in seal clearance are different. The thermal effect caused by the friction between the shaft and magnetic powder makes the magnetism of magnetic powder decrease and reduces the sealing ability. Experimental studies prove the application potential of magnetic powder seal.

Precisely controlled and deeply penetrated micro-nano hybrid multifunctional motors with enhanced antibacterial activity against refractory biofilm infections

The biofilm resistance of microorganisms has severe economic and environmental implications, especially the contamination of facilities associated with human life, including medical implants, air-conditioning systems, water supply systems, and food-processing equipment, resulting in the prevalence of infectious diseases. Once bacteria form biofilms, their antibiotic resistance can increase by 10–1,000-fold, posing a great challenge to the treatment of related diseases. In order to overcome the contamination of bacterial biofilm, destroying the biofilm’s matrix so as to solve the penetration depth dilemma of antibacterial agents is the most effective way. Here, a magnetically controlled multifunctional micromotor was developed by using H2O2 as the fuel and MnO2 as the catalyst to treat bacterial biofilm infection. In the presence of H2O2, the as-prepared motors could be self-propelled by the generated oxygen microbubbles. Thereby, the remotely controlled motors could drill into the EPS of biofilm and disrupt them completely with the help of bubbles. Finally, the generated highly toxic •OH could efficiently kill the unprotected bacteria. This strategy combined the mechanical damage, highly toxic •OH, and precise magnetic guidance in one system, which could effectively eliminate biologically infectious fouling in microchannels within 10 min, possessing a wide range of practical application prospects especially in large scale and complex infection sites.

Enhanced Light Extraction from Organic Light-Emitting Diodes with Micro-Nano Hybrid Structure.

In this study, an external light extraction layer with a micro-nano hybrid structure was applied to improve the external light extraction efficiency of organic light-emitting diodes (OLEDs). A reactive ion-etching (RIE) process, using O2 and CHF3 plasma, was performed on the surface of the micro-scale pattern to form micro-nano hybrid structures. According to the results of this study, the nanostructures formed by the treatment of O2 and CHF3 were different, and the efficiency according to the structures was analyzed experimentally and theoretically. As a result, the OLED, to which the micro-nano hybrid structure, manufactured through a simple process, is applied, improved the external light extraction efficiency by up to 38%, and an extended viewing angle profile was obtained. Additionally, an effective method for enhancing the out-coupling efficiency of OLEDs was presented by optimizing the micro-nano hybrid structure according to process conditions.

Space-Charge Characteristics in Epoxy Composites Under Square Pulse Wave of Different Polarities With Various Frequencies at Various Temperatures

Space-charge characteristics of the pure epoxy resin (EP) and epoxy-based hybrid composites under square pulse waves of different polarities and frequencies at different temperatures are investigated. A specially built high-speed pulsed electro-acoustic (PEA) equipment for high-temperature testing is used. The square pulse of 40 kV/mm with different polarities and frequencies at 25 °C, 50 °C, and 80 °C, respectively, are adopted. The findings reveal that a negative electric field with a greater frequency and a positive electric field with a lower frequency can increase the space-charge accumulation. At low temperatures, there is no noticeable difference between the pure epoxy and micro-nano hybrid (MN) samples. The MN sample has fewer accumulated charges than the pure epoxy sample under the same electric field of different frequencies at different temperatures. At different temperatures, the electric field inside the pure epoxy sample distorts more severely than the MN sample, and such distortion increases with the temperature. On the other side, the electric field in the MN sample remains steady even at high temperatures. Negative electric fields have a more significant impact on average charge amounts than positive electric fields, especially at higher frequencies. A relevant mechanism is proposed to explain the results.

Precisely Controlled and Deeply Penetrated Micro-Nano Hybrid Multifunctional Motors with Enhanced Antibacterial Activity Against Refractory Biofilm Infections

Precisely Controlled and Deeply Penetrated Micro-Nano Hybrid Multifunctional Motors with Enhanced Antibacterial Activity Against Refractory Biofilm Infections

Fabrication of Hybrid Micro-nano Structures Based on Plasma Treatment and Its Light Extraction Performances for OLED

Fabrication of Hybrid Micro-nano Structures Based on Plasma Treatment and Its Light Extraction Performances for OLED

Tensile properties and fracture behavior of carbon nanotube-sheets/carbon fibers epoxy-impregnated bundle composites

An interesting technique for modifying carbon fiber-reinforced polymer matrix composites is through hybridization with carbon nanotubes (CNTs). Carbon nanotubes sheets/carbon fibers offer potential benefits of nanoscale reinforcement to the well-established fibrous composites by creating multiscale hybrid micro-nano composites. In this study, the tensile properties of high tensile strength polyacrylonitrile (PAN)- and high modulus pitch-based carbon fiber-reinforced polymer matrix composites incorporating CNT sheets (CNT-sh/CFs/Ep-H: CNT sheets/carbon fibers/epoxy hybrid composites) were investigated. To fabricate CNT sheets, CNT was vertically grown on a quartz glass plate by chemical vapor deposition. A solid-state drawing and winding technique was applied to transform the vertically aligned CNT array into horizontally aligned CNT sheets. The tensile modulus of the CNT-sh/CFs/Ep-H was higher than that of the composite in the as-received state (CFs/Ep: carbon fibers/epoxy bundle composite). The tensile strength of the CNT-sh/PAN-based CF/Ep-H was lower than that of the PAN-based CF/Ep, whereas the tensile strength of the CNT-sh/pitch-based CF/Ep-H was higher than that of the pitch-based CF/Ep.

Space Charge Dynamics in Epoxy Based Composites Under DC and Square Pulse Wave of Different Polarities and Frequencies

Space charge dynamics of epoxy based micro-nano hybrid composites under DC and square pulse waves of different polarities and frequencies are investigated. A specially designed high-speed pulsed electro-acoustic (PEA) system is adopted to measure the space charge distributions of the prepared samples under different DC and square pulse voltage with positive and negative polarity. The DC electric field and the square pulse electric field of 20 kV/mm and 40 kV/mm with different polarities and frequencies are used. The results show that the micro-nano filler addition can suppress the space charge accumulation during the polarization. Furthermore, it can facilitate the dissipation of the accumulated charges during depolarization. No polarity effect is found in both samples under DC electric field. More space charges are accumulated in both samples under positive square pulse voltage with lower frequency, whereas the negative square pulse voltage with the higher frequency accelerates space charge accumulation in both samples. Moreover, the negative voltage has a more evident effect than the positive electric field on both samples. The space charge suppression effect of the micro-nano fillers is reduced under the square pulse voltage compared to the DC voltage. It is elucidated that epoxy based micro-nano hybrid composites are potential packaging materials for electronic devices. Still, their performance under the negative square pulse voltage with the high frequency and the positive square pulse voltage with the low frequency needs to be further investigated.