Efficient heat dissipation remains a critical challenge in advanced thermal management systems, particularly in high-performance electronics and energy-intensive applications. This study presents a novel thermal regulation microcapsule that integrates the magnetic properties of the core material with the stability and tunability of the shell material, offering significant application potential. Using needle-based double emulsion microfluidics, oil magnetic fluid (OMF) was encapsulated within a hexanediol diacrylate (HDDA) shell, achieving precise structural and size control with an average diameter of 406.87 mu m and size variation below 5%. Thermal characterization demonstrated that microcapsule heat dissipation efficiency depends on size, temperature, and magnetic flux density, with a thermal conductivity of 1.232 W/mK under a 300 mT magnetic field, outperforming conventional materials. Mechanical testing revealed variable stiffness, reaching similar to 1 MPa in a 300 mT direct current magnetic field, a thousandfold increase compared to non-magnetic conditions. Furthermore, photothermal effects under an alternating magnetic field confirmed their capacity for energy conversion via heat generation. In electronic chip cooling tests, OMF-HDDA microcapsules achieved a 36.86% enhancement in heat dissipation compared to traditional coolants. These findings highlight the microcapsules' innovative potential as a high-performance, environmentally friendly solution for next-generation thermal management systems.

Flexible intelligent materials are extensively utilized in fields such as soft robotics and flexible electronic devices due to their high tensile strength, reversible deformation, and environmental adaptability. A novel magneto-thermal responsive liquid-vapor phase transition composite material is proposed, integrating expansion deformation and load-bearing functions. The liquid-vapor phase change of low-boiling-point liquids within the elastomer is driven by the magnetocaloric effect of nano-Fe3O4 particles. The bilayer structure, which combines active and passive layers, can achieve various structures and deformations. The liquid-vapor phase change material serves as the active layer, providing reversible expansion deformation, while the silicone elastomer functions as the passive layer, providing constraint, thus driving the bilayer structure to bend and expand. Functional actuators suitable for different applications, such as flexible grippers, load-bearing dome structures, and on-demand deformation switches, were manufactured using 3D printing technology. Additionally, dual-response targeted delivery structures were developed by combining dynamic and static magnetic fields. These flexible actuators combine multiple characteristics, including customizable structures and deformations, reversible expansion deformation, stretchability, and load-bearing capacity, potentially opening new application avenues in flexible electronic devices and soft robotics.

With the rapid development of electric vehicles, lithium-ion battery has been widely used as an energy source. However, to avoid thermal runaway and to ensure the correct operation of lithium-ion battery system, effective battery thermal management would be required. In this study the capacity of phase change materials with different thermal-physical properties to respectively manage thermal issues associated with lithium-ion battery is theoretically investigated using computational fluid dynamics. The impacts of shell material, heat transfer coefficient, phase change material fill volume and the shape of the battery pack on the thermal performance of the lithium-ion battery/phase change material system are investigated in detail. The results show that when the ambient temperature was 20 degrees C or 30 degrees C, phase change material-RT35 shows the best temperature control ability for the proposed system, while the phase change material-RT50 has better thermal management capability when the ambient temperature is 40 degrees C. Also, higher heat transfer coefficient or shell material with higher thermal conductivity, effectively reduce the maximum temperature of the lithium-ion battery and the temperature difference within the proposed system. Specifically, the phase transition time in the lithium-ion battery/phase change material system with a heat transfer coefficient of 10 W/m2K is more than twice longer compared to that of 1 W/m2K and the maximum temperature is 47.18 degrees C after 150 min of charging and discharging. It is also observed that the phase change material with larger volume ratio leads to lower system temperature during phase transition and the continuous charging and discharging after completing transformation of the phase change material impacts negatively on the thermal management of the lithium-ion battery system. Besides, the rectangular lithium-ion battery/phase change material system surpasses the circular one by 14.78 degrees C in maximum temperature, while attaining a minimum temperature difference of 9.6 degrees C after 150 min of charging and discharging.

The application of TiO2 as a photocatalyst and UV protectant is limited by the difficulty of recovering TiO2 nanoparticles after water treatment. In this study, TiO2 nanoparticles were immobilized within easily recoverable poly(1,6-hexanediol diacrylate) (HDDA) based polymer microspheres, which were generated through photo-polymerization of droplets produced by microfluidics. Due to the rapid polymerization reaction, TiO2 nanoparticles were uniformly distributed within the polymer network. The microspheres containing 0.5wt% TiO2 embedded in the HDDA matrix degraded 100% of methylene blue from a 1ppm aqueous solution under 365 nm UV irradiation within 2.5 hours. The microspheres can be easily separated from water and reused without losing photocatalytic activity in repeated cycles. The inclusion of phase change material, n-hexadecane, within the HDDA shell demonstrates that the microcapsules also possess good energy storage capability.

The advancement of refractory multi-principal element alloys, exhibiting superior mechanical properties and wear resistance, is of paramount importance in materials engineering. This study introduces a novel series of refractory multi-principal element alloys, designated as TiNbCrMox (x=0, 0.2, 0.4, 0.6, 0.8, 1.0), and methodically explores the impact of varying molybdenum (Mo) content on their microstructural characteristics, phase composition, mechanical performance, and wear resistance. Empirical analyses reveal that these alloys are primarily composed of body-centered cubic (BCC) and Laves phases. The yield strength at ambient temperature is observed to span a range from 1572.8 MPa to 1902.5 MPa. Notably, the strategic addition of Mo in controlled proportions has been found to significantly enhance the hardness and ductility of the TiNbCrMox alloys. This improvement is attributed to the modification in the Laves phase concentration and the degree of lattice distortion. Moreover, the study identifies a marked increase in the hardness of the alloys, which, in conjunction with the formation of a lubricative oxide film, substantially reduces their wear rate. Specifically, the TiNbCrMo0.6 variant demonstrates a notably low wear rate, measured at 9.05 × 10−5mm3/(N m). This investigation offers invaluable insights into the design and development of high-strength, wear-resistant metallic materials, highlighting their potential for diverse industrial applications.

Laser cladding (LC) process parameters have a substantial influence on coating morphology and mechanical characteristics; it is necessary to optimize key parameters for laser processing. In this study, Stellite12 cobalt-based alloy powder with excellent corrosion and wear resistance was selected as the cladding material. The multi-objective optimization model of the LC process was established by response surface methodology, laser power, scanning speed, and powder feeding rate as input factors, and the target response variables involve dilution, aspect ratio, and microhardness of the single-track cladding. Combined with variance analysis (ANOVA), the multi-objective optimization of laser power, scanning speed, and powder feeding rate was conducted. A single-track cladding layer with a dilution of 18.29%, an aspect ratio of 3.88, and a microhardness of 634.67 HV0.2 was obtained using the optimized process parameters. Errors between the predicted and actual values of single-track cladding dilution, aspect ratio, and microhardness were less than 8%, which verified the accuracy of the established model.

Abstract The large‐sized nanofilm‐constructed hierarchical porous SiO2 (LNCHPS) is successfully prepared by the dual templating approach and subsequently used as the support for g‐C3N4. A series of characterization techniques are conducted to evaluate the structure and property of the as‐prepared materials. The LNCHPS possesses two sets of explicated successive pass‐through macropores (0.5–1.0 µm) with large specific surface area. In addition, the macropore wall is constructed by uniform mesoporous nanofilms with the thickness ranging from 35 to 50 nm. Then, the photocatalytic property is investigated by degradations towards Rhodamine B (RhB) under simulated sunlight, in which experiments have been performed through controlling the g‐C3N4 loading contents, solution pH values, and photocatalyst dosages. The apparent rate constant of g‐C3N4/LNCHPS could reach 0.03 min−1 under optimum conditions, showing 6.0 times that of the bulk g‐C3N4. In addition, g‐C3N4/LNCHPS also exhibits significantly enhanced performance in H2 evolution (39.9 µmol h−1) compared to that of the bulk g‐C3N4. High light absorption and utilization, enhanced adsorption capability and quick electron hole separation can render this fine structure excellent photocatalytic performance. Our work enables a facile route for large‐scale preparation of g‐C3N4/LNCHPS for addressing the wastewater treatment and hydrogen energy production simultaneously.

A novel phase-changing composite that gains multi-stage stiffness under the thermal stimulus has been developed to make a mechanism system to adapt to the complex environment, and complex design structures can be fabricated by 4D printing.

A soft structure with continuously variable stiffness and fast response was designed. Varying the electric field strength (0 to 4.5 kV mm −1 ), the rate of stiffness variation is over 1500%. The response time to load change is within 65 ms.

Screw extrusion 3D printing in the low-cost preparation of high-quality metal products, which offers an edge over fused deposition molding (FDM) and laser-based additive manufacturing. In this study, spherical 304 stainless steel (SS304) micronized powder and polypropylene (PP) pellets were used as raw materials to manufacture composite samples of SS304 with a mass fraction of up to 90 wt%. After high-temperature heat treatment, metal samples with good qualities were obtained. The influence of 3D printing paths and heat treatment processes on the microstructure and mechanical properties of printed parts were studied. The results reveal that the samples printed using 27°/152° cross paths achieved a relative density with 95.78% and a tensile strength with 484 MPa after 6 h of sintering at 1280 °C at a pre-debinding rate with 60%. The overall performance is on par with components created using metal injection techniques (MIM), and this work provides the novel proposals for the production of metal parts using affordable 3D printing.

Soft robots capable of responding to different actuation schemes are flourishing due to the appealing advantages of being highly flexible and adaptive to complex environments. However, it remains challenging to produce untether soft actuators that can sense their own motions. Herein, a novel photo-responsive liquid-vapor phase transition composite with integrated actuating and sensing performances is proposed. The composite is operated based on the principle that piezocapacitive sensing and liquid-vapor phase transition are caused by the photothermal effect of the embedded graphene plate. The composite exhibits superior and tunable optically responsive and self-sensing properties. As a proof of concept, the muscle-like actuator with effective actuating and real-time sensing feedback functions is produced. Furthermore, several "Janus" bilayer untethered actuators are fabricated via 3D printing, which can achieve a variety of light-driven programmed locomotion, such as bending, grasping, and crawling. This work holds great promise for designing and fabricating soft robots with integrated self-sensing capacity.

As an effective technique for fabricating conductive and thermally conductive polymer composites, a multi-filler system incorporates different types and sizes of multiple fillers to form interconnected networks with improved electrical, thermal, and processing properties. In this study, DIW forming of bifunctional composites was achieved by controlling the temperature of the printing platform. The study was based on enhancing the thermal and electrical transport properties of hybrid ternary polymer nanocomposites with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplates (GNPs). With thermoplastic polyurethane (TPU) used as the matrix, the addition of MWCNTs, GNPs and both mixtures further improved the thermal conductivity of the elastomers. By adjusting the weight fraction of the functional fillers (MWCNTs and GNPs), the thermal and electrical properties were gradually explored. Here, the thermal conductivity of the polymer composites increased nearly sevenfold (from 0.36 W·m−1·k−1 to 2.87 W·m−1·k−1) and the electrical conductivity increased up to 5.49 × 10−2 S·m−1. It is expected to be used in the field of electronic packaging and environmental thermal dissipation, especially for modern electronic industrial equipment.

The remarkable control function over the functional material formation process enabled by droplet microfluidic emulsification approaches can lead to the efficient and one-step encapsulation of active substances in microparticles, with the microparticle characteristics well regulated. In comparison to the conventional fabrication methods, droplet microfluidic technology can not only construct microparticles with various shapes, but also provide excellent templates, which enrich and expand the application fields of microparticles. For instance, intersection with disciplines in pharmacy, life sciences, and others, modifying the structure of microspheres and appending functional materials can be completed in the preparation of microparticles. The as-prepared polymer particles have great potential in a wide range of applications for chemical analysis, heavy metal adsorption, and detection. This review systematically introduces the devices and basic principles of particle preparation using droplet microfluidic technology and discusses the research of functional microparticle formation with high monodispersity, involving a plethora of types including spherical, nonspherical, and Janus type, as well as core-shell, hole-shell, and controllable multicompartment particles. Moreover, this review paper also exhibits a critical analysis of the current status and existing challenges, and outlook of the future development in the emerging fields has been discussed.

Materials that can be designed with programmable properties and which change in response to external stimuli are of great importance in numerous fields of soft actuators, involving robotics, drug delivery and aerospace applications. In order to improve the interaction of human and robots, materials with variable stiffness are introduced to develop their compliance. A variable stiffness composite has been investigated in this paper, which is composed of liquid metals (LMs) and silicone elastomers. The phase changing materials (LMs) have been encapsulated into silicone elastomer by printing the dual materials alternately with three-dimensional direct ink writing. Such composites enable the control over their own stiffness between soft and rigid states through LM effective phase transition. The tested splines demonstrated that the stiffness changes approximately exceeded 1900%, and the storage modulus is 4.75 MPa and 0.2 MPa when LM is rigid and soft, respectively. In the process of heating up, the stretching strain can be enlarged by at least three times, but the load capacity is weakened. At a high temperature, the resistance of the conductive composites changes with the deformation degree, which is expected to be applied in the field of soft sensing actuators.

Inspired from the nature, soft actuators have been attracting the incremental attention on account of the benefits in terms of high flexibility and safety for human operators, but material selection and manufacturing process remain challenging. Compared with the conventional actuators in solid state, smart phase change materials (PCMs) are superior for the soft actuation applications because of the capability to change their shapes or properties in response to a wide range of stimulants, such as heat, light, pH, or electrical field. This review provides a comprehensive analysis of smart PCM applications on soft actuators, including metal alloys and their polymer counterparts, shape memory materials and liquid crystalline polymers. Such materials generally exhibit large deformation degrees, high complexity in movement and diverse versatility, which are compliant and well suited for soft actuators in the vast applications of soft mechatronics and robots. Since stiffness variable plays a significant role on actuator transformation, this review focuses on smart materials with an emphasis on the different forms of phase transformation among solid, liquid, and gas phase. This review enables a better understanding of phase transformation, performances, and limitations of smart PCMs, and provides insights into the potential applications for soft actuators.

Conference Name:International Conference on Smart Materials and Nanotechnology in Engineering. Conference Address: Harbin, PEOPLES R CHINA. Time:JUL 01-04, 2007.