Hierarchical Flower-Like Hollow SiO2@TiO2 Spheres with Enhanced Thermal Insulation and Ultraviolet Resistance Performances for Building Coating

Polymerization-Induced Hierarchical Hybrid Particles from Siloxane Emulsification Endowing Polyurethane Composite Coating with Superhydrophobicity, Thermal Insulation, and Fluorescence

Hierarchically structural particles (HSPs) are highly regarded as favorable nanomaterials for superhydrophobic coating due to their special multiscale structure and surface physicochemical properties. However, most of the superhydrophobic coatings constructed from HSPs are monofunctional, constraining their broader applications. Moreover, traditional methods for constructing HSPs mostly rely on complicated chemical routes and template removal. Herein, we propose an innovative strategy (one-pot method) for producing multifunctional hierarchical hybrid particles (HHPs). Polysilsesquioxane (PSQ), generated from hydrolysis condensation of methyltriethoxylsilane, is used as the sole stabilizer to anchor on the surface of styrene and short fluoroalkyl compound tridecafluorooctyl acrylate comonomers droplets, forming a mesoporous PSQ shell. Subsequently, the comonomers inside of the shell perform restricted polymerization to generate the HHP due to the driving of the mesoporous capillary force. The HHP is then mixed with waterborne polyurethane (WPU) to develop a robust nanocomposite coating (WPU-HHP). Through the deliberate design of the HHP components, the WPU-HHP coating has thermal insulation, photoluminescence properties, and the ability to achieve a wettability transition during abrasion. Our research has achieved the integration of multifunctionality in one waterborne hybrid system, broadening the application areas of nanocomposite coatings.

In Situ Self-Assembly of Nitrogen-Doped 3D Flower-like Hierarchical Porous Carbon and Its Application for Supercapacitors

The hierarchical porous carbon-based materials derived from biomass are beneficial for the enhancement of electrochemical performances in supercapacitors. Herein, we report the fabrication of nitrogen-doped 3D flower-like hierarchical porous carbon (NPC) assembled by nanosheets using a mixture of urea, ZnCl2, and starch via a low-temperature hydrothermal reaction and high-temperature carbonization process. As a consequence, the optimized mass ratio for the mixture is 2:2:2 and the temperature is 700 °C. The NPC structures are capable of electron transport and ion diffusion owing to their high specific surface area (1498.4 m2 g-1) and rich heteroatoms. Thereby, the resultant NPC electrodes display excellent capacitive performance, with a high specific capacitance of 249.7 F g-1 at 1.0 A g-1 and good cycling stability. Remarkably, this implies a superior energy density of 42.98 Wh kg-1 with a power density of 7500 W kg-1 in organic electrolyte for the symmetrical supercapacitor. This result verifies the good performance of as-synthesized carbon materials in capacitive energy storage applications, which is inseparable from the hierarchical porous features of the materials.

Corrosion-Resistant Hydrophobic Thermal Barrier Composite Coating on Metal Strip: A New Dimension to Steel Strips for Roofing Segment

This study demonstrates a cost-effective, thin, multifunctional composite coating system with outstanding thermal insulation for thermal management and heat shield applications, such as roofs, as well as outstanding resistance to corrosion. The hydrophobic multifunctional epoxy composite coating systems were designed with surface-modified fillers to impart both reduced heat conduction and high infrared reflectance in a thin coating with a 65-100 μm dry film thickness (DFT). With a judicial combination of hollow microspheres (HMS) activated and modified with silica (sHMS) and stearic acid-modified TiO2 (sMO), the developed composite coating attained the highest thermal insulation property with a temperature drop of 21-31 °C at different distances below the coated panel, which is superior to the values of temperature drop reported earlier. The high solar reflectance of the composite coating in the near-infrared (NIR) region exceeds 72% with a low thermal conductivity of 0.178 W m-1 K-1. After 720 h of exposure in a 3.5 wt % NaCl solution, the composite coating revealed a corrosion protection efficiency of 99%. The work demonstrates that high solar reflectivity and low thermal conductivity must be active simultaneously to achieve superior thermal shielding in a thin coating on a metal. A careful selection of fillers and appropriate surface modifications ensures hydrophobicity and proper distribution of the fillers in the coating for a high barrier effect to prevent environmental deterioration. With these superior performance parameters, the developed composite coatings make an essential contribution to energy sustainability and the protection against environmental degradation.

Superhydrophobic and Photocatalytic Synergistic Self-Cleaning Coating Constructed by Hierarchically Structured Flower-like Hollow SiO2@TiO2 Spheres with Oxygen Vacancies

The self-cleaning coating has both superhydrophobic physical and photocatalytic chemical self-cleaning properties, which has attracted the wide attention of researchers in recent years. First, the flower-like hollow SiO2@TiO2 spheres with oxygen vacancies (rFHSTs) were prepared by the liquid-phase reduction method, in which several different functional components were integrated. Meanwhile, the influence mechanisms of the physical structure and chemical composition on the photocatalytic properties are discussed in detail. The results proved that rFHSTs exhibited the enhanced photoresponse range and photocatalytic degradation performance in visible light because of the synergistic effect of the microstructure (internal cavity, 3D flower-like nanosheet), SiO2/TiO2 heterojunction structure, and oxygen vacancies. After that, superhydrophobic modified rFHSTs were used as fillers to fabricate PVA/PFDTS-rFHSTs composite coatings with both physical and chemical self-cleaning properties. The self-cleaning performances and principles of the composite coating were examined and explored. The results showed that the low surface energy of the hydrophobic chain segment, the inherent particle effect, and the photocatalytic activity of rFHSTs were responsible for the superhydrophobic and photocatalytic effects, finally endowing the composite coating with self-cleaning performance. In short, this study is profound for the development and application of self-cleaning coatings with both physical and chemical performances.

Controllable Synthesis of Hollow Silica Nanoparticles Using Layered Double Hydroxide Templates and Application for Thermal Insulation Coating

The innovative hollow silica nanoparticle (HSN) material possesses substantial potential for application in the insulation field. The size and shell thickness of HSN are crucial factors in determining their inherent properties, which, in turn, impact their applicability. This research presents a facile approach to synthesizing HSN in which sodium silicate (Na2SiO3) was utilized as the silica precursor that can be directly deposited onto layered double hydroxide (LDH) nanoparticles without the utilization of any surfactant. A subsequent acid treatment was used to eliminate the templates, resulting in the formation of an HSN devoid of mesopores in silica shells. By utilizing various sizes of LDH cores, obtainable via coprecipitation followed by hydrothermal treatment, we were capable of successfully synthesizing the hollow particles with adjustable diameters ranging from 50 to 200 nm. In addition, the shell thickness is varied from 6.8 to 22.5 nm by varying the silicate solution concentration. Results demonstrate that prepared HSNs have low thermal conductivity and high reflectance in the UV-vis-NIR range (averaging 82.1%). These findings suggest that HSN can be utilized as an effective inorganic filler in the formulation of reflective and thermally insulating coatings.

Sol-gel dip-coated TiO2 nanofilms reduce heat production in titanium alloy implants produced by microwave diathermy

Objective: To verify that the TiO₂ nanofilm dip-coated by sol-gel can reduce titanium alloy implants (TAI)'s heat production after microwave diathermy (MD).Methods: The effect of 40 W and 60 W MD on the titanium alloy substrate coated with TiO₂ nanofilm (Experimental Group) and the titanium alloy substrate without film (Control Group) were analyzed in vitro and in vivo. Changes in the skeletal muscle around the implant were evaluated in ex vivo by histology.Results: After 20 min of MD, in vitro the temperature rise of the titanium substrate was less in the Experimental Group than in the Control Group (40 W: 1.4 °C vs. 2.6 °C, p < .01, 60 W: 2.5 °C vs. 3.7 °C, p < .01) and in vivo, the temperature rise of the muscle tissue adjacent to TAI was lower in the Experimental Group than in the Control Group (40 W: 3.29 °C vs. 4.8 °C, p < .01, 60 W: 4.16 °C vs. 6.52 °C, p < .01). Skeletal muscle thermal injury can be found in the Control Group but not in the Experimental Group.Conclusion: Sol-gel dip-coated TiO₂ nanofilm can reduce the heat production of TAIs under single 40～60 W and continuous 40 W MD and protect the muscle tissue adjacent to the implants against thermal injury caused by irradiation.

Fabrication of Dual Self-Healing Multifunctional Coating Based on Multicompartment Microcapsules

By designing and preparing multifunctional materials exhibiting self-healing ability, problems related to their durability outdoors can be solved. This study, inspired by the self-healing mechanism of natural creatures, successfully prepared a dual self-healing multifunctional coating using temperature stimuli-responsive multicompartment microcapsules. Phase change materials (PCMs) were employed to load multicompartment microcapsules that were produced through Pickering emulsion polymerization by applying hydrophobic materials encapsulated by titanium dioxide (TiO₂) nanocapsules as Pickering emulsifiers. The multifunctional coating produced using microcapsules and self-healing waterborne polyurethane (WPU) exhibited thermal insulation and antireflection properties, which was attributed to the application of PCMs and TiO₂, and it also achieved remarkable superhydrophobicity. Moreover, this coating exhibited the intrinsic and superficial dual self-healing ability, which was attributed to the release of hydrophobic materials from microcapsules and the self-healing ability of WPU. This study can be referenced to guide the fabrication of high-performance self-healing materials, and it can contribute to the long-term use of multifunctional coatings.

Flexible core-shell Cs x WO3-based films with high UV/NIR filtration efficiency and stability

Cesium-doped tungsten bronze Cs x WO3 (CWO) is an ideal near infrared (NIR) shielding material for solar filters. However, the NIR shielding ability of CWO-dispersed films easily deteriorates in hot humid environments, which severely hinders the commercial application of CWO. In this paper, UV/NIR shielding nanocomposite films were prepared by dispersing core-shell structured CWO@polydopamine (CWO@PDA) in a poly(vinyl alcohol) matrix. Because of the strong ultraviolet light absorption ability of PDA, it can shield ultraviolet light, which is generally detrimental to our health. The prepared nanocomposite films can efficiently shield 88.3% UV and 85.5% NIR radiation even though they show relatively high transparency in the visible range. Importantly, the good protection of the continuous PDA shells played an important role in enhancing the stability of CWO nanoparticles. The nanocomposite films also exhibit excellent stability in hot humid environments. Therefore, core-shell structured CWO@PDA nanoparticles have great potential as a novel UV/NIR shielding material for the development of efficient energy-saving windows.

A rapid screening method for thermal conductivity properties of thermal insulation materials by a thermochemiluminescence probe

Acridine-based 1,2-dioxetane as a thermochemiluminescence (TCL) probe for temperature sensing exhibited an excellent response for temperature in the range of 85-130 °C with favorable sensitivity and good resolution. The proposed TCL probe could be applied to screen thermal conductivity properties of different thermal insulation materials.