Controlling the Size of Hydrotalcite Particles and Its Impact on the Thermal Insulation Capabilities of Coatings.

This study focuses on the development of high-performance insulation materials to address the critical issue of reducing building energy consumption. Magnesium-aluminum layered double hydroxides (LDHs), known for their distinctive layered structure featuring positively charged brucite-like layers and an interlayer space, have been identified as promising candidates for insulation applications. Building upon previous research, which demonstrated the enhanced thermal insulation properties of methyl trimethoxysilane (MTS) functionalized LDHs synthesized through a one-step in situ hydrothermal method, this work delves into the systematic exploration of particle size regulation and its consequential effects on the thermal insulation performance of coatings. Our findings indicate a direct correlation between the dosage of MTS and the particle size of LDHs, with an optimal dosage of 4 wt% MTS yielding LDHs that exhibit a tightly interconnected hydrotalcite lamellar structure. This specific modification resulted in the most significant improvement in thermal insulation, achieving a temperature difference of approximately 25.5 °C. Furthermore, to gain a deeper understanding of the thermal insulation mechanism of MTS-modified LDHs, we conducted a thorough characterization of their UV-visible diffuse reflectance and thermal conductivity. This research contributes to the advancement of LDH-based materials for use in thermal insulation applications, offering a sustainable solution to energy conservation in the built environment.

Methyl-Trimethoxy-Siloxane-Modified Mg-Al-Layered Hydroxide Filler for Thermal-Insulation Coatings.

The development of high-performance insulation materials that facilitate the reduction in building energy consumption is of paramount significance. In this study, magnesium-aluminum-layered hydroxide (LDH) was prepared by the classical hydrothermal reaction. By implementing methyl trimethoxy siloxane (MTS), two different MTS-functionalized LDHs were prepared via a one-step in situ hydrothermal synthesis method and a two-step method. Furthermore, using techniques, such as X-ray diffraction, infrared spectroscopy, particle size analysis, and scanning electron microscopy, we evaluated and analyzed the composition, structure, and morphology of the various LDH samples. These LDHs were then employed as inorganic fillers in waterborne coatings, and their thermal-insulation capabilities were tested and compared. It was found that MTS-modified LDH via a one-step in situ hydrothermal synthesis method (M-LDH-2) exhibited the best thermal insulating properties by displaying a thermal-insulation-temperature difference (ΔT) of 25 °C compared with the blank panel. In contrast, the panels coated with unmodified LDH and the MTS-modified LDH via the two-step method exhibited thermal-insulation-temperature difference values of 13.5 °C and 9.5 °C, respectively. Our investigation involved a comprehensive characterization of LDH materials and coating films, unveiling the underlying mechanism of thermal insulation and establishing the correlation between LDH structure and the corresponding insulation performance of the coating. Our findings reveal that the particle size and distribution of LDHs are critical factors in dictating their thermal-insulation capabilities in the coatings. Specifically, we observed that the MTS-modified LDH, prepared via a one-step in situ hydrothermal approach, possessed a larger particle size and wider particle size distribution, resulting in superior thermal-insulation effectiveness. In contrast, the MTS-modified LDH via the two-step method exhibited a smaller particle size and narrow particle size distribution, causing a moderate thermal-insulation effect. This study has significant implications for opening up the potential for LDH-based thermal-insulation coatings. We believe the findings can promote the development of new products and help upgrade industries, while contributing to local economic growth.

Enhancing the Initial Whiteness and Long-Term Thermal Stability of Polyvinyl Chloride by Utilizing Layered Double Hydroxides with Low Surface Basicity.

This study investigated the impact of surface basicity on the performance of layered double hydroxides (LDHs) as heat stabilizers for polyvinyl chloride (PVC). LDHs with varying surface basicity were synthesized and characterized using XRD, SEM, BET, and CO2-TPD. The LDHs were then combined with zinc stearate and dibenzoylmethane to create an environmentally friendly heat stabilizer and added to PVC. The resulting PVC composites were evaluated for thermal stability using the oven-aging method. The results showed that a lower Mg/Al molar ratio (2.0) improved the initial whiteness and long-term thermal stability of PVC composites compared to higher ratios (2.5, 3.0, and 3.5). Replacing Mg with Zn in the LDHs had a similar effect to that of reducing the Mg/Al ratio. Crosslinking the laminae of LDHs with 5% silane coupling agent KH-560 reduced the surface basicity of LDHs by 79%, increasing the chromaticity index, b*, and thermal stability time of PVC composites by 48% and 14%, respectively. A descriptive relationship was established between the structure and surface basicity of LDHs and the initial whiteness and long-term thermal stability of PVC composites.

Insight into thermal regulation of supercapacitors via surface-engineered phase change microcapsules.

Constructing efficient thermal management system to settle the thermal runaway of energy storage devices via employing phase change microcapsules (MEPCMs) is of great significance. However, it is still a challenge that the conventional MEPCMs go against the electrochemical performance and hardly be homogenously fixed in the electrodes. In order to conquer these long-standing critical issues, we designed a novel electrochemically active double-shell phase change microcapsule by introducing polypyrrole on the surface of dense amine resin shell of the conventional inert MEPCM. The active MEPCMs@PPy are uniformly immobilized on the surface of the electrode material using reduced graphene oxide to ensure the stable and efficient operation of the flexible supercapacitor. The assembled all-solid-state supercapacitor containing MEPCMs@PPy (SCs@MEPCMs@PPy) lagged 103 s to 55 °C than the SCs@00 without the added phase change material. At a high temperature of 55 °C and a scan rate of 50 mV s-1, SCs@MEPCMs@PPy exhibits an areal specific capacitance of 110.6 mA cm-2, which is higher than that of the original SCs@MEPCMs. A capacitance retention of 79.8 % and coulombic efficiency of 98.4 % can be reached after 3000 cycles. This study opens a new avenue for developing applicable microencapsulated phase change materials in temperature-regulated electrode systems for supercapacitors and alkaline-ion batteries.