No abstract

As one of the most important biobased and biodegradable polymers with a promising commercial prospect, polylactic acid (PLA) has gained increasing interest. Nevertheless, its high mechanical strength is generally sacrificed when using tough matters to overcome its inherent brittleness. Concerning to develop strong and tough PLA-based materials, herein, polybutylene succinate (PBS) is blended with PLA, and epoxidized microfibrillated cellulose (MFC-EPI) is employed as an interfacial compatibilizer as well as a reinforcement filler. Effects of the amounts of PBS and MFC-EPI on crystallization behavior, thermal stability, and mechanical properties of the PLA-based materials are investigated. Notably, tensile strength and elongation at break of the resultant composite containing 2% MFC-EPI are up to 71.4 MPa and 273.6%, respectively. The “bridge” effect of the filler contributes to energy transfer and dissipation during deformation, accounting for the toughening mechanism that is confirmed by microscopy. Such a “two-in-one” modification strategy ensures the high strength and toughness, which can be used to develop more materials with high mechanical performances.

No abstract

The fire detection plays a critical role in the maintenance of public security. Previous approaches of early fire warning, based on smoke or temperature response must be set in the proximity of a fire. They cannot provide the additional information of fire location or size and are susceptible to complicated situations. It is still a big challenge to make rapid and accurate early fire warning in precombustion because of the lack of reliable alarm signals. Herein, a precursor molecular sensor (PMS) is designed and synthesized that can present the chemical structure transformation to form phthalocyanines (Pcs) and release a color change signal at about 180 °C, learning from the plant chlorophyll metabolism. Further, the PMS is assembled to an early fire warning component (EWC) and an intelligent image recognition algorithm is introduced for unburned fire detection. The EWC generates a colorful alarm within 20 s at 275 °C. Therefore, the facile PMS provides a reliable real-time monitoring strategy to the early fire warning detection in precombustion.

No abstract

Thermal comfort is of great significance to maintain people’s healthy state in physics, physiology, and psychology. Personal thermal management (PTM) that passively regulates the immediate environment around the human body has been proposed as a promising strategy to realize on-demand human thermal comfort. In this work, we propose a one-stop solution for the state of the art PTM by combining thermal shielding and thermal energy storage in a Janus-type wearable device, which is named a Janus-type hydroxyapatite-incorporated Kevlar aerogel@Kevlar aerogel supported phase-change material gel (HKA@KPG). The lower HKA with an ultralow thermal conductivity directly attached on the skin can effectively hinder heat transfer from the external environment to human skin. The upper KPG possessing a superior form stability and high energy storage capacity can absorb the heat generated by the human body to regulate the skin temperature. Both the HKA and KPG also demonstrate excellent biocompatibility. Due to its synergistic effect in thermal energy regulation, the Janus HKA@KPG has been applied in wearable PTM in static and dynamic modes to meet the thermal comfort requirements. It is anticipated that the one-stop thermal comfort solution for thermal shielding, thermal energy storage, self-supporting characteristics, wearability, and biosafety offers new possibilities for the next generation of wearable PTMs.

The state-of-the-art solar-thermal evaporators demonstrating high energy utilization efficiency, a high evaporation rate, and salt rejection are highly desirable in solar-driven low-energy water purification/harvesting. Herein, a novel Janus solar evaporator is constructed by loading polypyrrole (PPy) nanobelts on the polyvinyl alcohol (PVA) hydrogel. The PPy nanobelts present a high solar absorption of 98.3%, leading to a localized solar-thermal efficiency of 82.5% when insulated from bulk water by the PVA hydrogel. The porous PVA hydrogel and the hydrophilic PPy nanobelts enable the efficient three-dimensional water transport. Taking advantages of the synergistic effect in the water-energy nexus, the Janus PPy nanobelt@PVA hydrogel evaporator evaporates water with a high rate of 2.26 kg m −2 h −1 via 80.1% solar energy from 1 sun irradiance with a low PPy loading of ∼3 mg cm −2 even at a rate of 2.64 kg m −2 h −1 via 96.3% solar energy for a biomimetic conical evaporator. The Janus evaporator presents superior salt-resistant desalination and contaminant purification performance in seawater and sewage. Furthermore, a portable solar-thermal purifier equipped with the Janus evaporator desalts real seawater far above the drinking water standard with over a 99.9% salt rejection rate and eliminates 95.8% of chemical oxygen demand in real sewage, highlighting its potential for advanced clean water harvesting.

Using bio-based chemicals and recycling waste plastics are essential components of the circular economy. Wood−plastic composites (WPCs), fabricated from recycled plastic and wood-processing wastes, are new, green, and environmentally friendly materials. However, their flammability causes potential fire risks and hazards. Although bio-based flame retardants possess the essential advantage over inorganic or petroleum-based chemicals, their application, particularly that of fully bio-based flame retardants, in WPC has been seldom reported. Herein, we designed and synthesized a fully bio-based flame retardant, phytic acid-tyramine salt (referred to as PATA), using a green and environmentally friendly approach with only deionized water as the reaction solvent. PATA is subsequently utilized in conjunction with ammonium polyphosphate (APP) to synergistically impart flame-retardant properties to WPCs. PATA/APP shows a good flame-retardant effect, improving the flame retardant and smoke suppression properties of WPCs. The PATA/APP system can increase the limiting oxygen index by 31% and achieve a vertical combustion V-0 rating. Furthermore, the PATA/APP system can reduce the peak heat release rate, total heat release, and maximum smoke density by 49, 22, and 15%, respectively. The PATA/APP system can generate phosphoric acid substances during combustion, which promote the decomposition of wood flour to form stable char layers containing P−N−C or P−O−C structures. Consequently, we provide an environmental-friendly approach to enhance the flame retardancy of WPCs.