Dynamically Tunable All-Weather Daytime Cellulose Aerogel Radiative Supercooler for Energy-Saving Building.

A passive cooling strategy without any electricity input has shown a significant impact on overall energy consumption globally. However, designing tunable daytime radiative cooler to meet requirement of different weather conditions is still a big challenge, especially in hot, humid regions. Here, a novel type of tunable, thermally insulating and compressible cellulose nanocrystal (CNC) aerogel coolers is prepared via chemical cross-linking and unidirectional freeze casting process. Such aerogel coolers can achieve a subambient temperature drop of 9.2 °C under direct sunlight and promisingly reached the reduction of ∼7.4 °C even in hot, moist, and fickle extreme surroundings. The tunable cooling performance can be realized via controlling the compression ratio of shape-malleable aerogel coolers. Furthermore, energy consumption modeling of using such aerogel coolers in buildings in China shows 35.4% reduction of cooling energy. This work can pave the way toward designing high-performance, thermal-regulating materials for energy consumption savings.

A cellulose nanocrystal-based dual response of photonic colors and fluorescence for sensitive benzene gas detection.

Benzene, as a common volatile organic compound, represents serious risk to human health and environment even at low level concentration. There is an urgent concern on visualized, sensitive and real time detection of benzene gases. Herein, by doping Fe3+ and graphene quantum dots (GQDs), a cellulose nanocrystal (CNC) chiral nematic film was designed with dual response of photonic colors and fluorescence to benzene gas. The chiral nematic CNC/Fe/GQDs film could respond to benzene gas changes by reversible motion. Moreover, chiral nematic film also displays reversible responsive to humidity changes. The resulting CNC/Fe/GQDs chiral nematic film showed excellent response performance at benzene gas concentrations of 0-250 mg/m3. The maximal reflection wavelength film red shifted from 576 to 625 nm. Furthermore, structural color of CNC/Fe/GQDs chiral nematic film change at 44 %, 54 %, 76 %, 87 %, and 99 % relative humidity. Interestingly, due to the stability of GQDs to water molecules, CNC/Fe/GQDs chiral nematic film exhibit fluorescence response to benzene gas even in high humidity (RH = 99 %) environment. Besides, we further developed a smartphone-based response network system for quantitively determinization and signal transformation. This work provides a promising routine to realize a new benzene gas response regime and promotes the development of real-time benzene gas detection.

Eco-friendly wood-plastic composites from laminate sanding dust and waste poly(propylene) food pails.

Plastic pollution caused by non-degradable petrochemical-based plastics has become a serious environmental problem in China, and the reasonable management of industrial waste and renewable resources remains a huge challenge. Here, we report environment-friendly wood-plastic composites (WPCs), prepared from decorative high-pressure laminate (HPL) sanding dust (filler) and waste thermoplastic food pails (matrix), as well as comprehensively evaluate the processability, mechanical and interfacial properties, indoor safety evaluation. The elemental composition and thermal stability of these two residue materials were suitable for the WPC manufacturing process. The content of HPL sanding dust in WPC was fixed at 60 wt%, and the amount of maleic anhydride grafted polypropylene (MAPP) added was 5 wt%-7 wt%, which maximized the utilization of waste resources, and can obtain impact strength as high as 5-6 kJ/m2, tensile strength of 35-42 MPa and flexural strength as high as 43-46 MPa. The developed WPCs had low formaldehyde emissions (≤1.53 mg/m3) and slightly improved flame retardancy. Finally, their lower cost (5,035 yuan/ton) and higher eco-efficiency (12.81 yuan/kg CO2) characteristics allowed them to be compatible with the current sustainable development requirements. This study provides a novel approach for the utilization of industrial waste and recyclable resources for sustainable replacement of wood-based products.