Polyoxometalate-loaded Nanocellulose Sponge as a Novel Catalyst for the Regioselective Hydroboration of Phenylacetylene

In this work,an amino-modified cellulose nanofiber sponge was prepared and used as a support for polyoxometalate(POM)catalysts with a high loading efficiency.Fourier transform infrared spectroscopy,thermogravimetric analysis,and energy-dispersive X-ray spectroscopy revealed that an Anderson-type POM,(NH4)4[CuMo6O18(OH)6]·5H2O was successfully immobilized on the sponge based on electrostatic interactions.Morphological analysis indicated that the POM-loaded sponge retained its porous structure and that the POM was homogeneously distributed on the sponge walls.The POM-loaded sponge exhibited excellent mechanical properties by recovering 79.9%of its original thickness following a 60%compression strain.The POM-loaded sponge was found to effectively catalyze the hydroboration of phenylacetylenes,yielding excellent conversion and regioselectivity of up to 96%and 99%,respectively.Its catalytic activity remained unchanged after five reuse cycles.These findings represent a scalable strategy for immobilizing POMs on porous supports.

高灵敏度,超宽响应范围,环境耐受性高的多模式离子凝胶基传感器

近年来,离子类皮肤传感器因其高性能和良好的兼容性等优点而备受关注.然而,开发一种多功能、稳定、高灵敏度和耐用的离子类皮肤传感器仍面临挑战.本文通过简单的紫外引发聚合制备了具有良好耐用性、环境(抗冻、耐真空)稳定性、离子导电性、自愈性、高粘附性和拉伸性的复合离子凝胶.该离子凝胶可以组装为应变、压力和温度传感器,用于检测外部环境的变化.无论是作为应变传感器还是压力传感器,离子凝胶基传感器都具有高灵敏度(GF=14.7)、宽响应范围(1%-1600%)、快速响应时同(95.8 ms)、优异的稳定性和可重复性(1000次).因此,它不仅可以追踪关节运动,还可以监测细微的表情变化(皱眉).该离子凝胶还可以组装成敲击传感器和高精度书写板传感器,用于信息传递.此外,该传感器对温度变化具有较高的灵敏度,温度感知范围在0-120℃之间,且检测阈值较低(0.1℃).因此,基于离子凝胶的传感器有望应用于多功能电子和传感设备.

Experimental study of the flow and heat transfer of a gas–water mixture through a packed channel

Waste heat recovery from the flue gas of gasfired boilers was studied experimentally by measuring the flow and heat transfer of air and water through six kinds of packing with saturated humid air as the simulated flue gas.The experiments measured the effects of inlet air temperature, inlet air velocity and circulating water flow rate on the flow and heat transfer. The results show that higher inlet air temperatures and lower inlet air velocities lower the flow resistance and increase the heat transfer coefficient. The stainless steel packing had better surface wettability and larger thermal conductivity than the plastic packing, which enhanced the heat transfer between the water and the saturated moist air. When both the flow resistance reduction and the heat transfer enhancement were considered, the experimental results gave an optimal packing-specific surface area. A packed heat exchanger tower was designed for waste heat recovery from the flue gas of gas-fired boilers based on the experimental results which had better flow and heat transfer characteristics with lower pump and fan power consumption, more stable system operation and less thermal fluctuations compared with a non-packed heat transfer system with atomized water.

Thermally conductive poly(lactic acid)/boron nitride composites via regenerated cellulose assisted Pickering emulsion approach

Polymer-based thermally conductive composites have attracted tremendous interest in thermal management of electronics.However,it remains challenging to achieve high thermal conductivity partly because the difficulty to obtain favorable distribution and orientation of conductive fillers within the polymer matrix.Herein,networked boron nitride(BN)conductive pathway was realized within the poly(lactic acid)(PLA)matrix,via regenerated cellulose(RC)-assisted assembly of BN on Pickering emulsion interface based on the noncovalent interaction,followed by solvent evaporation and hot-compressing.The strong noncovalent interactions between BN and RC were found critical to enhance the wettability and stability of BN in aqueous media with a lowest mass ratio of 1:40 of RC and BN.The obtained PLA/BN composites feature a thermal conductivity of 1.06 W/(m K)at 28.4 wt%BN loading,representing an enhancement of 430%comparing to neat PLA,and the crystallinity of the composites could increase significantly from11.7%(neat PLA)to 43.7%.This simple,environmentally friendly and effective strategy could be easily extended for effective construction of thermally conductive composites.

Effect of Solvophilic Chain Length in PISA Particles on Pickering Emulsion

The morphology of polymeric nanoparticles prepared by polymerization-induced self-assembly(PISA)is depended on the degree of polymerization of the solvophilic and solvophobic blocks.Herein,a series of poly(N,N-dimethylaminoethyl methacrylate)-b-poly(benzyl methacrylate)(PDMA-b-PBzMA)diblock copolymer spherical nanoparticles were synthesized via reversible addition-frag-mentation chain transfer(RAFT)mediated PISA.These diblock copolymer nanoparticles are with nearly the same hydrodynamic size and solvophobic chain length,but with different solvophilic chain length.We used these nanoparticles to stabilize the oil-in-water Pickering emulsion.We find that the stability of Pickering emulsion increases with the length of solvophilic chain of the nanoparticles.Moreover,the droplet size of the Pickering emulsion can be tailored by varying the oil/water ratio and concentration of nanoparticles.