Solvent-enhanced Depolymerization of Lignin under Microwave Irradiation

Lignin is considered an ideal natural material for the production of sustainable monophenols.In this study,a microwave-assisted depolymerization(MAD)strategy was developed.The introduction of solvent vapors in the dynamic vapor flow reaction system was performed to enhance the lignin conversion efficiency.The results showed that no liquid products were generated from the MAD of lignin without solvent vapors.With the introduction of solvents(CH_(3)OH,HCHO,HCOOH,and CH_(2)Cl_(2)),liquid products appeared(especially with CH_(2)Cl_(2),which had the highest yield of 41.9 wt%).Results from gas chromatography/mass spectrometry of liquid products showed that seven kinds of compounds,including guaiacols,phenols,syringols,methoxyphenyls,heterocycles,esters,and aromatics were identified.CH_(2)Cl_(2) can significantly enhance the production of monophenols(guaiacols,phenols,and syringols).The introduction of these solvent vapors can also facilitate the generation of porous char with high Brunauer-Emmett-Teller specific surface areas.Some carbon nanospheres deposited on the surface of the char were obtained with the assistance of CH_(2)Cl_(2).This study provides a facile method for the utilization of lignin in the field of bio-based fine chemicals.

Close-loop recyclable and flexible halide perovskite@wool keratin sensor with piezoelectric property

Halide perovskites with excellent piezoelectric properties,but their poor stability hinders their largescale application.Herein,a sandwich-structured halide perovskite flexible sensor with good stability was developed according to a three-step procedure as follows:(ⅰ) in-situ growth of wool keratinCsPbBr_(3)(WK-CsPbBr_(3)) using wool keratin in interfacial passivation and coating,(ⅱ) electrospinning of a wool keratin-CsPbBr_(3)/polyacrylonitrile(WCP) nanofiber film,and(ⅲ) coating of the WCP nanofiber with polydimethylsiloxane(PDMS) to obtain a sensor(WCPP).The sensor could generate a piezoelectric voltage of 7.8 V at a pressure of 6 kPa in the stages of pressing and releasing,and the output characteristics did not decline even after 10,000 cycles.Compared to the 4-month stability of the perovskite sensor,WCPP sensor exhibited the output performance even after 16 months,which indicated that wool keratin as a multidentate improved the stability of the halide perovskite.Additionally,the sensor displayed a self-cleaning property and could also light up 14 commercial LEDs.The close-loop recycling of the lead halide perovskite was achieved by dissolving the WCP nanofiber film in DMF and then reelectrospinning.Therefore,the method proposed is a step forward for achieving the commercialization of WK-CsPbBr_(3) and providing new avenues for further utilization of wool waste.

Interaction between PCC Filler and Cellulosic Fiber in Fiber/Filler Co-refining System

Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the adding amount of filler in paper production.In this study,we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper;moreover,the synergistic interaction between fibers and precipitated calcium carbonate(PCC)fillers in the co-refining process was investigated.Results of fiber separation and PCC particle size analysis showed that,compared with conventional refining,the content of fines increased,whereas the PCC particle size decreased.More importantly,composites were formed between the PCC and fines,which promoted strength improvement of paper.Physical tests show that the tensile index of paper with 15%PCC content increased by 22%compared with that of the paper filled by conventional method,whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content.These findings provide a basis for the further development of co-refining filling technology.

Hyperbranched polymer surfactant: synthesis, characterization and surface tension activity

A series of hyperbranched polymer surfactants(HBP-C8,HBP-C12 and HBP-C16)were synthesized by the reaction between hydroxyl-terminated hyperbranched polymers(HBP)and fatty acyl chloride.The structure of obtained hyperbranched polymer surfactant was characterized by FTIR,NMR and GPC.The results showed that the products have amphiphilic structure.The thermal property of the hyperbranched polymer surfactant investigated by DSC and TGA was strongly influenced by the length of end alkyl chain.Surface activity of hyperbranched polymer surfactant was analyzed by surface tension method and UV spectrophotometry,respectively.The results showed that hyperbranched polymer surfactant took on better surface activity,which can effectively reduce the surface tension of the water.The hyperbranched polymer surfactant has a lower critical micelle concentration(CMC)and displays single molecular micellar properties,which can package small hydrophilic molecules in relatively low concentration.