To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in poly...To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in polymer matrices.Herein,on the basis of the three-dimensional(3D)skeleton and volume-exclusion effect of silane-modified tetra-needle ZnO(ST-ZnO)whiskers and the high conductivity of two-dimensional MXene nanosheets,multifunctional MXene/ST-ZnO/waterborne polyurethane(MTW)nanocomposite films are fabricated by coating of MXene on ST-ZnO followed by compounding with waterborne polyurethane.The 3D four-needles of the whiskers facilitate the formation of an interconnecting network in the waterborne polyurethane matrix,while the coating of MXene efficiently makes the interconnecting network of the whiskers conductive at a low amount of the MXene.The resultant MTW ternary nanocomposite film exhibits not only a high electrical conductivity of 4.8×10^(4)S/m,but also an excellent electromagnetic interference shielding effectiveness of over 70 dB in the X-band at a low thickness of 100µm.In addition,the ternary film also exhibits outstanding Joule heating performances with an equilibrium temperature of 113℃at a low driving voltage of 3 V.The multifunctional nanocomposite films are promising for applications in portable and wearable electronics and flexible electromagnetic interference shielding devices.展开更多
The use of organic catalysis AcrH2 enables the direct β-trifluoromethylation of carbonyl compounds by atom transfer radical addition reactions with broad substrate scopes under mild conditions.This operationally simp...The use of organic catalysis AcrH2 enables the direct β-trifluoromethylation of carbonyl compounds by atom transfer radical addition reactions with broad substrate scopes under mild conditions.This operationally simple and robust protocol successfully converts a variety of β-chloro carbonyl compounds into the corresponding α-chloro-β-fluoroalkylcarbonyl products.A significant advantage of this method is that it does not require the use of a metal catalyst,thereby avoiding metal residue problems in drug synthesis.展开更多
基金the National Natural Science Foundation of China(Nos.51922020 and 52090034)the Fundamental Research Funds for the Central Universities(Nos.BHYC1707B and XK1802-2).
文摘To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in polymer matrices.Herein,on the basis of the three-dimensional(3D)skeleton and volume-exclusion effect of silane-modified tetra-needle ZnO(ST-ZnO)whiskers and the high conductivity of two-dimensional MXene nanosheets,multifunctional MXene/ST-ZnO/waterborne polyurethane(MTW)nanocomposite films are fabricated by coating of MXene on ST-ZnO followed by compounding with waterborne polyurethane.The 3D four-needles of the whiskers facilitate the formation of an interconnecting network in the waterborne polyurethane matrix,while the coating of MXene efficiently makes the interconnecting network of the whiskers conductive at a low amount of the MXene.The resultant MTW ternary nanocomposite film exhibits not only a high electrical conductivity of 4.8×10^(4)S/m,but also an excellent electromagnetic interference shielding effectiveness of over 70 dB in the X-band at a low thickness of 100µm.In addition,the ternary film also exhibits outstanding Joule heating performances with an equilibrium temperature of 113℃at a low driving voltage of 3 V.The multifunctional nanocomposite films are promising for applications in portable and wearable electronics and flexible electromagnetic interference shielding devices.
基金We gratefully acknowledge financial support from the National Natural Science Foundation of China(Nos.21502038,21472033,and 21871074)the CPSF(Nos.2016M600478 and 2017T100444)the Fundamental Research Funds for the Central Universities.
文摘The use of organic catalysis AcrH2 enables the direct β-trifluoromethylation of carbonyl compounds by atom transfer radical addition reactions with broad substrate scopes under mild conditions.This operationally simple and robust protocol successfully converts a variety of β-chloro carbonyl compounds into the corresponding α-chloro-β-fluoroalkylcarbonyl products.A significant advantage of this method is that it does not require the use of a metal catalyst,thereby avoiding metal residue problems in drug synthesis.
