The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibr...The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibrium molecular dynamics simulations to investigate the shear response of the confined simple liquid as well as the n-hexadecane ultrathin films. The shear viscosity of the confined simple liquid increases with the decrease of the film thickness. Apart from the well-known ordered structure, the confined n-hexaxiecane exhibited a transition from 7 layers to 6 in our simulations while undergoing an increasing shear velocity. Various slip regimes of the confined n-hexadecane were obtained. Viscosity coefficients of individual layers were examined and the results revealed that the local viscosity＇coefficient varies with the distance from the wall. The individual n-hexadecane layers showed the shear-thinning behaviors which can be correlated with the occurrence of the slip. This study aimed at elucidating the detailed shear response of the confined liquid and may be used in the design and application of microand nano-devices.展开更多
In this work,we report that high catalytic performance of metal–organic frameworks(MOFs)can be obtained through a synergistic effect of postsynthetic modification of MOF nanoparticles and liquid superwetting and conf...In this work,we report that high catalytic performance of metal–organic frameworks(MOFs)can be obtained through a synergistic effect of postsynthetic modification of MOF nanoparticles and liquid superwetting and confinement in the MOF coating.Specifically,2-ureido-4[1H]pyrimidinone(UPy)functionalized polysiloxanes were covalently appended onto the UiO-66 nanoparticles via a postsynthetic approach,which were further anchored onto different porous films through multivalent hydrogen bonding of the UPy motifs.The hydrophobic MOF coating can preserve the porosity of the solid substrates,enable rapid liquid superwetting and confinement within the porous substrates.Using the Knoevenagel condensation as a modeled system,robust and highly catalytic performances of the MOF coating were observed on a range of aldehyde substrates.Gram-scale production of chromene,a pharmaceutical which is typically synthesized via expensive catalysis,was successfully demonstrated on the MOF coating with high yielding rates,demonstrating the great potential of the MOF coating in pharmaceutical synthesis.展开更多
基金supported by the National Natural Science Foundation of China (NSFC, Nos. 60936001 and 11072244)the National Basic Research Program of China (973 Program, No. 2007CB310500)the Shanghai Supercomputer Center
文摘The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibrium molecular dynamics simulations to investigate the shear response of the confined simple liquid as well as the n-hexadecane ultrathin films. The shear viscosity of the confined simple liquid increases with the decrease of the film thickness. Apart from the well-known ordered structure, the confined n-hexaxiecane exhibited a transition from 7 layers to 6 in our simulations while undergoing an increasing shear velocity. Various slip regimes of the confined n-hexadecane were obtained. Viscosity coefficients of individual layers were examined and the results revealed that the local viscosity＇coefficient varies with the distance from the wall. The individual n-hexadecane layers showed the shear-thinning behaviors which can be correlated with the occurrence of the slip. This study aimed at elucidating the detailed shear response of the confined liquid and may be used in the design and application of microand nano-devices.
基金X.Y.acknowledges the Research Grant Council of Hong Kong(Nos.11305219 and 11307220)CityU Applied Research Grant(ARG,No.9667203)+2 种基金Shenzhen Basic Research Program(No.JCYJ20210324134009024)Z.X.acknowledges a Shenzhen-HKMacao Science and Technology Grant(type CNo.SGDX2020110309300301)from the Science,Technology,and Innovation Commission of Shenzhen Municipality.
文摘In this work,we report that high catalytic performance of metal–organic frameworks(MOFs)can be obtained through a synergistic effect of postsynthetic modification of MOF nanoparticles and liquid superwetting and confinement in the MOF coating.Specifically,2-ureido-4[1H]pyrimidinone(UPy)functionalized polysiloxanes were covalently appended onto the UiO-66 nanoparticles via a postsynthetic approach,which were further anchored onto different porous films through multivalent hydrogen bonding of the UPy motifs.The hydrophobic MOF coating can preserve the porosity of the solid substrates,enable rapid liquid superwetting and confinement within the porous substrates.Using the Knoevenagel condensation as a modeled system,robust and highly catalytic performances of the MOF coating were observed on a range of aldehyde substrates.Gram-scale production of chromene,a pharmaceutical which is typically synthesized via expensive catalysis,was successfully demonstrated on the MOF coating with high yielding rates,demonstrating the great potential of the MOF coating in pharmaceutical synthesis.
