The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequentl...The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequently,low-energy anti/de-icing methods based on superhydrophobic surfaces have attracted widespread attention.Previous studies have demonstrated that for stationary components,superhydrophobic surfaces can significantly reduce anti-icing energy consumption by altering the flow behavior of runback water.However,for rotating inlet components of aero-engines,the effectiveness of superhydrophobic surfaces and the influence of surface wettability on the evolution of runback water flow remain unclear due to the effects of centrifugal and Coriolis forces.This study establishes a 3D liquid water flow simulation model using the volume of fluid(VOF)method to investigate the effects of rotational speed,airflow velocity,and surface wettability on the runback water flow behavior over the rotating spinner under dynamic rotation conditions.The results show that the rotational effects and surface wettability mutually reinforce one another.Specifically,increasing the rotational speed and contact angle can both enhance the flow velocity of liquid water and accelerate the breakup and rupture of liquid film,leading to the formation of rivulets,droplets,and subsequent detachment from the surface.A theoretical model based on force balance is proposed to describe the evolution of runback water flow,and the analysis reveals that as the rotational speed and contact angle increase,the water film is more likely to break up to form rivulets and beads,and the critical radius for droplet detachment from the surface decreases,making it easier removal from the surface.展开更多
Polymerizable ionic liquid copolymer P（MMA-co-BVIm-Br） was synthesized by radical polymerization technique, and characterized by Fourier transform infrared spectrometry （FTIR）, 1H Nuclear magnetic resonance （1H-...Polymerizable ionic liquid copolymer P（MMA-co-BVIm-Br） was synthesized by radical polymerization technique, and characterized by Fourier transform infrared spectrometry （FTIR）, 1H Nuclear magnetic resonance （1H-NMR） and gel permeation chromatography （GPC）. The resulting copolymer was used to prepare poly（vinylidene fluoride） （PVDF） blend membranes via a phase inversion method. The effects of the copolymer on the polymorphism, surface wettability and zeta potential （0 of the blend membranes were investigated by ATR-FTIR, contact angle instrument and zeta potential analyzer. Scanning electron microscopy （SEM and SEM-EDS） was also applied to investigate the morphology and the surface element changes of the fabricated membranes. The results indicated that P（MMA-co-BVIm-Br） copolymer existed on the surface of the membrane which made the blend membrane have a positive surface during the experimental pH range. The copolymer was also in favor of the formation of βcrystal phase in PVDF membranes. The contact angle experiment indicated that P（MMA-co-BVIm-Br） copolymer could switch the wettability of the blend membranes from hydrophilic to hydrophobic by exchanging Br- anion with PF6-. Compared with pure PVDF membranes, the water flux and water recovery flux of the blend membranes were enhanced obviously. The results from the flux recovery ratio （FR） and total fouling ratio （Rt） all suggested that the blend membranes had good anti-fouling properties.展开更多
The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping cha...The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping changes the chemical composition and wettability of the 3D graphene material.To realize the controllable surface wettability of graphene materials,aminobenzene sulfonic acid(ABSA)was selected as a typical doping agent for the preparation of nitrogen and sulfur co-doped 3D graphene foam(SNGF)using a hydrothermal method.Different from using o-ABSA or p-ABSA as the dopant,SNGF with tunable surface wettability is obtained only when m-ABSA is used.This result indicates that the substituent position of-SO3H group in the benzene ring of ABSA is rather important for the tunable wettability.This work provides some theo retical foundations for dopant selection and some new insights in manipulating the properties of 3D graphene foams by adjusting the configuration of dopants.展开更多
In this work, three-dimensional graphene foams （GFs） are synthesized and characterized by scanning electron micro- scope （SEM） and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the...In this work, three-dimensional graphene foams （GFs） are synthesized and characterized by scanning electron micro- scope （SEM） and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the graphene covers the surface of nickel （Ni） foam uniformly. Raman spectra show that the percentages of monolayer, bilayer, trilayer, and multilayer graphenes are - 58%, - 32%, - 8%, and ,.o 2%, respectively. The contact angle （CA） （-- 12°） of water droplet （3 p-L） on GF is found to be larger than that on Ni foam （,- 107°）, indicating that graphenes have changed the surface wettability of the Ni foam. Meanwhile, the dynamic characteristics of CA of water droplet on GF are different from those on Ni foam. The mechanisms for different behaviors are discussed, which are attributed to volatilization and seepage of water droplets.展开更多
Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stabilit...Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in oil.Herein we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil(W/O)emulsion.Silanes with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface wettabilities.While all the modified membranes exhibited excellent separation of the W/O without Span 80(surfactant),the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/O.The presence of Span 80 reduced the interfacial tension of water droplets,making them easier to deform and penetrate the modified membrane with the lowest surface energy.It reveals that engineering proper surface wettability is the key to separating the oil and water phases.Besides,the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.展开更多
The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes(PHPs)under three modified surfaces(superhydrophilic evaporation secti...The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes(PHPs)under three modified surfaces(superhydrophilic evaporation section paired with superhydrophilic,superhydrophobic,and hybrid condensation section).The Volume of Fluid(VOF)model was utilized to capture the phase-change process within the PHPs.The study also evaluated the influence of surface wettability on fluid patterns and thermo-dynamic heat transfer performance under various heat fluxes.The results indicated that the effective nucleation and detachment of droplets are critical factors influencing the thermal performance of the PHPs.The overall heat transfer performance of the superhydrophobic surface was significantly improved at low heat flux.Under medium to high heat flux,the superhydrophilic condensation section exhibits a strong oscillation effect and leads to the thickening of the liquid film.In addition,the hybrid surface possesses the heat transfer characteristics of both superhydrophilic and superhydrophobic walls.The hybrid condensation section exhibited the lowest thermal resistance by 0.45 K/W at the heat flux of 10731 W/m^(2).The thermal resistance is reduced by 13.1%and 5.4%,respectively,compared to the superhydrophobic and superhydrophilic conditions.The proposed surface-modification method for achieving highly efficient condensation heat transfer is helpful for the design and operation of device-cooling components.展开更多
A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited o...A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited on copper foil via a modified anodization technology,and the growth degree and density of the Cu（OH）2 arrays may be controlled varying with position along the substrate by slowly adding aqueous solution of KOH into the two-electrode cell of an anodization system to form the gradient surface.The prepared surface was water resistant and thermal stable,which could keep its gradient wetting property after being immersed in water bath at 100℃ for 10 h.The results of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS） demonstrate that the distribution of Cu（OH）2 nanoribbon arrays on copper surface are responsible for the gradient wettability.展开更多
Surface wettability is important to design biointerfaces and fimctional biomaterials in various biological applications. However, to date, it remains some confusions about how cells would response to the surfaces with...Surface wettability is important to design biointerfaces and fimctional biomaterials in various biological applications. However, to date, it remains some confusions about how cells would response to the surfaces with different wettabilities. Herein, we systematically explore the adhesive spectra of cells to the surface with wettability gradient from superhydrophilicity to superhydrophobicity, clarifying the effect of wettability on cell adhesion. We envision that this study may provide valuable information for the design of biomedical implants with controllable cell adhesion, such as neural interface devices and flexible implant.展开更多
Based on 1971-2005 monthly mean maximum/minimum temperature,wind speed,relative humidity,sunshine duration,and precipitation data at 25 stations over the Tibetan Plateau,a study of the largest potential evapotranspira...Based on 1971-2005 monthly mean maximum/minimum temperature,wind speed,relative humidity,sunshine duration,and precipitation data at 25 stations over the Tibetan Plateau,a study of the largest potential evapotranspiration（LPE） is performed by using the Penman-Monteith model.The surface wettability index（SWI） is calculated and examined,together with its space distribution,interannual and seasonal variations,as well as associated causes.The results suggest that the annual area rainfall exhibits a pronounced increasing trend at 15.0 mm per decade;the annual LPE shows a different-degree decrease at-4.6—-71.6 mm/10 yr.In the southwestern Ngari prefecture and Nyalam county,the annual SWI displays insignificant decline trends compared to increasing trends in other areas of Tibet（0.02-0.09 per decade）.For Tibet,on average,the SWI experiences a noticeable rise at 0.04/10 yr,particularly in 1981-2005.On a seasonal basis,the SWI shows increasing trends,especially in summer.In the 1970s-1980s,the interannual variation is characterized mainly by lower temperature and lower humidity.From the 1990s,air temperature keeps on rising,leading to an appreciable increase in SWI,displayed as a type of warm and humid climate.The salient increases（decrease） of precipitation and relative humidity（mean temperature daily range） are the principal causes of the greatly enhanced SWI in the region.The pronounced decrease in mean wind and sunshine duration also plays an active role.展开更多
Recently,smart superwetting porous materials have aroused much attention,and it is well known that tunable surface wettability and pore structure/size are extremely important for their functions.However,only one facto...Recently,smart superwetting porous materials have aroused much attention,and it is well known that tunable surface wettability and pore structure/size are extremely important for their functions.However,only one factor can be regulated on existing materials,which significantly restricts their controllability,functions,and applications.A new material was prepared by electrodepositing a layer of polypyrrole on a shape memory sponge,on which switchable superhydrophobicity/superhydrophilicity and adjustable pore size within the range of about 28 nm to 895μm can be observed.Through synergistically tuning the wettability and pore size,both ON/OFF water permeation and accurate flux can be obtained.Meanwhile,we also applied the sponge for molecule release,and diverse release manners with precise/smart controllability can be accomplished.This paper reports for the first time a smart material with controllability in both surface wetting and pore size,which provides a new strategy for the preparation of novel smart superwetting porous materials.展开更多
Loop heat pipes(LHPs),as high-efficiency heat dissipation components,are considered to be superior thermal conductors beyond any known materials.To apply LHPs to mobile electronics,a small,thin and compact system need...Loop heat pipes(LHPs),as high-efficiency heat dissipation components,are considered to be superior thermal conductors beyond any known materials.To apply LHPs to mobile electronics,a small,thin and compact system needs to be designed.However,with the trend of miniaturization,the heat transfer performance of LHPs degrades rapidly due to the significant increase of working fluid backflow resistance.This work aims to propose an effective solution to this problem.In this work,the surface wettability gradient(SWG)is introduced into the ultra-thin LHP,and the influence of SWG on mass and heat transfer performance is studied comprehensively by using a transient three-dimensional numerical model.It is observed that the SWG can significantly increase the vapor-liquid circulation efficiency and improve heat transfer performance.Numerical experiments have been performed to compare the two kinds of LHPs with and without SWG.At the heat load of 4–6 W,the start-up time for LHP with SWG is shortened by 11.5%and the thermal resistance is reduced by about 44.3%,compared with the LHP without SWG.This work provides a solution for the performance-degradation problem caused by miniaturization,as a numerical reference for experiments.展开更多
Mytilus galloprovincialis is a major fouling organism in the inter-tidal zone.However,the interactions between M.galloprovincialis plantigrade settlement,biofilm characteristics,and surface wettability remains unknown...Mytilus galloprovincialis is a major fouling organism in the inter-tidal zone.However,the interactions between M.galloprovincialis plantigrade settlement,biofilm characteristics,and surface wettability remains unknown.Here,we examined M.galloprovincialis plantigrade settlement responses to marine biofilms(BFs)on surfaces of varying wettability.No significant difference in mussel settlement was observed on young BFs(7 d)on surfaces of differing wettability;while settlement decreased on older BFs(14,21,and 28 d)formed on low compared to high wettability surfaces.Surface wettability affected BF characteristics.The standardized harmonic mean and water contact angles values were not correlated with diatom density and chlorophyll a concentration,but were correlated with bacterial density,dry weight,and thickness.Denaturing gradient gel electrophoresis revealed that bacterial community structure differed on BFs on surfaces of varying wettability.Thus,surface wettability affects biofilm characteristics,and the subsequent changes in BF characteristics may be responsible for the variation in biofilm-inducing activity of M.galloprovincialis plantigrade settlement.展开更多
Droplet controllable manipulation over a wide temperature range has promising applications in microelectronic heat dissipation, inkjet printing, and high temperature microfluidic system. However, the fabrication of a ...Droplet controllable manipulation over a wide temperature range has promising applications in microelectronic heat dissipation, inkjet printing, and high temperature microfluidic system. However, the fabrication of a platform for controllable droplet manipulation using the methods commonly used in industry remains a tremendously challenge. The popular method of controlling droplets is highly dependent on external energy input and has relatively poor controllability in terms of droplet motion behaviors and manipulation environment, such as distance, velocity, direction and a wide temperature range. Here, we report a facile and industrially applicable method for preparing Al superhydrophobic (S-phobic) surfaces, which enables controlled droplet bouncing, evaporation, and transport over a wide temperature range. Systematic mechanistic studies are also investigated. Extreme wettability surfaces were prepared on Al substrate by a composite process of electrochemical mask etching and micro-milling. To investigate the evaporation process and thermal coupling characteristics, controlled evaporation and controlled bouncing of droplet in a wide temperature range were conducted. Based on the evaporation regulation and bouncing mechanism of droplets on an extreme wettability surface, by using Laplace pressure gradients and temperature gradients, we realized controlled transport of droplets with confluence, split-flow, and gravity-resistant transport over a wide temperature range, offering a potential platform for a series of applications, such as new drug candidates and water collection.展开更多
We used silane coupling agents to improve the bonding ability between wheat straw particles and UF resin, and investigated surface properties （wettability and surface roughness） and hardness of parti-cleboard made f...We used silane coupling agents to improve the bonding ability between wheat straw particles and UF resin, and investigated surface properties （wettability and surface roughness） and hardness of parti-cleboard made from UF-bonded wheat straw （Triticum aestivum L.） combined with poplar wood as affected by silane coupling agent content and straw/poplar wood particle ratios. We manufactured one-layered particleboard panels at four different ratios of straw to poplar wood par-ticles （0%, 15%, 30% and 45% wheat straw） and silane coupling agent content at three levels of 0, 5% and 10%. Roughness measurements, average roughness （Ra）, mean peak-to-valley height （Rz）, and root mean square roughness （Rq） were measured on unsanded samples by using a fine stylus tracing technique. We obtained contact angle measurements by using a goniometer connected to a digital camera and computer sys-tem. Boards containing greater amounts of poplar particles had superior hardness compared to control samples and had lower wettability. Panels made with higher amounts of silane had lower Rq values.展开更多
This work presents the potentiostatic anodization study of titania nanotube array films fabricated in fluoride-based organic electrolytes including DEG(diethylene glycol)and EG(ethylene glycol).The work focuses on the...This work presents the potentiostatic anodization study of titania nanotube array films fabricated in fluoride-based organic electrolytes including DEG(diethylene glycol)and EG(ethylene glycol).The work focuses on the effect of important anodization parameters such as applied voltage,anodization time,and electrolyte type on nanotube morphologies and corresponding surface properties.Depending upon unique nanotube formation structures obtained from each anodizing electrolyte,wettability of the nanotube array layer has been determined by means of the contact angle measurement.The EG nanotube array films with close-packing cell orientation are found to show hydrophilic behavior.While the well separated DEG nanotube array films are found to exhibit hydrophobic behavior,with the characteristics of more discrete,wider cell separation obtained through manipulating the electrolyte conditions and the fabrication techniques offering considerable prospects for developing the superhydrophobic sample surface.Such formation structures observed for the DEG fabricated nanotube is believed to play a prominent role in determining the surface wettability of the anodized nanotube array film.The achieved result in this work is anticipated to pave the way to other relevant applications,where interfacial properties are critically concerned.展开更多
To improve the controllability of the wall-wetting process after the fuel spray-wall impingement in internal combustion engines,the methods of laser etching,chemical etching and surface free energy modification are us...To improve the controllability of the wall-wetting process after the fuel spray-wall impingement in internal combustion engines,the methods of laser etching,chemical etching and surface free energy modification are used to prepare biomimetic structured surfaces with different wettability.The impingement processes of diesel and n-butanol sprays on the walls under different conditions are experimentally investigated.As the surface oleophilicity increases,the spreading radius of wall-impinging sprays decreases.At about 5 s after the fuel injections,the fuel spray droplets hit the walls for the first time,and the secondary breakup and rebound occur.The mixture concentrations of different fuels hitting the various walls reach the peak value.Under a higher surface temperature,the peak value of the mixture concentration is mainly related to the heat flux to the fuel droplets in different boiling regimes from the metal surfaces.The concentration of the air–fuel mixture in the near wall region increases with increasing surface oleophilicity,increasing wall temperature and decreasing ambient pressure.Compared with diesel,n-butanol presents a higher air–fuel mixture concentration in the near wall region.展开更多
The local overheating issue is a serious threat to the safe operation of data centers(DCs).The chip level liquid cooling with pool boiling is expected to solve this problem.The effect of nano configuration and surface...The local overheating issue is a serious threat to the safe operation of data centers(DCs).The chip level liquid cooling with pool boiling is expected to solve this problem.The effect of nano configuration and surface wettability on the boiling characteristics of copper surfaces is studied using molecular dynamics(MD)simulation.The argon is chosen as the coolant,and the wall temperature is 300 K.The main findings and innovations are as follows.(1)Compared to the smooth surface and fin surface,the cylindrical nano cavity obtains the superior boiling performance with earlier onset of nucleate boiling(ONB),larger heat flux because of the higher heat transport rate.(2)The nano cavity with hydrophilicity can improve the response speed and heat dissipation efficiency.Compared to the contact angleθ=121°,the formation times of nucleate bubble and film boiling for theθ=0°are reduced by 90.84%and 93.57%,respectively.(3)A deeper cavity of 3.3 nm is beneficial for triggering boiling and improving the heat dissipation rate.The highest heat flux can be achieved at 21.86 x 10°W/m2,which can meet the cooling requirements of the micro devices with ultra-high heat flux(107-108 W/m2).The coupling effect of nano configuration and surface wettability is illustrated,and the essential reasons for the enhanced heat transport are revealed.The findings can guide the optimization of cooling systems and promote the practical application of phase change liquid cooling in DCs.展开更多
Using molecular dynamics simulations, we have revealed a novel wetting phenomenon with a droplet on composite structures formed by embedded water into(111) surface of β-cristobalite hydroxylated silica. This can be a...Using molecular dynamics simulations, we have revealed a novel wetting phenomenon with a droplet on composite structures formed by embedded water into(111) surface of β-cristobalite hydroxylated silica. This can be attributed to the formation of a composite structure composed of embedded water molecules and the surface hydroxyl(–OH) groups,which reduces the number of hydrogen bonds between the composite structure and the water droplet above the composite structure. Interestingly, a small uniform strain(±3%) applied to the crystal lattice of the hydroxylated silica surface can result in a notable change of the contact angles(> 40°) on the surface. The finding provides new insights into the correlation between the molecular-scale interfacial water structures and the macroscopic wettability of the hydroxylated silica surface.展开更多
Directional fluid transport is of significan</span><span style="font-family:Verdana;">ce</span><span style="font-family:Verdana;"> to many physical processes in nature. How ...Directional fluid transport is of significan</span><span style="font-family:Verdana;">ce</span><span style="font-family:Verdana;"> to many physical processes in nature. How to manipulate this process by man-made material is still a key challenge to scientists. In this study, Janus fabric was constructed by electrospinning a layer of polyvinylidene fluoride (PVDF) nanofibers on woven cotton or gauze. The chemical composition, morphology and surface wettability of two sides of Janus fabric were characterized by infrared spectroscopy, scanning electron microscope (SEM) and contact angle measurement. By controlling the PVDF electrospinning time, the maximum hydrostatic pressure of Janus fabric with different PVDF thickness was measured. It was found that PVDF/gauze is more favorable for unidirectional water transportation, and the moisture also can transfer from hydrophobic side to hydrophilic side. With the advantages of facile preparation, low-cost and one-way water/moisture transportation, the Janus fabric prepared in this study can be applied for water separation, humidity transfer and water collection from the air.展开更多
基金supported by the National Natural Science Foundation of China(No.12172029)the open Resarch Project of Key Laboratory of Icing and Anti/De-icing of CARDC(No.IADL 20230101)。
文摘The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequently,low-energy anti/de-icing methods based on superhydrophobic surfaces have attracted widespread attention.Previous studies have demonstrated that for stationary components,superhydrophobic surfaces can significantly reduce anti-icing energy consumption by altering the flow behavior of runback water.However,for rotating inlet components of aero-engines,the effectiveness of superhydrophobic surfaces and the influence of surface wettability on the evolution of runback water flow remain unclear due to the effects of centrifugal and Coriolis forces.This study establishes a 3D liquid water flow simulation model using the volume of fluid(VOF)method to investigate the effects of rotational speed,airflow velocity,and surface wettability on the runback water flow behavior over the rotating spinner under dynamic rotation conditions.The results show that the rotational effects and surface wettability mutually reinforce one another.Specifically,increasing the rotational speed and contact angle can both enhance the flow velocity of liquid water and accelerate the breakup and rupture of liquid film,leading to the formation of rivulets,droplets,and subsequent detachment from the surface.A theoretical model based on force balance is proposed to describe the evolution of runback water flow,and the analysis reveals that as the rotational speed and contact angle increase,the water film is more likely to break up to form rivulets and beads,and the critical radius for droplet detachment from the surface decreases,making it easier removal from the surface.
基金financially supported by the National Natural Science Foundation of China(Nos.51103130 and 21004051)Qianjiang Talents Project of Technology Office in Zhejiang Province(No.2013R10070)
文摘Polymerizable ionic liquid copolymer P（MMA-co-BVIm-Br） was synthesized by radical polymerization technique, and characterized by Fourier transform infrared spectrometry （FTIR）, 1H Nuclear magnetic resonance （1H-NMR） and gel permeation chromatography （GPC）. The resulting copolymer was used to prepare poly（vinylidene fluoride） （PVDF） blend membranes via a phase inversion method. The effects of the copolymer on the polymorphism, surface wettability and zeta potential （0 of the blend membranes were investigated by ATR-FTIR, contact angle instrument and zeta potential analyzer. Scanning electron microscopy （SEM and SEM-EDS） was also applied to investigate the morphology and the surface element changes of the fabricated membranes. The results indicated that P（MMA-co-BVIm-Br） copolymer existed on the surface of the membrane which made the blend membrane have a positive surface during the experimental pH range. The copolymer was also in favor of the formation of βcrystal phase in PVDF membranes. The contact angle experiment indicated that P（MMA-co-BVIm-Br） copolymer could switch the wettability of the blend membranes from hydrophilic to hydrophobic by exchanging Br- anion with PF6-. Compared with pure PVDF membranes, the water flux and water recovery flux of the blend membranes were enhanced obviously. The results from the flux recovery ratio （FR） and total fouling ratio （Rt） all suggested that the blend membranes had good anti-fouling properties.
基金the National Natural Science Foundation of China(No.21675133)。
文摘The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping changes the chemical composition and wettability of the 3D graphene material.To realize the controllable surface wettability of graphene materials,aminobenzene sulfonic acid(ABSA)was selected as a typical doping agent for the preparation of nitrogen and sulfur co-doped 3D graphene foam(SNGF)using a hydrothermal method.Different from using o-ABSA or p-ABSA as the dopant,SNGF with tunable surface wettability is obtained only when m-ABSA is used.This result indicates that the substituent position of-SO3H group in the benzene ring of ABSA is rather important for the tunable wettability.This work provides some theo retical foundations for dopant selection and some new insights in manipulating the properties of 3D graphene foams by adjusting the configuration of dopants.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10774032 and 90921001)the Key Knowledge Innovation Project ofthe Chinese Academy of Sciences on Water Science Research,Instrument Developing Project of the Chinese Academy of Sciences(Grant No.Y2010031)
文摘In this work, three-dimensional graphene foams （GFs） are synthesized and characterized by scanning electron micro- scope （SEM） and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the graphene covers the surface of nickel （Ni） foam uniformly. Raman spectra show that the percentages of monolayer, bilayer, trilayer, and multilayer graphenes are - 58%, - 32%, - 8%, and ,.o 2%, respectively. The contact angle （CA） （-- 12°） of water droplet （3 p-L） on GF is found to be larger than that on Ni foam （,- 107°）, indicating that graphenes have changed the surface wettability of the Ni foam. Meanwhile, the dynamic characteristics of CA of water droplet on GF are different from those on Ni foam. The mechanisms for different behaviors are discussed, which are attributed to volatilization and seepage of water droplets.
基金supported by the Guangzhou Science and Technology Plan(No.202102020219)National Natural Science Foundation of China(No.51908565)High-level talent research startup project of Chongqing Technology and Business University(No.2356007)。
文摘Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in oil.Herein we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil(W/O)emulsion.Silanes with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface wettabilities.While all the modified membranes exhibited excellent separation of the W/O without Span 80(surfactant),the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/O.The presence of Span 80 reduced the interfacial tension of water droplets,making them easier to deform and penetrate the modified membrane with the lowest surface energy.It reveals that engineering proper surface wettability is the key to separating the oil and water phases.Besides,the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.
基金support by Beijing Natural Science Foundation(3194046)BUCEA Post Graduate Innovation Project.
文摘The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes(PHPs)under three modified surfaces(superhydrophilic evaporation section paired with superhydrophilic,superhydrophobic,and hybrid condensation section).The Volume of Fluid(VOF)model was utilized to capture the phase-change process within the PHPs.The study also evaluated the influence of surface wettability on fluid patterns and thermo-dynamic heat transfer performance under various heat fluxes.The results indicated that the effective nucleation and detachment of droplets are critical factors influencing the thermal performance of the PHPs.The overall heat transfer performance of the superhydrophobic surface was significantly improved at low heat flux.Under medium to high heat flux,the superhydrophilic condensation section exhibits a strong oscillation effect and leads to the thickening of the liquid film.In addition,the hybrid surface possesses the heat transfer characteristics of both superhydrophilic and superhydrophobic walls.The hybrid condensation section exhibited the lowest thermal resistance by 0.45 K/W at the heat flux of 10731 W/m^(2).The thermal resistance is reduced by 13.1%and 5.4%,respectively,compared to the superhydrophobic and superhydrophilic conditions.The proposed surface-modification method for achieving highly efficient condensation heat transfer is helpful for the design and operation of device-cooling components.
基金Project(S2012010010417)supported by the Guangdong Natural Science Foundation,ChinaProject(20130172110008)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited on copper foil via a modified anodization technology,and the growth degree and density of the Cu（OH）2 arrays may be controlled varying with position along the substrate by slowly adding aqueous solution of KOH into the two-electrode cell of an anodization system to form the gradient surface.The prepared surface was water resistant and thermal stable,which could keep its gradient wetting property after being immersed in water bath at 100℃ for 10 h.The results of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS） demonstrate that the distribution of Cu（OH）2 nanoribbon arrays on copper surface are responsible for the gradient wettability.
基金supported by the National Natural Science Foundation of China(21425314,21501184,21434009,21421061,21504098)the Key Research Program of the Chinese Academy of Sciences(KJZD-EW-M01)+2 种基金Ministry of Science and Technology(2013YQ190467)the Top-Notch Young Talents Program of ChinaBeijing Municipal Science&Technology Commission(Z161100000116037)
文摘Surface wettability is important to design biointerfaces and fimctional biomaterials in various biological applications. However, to date, it remains some confusions about how cells would response to the surfaces with different wettabilities. Herein, we systematically explore the adhesive spectra of cells to the surface with wettability gradient from superhydrophilicity to superhydrophobicity, clarifying the effect of wettability on cell adhesion. We envision that this study may provide valuable information for the design of biomedical implants with controllable cell adhesion, such as neural interface devices and flexible implant.
基金Supported by the National Natural Science Foundation of China under Grant No. 40865008the CMA Chengdu Institute of Plateau Meteorology under Grant No. LPM2008010
文摘Based on 1971-2005 monthly mean maximum/minimum temperature,wind speed,relative humidity,sunshine duration,and precipitation data at 25 stations over the Tibetan Plateau,a study of the largest potential evapotranspiration（LPE） is performed by using the Penman-Monteith model.The surface wettability index（SWI） is calculated and examined,together with its space distribution,interannual and seasonal variations,as well as associated causes.The results suggest that the annual area rainfall exhibits a pronounced increasing trend at 15.0 mm per decade;the annual LPE shows a different-degree decrease at-4.6—-71.6 mm/10 yr.In the southwestern Ngari prefecture and Nyalam county,the annual SWI displays insignificant decline trends compared to increasing trends in other areas of Tibet（0.02-0.09 per decade）.For Tibet,on average,the SWI experiences a noticeable rise at 0.04/10 yr,particularly in 1981-2005.On a seasonal basis,the SWI shows increasing trends,especially in summer.In the 1970s-1980s,the interannual variation is characterized mainly by lower temperature and lower humidity.From the 1990s,air temperature keeps on rising,leading to an appreciable increase in SWI,displayed as a type of warm and humid climate.The salient increases（decrease） of precipitation and relative humidity（mean temperature daily range） are the principal causes of the greatly enhanced SWI in the region.The pronounced decrease in mean wind and sunshine duration also plays an active role.
基金supported by the National Natural Science Foundation of China (22075061, 21674030 and 51790502)
文摘Recently,smart superwetting porous materials have aroused much attention,and it is well known that tunable surface wettability and pore structure/size are extremely important for their functions.However,only one factor can be regulated on existing materials,which significantly restricts their controllability,functions,and applications.A new material was prepared by electrodepositing a layer of polypyrrole on a shape memory sponge,on which switchable superhydrophobicity/superhydrophilicity and adjustable pore size within the range of about 28 nm to 895μm can be observed.Through synergistically tuning the wettability and pore size,both ON/OFF water permeation and accurate flux can be obtained.Meanwhile,we also applied the sponge for molecule release,and diverse release manners with precise/smart controllability can be accomplished.This paper reports for the first time a smart material with controllability in both surface wetting and pore size,which provides a new strategy for the preparation of novel smart superwetting porous materials.
基金financial supports from the Science and Technology Innovation Commission of Shenzhen(Grant No.JCYJ20190809154007586)National Key Research and Development Program of China(Grant No.2017YFE0120800)+1 种基金National Natural Science Foundation of China(Grant No.U20A20241 and No.51702277)Science and Technology Development Fund of the Macao Special Administrative Region(Grant No.FDCT/013/2017/AMJ)。
文摘Loop heat pipes(LHPs),as high-efficiency heat dissipation components,are considered to be superior thermal conductors beyond any known materials.To apply LHPs to mobile electronics,a small,thin and compact system needs to be designed.However,with the trend of miniaturization,the heat transfer performance of LHPs degrades rapidly due to the significant increase of working fluid backflow resistance.This work aims to propose an effective solution to this problem.In this work,the surface wettability gradient(SWG)is introduced into the ultra-thin LHP,and the influence of SWG on mass and heat transfer performance is studied comprehensively by using a transient three-dimensional numerical model.It is observed that the SWG can significantly increase the vapor-liquid circulation efficiency and improve heat transfer performance.Numerical experiments have been performed to compare the two kinds of LHPs with and without SWG.At the heat load of 4–6 W,the start-up time for LHP with SWG is shortened by 11.5%and the thermal resistance is reduced by about 44.3%,compared with the LHP without SWG.This work provides a solution for the performance-degradation problem caused by miniaturization,as a numerical reference for experiments.
基金supported by the National Natural Science Foundation ofChina(Grant No.41476131)the Innovation Program of Shanghai Municipal Education Commission(Grant No.14ZZ143)the Shanghai Universities Plateau Discipline Project of Marine Sciences and the Peak Discipline Program for Fisheries from the Shanghai Municipal Government
文摘Mytilus galloprovincialis is a major fouling organism in the inter-tidal zone.However,the interactions between M.galloprovincialis plantigrade settlement,biofilm characteristics,and surface wettability remains unknown.Here,we examined M.galloprovincialis plantigrade settlement responses to marine biofilms(BFs)on surfaces of varying wettability.No significant difference in mussel settlement was observed on young BFs(7 d)on surfaces of differing wettability;while settlement decreased on older BFs(14,21,and 28 d)formed on low compared to high wettability surfaces.Surface wettability affected BF characteristics.The standardized harmonic mean and water contact angles values were not correlated with diatom density and chlorophyll a concentration,but were correlated with bacterial density,dry weight,and thickness.Denaturing gradient gel electrophoresis revealed that bacterial community structure differed on BFs on surfaces of varying wettability.Thus,surface wettability affects biofilm characteristics,and the subsequent changes in BF characteristics may be responsible for the variation in biofilm-inducing activity of M.galloprovincialis plantigrade settlement.
文摘Fluoroalkyl end-capped vinyltrimethoxysilane-<i><span style="font-family:Verdana;">N</span></i><span><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;">N</span></i></span><span style="font-family:Verdana;">-dimethylacrylamide cooli</span><span style="font-family:;" "=""><span style="font-family:Verdana;">gomer [R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(CH</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">-CHSi(OMe)</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">x</span></sub></i><span style="font-family:Verdana;">-(CH</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">-CHC(=O)NMe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">y</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">;R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;"> = CF(CF</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">)OC</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">F</span><sub><span style="font-family:Verdana;">7</span></sub><span style="font-family:Verdana;">:</span></span><span style="font-family:;" "=""><span style="font-family:Verdana;"> R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM)</span><i><sub><span style="font-family:Verdana;">x</span></sub></i><span style="font-family:Verdana;">-(DMAA)</span><i><sub><span style="font-family:Verdana;">y</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">] was synthesized by reaction of fluoroalkanoyl peroxide [R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-C(=O)O-O(O=)C-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">] with vinyltrimethoxysilane (VM) and </span><i><span style="font-family:Verdana;">N</span></i><span><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;">N</span></i></span><span style="font-family:Verdana;">-</span></span><span style="font-family:Verdana;">dimethylacrylamide (DMAA). The modified glass surface treated with the</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> cooligomeric nanoparticles [R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM-SiO</span><sub><span style="font-family:Verdana;">3/2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">x</span></sub></i><span style="font-family:Verdana;">-(DMAA)</span><i><sub><span style="font-family:Verdana;">y</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">] prepared under the sol-gel reaction of the cooligomer under alkaline conditions was found to exhibit an oleophobic/superhydrophilic property, although the corresponding fluorinated homooligomeric nanoparticles [R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM-SiO</span><sub><span style="font-family:Verdana;">3/2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">n</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">] afforded an </span><span style="font-family:Verdana;">oleophobic/hydrophobic property on the modified surface under similar </span><span style="font-family:Verdana;">con</span><span><span style="font-family:Verdana;">ditions. R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM-SiO</span><sub><span style="font-family:Verdana;">3/2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">n</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">/R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM-SiO</span><sub><span style="font-family:Verdana;">3/2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">x</span></sub></i><span style="font-family:Verdana;">-(DMAA)</span><i><sub><span style="font-family:Verdana;">y</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">/</span><b><i><span style="font-family:Verdana;">PSt</span></i></b><span style="font-family:Verdana;"> (micro-sized</span></span> <span style="font-family:Verdana;">polystyrene particles) composites, which were prepared by the sol-gel reac</span><span style="font-family:Verdana;">tions of the corresponding homooligomer and cooligomer in the presence of </span><b><i><span style="font-family:Verdana;">PSt </span></i></b><span style="font-family:Verdana;">particle under alkaline conditions, provided an oleophobic/superhydrophilic </span><span style="font-family:Verdana;">property on the modified surface. However, it was demonstrated that the</span><span><span style="font-family:Verdana;"> surface wettability on the modified surface treated with the R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM-</span></span><span><span style="font-family:Verdana;">SiO</span><sub><span style="font-family:Verdana;">3/2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">n</span></sub></i><span style="font-family:Verdana;">-</span></span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">/R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM-SiO</span><sub><span style="font-family:Verdana;">3/2</span></sub><span style="font-family:Verdana;">)</span><i><sub><span style="font-family:Verdana;">x</span></sub></i><span style="font-family:Verdana;">-(DMAA)</span><i><sub><span style="font-family:Verdana;">y</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">/</span><b><i><span style="font-family:Verdana;">PSt</span></i></b><span style="font-family:Verdana;"> composites changes dramatically from oleophobic/superhydrophilic to superoleophilic/superhydrophilic </span><span style="font-family:Verdana;">and superoleophilic/superhydrophobic characteristics, increasing with </span><span style="font-family:Verdana;">greater </span><span><span style="font-family:Verdana;">feed ratios (mg/mg) of the R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;">-(VM)</span><i><sub><span style="font-family:Verdana;">n</span></sub></i><span style="font-family:Verdana;">-R</span><sub><span style="font-family:Verdana;">F</span></sub><span style="font-family:Verdana;"> homooligomer in homooligo</span></span><span style="font-family:Verdana;">mer/cooligo</span></span><span style="font-family:Verdana;">mer from 0 to 100 in the preparation of the composites. Such controlled surfac</span>
基金supported by the National Key R&D Program of China(Grant No.2017YFE0116900)the National Natural Science Foundation of China(NSFC,Grant Nos.52275420 and 52130503)+1 种基金the Science and Technology Planning Project of Hunan Province(Grant No.2020WK2011)Postgraduate Scientific Research Innovation Project of Hunan Province(Grant No.CX20200409).
文摘Droplet controllable manipulation over a wide temperature range has promising applications in microelectronic heat dissipation, inkjet printing, and high temperature microfluidic system. However, the fabrication of a platform for controllable droplet manipulation using the methods commonly used in industry remains a tremendously challenge. The popular method of controlling droplets is highly dependent on external energy input and has relatively poor controllability in terms of droplet motion behaviors and manipulation environment, such as distance, velocity, direction and a wide temperature range. Here, we report a facile and industrially applicable method for preparing Al superhydrophobic (S-phobic) surfaces, which enables controlled droplet bouncing, evaporation, and transport over a wide temperature range. Systematic mechanistic studies are also investigated. Extreme wettability surfaces were prepared on Al substrate by a composite process of electrochemical mask etching and micro-milling. To investigate the evaporation process and thermal coupling characteristics, controlled evaporation and controlled bouncing of droplet in a wide temperature range were conducted. Based on the evaporation regulation and bouncing mechanism of droplets on an extreme wettability surface, by using Laplace pressure gradients and temperature gradients, we realized controlled transport of droplets with confluence, split-flow, and gravity-resistant transport over a wide temperature range, offering a potential platform for a series of applications, such as new drug candidates and water collection.
文摘We used silane coupling agents to improve the bonding ability between wheat straw particles and UF resin, and investigated surface properties （wettability and surface roughness） and hardness of parti-cleboard made from UF-bonded wheat straw （Triticum aestivum L.） combined with poplar wood as affected by silane coupling agent content and straw/poplar wood particle ratios. We manufactured one-layered particleboard panels at four different ratios of straw to poplar wood par-ticles （0%, 15%, 30% and 45% wheat straw） and silane coupling agent content at three levels of 0, 5% and 10%. Roughness measurements, average roughness （Ra）, mean peak-to-valley height （Rz）, and root mean square roughness （Rq） were measured on unsanded samples by using a fine stylus tracing technique. We obtained contact angle measurements by using a goniometer connected to a digital camera and computer sys-tem. Boards containing greater amounts of poplar particles had superior hardness compared to control samples and had lower wettability. Panels made with higher amounts of silane had lower Rq values.
文摘This work presents the potentiostatic anodization study of titania nanotube array films fabricated in fluoride-based organic electrolytes including DEG(diethylene glycol)and EG(ethylene glycol).The work focuses on the effect of important anodization parameters such as applied voltage,anodization time,and electrolyte type on nanotube morphologies and corresponding surface properties.Depending upon unique nanotube formation structures obtained from each anodizing electrolyte,wettability of the nanotube array layer has been determined by means of the contact angle measurement.The EG nanotube array films with close-packing cell orientation are found to show hydrophilic behavior.While the well separated DEG nanotube array films are found to exhibit hydrophobic behavior,with the characteristics of more discrete,wider cell separation obtained through manipulating the electrolyte conditions and the fabrication techniques offering considerable prospects for developing the superhydrophobic sample surface.Such formation structures observed for the DEG fabricated nanotube is believed to play a prominent role in determining the surface wettability of the anodized nanotube array film.The achieved result in this work is anticipated to pave the way to other relevant applications,where interfacial properties are critically concerned.
基金the financial support from the Natural Science Foundation of Jilin Province(Project code:20220101212JC)Jilin Province Specific Project of Industrial Technology Research&Development(Project code:2020C025-2)+2 种基金Free Exploration Project of Changsha Automotive Innovation Research Institute of Jilin University(Project code:CAIRIZT20220202)2021"Interdisciplinary Integration and Innovation"Project of Jilin University(Project code:XJRCYB07)Horizon 2020 MSCA(Project code:H2020-MSCA-RISE-778104-ThermaSMART).
文摘To improve the controllability of the wall-wetting process after the fuel spray-wall impingement in internal combustion engines,the methods of laser etching,chemical etching and surface free energy modification are used to prepare biomimetic structured surfaces with different wettability.The impingement processes of diesel and n-butanol sprays on the walls under different conditions are experimentally investigated.As the surface oleophilicity increases,the spreading radius of wall-impinging sprays decreases.At about 5 s after the fuel injections,the fuel spray droplets hit the walls for the first time,and the secondary breakup and rebound occur.The mixture concentrations of different fuels hitting the various walls reach the peak value.Under a higher surface temperature,the peak value of the mixture concentration is mainly related to the heat flux to the fuel droplets in different boiling regimes from the metal surfaces.The concentration of the air–fuel mixture in the near wall region increases with increasing surface oleophilicity,increasing wall temperature and decreasing ambient pressure.Compared with diesel,n-butanol presents a higher air–fuel mixture concentration in the near wall region.
基金the National Natural Science Foundation of China (No. 52406191, No. 52408123)the Science and Technology Project of Tianjin (No. 24YDTPJC00680).
文摘The local overheating issue is a serious threat to the safe operation of data centers(DCs).The chip level liquid cooling with pool boiling is expected to solve this problem.The effect of nano configuration and surface wettability on the boiling characteristics of copper surfaces is studied using molecular dynamics(MD)simulation.The argon is chosen as the coolant,and the wall temperature is 300 K.The main findings and innovations are as follows.(1)Compared to the smooth surface and fin surface,the cylindrical nano cavity obtains the superior boiling performance with earlier onset of nucleate boiling(ONB),larger heat flux because of the higher heat transport rate.(2)The nano cavity with hydrophilicity can improve the response speed and heat dissipation efficiency.Compared to the contact angleθ=121°,the formation times of nucleate bubble and film boiling for theθ=0°are reduced by 90.84%and 93.57%,respectively.(3)A deeper cavity of 3.3 nm is beneficial for triggering boiling and improving the heat dissipation rate.The highest heat flux can be achieved at 21.86 x 10°W/m2,which can meet the cooling requirements of the micro devices with ultra-high heat flux(107-108 W/m2).The coupling effect of nano configuration and surface wettability is illustrated,and the essential reasons for the enhanced heat transport are revealed.The findings can guide the optimization of cooling systems and promote the practical application of phase change liquid cooling in DCs.
基金Project supported by the National Natural Science Foundation of China (Grant No.11674345)the Key Research Program of Chinese Academy of Sciences(Grant No. QYZDJ-SSW-SLH019)the Fundamental Research Funds for the Central Universities,China。
文摘Using molecular dynamics simulations, we have revealed a novel wetting phenomenon with a droplet on composite structures formed by embedded water into(111) surface of β-cristobalite hydroxylated silica. This can be attributed to the formation of a composite structure composed of embedded water molecules and the surface hydroxyl(–OH) groups,which reduces the number of hydrogen bonds between the composite structure and the water droplet above the composite structure. Interestingly, a small uniform strain(±3%) applied to the crystal lattice of the hydroxylated silica surface can result in a notable change of the contact angles(> 40°) on the surface. The finding provides new insights into the correlation between the molecular-scale interfacial water structures and the macroscopic wettability of the hydroxylated silica surface.
文摘Directional fluid transport is of significan</span><span style="font-family:Verdana;">ce</span><span style="font-family:Verdana;"> to many physical processes in nature. How to manipulate this process by man-made material is still a key challenge to scientists. In this study, Janus fabric was constructed by electrospinning a layer of polyvinylidene fluoride (PVDF) nanofibers on woven cotton or gauze. The chemical composition, morphology and surface wettability of two sides of Janus fabric were characterized by infrared spectroscopy, scanning electron microscope (SEM) and contact angle measurement. By controlling the PVDF electrospinning time, the maximum hydrostatic pressure of Janus fabric with different PVDF thickness was measured. It was found that PVDF/gauze is more favorable for unidirectional water transportation, and the moisture also can transfer from hydrophobic side to hydrophilic side. With the advantages of facile preparation, low-cost and one-way water/moisture transportation, the Janus fabric prepared in this study can be applied for water separation, humidity transfer and water collection from the air.
