CN103723678B - Method for switching media for nano-particles or separating same from one another according to sizes and/or shapes of nano-particles - Google Patents
Method for switching media for nano-particles or separating same from one another according to sizes and/or shapes of nano-particles Download PDFInfo
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Abstract
The invention relates to a method for driving nano-particles by the aid of a density gradient centrifugation technology to penetrate oil-water phase interfaces so as to change the concentration the nano-particles and/or switching media. The method includes steps of (a), preparing initial water-based dispersion liquid of the nano-particles in first water-phase media or initial oil-base dispersion liquid of the nano-particles in first oil-phase media; (b), preparing second oil-phase media with the density higher than that of the first oil-phase media or second water-phase media with the density higher than that of the first water-phase media; (c), sequentially filling the second water-phase media, the second oil-phase media and the initial water-based dispersion liquid in aligned centrifuge tubes, or sequentially filling the second oil-phase media, the second water-phase media and the initial oil-based dispersion liquid into the aligned centrifuge tubes; (d), centrifugally treating the nano-particles at the rotational speed ranging from 1000rpm to 65000rpm for 5-600 minutes. The nano-particles penetrate the oil-water phase interfaces and are transferred into the bottommost media after the nano-particles are centrifugally treated, so that the concentration of the nano-particles can be changed, and/or the media are switched. The method further can be used for separating nano-particles with different sizes and/or shapes according to the sizes and/or the shapes of the nano-particles.
Description
Technical field
The invention belongs to nano-particle material technology field.
Background technology
In recent decades, with the progress of modern science and technology, nano material is being catalyzed, sensor, medicine, electronic device, too
Sun can all show huge potential with fields such as optics, and these performances are required for accurately controlling the size of particle, shape
Shape, concentration, whether surface functional group is clean etc..Thus to the process of some nano particles prepared by chemical method just particularly
Important.Just the nano particle of preparation is usually dispersed in medium, forms colloid.The method of traditional process nano particle is usually
By repeated centrifugation, supersound washing, come to realize, so, removes unnecessary medium and accessory substance takes time and effort, less efficient,
Washing repeatedly simultaneously is possible to lose the little nano particle of more size, and on the other hand, supersound washing repeatedly can be lost
Substantial amounts of surfactant and lead to irreversible reunion.
At present with regard to how separately obtaining the size nano particle different with pattern, technology comparative maturity, but whole
Individual process is often the process that a nano particle is diluted, and produces upper it is generally desirable to concentrating rather than diluting these nanometers
Grain.Additionally, in some field of nanometer technology, such as Nano medication field it is desirable to medium switching is carried out to nano particle, so that will
Used in nano particle preparation process, poisonous medium switches to harmless medium, how efficiently to carry out medium switching and not to damage
Lose the quantity of nano particle or property, be also a difficult problem in the industry.Therefore, urgent need searching in the art is a kind of quick, efficient, simple
Just and general method, to concentrate nano particle or to realize medium switching.
Content of the invention
In a first aspect, the present invention relates to one kind is ordered about nano particle using density gradient centrifugation and is passed through profit boundary
The method realizing its change in concentration and/or medium switching, comprises the steps：
A. prepare nano particle in the initial aqueous liquid dispersion in the first aqueous media or first in the first oil-phase medium
Beginning oily dispersion；
B. prepare the second oil-phase medium or second aqueous media with different densities, wherein said second oil-phase medium
Density is more than the density of the first oil-phase medium, and the density of the second aqueous media is more than the density of the first aqueous media；
C. take the second aqueous media to add centrifugation bottom of the tube, be subsequently adding the second oil-phase medium, be subsequently adding initially aqueous
Dispersion liquid；Or, take the second oil-phase medium to add centrifugation bottom of the tube, be subsequently adding the second aqueous media, be subsequently adding initial oil
Property dispersion liquid；
D. rotating speed be 1000-65000 rev/min, the time be 5-600 minute under conditions of carry out centrifugal treating so that
Nano particle passes through in the medium that profit boundary transfers to bottommost, realizes its change in concentration and/or medium switching.
Above technical scheme is the situation that nano particle only passes twice through profit boundary.Obviously, the method for the present invention
Can be generalized to the situation that nano particle passes through profit boundary more times.Therefore, in a broad sense, a second aspect of the present invention relates to
And a kind of order about nano particle using density gradient centrifugation and pass through that profit boundary realizes its change in concentration and/or medium is cut
The method changed, comprises the steps：
A. prepare nano particle in the initial aqueous liquid dispersion in the first aqueous media or first in the first oil-phase medium
Beginning oily dispersion；
B. prepare and there are a series of oil-phase mediums of different densities and a series of aqueous media, a series of wherein said oil phases
The density of medium Midst density reckling is more than the density of the first oil-phase medium, a series of described aqueous media Midst density recklings
Density is more than the density of the first aqueous media；Described oil-phase medium is immiscible with described aqueous media；
C. diminish successively and the alternate order of oil phase, aqueous phase from the bottom of centrifuge tube to top according to density, using described
A series of oil-phase mediums and a series of aqueous media filling centrifuge tube, and described initial aqueous dispersion liquid or initial oiliness are divided
Dispersion liquid is located at top, and so that top and the medium of bottommost is all aqueous phase or be all oil phase；
D. rotating speed be 1000-65000 rev/min, the time be 5-600 minute under conditions of carry out centrifugal treating so that
Nano particle repeatedly passes through in the medium that profit boundary transfers to bottommost, realizes its change in concentration and/or medium switching.
The third aspect, the present invention relates to one kind is ordered about nano particle using density gradient centrifugation and is passed through profit boundary
To realize this nano particle being carried out separate and/or by the detached method of pattern by size, comprise the steps：
A. prepare nano particle in the initial aqueous liquid dispersion in the first aqueous media or first in the first oil-phase medium
Beginning oily dispersion, this nano particle is of different sizes and/or pattern；
B. prepare and there are a series of oil-phase mediums of different densities and a series of aqueous media, a series of wherein said oil phases
The density of medium Midst density reckling is more than the density of the first oil-phase medium, a series of described aqueous media Midst density recklings
Density is more than the density of the first aqueous media；Described oil-phase medium is immiscible with described aqueous media；
C. diminish successively and the alternate order of oil phase, aqueous phase from the bottom of centrifuge tube to top according to density, using described
A series of oil-phase mediums and a series of aqueous media filling centrifuge tube, and described initial aqueous dispersion liquid or initial oiliness are divided
Dispersion liquid is located at top, and so that top and the medium of bottommost is all aqueous phase or be all oil phase；
D. rotating speed be 1000-65000 rev/min, the time be 5-600 minute under conditions of carry out centrifugal treating so that
There is specific dimensions scope and/or the nano particle of specific morphology repeatedly passes through the medium that profit boundary transfers to bottommost
In, and there is another specific dimensions scope and/or the nano particle of another specific morphology remains in its initial aqueous liquid dispersion
And/or in initial oily dispersion, thus realizing this nano particle being carried out separate by size and/or separate by pattern.
In above each aspect of the present invention, the nano particle described in step a is noble metal nano particles, oxidate nano
Grain, alloy nanoparticle or hydroxide nanoparticles, its particle size range is from 1 nanometer to 2 microns.
In above a first aspect of the present invention, described second oil-phase medium adopts hexamethylene, carbon tetrachloride, benzene, toluene, chlorine
At least one in imitative, pentane；Described second aqueous media adopts water, methyl alcohol, ethanol, acetone, N,N-dimethylformamide, second
At least one in glycol, acetonitrile.
In above a second aspect of the present invention and the third aspect, a series of described oil-phase mediums adopt hexamethylene, four chlorinations
At least two mixing in carbon, benzene, toluene, chloroform, pentane are made into；Described second aqueous media adopt water, methyl alcohol, ethanol, third
At least two mixing in ketone, N,N-dimethylformamide, ethylene glycol, acetonitrile are made into；And formed by medium and/or concentration Lai
Adjust Media density.
In above each aspect of the present invention, depending on volume and first aqueous media or first of centrifuge tube bottom medium
The volume ratio of oil-phase medium, described change in concentration can be dilution or concentrate, but practice in the most often carry out be concentrate.Through a large amount of
Experiment finds, when being concentrated, using the method for the present invention, concentration in centrifuge tube bottommost medium for the described nano particle
At least 10000 times of the concentration that can accomplish as it in initial aqueous liquid dispersion or initial oily dispersion, but still make to receive
Rice grain is not reunited, and this is that other method for concentration institutes are irrealizable.
In above each aspect of the present invention, centrifuge speed can do in the range of 1000-65000 rev/min further
Selecting, such as 3000-60000 rev/min, 5000-55000 rev/min, 7000-50000 rev/min, 9000-45000 turns/
Minute, 11000-45000 rev/min, 13000-40000 rev/min, 15000-35000 rev/min, 17000-30000 turns/
Minute, 19000-25000 rev/min, etc..Each upper and lower bound can independently selected and combination with one another.Centrifugation time is permissible
Selected according to centrifuge speed.When carrying out to nano particle by size and/or separating by pattern, need in above-mentioned model
Centrifuge speed and centrifugation time and the best match of various medium is carefully chosen in enclosing.
Brief description
Fig. 1 is to order about water-soluble Au nano particle using density gradient centrifugation in the embodiment of the present invention one to pass through water oil
Interface is realized concentrating and medium switching, the digital photograph of centrifuge tube before and after centrifugal treating（Left）, medium switching before and after Jenner
The ultraviolet figure of rice grain（In）TEM photo with the sample before and after medium switching（Right）.
Fig. 2 is to order about Mg-Al hydrotalcite using density gradient centrifugation in the embodiment of the present invention two to pass through water-oil interface
Realize concentrating and medium switching, the digital photograph of centrifuge tube before and after centrifugation.
Fig. 3 is to order about water-soluble Au nanometer rods using density gradient centrifugation in the embodiment of the present invention three to pass through water oil phase
Interface is realized concentrating and medium switching, the digital photograph of centrifuge tube before and after centrifugation（Left figure）, and medium switching before and after Au receive
The ultraviolet figure of rice rod（Right figure）.
Fig. 4 is to order about water-soluble nano Ag piece using density gradient centrifugation in the embodiment of the present invention four to pass through water oil phase
Interface is realized concentrating and medium switching, the digital photograph of centrifuge tube before and after centrifugation（Left figure）And ultraviolet figure（Right figure）.
Fig. 5 is to order about oil-soluble CeO using density gradient centrifugation in the embodiment of the present invention five2Pass through oil-water interfaces real
Now concentrate and medium switching, the digital photograph of centrifuge tube before and after centrifugation
Order about oil-soluble Au nano particle using density gradient centrifugation in Fig. 6 embodiment of the present invention six and pass through profit circle
Face is realized concentrating and medium switching, the digital photograph of centrifuge tube and ultraviolet figure before and after centrifugation.
Before and after Fig. 7 is the experiment using density gradient centrifugation separation different size gold grain in the embodiment of the present invention seven
The digital photograph of centrifuge tube, ultraviolet figure and TEM photo.
Fig. 8 is using density gradient centrifugation in the embodiment of the present invention seven, using water oil phase interface to gold grain and gold
Rod carries out the experimental result picture of Selective Separation, digital photograph, ultraviolet figure and the TEM photo before and after separating.
Fig. 9 is to order about Pt-Cu alloy using density gradient centrifugation in the embodiment of the present invention eight to pass through oil-water interfaces in fact
Now concentrate and medium switching, the digital photograph of centrifuge tube before and after centrifugation；And the cyclic voltammetric that commonly centrifuge washing obtains for 15 times
The contrast of the cyclic voltammetry curve that curve is obtained for a time with the method washing.
Figure 10 is using density gradient centrifugation in the embodiment of the present invention nine, respectively with the beginning of Pt-Cu alloy nanoparticle
Beginning aqueous liquid dispersion and CeO2As a example the initial oily dispersion of nano particle, and it is situated between using different aqueous mediums and different oiliness
Matter carries out medium switching, the digital photograph of centrifuge tube before and after centrifugation.
Figure 11 is the principle schematic of the present invention.
Specific embodiment
Embodiment one:
（a）The preparation of the initial aqueous dispersion of gold nano grain：
1. the preparation (Au NPs) of Au kind solution
Hexadecyltrimethylammonium chloride to 10mL0.1mol/L（Referred to as CTAC）Add in solution
The HAuCl of 0.25mL10mmol/L4Solution, obtains the HAuCl of 0.25mmol/L4Hexadecyltrimethylammonium chloride solution, to
The NaBH of 0.45mL0.02mol/L is added in above-mentioned solution4Solution, then stands 1h.
2. the preparation of growth solution
Add 2.5ml10mmol/L's in the hexadecyltrimethylammonium chloride aqueous solution of 100mL0.1mol/L
HAuCl4The aqueous solution, the NaBr aqueous solution of 100uL0.01mol/L and the ascorbic acid solution of 1mL0.1mol/L.
3. the growth of Au
Take 1ml Au kind solution, dilute 10 times.The Au kind solution 2mL after dilution, stirring is added in above-mentioned growth solution
1min, grows 1 week, obtains the initial aqueous liquid dispersion being dispersed with Au nano particle.
B () makes immiscible two-phase medium:Spent glycol and water dose volume are than the glycol water for 50%
（Referred to as " medium first "）, the hexamethylene being configured to the carbon tetrachloride that percent by volume is 30% with carbon tetrachloride and hexamethylene is molten
Liquid (referred to as " medium second ").
C () takes 2mL medium first to add in centrifuge tube, be then slowly added into 3mL medium second, then be dispersed with Au by above-mentioned for 3mL
The initial aqueous liquid dispersion of nano particle is added slowly in medium second.Due to each mutually immiscible, therefore form three layers in centrifuge tube
Medium.
（d）20 DEG C, 100 × 10-6High speed centrifugation 60min under atmospheric pressure, 15000rpm.In the process of being centrifuged at a high speed
In, the Au nano particle in initial aqueous liquid dispersion will sequentially pass through profit boundary twice, eventually arrive at and be scattered in centrifugation
In the medium first of pipe bottommost.By centrifugation after centrifuge tube in above two-layer remove, only retain bottommost medium first, wherein
It is dispersed with Au nano particle.After testing, concentration in this medium first for the Au nano particle is it in initial aqueous liquid dispersion
3 times of concentration.What deserves to be explained is, in the present embodiment and below each embodiment, the temperature and pressure in centrifugal condition is not
It is to realize necessary to the present invention, the present invention can select other temperature and pressure according to the property of nano particle to be separated
Power.It is used for the purpose of convenient experimental operation or the needs of protection centrifuge rotor using such temperature and pressure.
The experimental result of embodiment 1 is referring to Fig. 1.In Fig. 1, left figure is the photo of the centrifuge tube before and after centrifugation it is seen that adopting
With the method for the present invention, Au nano particle is successfully transferred in the medium first of bottommost from initial aqueous liquid dispersion, realizes
Medium switching.Middle figure in Fig. 1 is Au nano particle in initial aqueous liquid dispersion and the purple after transferring in medium first
External spectrum figure, it can be seen from the graph that the position of absworption peak is essentially identical, the pattern of this explanation Au nano particle and property are cut in medium
After changing, basic holding is unchanged, i.e. without reuniting, other chemical changes does not occur yet.Right figure in Fig. 1 shows Au
TEM photo in initial aqueous liquid dispersion and after transferring in medium first for the nano particle, can more intuitively see Au nanometer
The pattern of particle does not change, and does not also reunite, but concentration significantly improves.
Embodiment two:
The preparation of the initial aqueous liquid dispersion of (a) Mg-Al hydrotalcite nano particle：
1. alkali lye, 0.24g NaOH, 0.055g Na are prepared2CO3Add 30ml H2O, stirs；
2. saline solution, 0.375g Al (NO are prepared3)3,0.769g Mg(NO3)3Add 30ml H2O, stirs；
1. and 2. 3. will middle solution be simultaneously introduced in colloid mill, stirring 10min receives sample
4. centrifuge washing, 120 DEG C of crystallization 4h, obtain the initial aqueous liquid dispersion of Mg-Al hydrotalcite nano particle.
B () makes immiscible two-phase medium:Spent glycol and water dose volume are than the glycol water for 50%
（Medium first）, it is configured to cyclohexane solution (the medium of the carbon tetrachloride that percent by volume is 30% with carbon tetrachloride and hexamethylene
Second).
C () takes 4mL medium first to add in centrifuge tube, be slowly added to 3mL medium second, by 3mL Mg-Al hydrotalcite nano
The initial aqueous liquid dispersion of grain is added slowly in medium second.Due to each mutually immiscible, therefore form three layers of medium in centrifuge tube.
（d）20 DEG C, 100 × 10-6High speed centrifugation 30min under atmospheric pressure, 20000rpm.In the process of being centrifuged at a high speed
In, the Mg-Al hydrotalcite nano particle in initial aqueous liquid dispersion will sequentially pass through profit boundary twice, eventually arrive at and divide
Dissipate in the medium first of centrifuge tube bottommost.By centrifugation after centrifuge tube in above two-layer remove, only retain bottommost Jie
Matter first, is wherein dispersed with Mg-Al hydrotalcite nano particle.Achieve the switching of solvent.
The experimental result of embodiment 2 is referring to Fig. 2.In Fig. 2, left figure is the photo of the centrifuge tube before and after centrifugation it is seen that adopting
With the method for the present invention, Mg-Al hydrotalcite nano particle successfully transfers to the medium of bottommost from initial aqueous liquid dispersion
It is achieved that medium switches in first.
Equally use the molten of toluene and carbon tetrachloride, benzene and carbon tetrachloride, pentane and carbon tetrachloride or hexamethylene and chloroform
Liquid, as medium second, can obtain similar effect.
Embodiment three：
（a）Prepare the aqueous dispersion of Au nanometer rods；
1. the preparation (Au NRs) of Au kind
Add 0.125mL20mmol/L's in the cetyl trimethylammonium bromide aqueous solution of 10mL0.2mol/L
HAuCl4The aqueous solution, obtains the HAuCl of 0.25mmol/L4Hexadecyltrimethylammonium chloride solution, in above-mentioned solution add
The NaBH of 0.45mL0.02mol/L4The aqueous solution, then stands 30min；
2. the preparation of growth solution
Add 0.22g5- bromo ortho-oxybenzoic acid in the hexadecyltrimethylammonium chloride aqueous solution of 50mL0.1mol/L, add
The AgNO of 2.4mL4mmol/L3The aqueous solution, stirs 15min, adds 50mL1mmol/L HAuCl4The aqueous solution, stirs 15min, plus
Enter 0.4mL0.064mol/L aqueous ascorbic acid, stir 2min
3. the growth of Au
Add Au kind solution 0.08mL in growth solution, stir 1min, static growth 1 day, obtain the water of Au nanometer rods
Insoluble dispersion.
（b）Make immiscible two-phase medium:Spent glycol and water dose volume are than the glycol water for 50%
（Medium first）；It is configured to cyclohexane solution (the medium of the carbon tetrachloride that percent by volume is 30% with carbon tetrachloride and hexamethylene
Second).
（c）Take 4mL medium first to add in centrifuge tube, be slowly added to 3mL medium second, then the water solubility by 3mL Au nanometer rods
Dispersion liquid is added slowly in medium second.Due to each mutually immiscible, therefore form three layers of medium in centrifuge tube.
（d）20 DEG C, 100 × 10-6High speed centrifugation 40min under atmospheric pressure, 75000rpm.In the process of being centrifuged at a high speed
In, the Au nanometer rods in initial aqueous liquid dispersion will sequentially pass through profit boundary twice, eventually arrive at and be scattered in centrifuge tube
In the medium first of bottommost.By centrifugation after centrifuge tube in above two-layer remove, only retain bottommost medium first, wherein divide
Dissipate and have Au nanometer rods it is achieved that the switching of solvent.
The experimental result of embodiment three is referring to Fig. 3.In Fig. 3 left figure be the centrifuge tube before and after centrifugation photo it is seen that
Using the method for the present invention, Au nanometer rods are successfully transferred in the medium first of bottommost from initial aqueous liquid dispersion, realize
Medium switching.Right figure in Fig. 3 is Au nanometer rods in initial aqueous liquid dispersion and the ultraviolet after transferring in medium first
Spectrogram, it can be seen from the graph that the position of absworption peak is essentially identical, the pattern of this explanation Au nanometer rods and property are after medium switching
Basic holding is unchanged, i.e. without reuniting, other chemical changes does not occur yet.
Example IV：
（a）The preparation of the initial aqueous liquid dispersion of Nano silver piece
1. prepare solution：0.068g AgNO3It is dissolved in 100mL water, 0.882g sodium citrate is dissolved in 100mL water,
2.03g polyvinylpyrrolidone（Abbreviation PVP）It is dissolved in 100mL water, 0.0379 sodium borohydride is dissolved in 10mL water.
2. take 2.5mL AgNO3In 97.5mL water, stirring is lower to add 6mL sodium citrate solution to solution, and 6mL PVP is molten
Liquid, 240uL30% hydrogen peroxide, 0.6mL sodium borohydride solution.20min is reacted at 25 DEG C.
3. centrifuge washing, and this Nano silver piece is disperseed in ethanol；
B () makes immiscible two-phase medium:Added in centrifuge tube as medium first with 3mL ethylene glycol；Use 3mL toluene
It is slowly added on ethylene glycol layer as medium second, form immiscible two-phase density gradient.
C () 4mL Nano silver piece alcohol dispersion liquid is added slowly on toluene layer, due to each mutually immiscible, therefore in centrifugation
Form three layers of medium in pipe.
D () is at 15 DEG C, 100 × 10-6Atmospheric pressure, high speed centrifugation 30min under 20000rpm.In the process of being centrifuged at a high speed
In, the Nano silver piece in initial aqueous liquid dispersion will sequentially pass through profit boundary twice, eventually arrive at and be scattered in centrifuge tube
In the medium first of bottommost.By centrifugation after centrifuge tube in above two-layer remove, only retain bottommost medium first, wherein divide
Dissipating has Nano silver piece.After testing, concentration in this medium first for the Nano silver piece is its concentration in initial aqueous liquid dispersion
1.33 again.
The experimental result of example IV is referring to Fig. 4.In Fig. 4 left figure be the centrifuge tube before and after centrifugation photo it is seen that
Using the method for the present invention, Nano silver piece is successfully transferred in the medium first of bottommost from initial aqueous liquid dispersion, realizes
Medium switching.Right figure in Fig. 4 is Nano silver piece in initial aqueous liquid dispersion and the ultraviolet after transferring in medium first
Spectrogram, it can be seen from the graph that the position of absworption peak is essentially identical, the pattern of this explanation Nano silver piece and property are after medium switching
Basic holding is unchanged, i.e. without reuniting, other chemical changes does not occur yet.
Same toluene, benzene, cyclohexanone etc. do organic phase medium and can obtain similar effect.The volume changing medium first can
To obtain the Nano silver piece dispersion liquid of variable concentrations after purification.
Embodiment five:
A () prepares the oily dispersion of cerium oxide nanoparticles first：0.5g NaOH is added 10mL water dissolves, then
Plus 15mL ethanol and 4mL oleyl amine stir into homogeneous solution, separately by 4.4g（NH4）2Ce(NO3)6Add 5mL H2After O dissolving, instill
Above-mentioned homogeneous solution, after reaction 10h at 120 DEG C, washs one time to the product hexamethylene obtaining and ethanol, obtains.
B () makes immiscible two-phase medium:Be configured to that percent by volume is 50% with carbon tetrachloride and hexamethylene four
The cyclohexane solution of chlorination carbon（Medium first）, using water as medium second；
C () takes 1mL medium first to add test tube bottom, be slowly added into 1mL water as medium second, be then slowly added to 1.5mL
The oily dispersion of cerium oxide nanoparticles；
(d) 20 DEG C, 100 × 10-6Be centrifuged at a high speed under conditions of atmospheric pressure, 35000rpm 60min.In high speed centrifugation
In separation process, the cerium oxide nanoparticles in initial oily dispersion will sequentially pass through profit boundary twice, Zhongdao
Reach and be scattered in the medium first of centrifuge tube bottommost.By centrifugation after centrifuge tube in above two-layer remove, only retain bottom
The medium first in portion, is wherein dispersed with cerium oxide nanoparticles.After testing, cerium oxide nanoparticles are dense in this medium first
1.5 times of the concentration spent for it in initial aqueous liquid dispersion.
Separating resulting is referring to Fig. 5.
Equally use toluene and carbon tetrachloride, benzene and carbon tetrachloride, pentane and carbon tetrachloride or hexamethylene and chloroform, dichloro
Methane, octane etc. do organic phase medium, and water and ethanol, first alcohol and water, acetone etc., as aqueous medium, can obtain similar effect.
The volume changing organic phase medium of centrifuge tube bottommost can obtain the titanium dioxide of variable concentrations after medium switching
Cerium colloidal sol.
Embodiment six:
（a）Prepare the oil-soluble dispersion liquid of Au nano particle：First, by 10mg HAuCl4It is added in 2ml oleyl amine, so
After add 8ml hexamethylene, at 80 DEG C react 10h, generate about 1mg/ml Au nano particle hexamethylene colloidal solution.
（b）Make immiscible two-phase medium:Be configured to that percent by volume is 50% with carbon tetrachloride and hexamethylene four
The cyclohexane solution of chlorination carbon（Medium first）, using water as medium second.
（c）Take 1mL medium first to add test tube bottom, be slowly added into 2mL water as medium second, be then slowly added to 3.5mL
The oil-soluble dispersion liquid of Au nano particle；
（d）20 DEG C, 100 × 10-6Be centrifuged at a high speed under conditions of atmospheric pressure, 35000rpm 60min.In high speed centrifugation
In separation process, the Au nano particle in initial oily dispersion will sequentially pass through profit boundary twice, eventually arrive at and divide
Dissipate in the medium first of centrifuge tube bottommost.By centrifugation after centrifuge tube in above two-layer remove, only retain bottommost Jie
Matter first, is wherein dispersed with Au nano particle.After testing, concentration in this medium first for the Au nano particle is divided in initial oiliness for it
3.5 times of concentration in dispersion liquid.
Centrifuge tube digital photograph before and after separating（Fig. 6 left figure）And uv atlas（Fig. 6 right figure）Display, the success of Au nano particle
Achieve solvent switching, and the property of Au nano particle and pattern almost remain unchanged before and after switching, the phenomenon such as do not reunite is sent out
Raw.
Equally use toluene and carbon tetrachloride, benzene and carbon tetrachloride, pentane and carbon tetrachloride or hexamethylene and chloroform, dichloro
Methane, octane etc. do organic phase medium, and water can obtain similar effect with ethanol, first alcohol and water, acetone etc. as aqueous medium.
The volume changing organic phase medium of centrifugation bottom of the tube can obtain the oil-soluble Au of variable concentrations after medium switching
Colloidal sol.
Embodiment seven:
（a）First, prepare the aqueous liquid dispersion that 20nm gold nano grain and 50nm gold nano grain coexist, referred to as
Mix1；
（b）Make immiscible two-phase medium:Spent glycol and water dose volume are than the glycol water for 50%
（Medium first）,；It is configured to cyclohexane solution (the medium of the carbon tetrachloride that percent by volume is 30% with carbon tetrachloride and hexamethylene
Second)；
（c）Take 3mL medium first to add in centrifuge tube, be slowly added to 3mL medium second, 4mL Mix1 is added slowly to medium second
On；
（d）20 DEG C, 100 × 10-6High speed centrifugation 90min under the conditions of atmospheric pressure, 3000rpm.After centrifugation, by centrifuge tube
The aqueous phase on upper strata takes out detection, finds wherein to mainly contain the gold nano grain of 20nm；And it is then main in centrifuge tube bottom aqueous phase
Gold nano grain containing 50nm is it is seen that by the effect of the present invention, can carry out to the nano particle of different-grain diameter separating.
Fig. 7 shows the centrifuge tube digital photograph before and after centrifugation（Left figure）, uv atlas（Middle figure）And TEM photo
（Right figure）Referring to Fig. 7.Each in figure m represents mixing Au nano particle, and a represents the gold nano grain of 20nm, and b represents the Jenner of 50nm
Rice grain.From the left figure of Fig. 7, using the method for the present invention, successfully the nano particle of different-grain diameter is separated.
From the middle figure of Fig. 7, the gold nano grain of 20nm obtaining after being separated using the method for the present invention and the gold nano of 50nm
Grain, the uv atlas almost phase with the gold nano grain of the pure 20nm as standard sample and the gold nano grain of pure 50nm
With this illustrates that the separation between the gold nano grain of 20nm and the gold nano grain of 50nm is very complete.Can from the right figure of Fig. 7
See, after separating, take top layer aqueous phase and bottom aqueous layer, find wherein to mainly contain the gold nano grain of 20nm and the gold of 50nm respectively
Nano particle, the separation further illustrating between the gold nano grain of 20nm and the gold nano grain of 50nm is very complete.
Embodiment eight:
（a）First, the aqueous liquid dispersion that the gold nanorods of the gold nano grain of 20nm and 50nm length coexist, referred to as
Mix2.
（b）Make immiscible two-phase medium:Spent glycol and water dose volume are than the glycol water for 50%
（Medium first）,；It is configured to cyclohexane solution (the medium of the carbon tetrachloride that percent by volume is 30% with carbon tetrachloride and hexamethylene
Second)；
（c）Take 3mL medium first to add in centrifuge tube, be slowly added to 3mL medium second, then 4mL Mix2 is added slowly to medium
In second；
（d）20 DEG C, 100 × 10-6Be centrifuged at a high speed under the conditions of atmospheric pressure and 7000rpm 20min.After centrifugation, will be from
The aqueous medium of heart pipe top layer takes out, and finds wherein to mainly contain the gold nano grain of 20nm, and centrifuge tube bottom aqueous medium
In then mainly contain gold nanorods it is seen that by the effect of the present invention, being capable of Au nano particle with Au nanometer rods by shape
Looks separate.
Before and after separating, centrifuge tube digital photograph and uv atlas are referring to Fig. 8.Wherein m represents gold nano grain and gold nano
Excellent mixed dispersion liquid, a represents the gold nano grain of 20nm, and b represents the gold nanorods of long 50nm.Gold nano grain is because at three
Adjoining dimensions in dimension, therefore it only has a peak in ultraviolet in figure.And gold nanorods are because size is much larger than in the longitudinal direction
Size in two other dimension, therefore it has two peaks in ultraviolet in figure.Photo from the left figure of Fig. 8, the two realization
Separate；Ultraviolet figure from the right figure of Fig. 8, top is mainly the gold nano grain of 20nm, and bottom is mainly long 50nm
Gold nanorods it is seen that the two is nearly completely separated each other.
The volume changing the aqueous medium of centrifugation bottom of the tube can obtain the gold nanorods of variable concentrations.
Embodiment nine:
（a）Prepare Pt-Cu alloy nanoparticle dispersion liquid in ethanol first：By acetylacetone,2,4-pentanedione platinum (40mg,
0.10mmol), acetylacetone copper (26mg, 0.10mmol), KI (166mg, 1.0mmol) and polyvinylpyrrolidone (K30,
100mg) add in formamide (5ml), stirring, after reaction 4h at 150 DEG C, carry out being centrifuged repeatedly washing with acetone, ethanol,
Afterwards this nano particle is disperseed in ethanol, to obtain the Pt-Cu nano particle for 9nm for size dispersion liquid in ethanol；
（b）Make immiscible two-phase medium:Spent glycol and water dose volume are than the glycol water for 50%
（Medium first）,；It is configured to cyclohexane solution (the medium of the carbon tetrachloride that percent by volume is 30% with carbon tetrachloride and hexamethylene
Second)；
（c）Take 1mL medium first to add in centrifuge tube, be slowly added to 1mL medium second, by 1.5mL Pt-Cu alloy nano
Grain dispersion liquid in ethanol is added slowly in medium second；
（d）15 DEG C, 100 × 10-6High speed centrifugation 30min under the conditions of atmospheric pressure and 30000rpm.Bottom in centrifuge tube
Obtain the dispersion liquid that Pt-Cu alloy nanoparticle is dispersed in medium first.Take this sample, test following in methanol oxidation process
Ring volt-ampere curve (b), separately takes preparation Pt-Cu alloy nanoparticle dispersion liquid in step a, and the method using common centrifuge washing is washed
After washing 15 times, test its cyclic voltammetry curve in methanol oxidation process（a）,
Fig. 9 shows the digital photograph of the centrifuge tube before and after centrifugation（Left figure）And cyclic voltammetry curve（Right figure）.Digital photograph
Piece shows, the Pt-Cu alloy nanoparticle overwhelming majority is transferred in bottom aqueous phase medium.Cyclic voltammetry curve shows, using this
The Pt-Cu alloy nanoparticle that the method centrifugation of invention once obtains afterwards, is washed 15 times with the method for common centrifuge washing
The Pt-Cu alloy nanoparticle obtaining afterwards, electric property is essentially identical.But the method for the present invention is obviously more simply efficient.
The volume changing the aqueous medium of centrifugation bottom of the tube can obtain the Pt-Cu alloy of variable concentrations after medium switching
Nanoparticulate dispersion.
Same water and ethanol, water and methyl alcohol, water and acetonitrile, water and acetone etc. can obtain similar effect as aqueous medium
Really.
Embodiment ten:
（a）Prepare Pt-Cu alloy nanoparticle first respectively and disperse dispersion liquid in ethanol and cerium dioxide nano
Grain is dispersed in the dispersion liquid in hexamethylene；
（b）Make immiscible two-phase medium:In each experiment, concrete condition enters shown in following c1 and c2 step.
（c1）In five centrifuge tube G1-G5, take 1mL water, DMF, ethylene glycol, acetone or second respectively
Nitrile adds test tube bottom, as medium first, is then slowly added to 1mL medium second on each medium first（Medium second is to use tetrachloro
Change the cyclohexane solution that carbon and hexamethylene are configured to the carbon tetrachloride of percent by volume 5%）, then add in medium second respectively
1.5mLPt-Cu alloy dispersion dispersion liquid in ethanol；
（c2）Separately take five centrifuge tube G6-G10, G6-G8 bottom is separately added into 1mL dichloromethane, carbon tetrachloride thereto
Or chlorobenzene, then it is respectively added slowly to water 1mL, then it is slowly added into 1.5mL cerium oxide nanoparticles again and be dispersed in hexamethylene
Dispersion liquid；It is separately added into 1mL benzene and toluene to the bottom of G9-G10, be then slowly added into acetone or ethanol 1mL, then slowly
Slow addition 1.5mL cerium oxide nanoparticles are dispersed in the dispersion liquid in hexamethylene；
（d1）20 DEG C, 100 × 10-6To centrifuge tube G1-G5 high speed centrifugation 20min under the conditions of atmospheric pressure and 30000rpm；
（d2）20 DEG C, 100 × 10-6To centrifuge tube G6-G10 high speed centrifugation 60min under the conditions of atmospheric pressure and 35000rpm；
Before and after separating, centrifuge tube digital photograph is shown in Figure 10.
It can be seen that, various in the case of Pt-Cu alloy nanoparticle and cerium oxide nanoparticles all successfully achieve medium
Switching.This illustrates the broad applicability to various aqueous mediums and oil medium for the present invention.
The present invention has advantages below：
The present invention compared with prior art, has advantages below and high-lighting effect：1. easy to use, it is possible to achieve to Jie
The rapid translating of matter；2. concentration is adjustable, thus it is possible to vary the volume of centrifuge tube bottom dielectric is realizing the adjustable of concentration;3. applicable surface
Broad：The size of nano particle from nanometer to micrometer range, pattern from particle to bar-shaped, all effectively；And medium applicable surface width;④
The method both can play the effect changing concentrations of nanoparticles and/or medium switching, again can be according to the size of particle or shape
Looks carry out separating；5. the method is a kind of medium changing method that will not destroy nano particle property；6. the inventive method technique
Simply, easy to operate, it is possible to achieve industrialized production.Therefore, the present invention order about nanometer using density gradient centrifugation
Grain passes through the method that oil-water interfaces realize change in concentration and/or medium switching, and applications to nanostructures is had broad prospects
With great scientific meaning, especially provide powerful nanometer material for novel optoelectronic materials, nano-device and nanometer medicine and other fields
Material processing method.
Claims (9)
1. a kind of order about nano particle using density gradient centrifugation and pass through profit boundary realize its change in concentration and/or Jie
The method of matter switching, comprises the steps：
A. prepare nano particle in the initial aqueous liquid dispersion in the first aqueous media or the initial oil in the first oil-phase medium
Property dispersion liquid；
B. the second oil-phase medium and second aqueous media with different densities, the density of wherein said second oil-phase medium are prepared
More than the density of the first oil-phase medium, the density of the second aqueous media is more than the density of the first aqueous media；
C. take the second aqueous media to add centrifugation bottom of the tube, be subsequently adding the second oil-phase medium, be subsequently adding initial aqueous dispersion
Liquid；Or, take the second oil-phase medium to add centrifugation bottom of the tube, be subsequently adding the second aqueous media, be subsequently adding initial oiliness and divide
Dispersion liquid；
D. rotating speed be 1000-65000 rev/min, the time be 5-600 minute under conditions of carry out centrifugal treating so that nanometer
Particle passes through in the medium that profit boundary transfers to bottommost, realizes its change in concentration and/or medium switching.
2. method according to claim 1 it is characterised in that：Nano particle described in step a is noble metal nano particles, oxidation
Thing nano particle, alloy nanoparticle or hydroxide nanoparticles, its particle size range is from 1 nanometer to 2 microns.
3. method according to claim 1, wherein said second oil-phase medium adopts hexamethylene, carbon tetrachloride, benzene, toluene, chlorine
At least one in imitative, pentane；Described second aqueous media adopts water, methyl alcohol, ethanol, acetone, N,N-dimethylformamide, second
At least one in glycol, acetonitrile.
4. a kind of order about nano particle using density gradient centrifugation and pass through profit boundary realize its change in concentration and/or Jie
The method of matter switching, comprises the steps：
A. prepare nano particle in the initial aqueous liquid dispersion in the first aqueous media or the initial oil in the first oil-phase medium
Property dispersion liquid；
B. prepare and there are a series of oil-phase mediums of different densities and a series of aqueous media, a series of wherein said oil-phase mediums
The density of Midst density reckling is more than the density of the first oil-phase medium, a series of density of described aqueous media Midst density recklings
Density more than the first aqueous media；Described oil-phase medium is immiscible with described aqueous media；
C. diminish successively and the alternate order of oil phase, aqueous phase from the bottom of centrifuge tube to top according to density, using described one be
Row oil-phase medium and a series of aqueous media filling centrifuge tube, and make described initial aqueous dispersion liquid or initial oily dispersion
Positioned at top, and top and the medium of bottommost is made to be all aqueous phase or be all oil phase；
D. rotating speed be 1000-65000 rev/min, the time be 5-600 minute under conditions of carry out centrifugal treating so that nanometer
Particle repeatedly passes through in the medium that profit boundary transfers to bottommost, realizes its change in concentration and/or medium switching.
5. method according to claim 4 it is characterised in that：Nano particle described in step a is noble metal nano particles, oxidation
Thing nano particle, alloy nanoparticle or hydroxide nanoparticles, its particle size range is from 1 nanometer to 2 microns.
6. method according to claim 4, a series of wherein said oil-phase mediums adopt hexamethylene, carbon tetrachloride, benzene, toluene,
At least two mixing in chloroform, pentane are made into；A series of described aqueous media adopts water, methyl alcohol, ethanol, acetone, N, N- bis-
At least two mixing in NMF, ethylene glycol, acetonitrile are made into；And formed by medium and/or concentration is adjusting medium
Density.
7. the method for claim 1 or 4, wherein said change in concentration is to concentrate, and described nano particle is in centrifuge tube bottommost
Concentration in medium is more than 10000 times of its concentration in initial aqueous liquid dispersion or initial oily dispersion, and nanometer
The property of particle remains unchanged substantially.
8. a kind of order about nano particle using density gradient centrifugation and pass through profit boundary realize this nano particle is entered
Row is separated by size and/or presses the detached method of pattern, comprises the steps：
A. prepare nano particle in the initial aqueous liquid dispersion in the first aqueous media or the initial oil in the first oil-phase medium
Property dispersion liquid, this nano particle is of different sizes and/or pattern；
B. prepare and there are a series of oil-phase mediums of different densities and a series of aqueous media, a series of wherein said oil-phase mediums
The density of Midst density reckling is more than the density of the first oil-phase medium, a series of density of described aqueous media Midst density recklings
Density more than the first aqueous media；Described oil-phase medium is immiscible with described aqueous media；
C. diminish successively and the alternate order of oil phase, aqueous phase from the bottom of centrifuge tube to top according to density, using described one be
Row oil-phase medium and a series of aqueous media filling centrifuge tube, and make described initial aqueous dispersion liquid or initial oily dispersion
Positioned at top, and top and the medium of bottommost is made to be all aqueous phase or be all oil phase；
D. rotating speed be 1000-65000 rev/min, the time be 5-600 minute under conditions of carry out centrifugal treating so that having
The nano particle of specific dimensions scope and/or specific morphology repeatedly passes through in the medium that profit boundary transfers to bottommost, and
Have another specific dimensions scope and/or another specific morphology nano particle remain in its initial aqueous liquid dispersion and/or
In initial oily dispersion, thus realizing this nano particle being carried out separate by size and/or separate by pattern.
9. the method for claim 8, wherein said separation by pattern refers to enter graininess nano particle and rod-like nano particle
Row separates.
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| CN101712011A (en) * | 2009-11-13 | 2010-05-26 | 北京化工大学 | Method for centrifugally separating oil soluble nano particles by organic density gradient |
| CN102976373A (en) * | 2012-12-04 | 2013-03-20 | 北京化工大学 | Method for synthesizing monodisperse stable LDHs (layered double hydroxides) colloid nanocrystalline |
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| CN101559401A (en) * | 2009-05-26 | 2009-10-21 | 北京化工大学 | Method for separating nano-particles at water-phase density gradient centrifugation rate |
| CN101712011A (en) * | 2009-11-13 | 2010-05-26 | 北京化工大学 | Method for centrifugally separating oil soluble nano particles by organic density gradient |
| CN102976373A (en) * | 2012-12-04 | 2013-03-20 | 北京化工大学 | Method for synthesizing monodisperse stable LDHs (layered double hydroxides) colloid nanocrystalline |
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