KR20160149727A - Surface engineered graphene quantum dots and synthesizing method of the same - Google Patents
Surface engineered graphene quantum dots and synthesizing method of the same Download PDFInfo
- Publication number
- KR20160149727A KR20160149727A KR1020150087265A KR20150087265A KR20160149727A KR 20160149727 A KR20160149727 A KR 20160149727A KR 1020150087265 A KR1020150087265 A KR 1020150087265A KR 20150087265 A KR20150087265 A KR 20150087265A KR 20160149727 A KR20160149727 A KR 20160149727A
- Authority
- KR
- South Korea
- Prior art keywords
- gqds
- graphene quantum
- modified
- present
- quantum dots
- Prior art date
Links
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 110
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 6
- 239000004094 surface-active agent Substances 0.000 claims abstract description 37
- 125000001165 hydrophobic group Chemical group 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical class [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 48
- 239000000203 mixture Substances 0.000 claims description 20
- 229910021389 graphene Inorganic materials 0.000 claims description 18
- QOSSAOTZNIDXMA-UHFFFAOYSA-N Dicylcohexylcarbodiimide Chemical compound C1CCCCC1N=C=NC1CCCCC1 QOSSAOTZNIDXMA-UHFFFAOYSA-N 0.000 claims description 16
- 239000002096 quantum dot Substances 0.000 claims description 16
- VHYFNPMBLIVWCW-UHFFFAOYSA-N 4-Dimethylaminopyridine Chemical compound CN(C)C1=CC=NC=C1 VHYFNPMBLIVWCW-UHFFFAOYSA-N 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 11
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 10
- 150000001875 compounds Chemical class 0.000 claims description 10
- 239000002904 solvent Substances 0.000 claims description 10
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 9
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 8
- 150000003973 alkyl amines Chemical class 0.000 claims description 5
- 125000004432 carbon atom Chemical group C* 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 239000002244 precipitate Substances 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 229960000549 4-dimethylaminophenol Drugs 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 8
- 230000008878 coupling Effects 0.000 abstract description 4
- 238000010168 coupling process Methods 0.000 abstract description 4
- 238000005859 coupling reaction Methods 0.000 abstract description 4
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- 238000003385 ring cleavage reaction Methods 0.000 abstract 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 33
- BMVXCPBXGZKUPN-UHFFFAOYSA-N 1-hexanamine Chemical class CCCCCCN BMVXCPBXGZKUPN-UHFFFAOYSA-N 0.000 description 28
- 239000002245 particle Substances 0.000 description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 16
- 239000004793 Polystyrene Substances 0.000 description 15
- 229910002804 graphite Inorganic materials 0.000 description 15
- 239000010439 graphite Substances 0.000 description 15
- 239000000839 emulsion Substances 0.000 description 14
- 229920002223 polystyrene Polymers 0.000 description 14
- 239000006185 dispersion Substances 0.000 description 11
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 9
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 8
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 8
- 238000005424 photoluminescence Methods 0.000 description 8
- 238000009826 distribution Methods 0.000 description 7
- 238000007720 emulsion polymerization reaction Methods 0.000 description 7
- 239000002105 nanoparticle Substances 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 7
- 239000007787 solid Substances 0.000 description 7
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 6
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 6
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 description 6
- 239000002270 dispersing agent Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 5
- 238000006862 quantum yield reaction Methods 0.000 description 5
- 239000000523 sample Substances 0.000 description 5
- 125000003368 amide group Chemical group 0.000 description 4
- 125000002843 carboxylic acid group Chemical group 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 238000000295 emission spectrum Methods 0.000 description 4
- 230000005660 hydrophilic surface Effects 0.000 description 4
- 230000002209 hydrophobic effect Effects 0.000 description 4
- 230000003993 interaction Effects 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 230000009897 systematic effect Effects 0.000 description 4
- 239000004593 Epoxy Substances 0.000 description 3
- 238000001237 Raman spectrum Methods 0.000 description 3
- 238000003917 TEM image Methods 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 3
- 238000000862 absorption spectrum Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 150000001732 carboxylic acid derivatives Chemical group 0.000 description 3
- 239000000084 colloidal system Substances 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 230000005661 hydrophobic surface Effects 0.000 description 3
- 238000003384 imaging method Methods 0.000 description 3
- 238000002329 infrared spectrum Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000000879 optical micrograph Methods 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 3
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 description 2
- 238000003775 Density Functional Theory Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 238000000089 atomic force micrograph Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 238000012790 confirmation Methods 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 150000002118 epoxides Chemical class 0.000 description 2
- 125000003700 epoxy group Chemical group 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 2
- 239000007850 fluorescent dye Substances 0.000 description 2
- 238000001215 fluorescent labelling Methods 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- 238000000024 high-resolution transmission electron micrograph Methods 0.000 description 2
- 238000004770 highest occupied molecular orbital Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 238000004768 lowest unoccupied molecular orbital Methods 0.000 description 2
- 238000004020 luminiscence type Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002715 modification method Methods 0.000 description 2
- RZJRJXONCZWCBN-UHFFFAOYSA-N octadecane Chemical compound CCCCCCCCCCCCCCCCCC RZJRJXONCZWCBN-UHFFFAOYSA-N 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011541 reaction mixture Substances 0.000 description 2
- PYWVYCXTNDRMGF-UHFFFAOYSA-N rhodamine B Chemical compound [Cl-].C=12C=CC(=[N+](CC)CC)C=C2OC2=CC(N(CC)CC)=CC=C2C=1C1=CC=CC=C1C(O)=O PYWVYCXTNDRMGF-UHFFFAOYSA-N 0.000 description 2
- 229940043267 rhodamine b Drugs 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- -1 solar cells Substances 0.000 description 2
- 239000007962 solid dispersion Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- 238000004627 transmission electron microscopy Methods 0.000 description 2
- OCJBOOLMMGQPQU-UHFFFAOYSA-N 1,4-dichlorobenzene Chemical compound ClC1=CC=C(Cl)C=C1 OCJBOOLMMGQPQU-UHFFFAOYSA-N 0.000 description 1
- YOYAIZYFCNQIRF-UHFFFAOYSA-N 2,6-dichlorobenzonitrile Chemical compound ClC1=CC=CC(Cl)=C1C#N YOYAIZYFCNQIRF-UHFFFAOYSA-N 0.000 description 1
- PUAQLLVFLMYYJJ-UHFFFAOYSA-N 2-aminopropiophenone Chemical compound CC(N)C(=O)C1=CC=CC=C1 PUAQLLVFLMYYJJ-UHFFFAOYSA-N 0.000 description 1
- 241000269328 Amphibia Species 0.000 description 1
- 238000004057 DFT-B3LYP calculation Methods 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 239000003708 ampul Substances 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 238000004630 atomic force microscopy Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000002925 chemical effect Effects 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229940117389 dichlorobenzene Drugs 0.000 description 1
- 238000012674 dispersion polymerization Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000002073 fluorescence micrograph Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- HZVOZRGWRWCICA-UHFFFAOYSA-N methanediyl Chemical compound [CH2] HZVOZRGWRWCICA-UHFFFAOYSA-N 0.000 description 1
- 239000012982 microporous membrane Substances 0.000 description 1
- 238000012900 molecular simulation Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000007764 o/w emulsion Substances 0.000 description 1
- 229940038384 octadecane Drugs 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000007348 radical reaction Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007142 ring opening reaction Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 150000003335 secondary amines Chemical class 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000000935 solvent evaporation Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000011885 synergistic combination Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/65—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing carbon
-
- C01B31/0446—
-
- C01B31/0484—
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
- H01L33/502—Wavelength conversion materials
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Power Engineering (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
Description
The present invention relates to surface-modified graphene quantum dots and methods for their synthesis. Specifically, the present invention relates to a surface modification method for controlling the hydrophobic or hydrophilic surface activity of a graphene quantum dot, and the graphene quantum dot synthesized according to the present invention can be effectively used as a surfactant.
Nanoparticles (NPs) with modified surface properties can control the interfacial properties of two immiscible polymers or fluids. Thus, it can act as an efficient surfactant and produce new structured materials such as bicontinuous solar cells, membranes for catalyst supports, photonic bandgap materials and asymmetric-structured particles (Binks, BP, Colloid Interface Sci . 2002, 7, 21-41; Boker, A. et al ., Soft Matter 2007, 3, 1231-1248; Kwon, T. et al ., ACS Macro Lett . 404; Kim, J. et al ., J. Am. Chem. Soc . 2010, 132, 8180-8186). Unlike conventional organic surfactants, NP surfactants have interesting photonic, magnetic, electrical and catalytic properties, which can be combined with polymeric or fluid matrices to produce synergistic effects. Also, due to the quasi-irreversible adsorption at the interface between the blends by the particle surfactant, highly stable emulsions can be easily formed (Hore, MJA et al ., Macromolecules 2013, 47, 875-887; Srivastava, S. et al ., Adv. Mater . 2014, 26, 201-234; Melle, S. et al ., Langmuir 2005, 21, 2158-2162). However, the NP surfactant has difficulty in controlling the position of dispersion in the matrix due to the difficulty of surface modification, and thus shows a limit to the efficiency (Srivastava, S. et al ., Adv. Mater . 2014, 201-234; Hong, RY et al, J. Appl Polym Sci 2007, 105, 2176-2184;....... Shenhar, R. et al, Adv Mater 2005, 17, 657-669). Therefore, in order to precisely control the surface properties of NPs, an appropriate method should be developed. However, each type of NPs is difficult because it has inherent surface properties that require different methods to adjust the surface chemistry (Caruso, F., Adv. Mater . 2001, 13, 11-22).
Nanometer sized graphite derivatives, referred to as graphene quantum dots (GQDs), have received academic attention due to their excellent physical, mechanical and photoelectrical properties (Zhang, Z. et al ., Science . 2012, 5 , 8869-8890; Cheng, H. et al , ACS Nano 2012, 6, 2237-2244;. Zhuo, S. et al, ACS Nano 2012, 6, 1059-1064;.. Zheng, XT et al, ACS Nano 2013, 7, 6278-6286). It consists of a hydrophobic base plane similar to the well known graphene oxide (GO), but has a larger surface area per unit volume than a micron sized GO (Kim, J. et al ., J. Am. Chem. Soc . 2010, 132, 8180-8186; Zhu, Y. et al ., Adv. Mater . 2010, 22, 3906-3924; Dreyer, DR et al ., Chem. Soc. Rev. 2010, 39, 228-240). Thus, GQDs have the potential to be used as effective surfactants, suitable for the development of ultrafine emulsions or colloidal particles. In addition, distinct properties such as adjustable luminescent emission, biocompatibility and long term resistance to photobleaching enable the promising application of GQD-stabilized emulsions, for example in applications such as bio-imaging and fluorescence sensors (Zhang , Zhuo, S. et al ., ACS Nano 2012, 6, 1059 (1995), Zhen et al ., Science , 2012, 5, 8869-8890; Cheng, H. et al ., ACS Nano 2012, 6, 2237-2244; Zhen, XT et al ., ACS Nano 2013, 7, 6278-6286). However, GQDs are rarely used as solid surfactants because it is difficult to regulate surface properties in a systematic manner with high reproducibility (Yang, H. et al ., ACS Macro Lett . 2014, 985-990). Unlike the GO sheet, the surface of the GQDs is highly hydrophilic due to excessive oxygen functionality on the basal plane and rim, which limits solubility in organic solvents (Kim, J. et al ., J. Am. Chem. Soc ., 2010, 132, 8180-8186; Zhu, Y. et al ., Adv. Mater . 2010,22, 3906-3924; Dreyer, DR et al ., Chem. ). Recently, it has been reported that the surface of GQDs can be modified by a chemical-grafting approach (Zhu, S. et al ., Adv. Funct. Mater . 2012, 22, 4732-4740; Tetsuka, H et al ., Adv. Mater . 2012, 24, 5333-5338; Qian, Z. et al ., RSC Adv ., 2013, 3, 14571-14579). Nevertheless, chemically modified GQDs should be used as surfactants, since accurate and systematic control of the surface properties of GQDs by the chemical graft approach has not been achieved.
Accordingly, the present inventors have completed the present invention based on experiments to develop a surface modification method for applying stable nano-sized GQDs as a surfactant.
Accordingly, it is an object of the present invention to provide a method for synthesizing a graphene quantum dot having a hydrophilic surface and a hydrophobic surface modifiable surface, which can be applied as a stable and effective surfactant, and a graphene quantum dot synthesized thereby.
In order to accomplish the above object, the present invention provides a process for preparing a mixture comprising: a) preparing a mixture of a compound containing a hydrophobic group in a solvent, DMAP (4-dimethylaminopyridine) and a graphene quantum dot dissolved therein; b) adding DCC (N, N'-dicyclohexylcarbodiimide) to the mixture of step a), heating and cooling to room temperature; c) filtering and precipitating the cooled mixture in step b) to obtain a precipitate; And d) washing the precipitate obtained in the step c) with diethyl ether to remove unreacted materials. The present invention also provides a method for synthesizing Graphene quat dots (GQDs).
In the present invention, the graphene quantum dot is a nanometer-sized graphite derivative. Specifically, the graphene quantum dot refers to a material having a dot size of 10 nm or less so that quantum phenomenon may occur in order to convert graphen, which is a conductive material, into a semiconductor form. (Zhang, Z. et al ., Science , 2012, 5 (1), 5), which has been applied to various fields such as biosensors, photosensors, and bioimaging due to its physical and mechanical photoelectric properties including its unique quantum mechanical properties due to its small size , 8869-8890). Previously, however, it was not easy to control the surface properties in a systematic manner, and it was rarely used as a solid surfactant. Therefore, in the present invention, a relatively simple and effective method for modifying the graphene quantum dot surface has been developed and applied as a surfactant.
In the present invention, the synthesis method involves a single-step opening and grafting onto the surface of GQDs. Specifically, the surface-unmodified raw GQDs used in the present invention were prepared by chemical oxidation (Dong, Y. et al ., J Mater Chem 2012, 22, 8764-8766) Containing groups such as a hydroxyl group, a hydroxyl group, a hydroxyl group, a hydroxyl group, a hydroxyl group, a carboxyl group, a hydroxyl group, a carboxyl group, a carboxyl group and a hydroxyl group. The surface modification according to the invention also takes place via a single step reaction of DCC coupling with the carboxyl group of these original GQDs and / or opening of the epoxy moiety (see example 1.2).
In one embodiment of the present invention, the compound containing the hydrophobic group in step a) may be an alkylamine having 1 to 6 carbon atoms.
In the present invention, the alkylamine means a compound in which one to three hydrogens in the alkyl group are substituted with an amine group, and specifically includes alkylamine having 1 to 6 carbon atoms. In the present invention, the surface of graphene quantum dots is modified by appropriately adding a compound containing a hydrophobic group. When the number of carbon atoms is 6 or more, the hydrophobic property becomes too strong. On the other hand, if the number of carbon atoms is too small, the electrical properties become poor. Therefore, an alkylamine having an appropriate carbon number should be added according to the purpose.
In one embodiment of the present invention, the solvent of step a) may be THF (tetrahydrofuran) or DMF (N, N-dimethylformamide).
In one embodiment of the present invention, the compound including a hydrophobic group and the graphene quantum dot in the step a) may be mixed at a weight ratio of 1:10 to 10: 1, but preferably 1: 4 to 4: 1 Can be mixed in a weight ratio.
In the present invention, as the ratio of the hydrophobic group-containing compound increases, the surface-modified GQDs exhibit hydrophobicity. Particularly stable when the hydrophobic group-containing compound and the graphene quantum dots are mixed at a ratio of 3: 4 See example 2)
In one embodiment of the present invention, heating in step b) may be performed at 30-50 ° C for 10-15 hours, but preferably at 40 ° C for 12 hours.
Also, the present invention provides a graphene quantum dot having a surface modified by the above method.
The present invention also provides a surfactant comprising a graphene quantum dot modified by the above-described method.
In the present invention, the surfactant is a substance that adsorbs to an interface, which is an interface at which two other materials are in contact with each other, and reduces the surface tension thereof. The surfactant is a substance that reduces the surface tension of liquids, liquids, liquids and gases, liquids and solids, Applicable in all phases. In the present invention, the surfactant specifically refers to a solid nanoparticle surfactant, which controls the interfacial properties of two unmodified polymers or fluids. The nanoparticle surfactant according to the present invention is useful for the production of materials such as solar cells, films for catalyst supports, and photonic bandgap materials due to its magnetic and electrocatalytic properties (Binks, BP Colloid Interface Sci . 2002, 7, 21 -41)).
According to the present invention, it was confirmed that the surface of the graphene quantum dot can be modified through a single step reaction of coupling and / or exchange at a relatively low temperature. Further, according to the present invention, the hydrophilic group and the hydrophobic group of the graphene quantum dot can be appropriately regulated, and it is possible to apply the surfactant effectively and stably for several months.
Figure 1 shows the XRD profile (Figure 1a) and Raman spectrum (Figure 1a) under a 514 nm laser of GH0 , respectively.
Figure 2 shows the preparation route of surface modified GQDs having hexylamines. The photograph shows the solubility of GQDs.
FIG. 3A is a transmission infrared spectrum of GH0 , GH25 , GH50 , GH75 and GH100 , and the illustration shows a vector-normalized transmission infrared spectrum for a specified peak of a carboxyl group of about 1720 cm -1 .
Figure 3b shows the vector-normalized transmission infrared spectra of GH25 , GH50 , GH75 and GH100 ranging from 3200 to 2600 cm <" 1 >.
Figure 4 shows the carbon 1s XPS spectrum of GH0 (Figure 4a) and GH100 (Figure 4b), respectively, and Figure 4c shows the nitrogen 1s XPS spectrum of surface modified GQDs.
Figure 5 shows an atomic force microscope (AFM) image of GQDs and a corresponding histogram of the size distribution. Correspond to GH0 (Fig. 5A), GH25 (Fig. 5B), GH50 (Fig. 5C), GH75 (Fig. 5D) and GH100 (Fig.
Figure 6a is a graph showing the average height of synthesized GQDs measured by AFM and Figure 6b is a graph showing the chemical structure of the model GQD system with two grafted hexylamines on the base plane and its equilibrium geometry Fig.
Figure 7 is a histogram of transmission electron microscopy (TEM) images of GQDs and corresponding size distributions. Each GH0 (FIG. 7a) (sapdo: HRTEM image of GH0), GH25 (Fig. 7b), GH50 (Fig. 7c), GH75 (Fig. 7d): a graph of the (sapdo HRTEM image of a GH75) and GH100 (Fig. 7e) .
8 is a graph showing the average size of synthesized GQDs measured from a TEM image.
Figure 9 is a photograph showing the solubility of modified GQDs in a water / chloroform solvent system, in which 3 mg of each kind of five different GQDs were separately dissolved in a mixture of 2 mL water / chloroform (1: 1 v / v) .
10 is a photograph showing the solubilities of GH50 , GH75 and GH100 soluble in DCM, toluene, CB and DCB, respectively.
Figure 11a is a photograph of a Pickering emulsion stabilized by GH25 , GH50 and GH75 , and is a DCB-in-water pickling solution stabilized by GH25 (Figure 11b), GH50 (Figure 11c) and GH75 Is an optical microscope image of the emulsion. GH0 and GH100 could not stabilize Pickering emulsion. The illustration in Figures 11b-d shows the size distribution and average size of the emulsion droplets.
FIG. 12 shows the SEM image size distribution of PS colloidal particles prepared by mini-emulsion polymerization, using GH25 (FIG. 12A), GH50 (FIG. 12B) and GH75 (FIG. The illustration in Figures 12A-C shows the size distribution and average size of PS colloidal particles.
13 is a UV-visible absorption spectrum (FIG. 13A) and a PL emission spectrum (FIG. 13B) of GH25 , GH50 and GH75 excited at 365 nm wavelength.
14 is optical (Fig. 14A) and fluorescence microscope images (Fig. 14B) of PS colloidal particles stabilized by GH25 , and the excitation wavelength is 450 nm.
Figure 15 is a photograph of graphite powder in MeOH after several months with no dispersant (Figure 15a) and with GH0 , GH25 , GH50 , GH75 and GH100 as dispersants (Figure 15b).
Figures 15c-e also show optical microscope images and size distribution histograms of the graphite dispersion using GH25 (Figure 15c), GH50 (Figure 15d) and GH75 (Figure 15e), respectively.
Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are intended to further illustrate the present invention, and the scope of the present invention is not limited to these examples.
<Experimental Examples> Preparation and characterization of experimental materials
1. Experimental material
Vulcan CX-72 carbon black was purchased from Cabot Corporation. Styrene, hexylamine, DCC, 4-dimethylaminopyridine (DMAP) and toluene were purchased from Aldrich. Prior to the emulsion polymerization, styrene was purified by passing through an alumina column. Azobisisobutyronitrile (AIBN) was purchased from Junsei and purified by recrystallization from ethanol. Deionized water was used in all experiments.
2. Preparation of raw GQDs and surface modified GQDs
The raw GQDs were prepared by chemical oxidation (Dong, Y. et al ., J Mater Chem 2012, 22, 8764-8766). Briefly, CX-72 carbon black was refluxed with nitric acid (6 M) for 48 hours. Thereafter, the resulting mixture was cooled to room temperature and centrifuged at 4000 rpm for 20 minutes. The supernatant was carefully collected and the solvent was evaporated to give a reddish brown powder. GQDs were redispersed in tetrahydrofuran (THF) and filtered through an ultrafilter through a 0.22 μm microporous membrane.
Hexylamine (25 mg, 0.247 mmol), DMAP (60.3 mg, 0.494 mmol) and GQDs (100 mg) in the prepared state were dissolved in THF (20 mL) with nitrogen bubbling to produce surface modified GQDs. ≪ / RTI > and the mixture was stirred for 30 minutes. DCC (203.3 mg, 0.988 mmol) was then added and the mixture was heated at 40 < 0 > C for 12 hours. After cooling to room temperature, the mixture was passed through
3. Preparation of pickling emulsion
A; (DCB o -dichlorobenzene) -; a solution of the modified GQDs ride GH0 and GH25 (3 mg) ion (DI deionized) can be dissolved in dichlorobenzene (2 mL) and 1 mL of the GH50, GH75, and GH100 o , Which was then sonicated for 10 minutes. Then, 1 mL of DCB was added to the GHO and GH25 solutions and 2 mL of water was added to GH50 , GH75 and GH100 to make the same total amount of solution (3 mL) for each sample. The solution was emulsified at 15,000 rpm for 5 minutes using a homogenizer.
4. Preparation of polystyrene colloidal particles
Polystyrene (PS) colloidal particles were prepared by non-uniform mini-emulsion polymerization. In a 50 mL vial, GQDs (7.5 mg), styrene (100 mg), octadecane (5 mg) and AIBN (4 mg) were dispersed in methanol (MeOH) and stirred for 20 minutes. The mixture was then sonicated for 10 minutes. The resulting mixture was transferred to an ampoule and then degassed three times before performing the radical reaction. The reaction mixture was stirred at a constant rate at 70 < 0 > C for 24 hours. After the polymerization, the PS colloidal particles were quenched by pouring the reaction mixture into MeOH at room temperature. The PS colloidal particles were separated by filtration and washed several times with a mixture of MeOH, MeOH / distilled water (50:50 v / v) and distilled water, and finally dried at room temperature.
5. Preparation of Dispersion of Graphite
For solid dispersion experiments, graphite powder (Asbury, 3763) and 3 mg of GQDs were added in 3 mL of MeOH in a weight ratio of 5: 1 (graphite / GQD). Thereafter, the dispersion was ultrasonically decomposed for 30 minutes using an ultrasonic mill. The solution was then centrifuged at 1,000 rpm for 5 minutes to remove the finely dispersed mass. The supernatant was carefully collected and stored at room temperature for several months. Thereafter, an image of the dispersed graphite was obtained by an optical microscope.
6. Characterization
The size of the GQDs and the shape of the polymer particles stabilized by the modified GQDs were measured by field emission scanning electron microscopy (FE-SEM) (Hitachi S-4800), transmission electron microscopy (TEM) JEOL 2000FX) and an optical microscope (Nikon, Eclipse 80i). TEM samples were prepared by dropping an aqueous suspension of GQDs onto a Cu grid coated with a porous carbon film followed by solvent evaporation. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra were collected using Bruker ALPHA. X-ray photoelectron spectroscopy (XPS) was performed using Thermo
Where I is the measured integrated emission intensity,? Is the refractive index of the solvent, A is the optical density, the subscript "st" means a standard with a known quantum yield, "x "Means a sample.
≪ Example 1 > Measurement of properties of GQDs
According to Experimental Example 2, the original GQDs and the surface modified GQDs were synthesized, and their molecular characteristics were confirmed by the following method.
1.1 Observation of GQDs
The synthesized raw GQDs were labeled GHO . The resulting GHO showed a broad (002) XRD peak with a center of 21.1 DEG (0.419 nm interlayer spacing), similar to that from GQDs synthesized by thermal degradation (Fig. et al ., J Mater Chem 2012, 22, 8764-8766).
In addition, when GH0 was excited with a 514-nm laser, Raman spectra showed two distinct carbon-related bands, the D band at about 1356 cm -1 and the G band at about 1605 cm -1 , (Fig. 1B) (Cheng, H. et al .,
1.2 Observation of surface modified
Figure 1 shows that the surface chemistry of GQDs was systematically modified by varying the amount of hexylamine molecules. The molecule was chemically bonded onto the GQD surface by a single-step reaction of DCC coupling with the carboxylic acid moiety and / or opening of the epoxy moiety at a mild temperature of 40 ° C. As a result, four different kinds of GQDs were successfully obtained and they were designated as GH25 , GH50 , GH75 and GH100 according to the weight ratio of added hexylamine, i.e. 25, 50, 75 and 100 wt%, respectively.
ATR-FTIR measurements were performed to monitor the grafting reaction of hexylamines on the surface of GQDs (Figure 3). Several important vibration peaks of functional groups including carboxylic acid, epoxide and amide groups were monitored and compared. For GHO , strong stretching vibration of C = O was observed at 1720 cm -1 due to the carboxylic acid group at the edge of GQD. However, the intensity of the C = O stretching vibration gradually decreased in the order of GH25 , GH50 , GH75 and GH100 . Because the carboxylic acid groups were converted to amide groups, they exhibited new stretching vibration of C = O at 1644 cm -1 and bending vibration of NH at 1577 cm -1 . In addition, the stretching vibration of the secondary amine was observed at 3050-3150 cm -1 , whereas the epoxide band at 1035 cm -1 was reduced in strength due to the ring opening reaction with the hexylamine of the epoxide group. In addition, as the amount of grafted hexylamine increased in the order of GH25 , GH50 , GH75 and GH100 , the asymmetric stretching vibration peak at 2854 and 2927 cm -1 was increased. High resolution carbon 1s (C 1s) and nitrogen 1s (N 1s) XPS measurements were performed to further support the correct surface modification of GQDs (Figure 4). Table 1 below summarizes the atomic concentrations of the different GQDs measured by XPS.
The change between the GH0 and GH100 C 1s spectra showed a significant change in the ratio of carboxylic acid and amide groups. For GH100 , the C (O) -O peak at 289.4 eV disappeared, but the amide bond (C (O) -N) peak at 288.1 eV, as most of the carboxylic acid groups reacted with hexylamine. In the N 1s XPS spectrum, it was apparent that the total amount of nitrogen increased in the order of GH25 , GH50 , GH75 and GH100 , indicating that GQD surface properties were systematically controlled by successful grafting of hexylamine molecules onto GQDs.
1.3 Observation of surface modified
The average height of the surface modified GQDs was measured from the AFM image and the average size thereof was measured from the TEM image of each sample. As shown in Fig. 5, GH0 was monodisperse with an average height of 0.97 nm, which is mostly mono or bilayer (Zhu, S. et al ., Chem. Commun . 2011, 47, 6858-6860 ). Interestingly, upon grafting of hexylamine, the average height of GHlOO was sharply increased to 2.98 nm and showed a pronounced increase tendency in the order of GH25 , GH50 , GH75 and GH100 (Fig. 6A). The increase in average height was due to the chain length of hexylamine grafted onto the basal plane of GQDs, which can be well supported by molecular simulations (Zhu, S. et al ., Adv. Funct. Mater . 2012, 22 , 4732-4740).
The simulation was performed at the B3LYP / 6-31G (d, p) level on the basis of the GQD model with two hexylamines grafted on the base plane, using density functional theory (DFT) 6b). Since the chain length of hexylamine molecules extended in equilibrium geometry was about 1 nm, the calculated height of hexylamine-grafted GQDs was about 3 nm, which was consistent with our experimental results.
Also, the graft of hexylamine affected the size of GQDs. 7, the size was increased from 12.4 nm to 13.5 nm for GH0 on GH100, which demonstrates that the hexylamine molecule has been successfully grafted onto GQD corner. In addition, the calculated average size of the modified GQDs based on the simulation was increased when hexylamine molecules were grafted to the corners of GQDs , which is consistent with a sharp increase in size between GH0 and GH25 (FIG. 8). , The average size of the modified GQDs was gradually increased from 12.4 nm to 13.5 nm for GH0 on GH100 as the amount of the grafted hexylamine increases. However, the experimentally measured size (13.5 nm) of GH100 did not exactly match the calculated value. In the present invention, this is presumed that not all edge portions are grafted to the hexylamine chain, and that the grafted chains can be directed in different directions from the base plane of the GQDs. Also, as shown in the illustration of Figures 7a and d, the high resolution TEM image of GH0 and GH75 showed a crystalline structure with a lattice constant of 0.24 nm, corresponding to the (1120) lattice of graphene, Suggesting that the crystalline structure of GQDs was retained after amine grafting (Peng, J. et al ., Nano Lett . 2012, 12, 844-849).
≪ Example 2 > Effect of dissolution of modified GQDs
2.1 Modified surface chemical effect investigation
To investigate the effect of the modified surface chemistry on the solubility of GQDs, 3 mg of each of the five different GQDs was dissolved separately in a 2 mL water / chloroform (1: 1 v / v) mixture 9). While GH0 was only soluble in the water phase, most GH25 , GH50 and GH75 were located at the interface between the water phase and the organic phase, reducing the interfacial tension. On the other hand, GH100 was only soluble in organic phase. Thus, the surface properties of the modified GQDs were systematically controlled in the range from the hydrophilic surface to the hydrophobic surface. In addition, GH25 , GH50 , GH75 and GH100 were dispersed in other hydrophobic solvents such as dichloromethane (DCM), toluene, chlorobenzene (CB) and DCB to demonstrate the solubility of the surface modified GQDs. As shown in Figure 10, GH50 , GH75 and GH100 were clearly dispersed in the solvents without any aggregation. However, GH25 was only partially dispersed due to the relatively strong hydrophilic surface properties.
2.2 Possibility of use as surfactant
Next, droplets of micrometer sized organic solvent in water were generated to investigate the possibility of surface modified GQDs for their use as surfactants. For each of the five different GQDs, a 1 mg.ml -1 GQD solution in a DCB / water (1: 2 v / v) mixture was emulsified with a homogenizer at 15,000 rpm for 5 minutes to produce an oil-in-water emulsion . After vigorous stirring, GH0 and GH100 remained in a single phase, i.e., in water and DCB, respectively, thus failing to form a pickling emulsion. Conversely, as shown in FIG. 11 bd, GH25 , GH50 and GH75 reduced the total interfacial energy by replacing the oil-water portion at the interface and resulted in a dispersion of oil droplets in water (Binks, BP, Colloid Interface Sci 2002, 7, 21-41; Boker, A. et al .,
Three months after the preparation of the emulsion, an optical microscope image was obtained. Most of the emulsified droplets were about 2-3 μm in diameter, indicating a high interfacial activity of GH25 , GH50 and GH75 . However, each sample had a different volume fraction of the residual emulsion; Respectively, with respect to the GH25, GH50 and GH75 9, 77 and 76% by volume (Fig. 11a) (He, Y. et al ., ACS Appl. Mater.
Example 3: Confirmation of use of surface-modified GQDs as a surfactant
3.1 Confirmation of amphibia of GQDs
The amphiphilic properties of GH25 , GH50 and GH75 make them suitable for use as surfactants in heterogeneous polymerization. Mini-emulsion polymerization of styrene was carried out at 70 캜 for 24 hours using GQDs as a surfactant. When GH0 and GH100 were used, no PS colloidal particles were produced, which is consistent with the results from Pickering emulsion. Conversely, mini-emulsion polymerization using GH25 , GH50 and GH75 produced spherical PS colloidal particles of ultra-fine size with a smooth surface, similar to the surface morphology of particles stabilized by conventional organic surfactants ( 12). This surface morphology differs from the rough surface morphology observed in PS colloidal particles formed when a large GO sheet is used as the stabilizer (Thickett, SC et al ., ACS Macro Lett . 2013, 2, 630-634; Che Man, SH et al ., J. Polym. Sci., Part A: Polym Chem ., 2013, 51, 47-58). All mini-emulsion polymerization conversions were greater than 90%, demonstrating the effectiveness of the surfactant behavior of GH25 , GH50 and GH75 . The average sizes of PS colloidal particles stabilized by GH25 , GH50 and GH75 were 655, 641 and 278 nm, respectively. In addition, the particle size distribution was narrowed in the order of GH25 , GH50 and GH75 , indicating that GH75 had the highest surface activity of the GQDs used in this study due to well-balanced amphipathies.
3.2 Investigation of luminescence characteristics of GQDs
In addition, the tunable luminescent emission of GQDs can be synergistically combined with the properties of the surfactant for promising applications such as fluorescent labeling and bio-imaging. The inventors measured the UV-visible absorption spectra and the photoluminescence (PL) emission spectra of GH25 , GH50 and GH75 to investigate the luminescent properties of GQDs.
As shown in FIG. 13A, a strong absorption band for surface modified GQDs was observed at about 278 nm, which was attributed to the amide group at the corner of GQDs (Sandeep Kumar, G. et al ., Nanoscale 2014, 6, 3384 -3391).
Figure 13b shows the PL emission spectra of GH25 , GH50 and GH75 under excitation at 365 nm. All surface modified GQDs emitted green luminescence with a maximum emission peak of 540 nm, regardless of the amount of hexylamine grafted. This indicates that the PL emission of GQDs is due to the emission of excited electrons from the lowest unoccupied molecular orbital (LOMO) of the carbene at the zigzag edge to the highest occupied molecular orbital (HOMO) (Zhu, S. et al ., Adv. Funct. Mater . 2012, 22, 4732-4740; Tetsuka, H. et al ., Adv. Mater . 2012, 24, 5333-5338) .
Carbenes at the zigzag edges of the original GQDs were also expected to be well conserved after the hexylamine chains were grafted onto the corners of the GQDs, because the sites were not affected by surface modification. Thus, PL release was well observed in surface modified GQDs, GH25 , GH50 and GH75 . The QYs of surface modified GQDs were calculated based on rhodamine B as a standard. QYs of GH25 , GH50 and GH75 decreased slightly in the order of 1.91, 1.56 and 1.41%, respectively. The -CONHR and CNHR groups formed by surface modification induced non-radioactive recombination of the local electron-hole pairs, and the QY gradually decreased as the amount of grafted hexylamine increased (Zhu, S. et al . , Adv. Funct. Materials, 2012, 22, 4732-4740). To demonstrate the possibility of surface modified GQDs as fluorescent surfactants, optical and fluorescence microscopic images of PS particles stabilized by GH25 were measured. Figure 14 shows that the PS colloidal particles stabilized by GH25 have green emission, indicating that the fluorescent GQDs are strongly coated on the surface of the PS particles.
Example 4 Identification of Dispersant Uses of Modified GQDs
Another major use of surfactants is their use as dispersants for insoluble solids by reducing the interfacial energy between solids and liquids (Kim, J. et al ., J. Am. Chem. Soc . 2010, 132, 8180-8186). To investigate the surfactant behavior of surface modified GQDs for solid dispersion, a model system with graphite as insoluble solids and MeOH as solvent was selected (Fig. 15A).
The graphite powder and GQDs were dispersed in MeOH in a mass ratio of 15: 1 and the dispersion was sonicated for 30 minutes using an ultrasonic mill. The dispersion was then centrifuged at 1000 rpm for 5 minutes for separation. Since GQDs have a pi-conjugated aromatic ring in the base plane, this can be adsorbed to the graphite surface through a pi-pi interaction, which reduces the interfacial energy between graphite and MeOH. Thus, GH25 , GH50 and GH75 produced good dispersions of graphite powder. However, GH100 did not stabilize the graphite powder well. This was because a large amount of hexylamine grafted onto GH100 could prevent interaction with graphite. It was observed that 1 mg of GH25 , GH50 and GH75 were dispersed in 0.8, 1.8 and 3.0 mg of graphite, respectively, whereas GH0 and GH100 were dispersed only in 0.1 mg and 0.2 mg of graphite, respectively. It should also be noted that the graphite dispersions with GH25 , GH50 and GH75 were very stable for at least several months after production (Fig. 15B). In comparison, it has been previously reported that the dispersion of graphite by GO is stable for several days (Kim, J. et al ., J. Am. Chem. Soc . 2010, 132, 8180-8186). As shown in Fig. 15c-e, the size of the dispersed graphite was very different and decreased from 13.4 to 2.6 탆 in the order of GH25 , GH50 and GH75 . In particular, GH75 with well-balanced amphipathic properties exhibited excellent surfactant behavior in oil-water systems and was also the most effective dispersant for graphite.
That is, according to the present invention, a series of modified GQDs having tailored surface properties are synthesized and their use as an efficient surfactant in an immiscible blend can be confirmed. Extensive control of the surface properties of GQDs, from highly hydrophilic to fully hydrophobic properties, has been achieved in a systematic way by grafting a controlled amount of hexylamine onto the GQD surface. Also, since the reaction conditions were very mild at 40 ° C, the reaction did not affect any inherent properties of GQDs. Amphipathic GQDs, namely GH25 , GH50 and GH75, were placed at the interface between the two immiscible blends, and thus preferred surfactant behavior was achieved with modified GQDs (see Example 2). Specifically, the GQDs stabilized mini-emulsion polymerization of Pickering emulsion and PS colloidal particles, the size of which was less than a few hundred nanometers. GQDs were also used to control the dispersion of graphite in MeOH. The strategy of the present invention for controlling the surface activity of GQDs is a simple and versatile way to extend the range of uses from emulsifiers to dispersants. In addition, synergistic combinations of the fluorescence and surfactant properties of surface modified GQDs are applicable to techniques such as fluorescent labeling and bio-imaging (see Examples 3 and 4).
The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.
Claims (7)
a) preparing a mixture of a compound containing a hydrophobic group in a solvent, DMAP (4-dimethylaminopyridine) and a graphene quantum dot dissolved therein;
b) adding DCC (N, N'-dicyclohexylcarbodiimide) to the mixture of step a), heating and cooling to room temperature;
c) filtering and precipitating the cooled mixture in step b) to obtain a precipitate; And
d) washing the precipitate obtained in step c) with diethyl ether to remove unreacted material.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020150087265A KR20160149727A (en) | 2015-06-19 | 2015-06-19 | Surface engineered graphene quantum dots and synthesizing method of the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020150087265A KR20160149727A (en) | 2015-06-19 | 2015-06-19 | Surface engineered graphene quantum dots and synthesizing method of the same |
Publications (1)
Publication Number | Publication Date |
---|---|
KR20160149727A true KR20160149727A (en) | 2016-12-28 |
Family
ID=57724341
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
KR1020150087265A KR20160149727A (en) | 2015-06-19 | 2015-06-19 | Surface engineered graphene quantum dots and synthesizing method of the same |
Country Status (1)
Country | Link |
---|---|
KR (1) | KR20160149727A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113651319A (en) * | 2021-08-25 | 2021-11-16 | 深圳华算科技有限公司 | Preparation method of graphene quantum dot nanocluster |
-
2015
- 2015-06-19 KR KR1020150087265A patent/KR20160149727A/en active Search and Examination
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113651319A (en) * | 2021-08-25 | 2021-11-16 | 深圳华算科技有限公司 | Preparation method of graphene quantum dot nanocluster |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Du et al. | Cage-like silsesquioxanes-based hybrid materials | |
Ganguly et al. | Advancement in science and technology of carbon dot-polymer hybrid composites: a review | |
KR101490776B1 (en) | Manufacturing methods of carbon quantum dots using emulsion | |
Cho et al. | Surface engineering of graphene quantum dots and their applications as efficient surfactants | |
WO2014179708A1 (en) | Methods of producing graphene quantum dots from coal and coke | |
JP2020528876A (en) | Small molecule self-supporting film and hybrid material | |
KR101981853B1 (en) | Pickering emulsion composition using polyimide particles and preparation method thereof | |
CN108300463B (en) | Amphiphilic graphene quantum dot and preparation method and application thereof | |
WO2005016824A2 (en) | Synthesis of nanoparticles by an emulsion-gas contacting process | |
Wu et al. | A versatile platform for the highly efficient preparation of graphene quantum dots: photoluminescence emission and hydrophilicity–hydrophobicity regulation and organelle imaging | |
Liu et al. | Facile synthesis, high fluorescence and flame retardancy of carbon dots | |
Wang et al. | Polymer microsphere for water-soluble drug delivery via carbon dot-stabilizing W/O emulsion | |
KR20130027317A (en) | Quantum dot complex and fabricating method of the same | |
Xue et al. | A simple and controllable graphene-templated approach to synthesise 2D silica-based nanomaterials using water-in-oil microemulsions | |
Huang et al. | Self-assembly of 2D nanosheets into 3D dendrites based on the organic small molecule ANPZ and their size-dependent thermal properties | |
Hwang et al. | Preparation and characterization of poly (MSMA-co-MMA)-TiO2/SiO2 nanocomposites using the colloidal TiO2/SiO2 particles via blending method | |
Samanta et al. | Graphene Quantum Dots-Ornamented Waterborne Epoxy-Based Fluorescent Adhesive via Reversible Addition–Fragmentation Chain Transfer-Mediated Miniemulsion Polymerization: A Potential Material for Art Conservation | |
Dolai et al. | Solvent‐Assisted Synthesis of Supramolecular‐Assembled Graphitic Carbon Nitride for Visible Light Induced Hydrogen Evolution–A Review | |
WO2013029278A1 (en) | A method for preparing functionalized silicon nanoparticles | |
Shi et al. | Facile preparation of highly luminescent CdTe quantum dots within hyperbranched poly (amidoamine) s and their application in bio-imaging | |
Gao et al. | APhen-functionalized nanoparticles–polymer fluorescent nanocomposites via ligand exchange and in situ bulk polymerization | |
KR20160149727A (en) | Surface engineered graphene quantum dots and synthesizing method of the same | |
Chen et al. | Triple phase inversion of emulsions stabilized by amphiphilic graphene oxide and cationic surfactants | |
Zhang et al. | ZnO@ PNIPAM nanospheres synthesis from inverse Pickering miniemulsion polymerization | |
CN115057428A (en) | Hydrophobic near-infrared emission carbon quantum dot and preparation method and application thereof |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A201 | Request for examination | ||
E902 | Notification of reason for refusal | ||
AMND | Amendment | ||
E601 | Decision to refuse application | ||
AMND | Amendment |