Nyob rau hauv lub tshav pob ntawm precision polishing, nanodiamonds muaj ib tug heev Mohs hardness ntawm 10, nrog rau qhov chaw tshwj xeeb nto thiab siab nto ua hauj lwm ntawm lub nanoscale. Thaum ua cov ntaub ntawv nyuaj thiab nkig xws li silicon carbide thiab sapphire, lawv muaj peev xwm ntawm atomic - theem cov khoom tshem tawm. Txawm li cas los xij, cov khoom nanodiamond ib txwm ua los ntawm cov khoom siv hluav taws xob tam sim no thiab siab - kub siab - siab (HTHP) cov txheej txheem synthesis zoo li spontaneously agglomerate. Thaum siv nyob rau hauv workpiece polishing, qhov no yooj yim ua rau nto khawb, pits, tsis zoo flatness, thiab lwm yam teeb meem, ncaj qha txo cov khoom yield. Nws kuj txwv lawv daim ntawv thov hauv lubricating coatings, biosensing, siab- cov ntaub ntawv sib xyaw kawg, thiab lwm yam. Yog li ntawd, kev ua tau zoo deagglomeration thiab ruaj khov dispersion ntawm nanodiamonds yog qhov tseem ceeb rau kev siv tag nrho lawv cov khoom zoo thiab qhib siab siab -kawg daim ntawv thov kev lag luam. Kab lus no pib nrog qhov ua rau nanodiamond agglomeration thiab tshuaj xyuas plaub qhov loj deagglomeration thev naus laus zis txoj hauv kev thoob plaws hauv kev lag luam.
Vim li cas nanodiamonds ua ke ua ke?
Nanodiamond hais yog heev me me, nrog diameters li ntawm tsuas yog 2 mus rau 50 nanometers, thiab muaj ib tug loj heev cheeb tsam. Lub cev, lawv nyob hauv lub xeev tsis ruaj khov. Txhawm rau ua tiav qhov kev teeb tsa ruaj khov dua, cov khoom siv ultrafine spontaneously adsorb rau ib leeg thiab agglomerate-qhov no yog lub hauv paus ua rau lawv nyiam ua pawg. Nyob rau tib lub sijhawm, cov nplais me me muaj ntau qhov chaw tsis muaj dej tsis txaus uas nkag mus rau cov dej noo thiab impurities los ntawm huab cua, ua rau cov khoom ua kom nruj ua ke thiab ua rau cov teeb meem clumping, tsim cov pa agglomerates. Feem ntau, xws li cov agglomerates yog feem ntau tuav ua ke los ntawm lub cev rog xws li van der Waals rog, electrostatic attraction, thiab capillary rog, nrog rau feem ntau nyob rau hauv taw tes los yog angular sib cuag, uas ua rau cov tsis muaj zog bonding rog.
Txawm li cas los xij, nanodiamonds tsim los ntawm txoj kev detonation muaj cov khoom seem ntawm lawv qhov chaw, xws li graphitic carbon thiab amorphous carbon. Thaum lub sij hawm siab - kub synthesis, cov khoom uas nyob ib sab tuaj yeem ncaj qha tsim cov carbon-carbon bonds muaj zog. Ua ke nrog lub cev qhuav dej thiab kho cov pab pawg saum npoo thaum lub sij hawm tom qab ziab thiab khaws cia, qhov no thaum kawg ua rau ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom. Cov agglomerates nyuaj no tsis tuaj yeem sib cais los ntawm cov rog sab nraud ib leeg, ua rau muaj kev sib tw loj rau kev siv nanodiamonds.
Yuav ua li cas deagglomerate nanodiamonds?
Hauv kev teb rau cov txheej txheem agglomeration saum toj no, kev lag luam tau tsim ntau hom deagglomeration technologies rau nanodiamonds, uas tuaj yeem muab faib ua plaub yam loj: txoj hauv kev dispersion lub cev, txoj kev siv tshuaj inorganic, siab - zog teb txoj kev, thiab kev hloov tshuaj lom neeg.
01 Lub Cev Dispersion Methods
Lub cev dispersion txoj kev vam khom rau cov neeg kho tshuab quab yuam kom kov yeej interparticle attraction thiab yuam kom tawg cov mos agglomerates. Txawm li cas los xij, qhov kev cuam tshuam ntawm lub cev tsis tuaj yeem lav tau ntev - lub sij hawm ruaj khov ntawm qhov raug ncua thiab feem ntau yog siv los ua cov txheej txheem cuam tshuam. Cov txheej txheem muaj xws li:
(1) Siab -lub zog pob zeb: Qhov no yog txoj kev siv tshuab feem ntau. Nws siv lub zog siv hluav taws xob tsim los ntawm siab - kev sib tsoo ceev thiab kev sib tsoo ntawm cov pob sib tsoo kom tsoo cov micron-loj agglomerates mus rau qhov ntsuas nanometer. Feem ntau, qhov nruab nrab dispersion (xws li, dej los yog cawv) muab lubrication thiab ua ntej stabilization, yog li ntub pob milling yog ntau npaum li cas qhuav pob milling.
(2) Ultrasound-pab dispersion: Txoj kev no siv cov nyhuv cavitation hauv cov kua rau deagglomerate pawg. Thaum lub sij hawm ultrasonic propagation, microbubbles tsim nyob rau hauv cov kua. Nyob rau hauv lub sij hawm compression thiab rarefaction ntawm ultrasonic teb, cov npuas no loj hlob mus rau resonance loj thiab ces vau hnyav. Lub cev qhuav dej tam sim no ua rau muaj qhov kub thiab txias, siab siab, thiab muaj zog poob siab tsis muaj zog nrog rau kev kub ceev microjets hauv qhov chaw me me, yog li cuam tshuam van der Waals rog, electrostatic adsorption, thiab lwm yam kev sib txuas ntawm cov khoom, thiab tawg loj agglomerates rau hauv micron- rau nanoscale ib tus zuj zus dispersed hais.
02 Inorganic Chemical Methods
Inorganic chemical txoj kev koom nrog cov txheej txheem xws li kua qaub ntxuav, hydrogenation annealing, thiab oxidation annealing kom tshem tawm cov hlau sib txuas thiab cov pob zeb diamond uas tsis yog cov pa roj carbon (xws li graphite thiab amorphous carbon) los ntawm cov nanodiamonds, yog li txo cov agglomeration nyuaj.
(1) Acid ntxuav: Kev kho cov kua qaub uas muaj zog xws li nitric acid lossis hydrochloric acid tuaj yeem yaj thiab tshem tawm cov hlau tsis huv, thaum tseem qhia txog ntau cov pa oxygen uas muaj cov pab pawg ua haujlwm zoo- xws li carboxyl (-COOH), hydroxyl (-OH), thiab carbonyl (C=O) pawg{4}. Nyob rau hauv cov kev daws teeb meem aqueous, cov pawg polar ionizes, imparting ib tug tsis zoo nto nqi rau cov hais, generating electrostatic repulsion ntawm hais thiab yog li hindering agglomeration.
(2) Oxidation annealing: Cua sov nanodiamonds hauv cov huab cua lossis cov pa oxygen zoo ib yam qhia cov pa oxygen uas muaj cov haujlwm ua haujlwm ntawm qhov chaw. Piv nrog rau cov kua-theem acid oxidation, nws qhov zoo yog qhov tsis muaj kua pov tseg thaum lub sij hawm ua, ua rau nws haum rau loj-scale nruam ntau lawm.
(3) Hydrogenation annealing: Nyob rau hauv sib piv rau oxidation, hydrogenation annealing muaj cua sov nanodiamonds nyob rau hauv high kub nyob rau hauv ib tug hydrogen cua kom tshem tawm cov pa oxygen-muaj pawg nto, tsim ib tug hydrogen-terminated nto (xws li, -CH₂ pawg). Tom qab kev kho hydrogenation, nanodiamond nto ua hydrophobic, txhim kho nws cov dispersibility nyob rau hauv non-polar solvents.
03 Txoj Kev Ua Haujlwm Siab Zog
Txoj kev siv hluav taws xob siab siv lub cev hnyav xws li lasers lossis plasma los ua ncaj qha rau ntawm cov qauv agglomerated, ua kom zoo thiab huv si rhuav tshem nyuaj agglomerates ntawm nanodiamonds thiab txhawb kev ruaj khov dispersion hauv xov xwm.
(1) Plasma-pab dispersion: Cov khoom siv hluav taws xob siab (piv txwv li, ions, electrons) tsim los ntawm plasma bombard lub nanodiamond agglomerates, tsis tsuas yog ua rau lub cev muaj zog thiab microjets, tab sis kuj ncaj qha cuam tshuam covalent bonds ntawm nanodiamond hais thiab hloov lawv cov tshuaj lom neeg lub xeev, thaum kawg cuam tshuam nyuaj agglomeration.
(2) Laser-pab dispersion: Lub zog ultra-siab zog ntawm lasers tuaj yeem, ntawm ib sab, ncaj qha tawg covalent bonds ntawm nanodiamond hais (tshwj xeeb tshaj yog cov interfacial bonds ntawm lub nto sp²-hybridized carbon txheej thiab sp³ pob zeb diamond core) thiab intermolecular van der Waals rog. Ntawm qhov tod tes, lub zog laser tuaj yeem nqus tau los ntawm cov kua dej xws li dej, ua rau lub avalanche ionization thiab tsim cov plasma plumes. Lub nrawm nrawm nrawm ntawm cov ntshav ua rau muaj zog poob siab tsis muaj zog hauv zos, cuam tshuam thiab rhuav tshem lub cev sib koom ua ke ntawm nanodiamond agglomerates, yog li ua tau zoo deagglomeration.
04 Nto Organic Kev Hloov Kho Tshuaj
Agglomeration yog txheej txheem spontaneous nrog qis ua kom lub zog. Txawm hais tias agglomerates tau tawg ib ntus los ntawm cov quab yuam sab nraud, tsuav yog qhov particle deg lub xeev tsis tau hloov pauv, cov chaw tshiab uas tau tshwm sim yuav sai sai rov ua dua los ntawm cov lus hais saum toj no. Kev hloov kho cov tshuaj organic deg yog li ntawd yog ib qho tseem ceeb txhais tau tias kom muaj kev ruaj ntseg dispersion tom qab deagglomeration los ntawm kev hloov cov particle deg xeev. Tam sim no, txoj hauv kev tseem ceeb suav nrog arylation, sulfonation-diamond functionalization, thiab photografting.
(1) Arylation: Qhia cov pab pawg uas muaj ntxhiab tsw xws li phenyl lossis naphthyl mus rau nanodiamond nto tuaj yeem nyob hauv qhov chaw dangling daim ntawv cog lus, thaum lub steric hindrance muab los ntawm lawv cov txheej txheem nruj zoo tiv thaiv particle mus kom ze. Tsis tas li ntawd, cov nplhaib uas muaj ntxhiab tsw qab tuaj yeem ua cov ntsiab lus txuas ntxiv rau kev ua haujlwm ntxiv.
(2) Sulfonation: Qhia cov pab pawg sulfonic acid (-SO₃H) mus rau nanodiamond nto ntawm sulfonation cov tshuaj tiv thaiv. Sulfonic acid pawg yog cov acidic thiab tag nrho ionize nyob rau hauv aqueous tov, ho hloov lub nto zeta tej zaum ntawm cov hais. Qhov no ua rau muaj zog electrostatic repulsion ntawm nanodiamond hais, zoo counteracting van der Waals thiab tiv thaiv re-agglomeration, yog li ua tiav deagglomeration thiab tuav ruaj khov dispersion. Nyob rau tib lub sijhawm, sulfonation hloov pauv qhov chaw chemistry ntawm nanodiamonds, txhim kho qhov polarity thiab txhim kho particle wettability hauv polar solvents (xws li dej).
(3) Photografting: Siv ultraviolet los yog pom lub teeb irradiation kom excite lub nanodiamond nto los yog photosensitizers tsim dawb radicals, uas pib polymerization ntawm olefinic monomers rau saum npoo, grafting ntev polymer chains. Feem ntau grafting monomers muaj xws li acrylic acid, acrylamide, methyl methacrylate, thiab lwm yam. Lub polymer chains xav tias txuas ntxiv conformations nyob rau hauv cov kuab tshuaj, ua ib tug steric hindrance txheej nrog thickness xws li los ntawm ob peb nanometers mus rau kaum nanometers. Lub zog repulsive nce sharply raws li qhov kev ncua deb ntawm interparticle txo, ua qhov no yog ib qho zoo tshaj plaws txhais tau tias tiv thaiv agglomeration. Qhov zoo ntawm photografting muaj xws li cov tshuaj tiv thaiv me me thiab kev tswj xyuas meej ntawm grafting ceev thiab saw ntev los ntawm kev kho lub sij hawm irradiation thiab monomer concentration.