Cov nyhuv ntub dej, qhov yuav tsum tau ua: HLB: 7-9
Kev ntub dej yog txhais tias yog qhov xwm txheej uas cov pa roj uas nqus rau ntawm qhov chaw khov kho raug tshem tawm los ntawm cov kua. Cov tshuaj uas tuaj yeem txhim kho lub peev xwm hloov pauv no hu ua cov neeg sawv cev ntub dej. Kev ntub dej feem ntau yog muab faib ua peb hom: kev ntub dej sib cuag (kev ntub dej nplaum), kev ntub dej rau hauv dej (kev ntub dej rau hauv dej), thiab kev ntub dej kis mus (kev nthuav dav). Ntawm cov no, kev nthuav dav sawv cev rau tus qauv siab tshaj plaws ntawm kev ntub dej, thiab cov coefficient nthuav dav feem ntau siv ua qhov qhia txog kev ntsuas kev ua tau zoo ntawm kev ntub dej ntawm ntau lub tshuab sib txawv. Tsis tas li ntawd, lub kaum sab xis sib cuag kuj yog qhov ntsuas rau kev txiav txim siab qhov zoo ntawm kev ntub dej. Cov tshuaj surfactants tuaj yeem siv los tswj qib ntawm kev ntub dej ntawm cov kua thiab cov khoom khov kho.
Hauv kev lag luam tshuaj tua kab, qee cov tshuaj granular thiab cov hmoov uas muaj plua plav kuj muaj qee cov surfactants. Lawv lub hom phiaj yog los txhim kho qhov lo thiab tso cov tshuaj tua kab rau ntawm qhov chaw, ua kom nrawm dua thiab nthuav qhov chaw kis ntawm cov khoom xyaw nquag hauv cov huab cua noo, yog li ua kom zoo dua ntawm kev tiv thaiv thiab kho kab mob.
Hauv kev lag luam tshuaj pleev ib ce, surfactants ua haujlwm ua emulsifiers thiab yog cov khoom tseem ceeb hauv cov khoom siv tawv nqaij xws li cream, lotions, cleansers ntsej muag thiab makeup remover.
Micelles thiab Solubilization,cov kev cai: C > CMC (HLB 13–18)
Qhov tsawg kawg nkaus concentration uas surfactant molecules koom nrog los ua micelles. Thaum qhov concentration tshaj qhov CMC tus nqi, surfactant molecules npaj lawv tus kheej rau hauv cov qauv xws li spherical, rod-like, lamellar, lossis plate-like configurations.
Cov txheej txheem Solubilization yog cov txheej txheem thermodynamic equilibrium. Qhov qis dua CMC thiab qhov siab dua ntawm kev sib koom ua ke, qhov ntau dua qhov siab tshaj plaws ntawm cov khoom ntxiv (MAC). Qhov cuam tshuam ntawm qhov kub ntawm kev solubilization yog pom tseeb hauv peb yam: nws cuam tshuam rau kev tsim micelle, qhov solubility ntawm solubilizates, thiab solubility ntawm surfactants lawv tus kheej. Rau ionic surfactants, lawv qhov solubility nce ntxiv nrog rau qhov kub nce, thiab qhov kub uas qhov kev nce siab sai no tshwm sim hu ua Krafft point. Qhov siab dua Krafft point, qhov qis dua qhov tseem ceeb micelle concentration.
Rau cov polyoxyethylene nonionic surfactants, thaum qhov kub nce mus txog ib qib, lawv cov solubility poob qis thiab nag los, ua rau cov tshuaj tig turbid. Qhov xwm txheej no hu ua clouding, thiab qhov kub sib xws hu ua huab point. Rau cov surfactants nrog tib lub polyoxyethylene saw ntev, qhov ntev ntawm cov hydrocarbon saw, qhov qis dua qhov huab point; conversely, nrog tib lub hydrocarbon saw ntev, qhov ntev ntawm cov polyoxyethylene saw, qhov siab dua qhov huab point.
Cov tshuaj organic uas tsis yog polar (piv txwv li, benzene) muaj qhov solubility qis heev hauv dej. Txawm li cas los xij, kev ntxiv cov surfactants xws li sodium oleate tuaj yeem ua rau kom muaj kev solubility ntawm benzene hauv dej ntau ntxiv - ib qho txheej txheem hu ua solubilization. Solubilization yog qhov sib txawv ntawm kev yaj ib txwm muaj: cov benzene uas yaj tsis tau sib xyaw ua ke hauv cov dej molecules tab sis raug kaw hauv cov micelles uas tsim los ntawm oleate ions. Kev tshawb fawb X-ray diffraction tau lees paub tias txhua hom micelles nthuav dav mus rau ntau qib tom qab solubilization, thaum cov khoom colligative ntawm tag nrho cov tshuaj tseem tsis hloov pauv ntau.
Thaum cov surfactants hauv dej nce ntxiv, cov surfactant molecules sib sau ua ke rau ntawm cov kua dej kom tsim tau ib txheej monomolecular uas sib sau ua ke. Cov molecules ntau dhau hauv cov theem loj sib sau ua ke nrog lawv cov pab pawg hydrophobic tig mus rau sab hauv, tsim cov micelles. Qhov concentration tsawg kawg nkaus uas xav tau los pib tsim micelle yog txhais tias yog qhov concentration micelle tseem ceeb (CMC). Ntawm qhov concentration no, cov tshuaj hloov pauv ntawm tus cwj pwm zoo tagnrho, thiab muaj qhov taw qhia sib txawv tshwm sim ntawm qhov nkhaus ntawm qhov nro ntawm qhov chaw vs. concentration. Kev nce ntxiv ntawm qhov concentration surfactant yuav tsis txo qhov nro ntawm qhov chaw; hloov chaw, nws yuav txhawb kev loj hlob tas mus li thiab kev sib kis ntawm cov micelles hauv theem loj.
Thaum cov tshuaj surfactant molecules tawg ua tej daim me me hauv cov tshuaj thiab mus txog qhov concentration threshold, lawv sib txuas los ntawm cov monomers (ions lossis molecules) mus rau hauv cov colloidal aggregates hu ua micelles. Qhov kev hloov pauv no ua rau muaj kev hloov pauv sai sai hauv cov khoom siv lub cev thiab tshuaj ntawm cov tshuaj, thiab qhov concentration uas qhov no tshwm sim yog CMC. Cov txheej txheem ntawm kev tsim micelle hu ua micellization.
Kev tsim cov micelles hauv cov tshuaj surfactant hauv dej yog ib qho txheej txheem uas nyob ntawm qhov concentration. Hauv cov tshuaj uas dilute heev, dej thiab cua yuav luag sib cuag ncaj qha, yog li qhov kev nruj ntawm qhov chaw tsuas yog txo qis me ntsis xwb, tseem nyob ze rau cov dej ntshiab, nrog rau ob peb lub surfactant molecules uas tawg ua pawg hauv theem loj. Thaum qhov kev nruj ntawm surfactant nce me ntsis, cov molecules sai sai nqus mus rau ntawm qhov chaw dej, txo qhov chaw sib cuag ntawm dej thiab cua thiab ua rau qhov kev nruj ntawm qhov chaw poob qis. Lub caij no, qee cov surfactant molecules hauv theem loj sib sau ua ke nrog lawv cov pab pawg hydrophobic sib phim, tsim cov micelles me me.
Thaum qhov concentration txuas ntxiv nce thiab cov tshuaj mus txog qhov saturation adsorption, ib zaj duab xis monomolecular uas ntim ntau heev tsim rau ntawm qhov chaw ua kua. Thaum qhov concentration ntaus CMC, qhov kev nruj ntawm qhov chaw ntawm cov tshuaj mus txog nws qhov tsawg kawg nkaus. Dhau ntawm CMC, kev nce ntxiv ntawm qhov surfactant concentration tsis cuam tshuam rau qhov kev nruj ntawm qhov chaw; hloov chaw, nws nce tus lej thiab qhov loj ntawm micelles hauv theem bulk. Cov tshuaj ces yog dominated los ntawm micelles, uas ua haujlwm ua microreactors hauv kev tsim cov nanopowders. Nrog rau qhov kev nce ntxiv ntawm qhov concentration, lub kaw lus maj mam hloov mus rau lub xeev kua crystalline.
Thaum qhov concentration ntawm cov kua surfactant aqueous ncav cuag CMC, kev tsim cov micelles yuav pom tseeb nrog rau qhov concentration nce ntxiv. Qhov no yog tus cwj pwm los ntawm qhov inflection point hauv qhov nro ntawm qhov chaw vs. log concentration curve (γ-log c curve), nrog rau qhov tshwm sim ntawm cov khoom tsis zoo thiab cov tshuaj lom neeg hauv cov kua.
Cov micelles surfactant ionic nqa cov nqi siab ntawm qhov chaw. Vim yog qhov electrostatic attraction, cov counterions raug nyiam rau ntawm qhov chaw micelle, ua rau ib feem ntawm cov nqi zoo thiab tsis zoo tsis zoo. Txawm li cas los xij, thaum cov micelles tsim cov qauv them siab, lub zog retarding ntawm huab cua ionic tsim los ntawm cov counterions nce ntxiv ntau heev - ib yam khoom uas tuaj yeem siv los kho qhov dispersibility ntawm nanopowders. Vim ob qho laj thawj no, qhov sib npaug conductivity ntawm cov tshuaj txo qis sai sai nrog kev nce concentration dhau CMC, ua rau qhov no yog ib txoj hauv kev txhim khu kev qha rau kev txiav txim siab qhov tseem ceeb ntawm micelle concentration ntawm surfactants.
Cov qauv ntawm ionic surfactant micelles feem ntau yog spherical, muaj peb ntu: lub hauv paus, lub plhaub, thiab lub hluav taws xob ob txheej. Lub hauv paus yog tsim los ntawm hydrophobic hydrocarbon saw, zoo ib yam li cov kua hydrocarbons, nrog rau txoj kab uas hla ntawm kwv yees li 1 txog 2.8 nm. Cov methylene pawg (-CH₂-) nyob ib sab ntawm cov taub hau polar muaj ib feem polarity, khaws qee cov dej molecules nyob ib puag ncig lub hauv paus. Yog li, lub hauv paus micelle muajmuaj dej ntau heev, thiab cov pab pawg -CH₂- no tsis tau koom ua ke tag nrho rau hauv cov kua hydrocarbon core tab sis hloov chaw ua ib feem ntawm lub plhaub micelle uas tsis yog kua.
Lub plhaub micelle kuj tseem hu ua micelle-water interface lossis qhov nto. Nws tsis yog hais txog qhov macroscopic interface ntawm micelles thiab dej tab sis yog thaj tsam ntawm micelles thiab cov kua monomeric aqueous surfactant. Rau ionic surfactant micelles, lub plhaub yog tsim los ntawm txheej Stern sab hauv (lossis txheej adsorption ruaj khov) ntawm cov txheej hluav taws xob ob txheej, nrog rau qhov tuab ntawm li 0.2 txog 0.3 nm. Lub plhaub tsis yog tsuas yog cov pab pawg ionic taub hau ntawm surfactants thiab ib feem ntawm cov counterions khi tab sis kuj muaj txheej hydration vim yog hydration ntawm cov ions no. Lub plhaub micelle tsis yog qhov du tab sis yog qhov "rough", qhov tshwm sim ntawm kev hloov pauv los ntawm kev txav thermal ntawm surfactant monomer molecules.
Hauv cov xov xwm uas tsis yog dej (roj-raws li), qhov twg cov roj molecules predominant, cov pab pawg hydrophilic ntawm surfactants sib sau ua ke sab hauv los tsim lub hauv paus polar, thaum cov saw hydrophobic hydrocarbon tsim lub plhaub sab nraud ntawm micelle. Hom micelle no muaj cov qauv rov qab piv rau cov micelles aqueous ib txwm muaj thiab yog li ntawd hu ua micelle rov qab; los ntawm qhov sib piv, micelles tsim hauv dej hu ua micelles ib txwm muaj. Daim duab 4 qhia txog cov qauv schematic ntawm cov micelles rov qab tsim los ntawm surfactants hauv cov tshuaj tsis yog dej. Nyob rau hauv xyoo tas los no, cov micelles rov qab tau siv dav hauv kev tsim thiab kev npaj ntawm nanoscale tshuaj carriers, tshwj xeeb tshaj yog rau encapsulation ntawm hydrophilic tshuaj.
Lub sijhawm tshaj tawm: Lub Kaum Ob Hlis-26-2025