表界面化學(xué)表面活性劑

表界面化學(xué)表面活性劑3、1Molecularstructureofsurfactant結(jié)構(gòu)上雙親物質(zhì)得定義Anamphiphileisasubstancethatbinesintheonemoleculeasegmentthattendstowaterinsoluble(不溶于水)andoilsoluble(溶于油),i、e、hydrophobicoroleophilic,andasegmentthattendstobewatersoluble,i、e,hydrophilic、Phospholipidshaveamphipathiccharacter、磷脂得分子結(jié)構(gòu)BEAConfidential、|33、1MolecularstructureofsurfactantAsurfactantisapoundthatlowersthesurfacetension(降低表面張力)ofaliquid,increasingthecontactbetweentheliquidandanothersubstance、功能上表面活性劑得定義3、1MolecularstructureofsurfactantSurfactantsarewater-solubleamphiphilesandarestronglyadsorbedatsurfaces、Thedrivingforceforthisstrongadsorptionesfromtheamphiphilcnatureofthesurfactantmolecule、表面活性劑可在表面吸附強(qiáng)烈,驅(qū)動(dòng)力來自于其雙親性。3、1MolecularstructureofsurfactantThehydrophobicportionofthemoleculecanbelargelylocatedinthevapourphaseoutofwaterwhilethehydrophilicportioncanbeimmersedinthewater、疏水端在氣相,親水端在水相3、1MolecularstructureofsurfactantSuchadsorbedfilmsareknownasGibbsmonolayers(Monolayerbecausethereisnormallyonlyonelayer)、這樣得吸附層被稱為吉布斯單分子層

BEAConfidential、|83、2SurfactantClassificationTherearefourclassesofsurfactant,definedbytheionicnatureofthehydrophilicmoiety:anionic(陰離子型),cationic(陽離子型),non-ionic(非離子型)andzwitterionic(兩性離子型)、十二酸(月桂酸)鈉-肥皂十二烷基苯磺酸鈉鹽-洗衣粉十二烷基硫酸鈉3、2SurfactantClassification溴化十六烷基三甲銨十二烷基氯化吡啶大家學(xué)習(xí)辛苦了，還是要堅(jiān)持繼續(xù)保持安靜3、2SurfactantClassification環(huán)氧乙烷類-佰草集3、2SurfactantClassification十二烷基二甲基甜菜堿pH不敏感-完美十二烷基丙氨酸3、3Surfacetensionofsurfactantsolutions

表面活性劑溶液得表面張力Thesurfacetensionofasurfactantsolution,whenplottedagainstconcentration,usuallyfallssmoothlytoalowerlimitwhichitremainsconstant、表面活性劑溶液表面張力和濃度得變化曲線——下降后保持水平3、3Surfacetensionofsurfactantsolutions

表面活性劑溶液得表面張力ThecurveisnearlylinearatverylowconcentrationsandtheGibbsequation(吉布斯吸附方程)indicatesthattheadsorptionisthenproportionaltotheconcentration、a活度,Γ(gama)吸附量非離子型離子型1、dg/da<0,增加溶質(zhì)得濃度使表面張力下降,Γ為正值,就是正吸附。表面層中溶質(zhì)濃度大于本體濃度。表面活性物質(zhì)屬于這種情況。2、dg/da>0,增加溶質(zhì)得濃度使表面張力升高,Γ為負(fù)值,就是負(fù)吸附。表面層中溶質(zhì)濃度低于本體濃度。非表面活性物質(zhì)屬于這種情況。3、3SurfacetensionofsurfactantsolutionsWhenthesurfacetensionisplottedagainstlncthereisanearlylinearfalljustbeforeanabruptchangetotheconstantvalueofsurfacetension、若以表面張力和lnc做直線,則會(huì)在表面張力突變?yōu)槎ㄖ抵坝幸欢尉€性得下降區(qū)域。3、3SurfacetensionofsurfactantsolutionsTheGibbsequationshowsthatwheretheγ-lnccurveislineartheadsorptionisconstant,suggestingthattheadsorptionhasreachedalimit、Saturationadsorption3、3Surfacetensionofsurfactantsolutions吸附量得計(jì)算AdsorptionvaluescanbecalculatedfromsuchsurfacetensiondatausingtheGibbsequation、3、3Surfacetensionofsurfactantsolutions數(shù)據(jù)較少時(shí)候得兩個(gè)可以得近似Atlowsurfactantconcentrationstheslopedγ/dcisnearlyconstant,andatconcentrationsjustbelowtheregionofconstantsurfacetensiontheslopedγ-lncisnealyconstant、

3、3Surfacetensionofsurfactantsolutions吸附等溫線Adsorptionisotherms3、3Surfacetensionofsurfactantsolutions例題——分子截面積得求取3、3Surfacetensionofsurfactantsolutions例題——分子截面積得求取3、3Surfacetensionofsurfactantsolutions例題——分子截面積得求取3、3Surfacetensionofsurfactantsolutions例題——分子截面積得求取3、4Micelles(膠束)3、4Micelles(膠束)Asthesurfacebeescrowdedwithsurfactant,moremoleculeswillarrangeintomicelles、Atsomeconcentrationthesurfacebeespletelyloadedwithsurfactantandanyfurtheradditionsmustarrangeasmicelles、3、4Micelles(膠束)ThisconcentrationiscalledtheCriticalMicelleConcentration(CMC,臨界膠束濃度)、CMC處得變化A,surfacetensionB,interfacialtensionC,osmoticpressure;D,equivalentconductivity;E,solubilityofpoundswithloworzerosolubilityinwaterCMC處得變化I-AcontinuousdecreaseinSurfaceandinterfacialtensionswithsurfactantsconcentrationuntilCMCtheSurfaceandinterfacialtensionslevelbeeconstantowingtocrowdingofsurfactantmoleculesadsorbedatsurfacesandinterfaces、A,surfacetensionB,interfacialtensionC,osmoticpressure(滲透壓)D,equivalentconductivityE,solubilityofpoundswithloworzerosolubilityinwaterCMC處得變化CMC處得變化II-TheosmoticpressurerisesmuchmoreslowlywithincreasingsurfactantconcentrationabovethanitdoesbelowtheCMCbecauseitdependsonthenumberofdissolvedparticles、A,surfacetensionB,interfacialtensionC,osmoticpressureD,equivalentconductivity(當(dāng)量電導(dǎo))E,solubilityofpoundswithloworzerosolubilityinwaterCMC處得變化CMC處得變化III-Forionicsurfactants,theequivalentconductivitydropssharplyabovetheCMC、Onlythecounterionsofnon-associatedsurfactantmoleculescancarrycurrent、A,surfacetensionB,interfacialtensionC,osmoticpressureD,equivalentconductivityE,solubilityofpoundswithloworzerosolubilityinwaterCMC處得變化CMC處得變化IV-SolubilityofmanydrugsareincreasedafterCMC、A,surfacetensionB,interfacialtensionC,osmoticpressureD,equivalentconductivityE,solubilityofpoundswithloworzerosolubilityinwaterCMC處得變化AllthesepropertiescanbeusedtodeterminetheCMC、3、4Micelles(膠束)膠束不影響溶液表面張力3、4Micelles(膠束)膠束不影響溶液表面張力3、4Micelles(膠束)膠束得結(jié)構(gòu)Hydrophilicgroupsoutwardandhydrophilicsegmentsinside3、5PropertiesofsurfactantsolutionsKrafftpoint(離子型表面活性劑)TheKrafftpointistheminimumtemperatureatwhichsurfactantsformmicelles、3、5PropertiesofsurfactantsolutionsKrafftpoint(離子型表面活性劑)TheKrafftpointistheminimumtemperatureatwhichsurfactantsformmicelles、3、5Propertiesofsurfactantsolutions您認(rèn)為,如果我們需要使用膠束得話,Krafftpoint就是越高越好還就是越低越好？BEAConfidential、|45BEAConfidential、|46BEAConfidential、|47BEAConfidential、|48BEAConfidential、|49BEAConfidential、|50BEAConfidential、|513、5PropertiesofsurfactantsolutionsCloudpoint(非離子型表面活性劑)Withnon-ionicsurfactants,raisingthetemperaturedecreasesthesolubility,duetoweakeningofthehydrogenbondswithwater、Consequentlyatacertaintemperature,knownasthecloudpoint,large