Emulsion Formation and Stability

262 Pages·2013·2.85 MB·English

Editedby
TharwatF.Tadros
EmulsionFormationandStability
RelatedTitles
Tadros,T.F. Tadros,T.F.
DispersionofPowders Rheology ofDispersions
inLiquidsandStabilizationofSuspensions
2010
2012 ISBN:978-3-527-32003-5
ISBN:978-3-527-32941-0
Wilkinson,K.J.,Lead,J.R.(eds.)
Tadros,T.F.(ed.)
Environmental Colloids
Self-OrganizedSurfactant andParticles
Structures Behaviour,Separation
andCharacterisation
2010
ISBN:978-3-527-31990-9 2007
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Tadros,T.F.(ed.)
Colloids andInterfaceScience
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6VolumeSet
2010
ISBN:978-3-527-31461-4
Edited by Tharwat F. Tadros
Emulsion Formation and Stability
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V
Contents
Preface XI
ListofContributors XIII
1 EmulsionFormation,Stability,andRheology 1
TharwatF.Tadros
1.1 Introduction 1
1.1.1 NatureoftheEmulsifier 1
1.1.2 StructureoftheSystem 2
1.1.3 BreakdownProcessesinEmulsions 3
1.1.4 CreamingandSedimentation 3
1.1.5 Flocculation 4
1.1.6 OstwaldRipening(Disproportionation) 4
1.1.7 Coalescence 4
1.1.8 PhaseInversion 4
1.2 IndustrialApplicationsofEmulsions 4
1.3 PhysicalChemistryofEmulsionSystems 5
1.3.1 TheInterface(GibbsDividingLine) 5
1.4 ThermodynamicsofEmulsionFormationandBreakdown 6
1.5 InteractionEnergies(Forces)betweenEmulsionDroplets
andTheirCombinations 8
1.5.1 vanderWaalsAttraction 8
1.5.2 ElectrostaticRepulsion 9
1.5.3 StericRepulsion 12
1.6 AdsorptionofSurfactantsattheLiquid/LiquidInterface 14
1.6.1 TheGibbsAdsorptionIsotherm 14
1.6.2 MechanismofEmulsification 17
1.6.3 MethodsofEmulsification 19
1.6.4 RoleofSurfactantsinEmulsionFormation 21
1.6.5 RoleofSurfactantsinDropletDeformation 22
1.7 SelectionofEmulsifiers 26
1.7.1 TheHydrophilic–LipophilicBalance(HLB)Concept 26
1.7.2 ThePhaseInversionTemperature(PIT)Concept 29
1.7.3 TheCohesiveEnergyRatio(CER)Concept 31
VI Contents
1.7.4 TheCriticalPackingParameter(CPP)forEmulsionSelection 32
1.8 CreamingorSedimentationofEmulsions 35
1.8.1 CreamingorSedimentationRates 36
1.8.2 PreventionofCreamingorSedimentation 37
1.9 FlocculationofEmulsions 40
1.9.1 MechanismofEmulsionFlocculation 40
1.9.1.1 FlocculationofElectrostaticallyStabilizedEmulsions 41
1.9.1.2 FlocculationofStericallyStabilizedEmulsions 42
1.9.2 GeneralRulesforReducing(Eliminating)Flocculation 43
1.10 OstwaldRipening 44
1.11 EmulsionCoalescence 45
1.11.1 RateofCoalescence 46
1.11.2 PhaseInversion 47
1.12 RheologyofEmulsions 48
1.12.1 InterfacialRheology 48
1.12.1.1 InterfacialTensionandSurfacePressure 48
1.12.1.2 InterfacialShearViscosity 49
1.12.2 MeasurementofInterfacialViscosity 49
1.12.3 InterfacialDilationalElasticity 50
1.12.4 InterfacialDilationalViscosity 51
1.12.5 Non-NewtonianEffects 51
1.12.6 CorrelationofEmulsionStabilitywithInterfacialRheology 51
1.12.6.1 MixedSurfactantFilms 51
1.12.6.2 ProteinFilms 51
1.13 BulkRheologyofEmulsions 53
1.13.1 AnalysisoftheRheologicalBehaviorofConcentratedEmulsions 54
1.14 Experimentalη −φCurves 57
r
1.14.1 Experimentalη −φCurves 58
r
1.14.2 InfluenceofDropletDeformability 58
1.15 ViscoelasticPropertiesofConcentratedEmulsions 59
1.15.1 HighInternalPhaseEmulsions(HIPEs) 61
1.15.2 DeformationandBreakupofDropletsinEmulsionsduringFlow 66
References 73
2 EmulsionFormationinMembraneandMicrofluidicDevices 77
GoranT.Vladisavljevic´,IsaoKobayashi,andMitsutoshiNakajima
2.1 Introduction 77
2.2 MembraneEmulsification(ME) 78
2.2.1 DirectMembraneEmulsification 78
2.2.2 PremixMembraneEmulsification 79
2.2.3 OperatingParametersinMembraneEmulsification 80
2.2.4 MembraneType 80
2.2.4.1 SurfactantType 80
2.2.4.2 TransmembranePressureandWallShearStress 81
2.3 MicrofluidicJunctionsandFlow-FocusingDevices 82
Contents VII
2.3.1 MicrofluidicJunctions 82
2.3.2 MicrofluidicFlow-FocusingDevices(MFFD) 83
2.4 MicrofluidicDeviceswithParallelMicrochannelArrays 85
2.4.1 Grooved-TypeMicrochannelArrays 86
2.4.2 Straight-throughMicrochannelArrays 88
2.5 GlassCapillaryMicrofluidicDevices 89
2.6 ApplicationofDropletsFormedinMembraneandMicrofluidic
Devices 93
2.7 Conclusions 93
Acknowledgments 94
References 94
3 AdsorptionCharacteristicsofIonicSurfactantsatWater/Hexane
InterfaceObtainedbyPATandODBA 99
NenadMucic,VincentPradines,AliyarJavadi,AltynaySharipova,
Ju¨rgenKra¨gel,MartinE.Leser,EugeneV.Aksenenko,
ValentinB.Fainerman,andReinhardMiller
3.1 Introduction 99
3.2 ExperimentalTools 99
3.3 Theory 101
3.4 Results 102
3.5 Summary 107
Acknowledgments 107
References 107
4 MeasurementTechniquesApplicabletotheInvestigationofEmulsion
FormationduringProcessing 109
NimaNiknafs,RobinD.Hancocks,andIanT.Norton
4.1 Introduction 109
4.2 OnlineDropletSizeMeasurementTechniques 112
4.2.1 LaserSystems 112
4.2.2 SoundSystems 115
4.2.3 DirectImaging 115
4.2.4 OtherTechniques 118
4.3 TechniquesInvestigatingDropletCoalescence 121
4.4 ConcludingRemarks 123
References 125
5 EmulsificationinRotor–StatorMixers 127
AndrzejW.Pacek,StevenHall,MichaelCooke,andAdamJ.Kowalski
5.1 Introduction 127
5.2 ClassificationandApplicationsofRotor–StatorMixers 128
5.2.1 ColloidMills 129
5.2.2 In-LineRadialDischargeMixers 130
5.2.3 ToothedDevices 131
VIII Contents
5.2.4 BatchRadialDischargeMixers 132
5.2.5 DesignandArrangement 133
5.2.6 Operation 136
5.3 EngineeringDescriptionofEmulsification/DispersionProcesses 138
5.3.1 DropSizeDistributionsandAverageDropSizes 138
5.3.2 DropSizeinLiquid–LiquidTwo-PhaseSystems – Theory 140
5.3.3 MaximumStableDropSizeinLaminarFlow 141
5.3.4 MaximumStableDropSizeinTurbulentFlow 142
5.3.5 CharacterizationofFlowinRotor–StatorMixers 143
5.3.5.1 ShearStress 143
5.3.5.2 AverageEnergyDissipationRate 144
5.3.5.3 PowerDraw 144
5.3.6 AverageDropSizeinLiquid–LiquidSystems 145
5.3.7 Scaling-upofRotor–StatorMixers 147
5.4 AdvancedAnalysisofEmulsification/DispersionProcessesin
Rotor–StatorMixers 152
5.4.1 VelocityandEnergyDissipationRateinRotor–StatorMixers 153
5.4.1.1 BatchRotor–StatorMixers 154
5.4.1.2 In-LineRotor–StatorMixers 157
5.4.2 PredictionofDropSizeDistributionsduringEmulsification 160
5.5 Conclusion 163
Nomenclature 163
References 165
6 Formulation,Characterization,andPropertyControlofParaffin
Emulsions 169
JordiEsquenaandJonVilasau
6.1 Introduction 169
6.1.1 IndustrialApplicationsofParaffinEmulsions 170
6.1.2 PropertiesofParaffin 170
6.1.3 PreparationofParaffinEmulsions 172
6.2 SurfactantSystemsUsedinFormulationofParaffinEmulsions 174
6.2.1 PhaseBehavior 175
6.3 FormationandCharacterizationofParaffinEmulsions 178
6.4 ControlofParticleSize 181
6.5 StabilityofParaffinEmulsions 185
6.5.1 StabilityasaFunctionofTimeunderShear(Orthokinetic
Stability) 185
6.5.2 StabilityasaFunctionofFreeze–ThawCycles 186
6.5.3 StabilityasaFunctionofElectrolytes 189
6.6 Conclusions 195
Acknowledgments 196
References 196
Contents IX
7 PolymericO/WNano-emulsionsObtainedbythePhaseInversion
Composition(PIC)MethodforBiomedicalNanoparticle
Preparation 199
GabrielaCaldero´andConxitaSolans
7.1 Introduction 199
7.2 PhaseInversionEmulsificationMethods 200
7.3 AspectsontheChoiceoftheComponents 201
7.4 EthylcelluloseNano-EmulsionsforNanoparticlePreparation 202
7.5 FinalRemarks 204
Acknowledgments 205
References 205
8 RheologyandStabilityofStericallyStabilizedEmulsions 209
TharwatF.Tadros
8.1 Introduction 209
8.2 GeneralClassificationofPolymericSurfactants 210
8.3 InteractionbetweenDropletsContainingAdsorbedPolymeric
SurfactantLayers:StericStabilization 212
8.3.1 MixingInteractionG 213
mix
8.3.2 ElasticInteractionG 214
el
8.4 EmulsionsStabilizedbyPolymericSurfactants 216
8.4.1 W/OEmulsionsStabilizedwithPHS-PEO-PHSBlockCopolymer 219
8.5 PrinciplesofRheologicalTechniques 220
8.5.1 SteadyStateMeasurements 220
8.5.1.1 BinghamPlasticSystems 221
8.5.1.2 Pseudoplastic(ShearThinning)System 221
8.5.1.3 Herschel–BulkleyGeneralModel 222
8.5.2 ConstantStress(Creep)Measurements 222
8.5.3 Dynamic(Oscillatory)Measurements 223
8.6 RheologyofOil-in-Water(O/W)EmulsionsStabilizedwithPoly(Vinyl
Alcohol) 226
8.6.1 EffectofOilVolumeFractionontheRheologyoftheEmulsions 226
8.6.2 StabilityofPVA-StabilizedEmulsions 229
8.6.3 EmulsionsStabilizedwithanA-B-ABlockCopolymer 236
8.6.4 Water-in-OilEmulsionsStabilizedwithA-B-ABlockCopolymer 240
References 245
Index 247
XI
Preface
ThisbookisbasedonselectionofsomepapersfromtheFifthWorldCongresson
EmulsionsthatwasheldinLyon,inOctober2010.TheseseriesofWorldcongresses
emphasize the importance of emulsions in industry, including food, cosmetics,
pharmaceuticals, agrochemicals, and paints. Following each meeting, a number
of topics were selected, the details of which were subsequently published in the
journals, Colloids and Surfaces and Advances in Colloid and Interface Science.
TheselectedpapersofthefourthCongress(2006)werepublishedbyWiley-VCH
(Germany).
This book contains selected topics from the Fifth World Congress, the title of
which ‘‘Emulsion Formation and Stability’’ reflects the importance of emulsifi-
cationtechniques,theproductionofnanoparticlesforbiomedicalapplicationsas
well as the importance of application of rheological techniques for studying the
interactionbetweentheemulsiondroplets.
Chapter 1 describes the principles of emulsion formation, selection of emul-
sifiers, and control of emulsion stability. A section is devoted to the rheology of
emulsions,includingbothinterfacialrheologyaswellasthebulkrheologyofemul-
sions.Chapter2dealswithemulsionformationusingmembraneandmicrofluidics
devices.Inmembraneemulsification(ME),thesystemisproducedbyinjectionof
apuredispersephaseorapremixofacoarseemulsionintothecontinuousphase
throughamicroporousmembrane.Hydrophobicmembranesareusedtoproduce
water-in-oil (W/O) emulsions, whereas hydrophilic membranes are used to pro-
duceoil-in-water(O/W)emulsions.Inmicrofluidics,thecombinedtwo-phaseflow
isforcedthroughasmallorificethatallowsonetoobtainmonodispersedroplets.
Chapter3dealswithadsorptionofionicsurfactantsatthehexane/waterinterface
using the profile analysis technique (PAT) and the oscillating drop and bubble
analyzer(ODBA).Theoreticalmodelswereusedtoanalyzetheadsorptionresults.
Chapter4describesthevarioustechniquesthatcanbeappliedtoinvestigateemul-
sionformationduringprocessing.Theeffectofdifferentemulsiontechniqueson
thedropletsizedistributionwasinvestigatedusingvariousmethodssuchaslight
diffraction and ultrasound. Particular attention was given to online droplet size
measurements.Chapter5dealswithemulsificationusingrotor–statormixersthat
are commonly used in industry, both in laboratory and large-scale production of
emulsions. The various types of rotor–stator mixers are described. The selection