if a formulation variable is changed (along a formulation ...€¦ · extended surfactant (smart)...

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Principles and Recent Advances withExtended Surfactant (smart) Structures

Jean-Louis SalagerFIRP Laboratory

UNICAMP Brazil, November 3, 2009 2 / 72

What is Solubilization? it is the ability of a surfactant to produce a

monophasic system containing both oil and water

surfactant(+ alcohol)

water oil

polyphasiczone

monophasiczone

“height” ofpolyphasic zone

generally at center(Water/oil ratio = 1)

S+A

3 / 72

If a formulation variable is changed (along a Formulation scan) How does solubilization change?

Bourrel M., Schechter R. S., Microemulsions and Related Systems,Marcel Dekker, New York 1988

All phase diagrams contain amonophasic zone

4 / 72

The “height” of polyphasic zone at fixedoil/water composition (e.g. 50/50) is monitored

lowest “height” = maximum solubilizationat optimum formulation

“Height”Formulation Scan

S + A

Bourrel M., et al., The Topology of phase boundaries for oil-brine-surfactant systems and its relationship to oil Recovery,Society of Petroleum Engineers J., 22 (1), 28-36 (1981)

5 / 72

Normal Case (Winsor)

!1

23

2!

!!

Formulation (S)

W IIW I

S+A (%)

Formulation (e.g. S)

sometimescalled“fish”

diagram

Bourrel’sgamma (γ)diagram

6 / 72

in all cases

the “cross” locates the point with highest solubilization

MinimumS + A

Optimum Formulation

12

3

2

7 / 72

Solubilization Parameters

SP* Solubilization parameter at crossing

SP water in m SP oil in m

3 φ

Formulation Scan

8 / 72

At optimum formulation Bicontinuous microemulsionBicontinuous microemulsion

Formulation ScanSalager JL et al. Formulation of microemulsions. Chap 3, in Microemulsions, Background,New Concepts, Perspectives. C. Stubenrauch Ed., Blackwell Pub. - Wiley, Oxford (2009)

9 / 72

Scriven S., Nature 263: 123 (1976)

At optimum formulationBicontinuous microemulsion

zero curvature structure

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At optimum formulationBicontinuous microemulsion

zero curvature structure

11 / 72

Transparent microemulsion ? Near R =1 curvature ≅ 0 Swollen Micelles large size

Surfactant Layer Solubilized Liquid

Qty. of Surfactant depends on area

α R2

Solubilized Qty. depends on volume

α R3

SP α R3 / R2 valid for micelles and microemulsions

12 / 72

High solubilization =3φ with turbid microemulsions

SP* = 7 10 17 33 ml/gγ* = 0.01 0.004 0.001 0.0002 mN/m

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10-1

10-2

10-3

10-4

0 0.4 0.8

IN

TE

RF

AC

IAL

TE

NS

ION

(m

N/m

)

1.2 1.6 2.0 2.4 2.8 3.2 0.8

4

8

16

20

12

0

Salinity, % NaCl

l m u

Vw/VsVo/Vs

mo mw! !

SO

LU

BIL

IZA

TIO

N P

AR

AM

ET

ER

S

ml/m

l

SP*

Tension-Solubilization Relationship Solubilization varies as the inverse

of interfacial tension

Reed R. L., Healy R. N.,Some physicochemical aspects ofmicroemulsion flooding: A review.In Improved Oil Recovery bySurfactant and Polymer Flooding,Shah D. O. &��Schechter R. S., Eds.,Academic Press 1977

Formulation

3 φ

OptimumFormulation

14 / 72

SolubilizationParameters ml/g

0 20

0.1

0.01

0.001

C. Huh, J. Colloid Interface Sci.71: 408-425 (1979)

γ x SP2 = Constant

The constant depends onsurfactant (it is the samealong the scan)

variationtension-SP

along ascan

-

-

-

Tension-Solubilization Relationship

Inte

rfaci

al T

ensi

on m

N/m

Solubilization varies as the inverseof interfacial tension

15 / 72

oil(O)

water(W)

Aco

Acw

surfactant(C)

Winsor’s R Ratio of interactions

R = =Aco ... NAcw ... D

R < 1 R = 1 R > 1

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Winsor’s R Ratio

Maximum Solubilization when N = D

R = =Aco - Aoo ... NAcw - Aww ... D

R = 1 = = = 2 5 10 2 5 10

is it the same thing?

but ....

Winsor P. Solvent properties of amphiphilic compounds.Butterworths, London (1954)

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Winsor’s Premise

• higher interactions• higher N (or D)• higher solubilization

R = 1 = = = 2 5 10 2 5 10

Aco

Acw

BETTER

18 / 72

Examples

C8 C8 —— Ø Ø —— 5.3 EO SP* = 5 ml/g 5.3 EO SP* = 5 ml/g C9 C9 —— Ø Ø —— 5.7 EO SP* = 8 ml/g 5.7 EO SP* = 8 ml/g C12 C12 –– Ø Ø —— 8.3 EO SP* = 20 ml/g 8.3 EO SP* = 20 ml/g

Alkyl phenol ethoxylates / octane / no alcohol

C12-O-SOC12-O-SO33NaNa

C18-CH C18-CH << COONaCOONaNHCOCHNHCOCH33

SP* = 5.2 ml/gSP* = 5.2 ml/g

SP* = 15 ml/gSP* = 15 ml/g

N-hexane, 4.5 wt% NaCl, Surf/n-butanol=2/3

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In order to change N or D formulation must be changed

To keep R = 1 situation 2 variables (at least) must be changed

Two alternatives 2 changes on different sides of interface 2 changes on the same side of interface

Bourrel M., Chambu C., The Rules for Achieving High Solubilization of brine and oil byAmphiphilic Molecules. Society of Petroleum Engineers J., 23 : 327-338 (1983)

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Solubilization increases

But, when chain reaches 18–20 carbon atoms,the surfactant precipitates (Krafft Temperature)

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Mixing lipophilic andhydrophilic species

Extends the reach onExtends the reach onboth sidesboth sides

Avoids precipitationAvoids precipitation Increases packingIncreases packing

22 / 72

Mixture of 2 different Surfactantsincreases interactions at interface

Better interactionsBetter interactionsat interfaceat interface

Better packingBetter packing

High interfacial SPint*

Vol Oil or WaterMass Adsorbed surfactantSPint* =

23 / 72

Increasing difference

Example

Graciaa A. et al. Langmuir 9, 1473 (1993)

24 / 72

Beware that adding a shortalcohol (balanced) cosurfactant

decreases solubilization

Reduces the averageReduces the averagereach on both sidesreach on both sides

Decreases packingDecreases packing

25 / 72

But unbalanced (segregated)additives increases

solubilization Increases the averageIncreases the average

reach of surfactantreach of surfactant Do not decreasesDo not decreases

packingpacking

LINKERconcept

26 / 72

But mixtures fractionateLipophilic species go in oilHydrophilic species in water= preferential partitioning

Only a small % at interface= Surfactant loss= Low apparent SPapp*

Vol Oil or WaterMass Total surfactant

SPapp* =

Graciaa A et al. Adv. Colloid Interface Sci. 123-126, 63 (2006)Salager JL et al. Adv. Polymer Sci. 218: 83-113 (2008)

27 / 72

Increasing difference

Example

= Lipophilic Linker+ Surfactant

fractionation

28 / 72

Caution There are (often) opposite phenomena, due

to the complexity of the R expression

Don’t be afraid to go to the EOR literature …

Bourrel M., Schechter R. S., Microemulsions and Related Systems, MarcelDekker, New York 1988

Graciaa A., et al., Criteria for structuring to maximize solubilization of oil and water -I : Commercial non-ionics. Paper SPE/DOE 9815, 2nd Joint SPE/DOESymposium on Enhanced Oil Recovery, Tulsa, April 5-8 (1981)

Reed R. L., Healy R. N., Some physico-chemical aspects of microemulsion flooding:A review. in Improved oil recovery by surfactant and Polymer Flooding. Shah D.,Schecheter R.S. Eds., pag 383 Academic Press (1977)

Huh C., Interfacial tensions and solubilizing ability of a microemulsion phase thatcoexists with oil and Brine. J. Colloid Interface Science, 71 : 408-426 (1979)

Shiao S. Y., et al. The importance of sub-angstrom distaces in mixed surfactantsystems for technological processes. Colloids Surfaces A, 128: 197 (1997)

29 / 72In some cases Winsor’s modeldoes not explain the observed

increase in solubilization

% aditivo en aceite

20

43210

% Additive in oil

10

0

OP 0 EOOP 1 EOOP 1.5 EOOP 3 EO

Additive

SP* ml/g 0.034 M SurfactantEthoxylated Octylphenol(EON near 5)Isooctane, WOR =1, 25ºC

Lipophilic AdditiveLipophilic Additiveincreasesincreasessolubilizationsolubilization

Graciaa A., et al. Improving Solubilization in Microemulsions withAdditives - 1 : The lipophilic linker role, Langmuir 9 : 669-672 (1993)

LipophilicLinker effect

30 / 72 Proposed Mechanism

“or

dere

d” z

one

“ord

ered

” zo

ne

The Lipophilic Linker increases interactions on the oil sideby “ordering” the molecules deeper inside the oil bulk phase

OILOIL

INTERFACEInterface

LipophilicLinker

WATERWATER

31 / 72

The Lipophilic Linker

does not adsorb at interface (it is not a cosurfactant) is a slightly polar oil (or a very lipophilic amphiphile) is located inside oil phase near interface (interfacial segregation) gets oriented perpendicular to interface “stretches” the reach of surfactant in oil (without producing precipitation)

32 / 72

The LIPOPHILIC LINKER effect is dueto the SEGREGATION of the mostpolar substances in the oil phasewhich concentrate near interfacewhich concentrate near interface

The other phase and the surfactantonly “see” the most superficial layerof the oil phase(similar to a chocolate covered candy)

Interesting forInteresting forapplications !applications !

33 / 72

Lipophilic Linker RoleThe L.L. The L.L. ““stretchesstretches”” (in situ)... (in situ)... …… the surfactant hydrophobic the surfactant hydrophobic ““tailtail””

The L.L. produces aslightly polar zoneinside the oil phase,near the interface

34 / 72

Examples of Lipophilic Linkers

Long chain n-alcohols ( > 8)Long chain n-alcohols ( > 8) Long chain alkylphenols ( > 8)Long chain alkylphenols ( > 8) idem slightly ethoxylated (EON idem slightly ethoxylated (EON << 2) 2)

Single chain esters (ethyl oleate)Single chain esters (ethyl oleate)

probably other linear lipophilic amphiphilesprobably other linear lipophilic amphiphiles

Graciaa A. et al., Improving Solubilization in Microemulsions with Additives - Part II :Long chain Alcohol as Lipophilic Linkers, Langmuir 9: 3371 (1993)Salager J.L, et al. Improving Solubilization in microemulsion with aditives - Part III:Lipophilic Linker Optimization J. Surfactants & Detergents 1: 403 (1998)

35 / 72

Alcohol (LL) Mixture

Mixing LLMixing LLimprovesimprovessolubilizationsolubilization= Longer LL= Longer LL

36 / 72

0 2 4 6 8 10 12 14 16

0.02 M Ethoxylated Alkylphenol T = 25 °C0.0325 M n-alcohol Isooctane WOR = 1

ALCOHOL CARBON NUMBER

SP (ml/g)

Alcohols as Lipophilic Linkers

LipophilicLinker effectadds up tosurfactanteffect

DODECYL

NONYL

OCTYL

8.3

8.3

8.9

9.4

9.59.5

5.3

5.6

5.6

5.8 5.8

5.8

5.75.1

5.3

5.75.6

5.3

EON*

37 / 72

The Lipophilic Linker is ... ... a very lipophilic amphiphile or a polar oil ...or a polar oil ... ... which acts at very low concentration ... which acts at very low concentration because it locates itself ...because it locates itself ... ... near interface ... near interface

It is not a case of adsorption ... ... but of segregation

38 / 72

Interfacial Segregation Take a oil mixture...Take a oil mixture... ... (same molar volume oils)... (same molar volume oils) Hexadecane —> non polar (ACN=16)Hexadecane —> non polar (ACN=16) Ethyl Oleate —> polar (EACN=6)Ethyl Oleate —> polar (EACN=6)

Measure or evaluate interfacial tension optimum formulation oil composition near interface

Graciaa A. et al., Interfacial Segregation of Ethyl Oleate/Hexadecane OilMixture in Microemulsion Systems, Langmuir 9: 1473 (1993)

39 / 72

10.80.60.40.20

Tension interfacial

Interfacial Segregation

ETHYL OLEATE FRACTION in OIL

Everything happens asif the “interfacial” oilwere “pure” polar oil,when there is 50% ofthis oil in the mixture(green arrow)

= polar oilsegregationnear interface

ETHYL OLEATEHEXADECANE{Oil

40 / 72

Hydrophilic Linker

SO3Na

SO3Na

H3C-CH2 -CH2 -CH2

H3C-CH2 -CH2 -CH2

Naphtalene Sulfonate= hydrotrope

Di-butyl Naphtalene Sulfonate= hydrophilic surfactant

SO3Na

H3C

SO3Na

H3C

H3C

Mono/Dimethyl Naphtalene Sulfonate= hydrophilic linker

41 / 72

Hydrophilic Linker

Similar role on the water sidealthought much less

Acosta E. et al, The Role of Hydrophilic Linkers, J. Surfactants Detergents, 5: 151 (2002)

di-hexyl-sulfosuccinate

The H.L. produces aslightly less polar zonein the water phase,close to interface

42 / 72

Lipophilic and Hydrophilic Linkers = thickness + mixture But fractionation

adsorbed Surfactant

Lipohilic Linker

Hydrophilic Linker

oil

water

produce:Better match(oil does notcontact water)Continuouspolarityvariation

Graciaa A. Langmuir 9, 1473 & 9, 3371 (1993) Salager JL J. Surf. Deterg 1, 403 (1998)Uchiyama H. Ind. Eng. Chem. Res 39, 2704 (2000) Acosta E. J. Surf. Deterg 5, 151 (2002)

43 / 72Amphiphilic Linker

= thickness + mixture + no fractionation

It becomes anchored onboth sides of interface(low MW diblock polymer)

There is no precipitationproblem only if used atvery low concentration

Considerableenhancement ofsolubilization

Jakobs B. et al., Langmuir 15, 6707 (1999)

LL effect

HL effect

anchoredatinterface

But precipitates

44 / 72

continuity in interfacial transition and a good match on both sides no partitioning

Favorables factors are :

45 / 72

What should be done?

Far away reach

Goodhydrophilicinteraction

Thick intermediate zonebut no precipitation(mixture + intermediate polarity)

}Easier to get agood interactionwith water

Longer is OKbut mustavoidprecipitationproblem

}Intra

-mol

ecul

ar m

ixtur

e(=

no

parti

tioni

ng)

Interface here !

46 / 72

Surfactant+linker effect could be attainedwith a single “extended” surfactant !

Surfactant+ Linker Extended

Surfactant

hydrophilicgroup

hydrophobicchain

POLY-PROPYLENE

OXIDE

Spacer arm ishydrophobic but

slightly polar?

= intramolecular mixture

47 / 72

Extended Surfactants(1rst Generation)

dodecyl

poly-propylene oxide (variable length) = mixture feature

ethoxy (2EO)sulfate sodium salt

Miñana M. et al., Solubilization of Polar oils in Microemulsion Systems,Progress Colloid Polymer Science, 98 : 177-179 (1995)

48 / 72

CMC decreases Cloud Point is lowered Optimum Salinity (3φ) decreases

depend on Propylene Oxide Number (PON)

When PON increases

Conclusion: When PON increases ... ... surfactant becomes more lipophilic ... but does not precipitate (mixture)

Extended Surfactant Properties

49 / 72

Usual behavior of anionicsLn S = k ACN + ...

Idem but k depends on PON

Extended Surfactant Properties50 / 72

ES Produce a highES Produce a high SOLUBILIZATION SOLUBILIZATION and LOW TENSION and LOW TENSION

particularly withparticularly withnatural oilsnatural oils

PROPYLENE OXIDE NUMBER14106

WOR = 1 T = 35 °C 1.25 wt.% extended Surfactants

Mygyol 812

Soja oil

HexadecaneEthyl Oleate

10

20

30

40

0

SP (ml/g)

Soja oil = natural

triglyceride

Miñana-Perez M. et al., Solubilization of Polar Oils with Extended Surfactants,Colloids Surfaces A. 100 : 217-224 (1995).


51 / 72

ES produce 3 φ withHIGH SOLUBILIZATIONand LOW TENSIONwith polar oils

Miñana-Pérez M. et al., Solubilization of Polar Oils with Extended Surfactants,Colloids Surfaces A. 100 : 217-224 (1995).

Ethyl oleateMiglyolsSoya Oil


Fernández A., MSc Thesis, Universidad de Los Andes (2002)

Micellar aggregation of extended surfactant

SOSO44GroupGroup

PolyPO sp

acer

SOSO44GroupGroup

HydrophilicGroups

LipophilicCore

Intermediatepolarity zone

53 / 72

Micellar aggregation of extended surfactant

Large volume in which polar oil can be solubilized

Intermediatepolarity zone

54 / 72

Usually SP* decreases as ACN increases

At low PON it does too!At high PON it increases with ACN

At PON=10SP* does notvary with ACN

SP* increaseswith alkyl tail

Good forLONG

ALKANES

Salager J.L et al., 7th Word Surfactant Congress CESIO, Paris, June 2008


55 / 72

Usual mixing rulevs formulation

Mixing rule of ESwith nonionics

Obeys HLD = β – kACN + b S – f(A) + cT (T-25)With β = α – EON for C9EON


As far as SP*MIX is concerned the rule is(only) approximately linear for polar oils

and dependent only on extended surfactant

Mixture feature does not work the same way !

Othersurfactants

]


57 / 72

ANIONICS

PolyEO NONIONICS

First 2–3 POsare wet by water !

ES with PPOIndependent of PON

ES with PPO less hydrophilic as Temp increases

Velasquez J. et al., Effect of the temperature Velasquez J. et al., Effect of the temperature …… J. Surfactants Deterg.J. Surfactants Deterg. published on line (2009) published on line (2009)


ES with PPO less hydrophilic as Temp increases

Other POs are not !

First 2–3 PO groupsare wet by water !


59 / 72

Current availability ... poor

Some samples of alkyl PolyPO (EO) sulfates have beenprepared by three surfactant manufacturers (Seppic,Sasol, Hunstman) and some studies reported.

60 / 72

Recent Publications GOETHALS G. et al., Spacer Arm influence on Glucido-amphiphilic Compound PropertiesGOETHALS G. et al., Spacer Arm influence on Glucido-amphiphilic Compound Properties,,

Carbohydrate PolymersCarbohydrate Polymers 45 : 147 (2001) 45 : 147 (2001) SCORZA C. et al., Synthèse de dérivés polypropilèneglycol à tête glucidyl ou ityl comme surfactifs,SCORZA C. et al., Synthèse de dérivés polypropilèneglycol à tête glucidyl ou ityl comme surfactifs,

XVIIº Journées Chimie et Chimie des Glucides,XVIIº Journées Chimie et Chimie des Glucides, Tregastel, France, June 1998 Tregastel, France, June 1998 SCORZA C., et al., New amphiphilic polypropileneglycol derivatives with carbohydrate polar head, SCORZA C., et al., New amphiphilic polypropileneglycol derivatives with carbohydrate polar head, 24º24º

Congr. Anual Comite Español Detergencia,Congr. Anual Comite Español Detergencia, Barcelona, Spain, May 1999 Barcelona, Spain, May 1999 SCORZZA C., et al., Synthesis and Surfactant Properties of a new "extended" glucidoamphiphile madeSCORZZA C., et al., Synthesis and Surfactant Properties of a new "extended" glucidoamphiphile made

from D-Glucose, from D-Glucose, J. Surfactants & DetergentsJ. Surfactants & Detergents, 5: 331 (2002), 5: 331 (2002) SCORZZA C., et al., An other new familly of "extended" Glucidoamphiphiles. Synthesis and SurfactantSCORZZA C., et al., An other new familly of "extended" Glucidoamphiphiles. Synthesis and Surfactant

Properties for different Sugar head Groups and Spacer Arm lengths, Properties for different Sugar head Groups and Spacer Arm lengths, J. Surfactants & DetergentsJ. Surfactants & Detergents, 5: 337, 5: 337(2002)(2002)

HUANG L. et al. Microemulsification of triglyceride sebum and the role of interfacial structure onHUANG L. et al. Microemulsification of triglyceride sebum and the role of interfacial structure onbicontinuous phase behavior. bicontinuous phase behavior. Langmuir Langmuir 2004, 20: 3559-3563 (2004)2004, 20: 3559-3563 (2004)

FERNANDEZ A. et al., Synthesis of new extended surfactants containing a carboxylate or sulfate polarFERNANDEZ A. et al., Synthesis of new extended surfactants containing a carboxylate or sulfate polargroup. J. Surfactants Detergents 8: 187 (2005)group. J. Surfactants Detergents 8: 187 (2005)

FERNANDEZ A., et al., Synthesis of new extended surfactants containing a Xylitol polar group. FERNANDEZ A., et al., Synthesis of new extended surfactants containing a Xylitol polar group. J.J.Surfactants DetergentsSurfactants Detergents 8: 193 (2005) 8: 193 (2005)

WITTHAYAPANYANON A., et al. Formulation of ultralow interfacial tension systems using extendedWITTHAYAPANYANON A., et al. Formulation of ultralow interfacial tension systems using extendedsurfactants, surfactants, J. Surfactants DetergentsJ. Surfactants Detergents 9: 331 (2006) 9: 331 (2006)

SALAGER J. L. et al. Amphiphilic mixture versus surfactant structure with smooth polarity transitionSALAGER J. L. et al. Amphiphilic mixture versus surfactant structure with smooth polarity transitionacross interface to improve solubilization performance. CESIO 2008 7th World Surfactant Congressacross interface to improve solubilization performance. CESIO 2008 7th World Surfactant CongressParis, June 23-25 2008. Proceedings Paper O-A17.Paris, June 23-25 2008. Proceedings Paper O-A17.

WITTHAYAPANYANON A., et al. HLD method for characterizing coventional and extendedWITTHAYAPANYANON A., et al. HLD method for characterizing coventional and extendedsurfactants. surfactants. J. Colloid Interface Sci.J. Colloid Interface Sci. 325: 259 (2008) 325: 259 (2008)

61 / 72

Optimize nature and size of the 3 pieces: Adjust structure to oil nature New generation of extended surfactants: Biocompatible “green” polar groups Determine mixing rules Conventional + extended surfactants

62 / 72

2 nd Generation of extended surfactantsfor biocompatible applications

sugarpolargroup

Fatty acid derivative(hydrophobic tail)

tayloredspacer arm

Physico-chemicalProperties of thesesProducts are under study

Goethals G. et al., Spacer Arm influence on Glucido-amphiphilicCompound Properties, Carbohydrate Polymers, 45 : 147-154 (2001)

63 / 72

Polar heads (simple or combined)currently synthesized and tested

sulfateethoxy-sulfatecarboxylateethoxy-carboxylateC6 sugarsxylitol (C5 sugar)di-xylitolethoxy-xylitolcarboxylate & xylitolcarboxylate & glucose

Linear C12-C18 chainattached at end or centersaturated or unsaturated

Different kinds of spacersyou could think about

Different head groups

64 / 72

extended soaps

C

1

2

H

2

5

O

O

O

C

O

2

N

a

n

n

_

+

Fernandez A. Fernandez A. et al.,et al., Synthesis of new extended surfactants containing a carboxylate or Synthesis of new extended surfactants containing a carboxylate orsulfate polar group. sulfate polar group. J. Surfactants DetergentsJ. Surfactants Detergents 8:8: 187 (2005) 187 (2005)

65 / 72

extended alkyl monoglycoside

Scorzza C. et al. , J. Surfactants & Detergents, 5 (4) 331-335 & 337-343 (2002)

O

O

O

H

O

H

O

H

O

H

O

O

O

R

n

n

66 / 72

O

O

C

1

2

H

2

5

O

O

n

n

z

z

O

O

C

1

2

H

2

5

O

n

n

O

N

a

O

O

z

_ +

extended mono-di-xylitola non-cyclicglycoside

O

H

O

H

O

H

O

H

O

H

O

H

O

H

O

H

Z = Xylitol

Fernandez et al., Synthesis of new extended surfactants containing a Xylitol polar group Fernandez et al., Synthesis of new extended surfactants containing a Xylitol polar groupJ. Surfactants DetergentsJ. Surfactants Detergents 88: 193 (2005): 193 (2005)

67 / 72

Current best solubilization :

1 g of high performance extended surfactantcan solubilize almost 40 g of hexadecane orethyl oleate and 15 g of C18 triglyceride

68 / 72

Potencial Applications

Microemulsions to be directly injected in bloodstream (Drugs are generally oil soluble)

Soak-only Detergents (no stirring required)

Solvent like extraction (e.g. edible oil in pressing residue)

Transdermic transfer (pharmaceuticals and cosmetics)

Crude Oil dehydration (ext. surf. combine with asphaltenes)

For some applications, the usedsurfactants must be completelybiocompatible, biodegradable,non-toxic, “green” … etc …!

69 / 72

Just a slight improvement in solubilization andthe original R&D goal (1987) may be attained

Infinite (microemulsion) dilution in blood of abiocompatible oil containing a lipophilic drug ( )

70 / 72

Solubilization may be increased by increasingthe thickness of the polar-apolar transition zone:

Increasing the surfactant size..... up to a limit > precipitationUsing a mixture of Lipo-/Hydro-philic amphiphiles..... up to a limit > partitioningUsing an intramolecular mixture with spacer arm ofintermediate polarity = extented surfactant ...Probably better if intermediate is a mixture (polyPO)... up to a limit ... to be found !

71 / 72

A Comment on this Research Progress

Understandingaccording toWinsor

anomalydiagnostic

innovation

LIPOPHILICLINKER

EXTENDEDSURFACTANT

Understandingproperties

New structures,Biocompatibilityissues

Property

interpretation

PRO

GRE

SS

TIME1950 1988 1993 2009

72 / 72Visit us at

http://www.firp.ula.ve

More information: Salager JL et al., Enhancing Solubilization in Microemulsion –State of the Art and Current Trends, J. Surfactants Detergents 8 : 3-21 (2005)

if a formulation variable is changed (along a formulation ...€¦ · extended surfactant (smart)...

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