SURFACTANTS

INTRODUCTION

Are surfactants of natural or synthetic

origin ?

They can be either. Surfactants from natural origin (vegetable or animal) are known as oleo-chemicals and are derived from sources such as palm oil or tallow. Surfactants from synthetic origin are known as petro-chemicals and are derived from petroleum.

What does surfactant do ?

Water & Oil are mortal enemies

Surfactants acts as clamp

binding Water & Oil are together

Surface Tension –

Force between

two liquids

How does surfactant work?

Cleaning/DetergencyHow does cleaning take place ?

Real Soil Composition

Required Effects when Cleaning

How Surfactants Work

SurfactantDefinition

Surface Active Agent Substance which reduces surface/interfacial tension between two

phases Compounds having tendency to gather around the interface between two different materials by altering the properties of interface remarkably Serves as good mediator to settle dispute between two phases which are not friends

• Water: surface tension = 72 dynes/cm• Water + 1.0% Surfactant: Surface tension = 20 – 40 dynes/cm

Surfactants reduce the surface tension of water by adsorbing at the liquid-gas interface.

They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface.

TYPES

INTRODUCTION

• Anionic (-ve)• Cationic (+ve)• Zwitterionic

(Charge depends on pH)• Nonionic (No charge)

N+

Br-

SO-Na+

O

OSodium dodecylsulfate (SDS)

Cetylpyridinium bromide

O

OP

O

OO

OCH2CH2N(CH3)3+

O-

Dipalmitoylphosphatidylcholine (lecithin)

O O O O OH

Polyoxyethylene(4) lauryl ether (Brij 30)

Types of Surfactants

Ionic Surfactants Anionic Surfactants

Carboxylates

Alkyl benzene Sulphonates

Soaps

LABS

FAS

Ionic Surfactants Anionic

Surfactants

Sulfosuccinate

Diester

Sulfosuccinate

Monoester

Ionic Surfactants: Uses Anionic Surfactants

• Cleansing Formulation– Shampoo– Hand wash– Bath gels– Tooth Paste– Soaps & Detergents

Cationic Surfactants(1)

Cationic Surfactants(2)

Important Property Substantivity

Cationic Surfactants

Ionic Surfactants Amphoteric Surfactants

N+

CH3

CH3

CH2COO-

CONH(CH2)3N+

CH3

CH3

CH2COO-

Cocobetaine (CB)

Cocoamidopropylbetaine ( CAPB)

Uses : Amphoteric Surfactants

• Betaines are used in personal care products e.g. hair shampoos, liquid soaps, and cleansing lotions.

• All-purpose cleaning agents, hand dishwashing agents, and special textile detergents..

Nonionic Surfactants

Nonionic Surfactants

Water Solubility of NonionicsReason

Cloud Point

Effect of moles of EO on Cloud Points of Nonionic

Influence of Cloud Point on Soil Removal

HLB –Hydrophilic Lipophilic Balance

HLB is a means of expressing the hydrophilic property of surfactants in figures

HLB ValueSignificance

HLB Value 1 2 3 4 5 6 7 8 9 1011 12

13

14 15 16

17

18

Use

Water in oil emulsifier

Oil in water Emulsifiers

 

Wetting AgentsDetergent

s

 

 

Solubilizer

HLB According to Griffin (only for PEG types)

substantive to skin and hair

HLB = 20 ( 1 – SV / AV ) Where S V = Sap value of ester of polyhydric alcohol AV = Acid value of fatty acid used

Calculation of HLB value of PEG-7-glyceryl-cocoate

AV of cocofatty acid = 265 mg KOH/g SV of PEG-7-glyceryl-cocoate = 95

HLB = 20 ( 1 – 95 / 265 ) = 12.8

HLB According to Griffin (only for polyhydric alcohol types)

HLB = 7 + m * Hh + n * Hl where

• m - number of hydrophilic groups in the molecule• Hh - Value of the hydrophilic groups• n - Number of lipophilic groups in the molecule• Hl - Value of the lipophilic groups

HLB According to Davis

Ex : Calculation of HLB of SLES

Formula of SLES : CH3(CH2)11O (CH2CH2O)2SO3Na

HLB = 7 + (1 x 1.3 + 2 x 0.33 + 38.7)+(12 x - 0.475) = 42

Nonionic SurfactantsProperties

• Cleansing agent in detergents

• Emulsifying agents household & I & I formulations

• Wetting agents in textile processing, agrochemical formulations

Nonionic SurfactantsApplications

CONTENTS

CONTENTS

• Selection criteria

• Types

• Emulsifiers

• Foam Stabilizers

• Wetting agents

• Lipid Crystal Modifiers

• Solubilizers/ Dispersing

agent

• Starch Complexers

• Protein Modifiers

• Protein Modifiers

• Builders

• Fillers

• Perfumery agents

• Detergents

• Terms

• Selection criteria

• Thickening

SELECTION CRITERIA

Selection criteria

• Type selection : Anionic, cationic…..• Correct solubility for unique application

TERMS

TERMS

• CMC• Solid Fat Index (SFI) & SFC• Span 60/ Span 80• Tween 60/ Tween 80

Term Definition

SOLVENTThe medium in which soil is suspended and carried away from the surface. The customer adds most of the solvent to Simple Green Products- I.E. water

SURFACTANTS

Abbreviation for “Surface Active Agent”,surfactants work at the boundary layer (the interface) between the soil and the solvent. Each molecule of surfactant has a hydrophilic end which is attracted to water, and a hydrophobia end which is attracted to soil. In an effective cleaner/degreaser such as Simple Green, many surfactant molecules attack the soil with their hydrophobic ends, breaking it up into small bits and surrounding it. Their hydrophilic ends then allowthe soil to be lifted, suspended, and washed away.

PENETRATING & WETTING AGENTS

By changing the chemical composition of the hydrophilic and hydrophobic ends of the surfactant molecule, different surfactants with varying degrees of effectiveness can be created. By "punching up" the penetration and wetting ability of the surfactant, more water is able to surround soil particles that would otherwise repel water.

EMULSIFIERS Enable surfactants to break up soils (particularly petroleum soils) into smaller droplets that are more easily dispersed throughout the solvent.

SOLUBILIZERS Enable soils to be dissolved so that they are no longer solid particles, thereby making them easier to break apart.

DISPERSANTS Enable the spreading of particles throughout the solvent and prevent them from re-adhering to the cleaned surface.

CHELATING AGENTS

Chelators [ “key-laters” ] “bind up” hardness minerals found in water, enabling the other active ingredients to more effectively attack the soils. Chelators can also pull minerals and metals into solution and, in some extreme precision applications, this is not always desirable.

SAPONIFIERS Are strong alkaline chemicals that make animal fats soluble in water and more easily washed away.

BUILDERS Give the overall solution additional strength to hold heavy soil loads. The most common builder is phosphate –but, due to environmental concerns, phosphate is not used as much in modern solvents.

Critical Micelle Concentration

• Minimum concentration at which surfactants molecules begin to form micelles

• Determined by surface tension measurements• < Below CMC = Surfactant adsorbs on the surface

decreases surface tension• > Above CMC the micelles are formed

CMC

Important Property MicelleSmall Micelle

Extremely Dil. Soln

Dil. Soln Soln at CMC

Soln above CMC

• As surface concentration of ionic surfactant increases, if attractive hydrophobic interactions between alkyl chains can compensate for ionic head group repulsion, hemimicelles can form.

• At low coverages, patches can form on the surface.

_ _+

_ _ _ _ _ _+ + + + +

Specific Interactions: Chain-Chain

Surfactant Behavior

Solid Fat Index (SFI) & Solid Fat Content (SFC)

Solid Fat Index (SFI) • Ratio of solid fat to total fat• Based on dilatometry

(change in volume – liquid fat has a greater volume than solid fat)

• Common among US suppliers. They converts SFI to SFC based on empirical equation

Solid Fat Content (SFC)• Ratio of solid fat to total fat (same as SFI)• determined by NMR

Hydrophillic-Lipophillic Balance (HLB)

• Invented by Willam Graffin (55 yrs ago)• Ratio of oil loving portion to water loving portion• Made for easier use of nonionics (end use appln.)• Intended as a large scale use of emulsion performance• concept for choosing emulsifiers• Ranges = 1-20• Low HLB emulsifiers = lipophilic/ soluble in oil • high HLB = hydrophilic/ emulsifiers are soluble in

water

HLB –Hydrophilic Lipophilic Balance

HLB is a means of expressing the hydrophilic property of surfactants in figures

HLB determination• HLB = [M.W. hydrophilic portion / M.W. of lopophilic portion]/ 5

• Example : 20 mole ethoxylate of oleyl alcohol

M.W. 20 moles of ethylene oxide ( one mole ETO =44 )= 20 x 44 = 880

M.W. (oleyl alcohol)= 270880+ 270 = 1150 ( M.W. of whole compound)

What percentage of 1150 is 880 ?880/1150 = 76.5%

76.5% divided by 5 = 15.315.3 is the HLB value of (20 mole ethoxylate of oleyl alcohol)

HLB = 20 ( 1 – SV / AV ) Where S V = Sap value of ester of polyhydric alcohol AV = Acid value of fatty acid used

Calculation of HLB value of PEG-7-glyceryl-cocoate

AV of cocofatty acid = 265 mg KOH/g SV of PEG-7-glyceryl-cocoate = 95

HLB = 20 ( 1 – 95 / 265 ) = 12.8

HLB According to Griffin (only for polyhydric alcohol types)

HLB ValueSignificance

HLB Value 1 2 3 4 5 6 7 8 9 1011 12

13

14 15 16

17

18

Use

Water in oil emulsifier

Oil in water Emulsifiers

 

Wetting AgentsDetergent

s

 

 

Solubilizer

HLB and Use of Surfactants

Solubility HLB Range • Antifoam 1-3.5 (Reverse micelle)• W/O emulsifiers 3.5-8• Wetting & spreading agents

powder (in oils) 7-9• O/W emulsifiers 8-16• Detergent solution 13-15• Solubilizers 15-40

PROPERTIES

SolubilizationSolubilization• Spontaneous transfer of a compound insoluble in

the bulk solvent into solution due to incorporation into the surfactant micelles

polar compound

Reverse micelles

non-polar compound

Normal micelles

amphiphilic compound

• Correct solubility for unique application– High - for detergents– Medium - spreading & dispersion– Low - invert emulsion

• Examples- 1. Soaps - Medium to high in water - Low in oils/fats.2. Anionics (SLS) - Very High in water, low in oil3. Cationics & amphoterics- Very High in water4. Nonionics - predicted by HLB

5. .

• \

Wetting effectParaffin or new cotton cloth barely wetted by water

ButWhen surfactant is added to water their surfaceeasily becomes wet

Surfactant in floor cleaner as a wetting agent

Wetting

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Contact Angle and Wetting

Emulsifiers

• Role :Form emulsions, Stabilize emulsions, Modify structures• Types : Water In Oil - Low Hlb

Oil In Water - High Hlb• Examples :

1. Mono & diglycerides: HLB = 1 to 10 (Highly lipophilic) : produced by transesterification of glycerol and triacylcerides

2. Polysorbates: Polyoxyenthyene esters of sorbitan monoesters

3. Lecithin: A mixture of phospholipids including phosphatidyl cholines, phosphatidyl ethanolamines, inositol phosphatides, etc

Example 1. Glycerol Monostearate : HLB value of 3.6~4.2

Dissolves in hot grease, paraffine, ethanol, chloroform, acetone and aether, the material is widely used when producing of chocolate, margarine, ice cream, skin care balsam, cold cream, hair oil and drug ointment, also lubricant for plastic processing

Emulsions

Emulsification

Examples of Emulsions

Foaming effect

Foam consist of gas covered with thin liquid film.Surfactant molecule absorbed to interface betweengas and liquid

Substantivity

• Adsorptive property of Cationics & related nitrogen compounds

• Adsorption, particularly into solid surfaces• Attraction between +ve charge on nitrogen

atom & -ve charge surfaces

cloud point & pour point

• The Cloud point of a fluid is the temperature at which dissolved solids are no longer completely soluble, precipitating as a second phase giving the fluid a cloudy appearance.

• The highest temp at which a nonionic surfactant solution is clear.

• The pour point of a liquid is the lowest temperature at which it will pour or flow under prescribed conditions.

What causes cloud points?

• The solution becomes cloudy at & above the CPt temperature as the solution splits in to two phases– Phase1 : Very dilute surfactant solution– Phase2 : Surfactant-rich micellar phase

• The cloudiness you see comes from the micelles growing large enough to scatter light

• Cloud points are reversible, and upon cooling, the solution will return to the original clear state.

cloud point & pour point

Fabric softener

(also called Fabric Conditioner) *is used to prevent static cling and makes the fabric

softer.

An emulsifier *(also known as an

emulgent or surfactant) is a substance which stabilizes an emulsion.

An adhesive

*is a compound that adheres or bonds two items together.

An ink

*is a liquid containing various pigments and/or dyes used for colouring a surface to render an image or text. Ink is used for drawing or writing with a pen or

brush.

A laxative

*is a preparation used for encouraging defecation, or the expulsion of feces. Laxatives are most often taken to treat constipation.

DETERGENTS

Detergent

*is a compound, or a mixture of compounds, intended to assist cleaning. The term is often used to differentiate between soap and other chemical surfactants used for cleaning purposes.

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Soil Removal Mechanisms

ChemicalMechanicalDetergency (surface chemistry)

Liquid Soil Roll-up

Solid SoilReduction in Soil Adhesion

Liquefaction / Solubilization

76

Mechanism for Stain Removal

Liquid soil(Roll-up)

Solid soil(Emulsification)

77

Anionic SurfactantsLinear Alkyl benzene sulfonate (LAS)

• Main Strengths– Inexpensive (unless oil is expensive)– Very effective at particulate soil removal

• Weaknesses– Ca2+ sensitive (although not like soap)– Environmental Degradation concerns (banned in the

Nordic swan countries)

S

O

O

O-

78

Anionic Surfactants

Soap• Advantages

– Non-petroleum derived– Oil particulate soil removal

• Weakness– Very Ca2+ sensitive– Need to separate low and high molecular weight

acids and hydrogenate for odor control

O -C

O

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Composition of Coconut Oil Fatty AcidFatty Acid Composition %

Caproic acid C 6:0 ND - 0.7

Caprylic acid C 8:0 4.6 - 10.0

Capric acid C 10:0 5.0 - 8.0

Lauric acid C 12:0 45.1- 53.2

Myristic acid C 14:0 16.8 - 21

Palmitic acid C 16:0 7.5 - 10.2

Palmitoleic acid C 16.1 ND

Stearic acid C 18:0 2.0 - 4.0

Oleic acid C 18:1 5.0 - 10.0

Linoleic acid C 18:2 1.0 - 2.5

Linolenic acid C 18:3 ND - 0.2

80

Anionic Surfactants

• Alcohol ether sulfate

• Strengths– Milder to the skin than alkyl benzene sulfonate – Less effected by water hardness than other anionic surfactants– High foaming– Both the hydrophile and hydrophobe can be modified to give a

range of chemical and physical properties– Improved proteinaceous soil removal

• Weaknesses– More expensive of than alkyl benzene sulfonate.

C12 -C15 O CH2CH2O - CH2CH2O - CH2CH2O S

O

O

O - Na+

Alcohol ethoxy sulfate

81

Nonionic SurfactantsAlcohol Ethoxylate• Strengths

– Ca2+ insensitive– Decrease critical micelle concentration (CMC)– Good for oil soil removal

• Weakness– Very harsh towards hands (lipid extraction)– Forms a gel phase on dilution with H2O and needs to be processed at T > 125

oF (52 oC) or utilize significant amounts of mechanical energy– Higher levels of ethoxylation are solids and need to be melted and / or

transported and stored hot– Alkyl phenol ethoxylates are less expensive than linear ethoxylates but are

possible endocrine disruptors.

RO CH2CH2O n H R= C11 - C16 Alkyl and n = 7 - 9

C4 -C10 Alkyl O CH2CH2O n H n = 7 - 9

82

Commercial Routes for Production of Linear Alkylbenzenesulfonate

S

O

O

OHS

O

O

O - Na+

SO3

Blend of C10 to C14 olefins Catalyst

AlCl3 or HF+

linear alkylbenzene

NaOH

linear alkylbenzene sulfonic acidsodium linear alkylbenzene sulfonate

83

CH2

CH

CH2

O

O

O

C

C

C

O

O

O

R

R

R

R C OH

OH2O

+

Triglyceride

CH2OH

C

CH2OH

OHH

Fatty Acid Glycerine

transesterification

R C OCH3

O

R CH2OH

hydrogenation

H2CH3OH

hydrogenation

Methyl ester

+

Glycerine

H2

Synthesis of Fatty Acids and Alcohols from Plants & Animals

84

Synthesis of Alcohol Ethoxylate & Alcohol Ether Sulfate

R OH H2C CH2

Ocatalyst

RO CH2CH2O n

alcohol ethylene oxide

alcohol ethoxylate

SO3

RO CH2CH2O SO3HnNaOH

RO CH2CH2O SO3- Na+

n

alkyl ether sulfuric acidalcohol ether sulfate

+ H

85

Laundry Detergent FormulationsRaw Materials Percentage

Surfactants 10 – 30 %

Wt. ratio of anion : nonionic ~ 2:1

Buffer 1 – 3 %

Chelating Agent 0 – 5 %

Polymers 0 – 1%

Enzymes 0 – 1 %

Optical Brightener 0 – 0.20 %

Fragrance 0 – 0.50 %

Water (or Powder Filler) 90 – 50 %

86

Detergent Evaluations• Evaluations normally done in washing

machines or on tergotometers.

87

Evaluation• Need to acquire or make stains

– Laborious and time consuming process– Reproducibility is major concern

• For consumer stained garments, need to match stain intensity.• Laboratory made stains, need to weigh and apply stain reproducibly.

– For example, to evaluate 4 products on 10 stain sets requires: (4 clothes/stain)*10 stains*4 products * 2 repeats = 320 stain clothes

• Evaluation either by instrumental reading or panelists– Reflectance Colorimeter shades of color calibrated with black (0)

and white (100).

Reflectance Colorimeter

88

Challenges Facing the Detergent Industry

• Increasing cost of raw materials• Cost of transportation • Changing demographics

– Manufacturing sector of the economy in decline means that few consumers get clothes really dirty

– Nintendo effect leads to less youth participation in organized sports• Wal-Mart effect• Wall Street effect

– Emphasis of reduction in capital expenditures– Leads to downsizing and outsourcing of manufacturing requirements

89

CEOCFO

Structure of a Personal Care Corporation

Marketing

Raw Material Suppliers

Consumers

CustomersRetailersWal-Mart

Drug / Food Stores

Finance Supplier Chain

Purchasing

Manufacturing

R&D

AdvertisingFocus Groups

DETERGENTS INGREDIENTS

91

BuffersImportance of buffers • Maintaining an alkalinity reserve • Ease of obtaining the target pH during manufacturing

Common Detergent Buffers pKa

Sodium Citrate pKa3 = 6.3

Phosphates pKa2 = 7.2

pKa3 =12.67

Borate (Borax, Na2B4O7·10H2O) pKa = 9.24

Sodium Carbonate (Soda Ash) pKa2 = 10.33

Sodium Silicate (Sand + NaOH) pKa ~ 10 -11.2

92

Chelating AgentsChelating agents complex Ca2+ and Mg2+ which

allows for better surfactant efficiency.

Detergent Chelating Agents Comments

EDTA Impacts bioavailability of Ca2+. Not normally used in laundry applications.

Phosphates Eutrophication

Zeolites Solid particles, Increases septic tank burden

Sodium Carbonate Precipitation of CaCO3 (used in powders)

Polymers of polycarboxylic acids Very Expensive

Sodium Citrate Most commonly used in liquid laundry detergents.

93

EnzymesBiological macromolecules which have a high affinity for a select

subset of stains

• Advantages– Very efficient catalysts

• Disadvantages– Difficult to stabilize (lifetime of a laundry detergent may last more

than 6 months to 1 year• Sensitive to high pH (pH > 9)• Some surfactants denature proteins

– Very expensive

94

Classes of Enzymes• Protease

– Protein sensitive stains include: milk (casein), grass, meats, blood– Most widely used enzyme– Proteases will destroy other enzymes (enzymes are proteins)

• Amylase– Degrade starch based foods

• Cellulase– Reduces pilling by cleaving cellulose linkages

• Lipase– Breaks down triglycerides (natural oils)– Works slowly and most effectively after the wash cycle is complete.

Results in potential odor issues from the release of low molecular weight fatty acids.

95

Anti-Redeposition Keep suspended soils from redepositing on garments.• Modified cellulosics

– Sacrificial layer provides a multi-wash benefit. • Cellulose deposits on cotton. Soil/stain deposits on cellulose.

Cellulose (with soil) removed by detergent.– Benefit is only for cotton

• Combination of anionic polymer (polyacrylate) with partially cationic polymer (polyvinylpyrolidone, PVP).– Mechanism is likely entrapment of particulates.– PVP also effective at reducing dye transfer

PVP

Lauryl methacrylate Acrylic acid copolymer, z/y > 10

96

Bleach• Normally added to laundry process as a separate product.

– Tide with Bleach powder is exception• Most common bleaches are chlorine bleach (¯OCl and

peroxides)

– Difficult or expensive to stabilize the bleach or other raw materials (from bleach) in the formulation.

– Reacts with conjugated carbon double bonds to decolorize chromophores.

– Denatures proteins by oxidizing the S-H bonds.-Carotene

R C

O

O O H

Peroxy Acid

97

Optical Brighteners• Fluorescent Whitening Agents• Generate a bluish hue that most people associate with a

more satisfying white.• Worldwide consumers recognize about 2500 different

shade of white.• Increases the brightness by converting UV light into visible

light.• Emitted blue light hides yellow and brown tones making

treated textiles (or paper appear whiter).• Generate a strong purple color when exposed to UV light.

98

How Do Optical Brighteners Work?

• Highly strained system (steric hindrance)• Can control wavelength of light emission by

changing steric and/or electron donating characteristics

• Can alter solubility and deposition by changing the substituents (more hydrophobic or hydrophilic)

N

H

N N

N

N H

N

H

C

+Na - O3S

C N

H

NN

N

NH

N

H

SO3 - Na+H

Optical Brightner

H

99

Fragrances

• Important factor in consumer acceptance or rejection of product.

• Top notes: Fragrance out of bottle.• Middle notes: Fragrance while doing

laundry (smell on wet clothes).• Bottom notes: Fragrance on dry

garments (need to with stand heat of dryer).

• Target: Elusive “fresh and clean” smell.• Different cultures have different

preferences, e.g., Gain targeted towards Hispanic market.

Oral

Skin Hair Soap

Bath

Sun protection

Disinfectant/Bleaching

Sodium Lauryl Sulfate

√ √ √ √ √

Ammonium Lauryl Sulfate

√ √

Sodium Lauryl Ether Sulfate

√ √ √ √

Ammonium Lauryl Ether Sulfate

√ √ √

Alcohol ethoxylates

√

Sulfosuccinate √ √ √ √

Ethanolamides √ √ √ √

Amine oxide √

Surfactant applications

Oral Skin Hair Soap Bath Disinfectant/ Bleaching

Benzalkonium chloride √ √

CAPB √ √ √ √

CAPB - DC √

PEG -7 Glyceryl Cocoate

√ √ √

Surfactant based Soap noodles & flakes

√

Surfactant applications