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Shampoo and
Conditioner ScienceRobert Y. LochheadUniversity of Southern Mississippi
Shampoos and conditioners are the highest volume o products
sold in personal care. In this chapter, we will consider the science
that underpins the unctioning o these product types. Te principal
unction o shampoos is to cleanse the hair. However, since theintroduction o two-in-one shampoos in the 1970s, it has not
been sufficient or a shampoo to merely cleanse the hair. Modern
shampoos should at least cleanse, condition, make the hair easier
to style, and ragrance the hair with a pleasant, lingering smell.
Modern conditioners should lower the riction between hair fibers to
allow easier grooming and alignment o the hair fibers while leaving
them glossy and avoiding lankness.Te science o shampoos and conditioners is still evolving and
in addition to describing undamentals, this chapter attempts
to take the reader to the rontiers o research in shampoo and
conditioner science.
Introduction
Located within the hair ollicle is a sebaceous gland thatcontinuously excretes an oily material, known as sebum, onto
the hair and scalp. Tis substance consists o compounds such as
atty acids, hydrocarbons, and triglycerides, and serves as natures
conditioning treatmentproviding lubrication and surace
Practical Modern Hair Science
www.Alluredbooks.comCHAPTER 3
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hydrophobicity, while potentially replenishing components o
the cell membrane complex. However, aer a day or so, buildup
o this substance begins to result in a greasy look and eel.
Moreover, particulate dust and dirt adhere readily to this sebum
layer. In modern cultures such sebum-soiled hair is deemed to
be undesirable, and thereore, it should be removed on a regular
basis by a acile process. Tis process is, o course, shampooing.
Sebum cannot be removed by water because oil and water do not
mix. Aqueous shampoos can remove oily soil rom the hair surace
because shampoos contain surace-active agents, commonlyabbreviated as surfactants.Te molecules o these surace-active
agents sel-assemble into micelles, which are the agents that
solubilize oily soils.
o understand how suractants work, it is necessary to consider
the exact process that leads to oil and water being incompatible.
Tere are two different possibilities or substances to be insoluble
in water. In one case, substances have stronger intermolecularcohesion than water. Tis is why substances like sand, clay, and
glass are insoluble in water; the molecules o sand attract each
other more strongly than the molecules o water and this attraction
leads to the sand being insoluble. Tis reason or the insolubility is
exactly opposite to the reasons or the insolubility o hydrophobic
substances such as oils. Te intermolecular orces between the oil
molecules are weaker than the intermolecular bonds between watermolecules and the oils are expelledrom water. Tis expulsion arises
largely rom entropy and the effect has been coined hydrophobic
interaction.1,2From the time o the Phoenicians, it has been known
that oil spreads to calm troubled waters. Tis effect arises rom the
act that the spread oil has a lower surace tension than the water. At
this point it is appropriate to consider the effect known as surace
tension. Molecules in the bulk o liquids are attracted on all sides
by their neighboring molecules. However, molecules at the surace
are subjected to imbalanced orces because they are attracted by the
underlying liquid molecules, but there is essentially no interaction
with the vapor/gas molecules on the other side o the liquid/vapor
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boundary. Tis imbalance leads to a two-dimensional orce at the
surace, namely surace tension. Te surace tension is numerically
equal to the surace ree energy.3Te magnitude o surace tension
directly correlates with the strength o the intermolecular orces.
Water has hydrogen bonds, dipole-dipole interaction, and dispersion
orces between its molecules, and as a consequence the surace
tension o water is rather high72 mN/meter at room temperature.
On the other hand, only dispersion orces are present between the
molecules o alkanes. As a consequence, the surace tension o
alkanes is relatively lowranging 2030 mN/meter.Suractants comprise molecules that contain two parts: a
hydrophobic segment that is expelled by water and a hydrophilic
segment that interacts strongly with water. Such molecules are said
to be amphipathic(amphi meaning dual andpathic rom the
same root aspathoswhich can be interpreted as suffering). Tus,
a suractant molecule suffers both oil and water. Tis dual nature
coners interesting properties on suractants in aqueous solution.At very low concentrations, the suractant is expelled to the surace,
a process called adsorption. Tis adsorption causes the suractant
concentration at the surace to be much higher than the suractant
concentration in the bulk o the solution. At extremely low
concentrations, when the suractant molecules on the surace are
located too ar apart to effectively interact with each other, raubes
Rule applies. raubes Rule states that the ratio o the suraceconcentration to the bulk concentration increases threeold or each
CH2group o an alkyl chain.4Tis ratio is called the surace excess
concentration.5According to this rule, soap with a dodecyl chain
should have a surace excess concentration that is more than a hal-
million times its concentration in the bulk solution. At extremely
low concentrations, the suractant molecules on the surace act as a
two-dimensional gas. As the concentration increases, the suractant
molecules begin to interact, but they are still mobile within the
plane; they behave as two-dimensional liquids. At even higher
concentrations, as the suractant saturates the surace, the chains
orient out o the surace plane and the chain-chain interactions
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cause the suractant to behave as a two-dimensional solid. Irving
Langmuir was awarded the 1932 Nobel Prize in Chemistry or
measuring this effect and explaining it on a molecular basis.6
When a suractant adsorbs to saturate an aqueous surace, the
surace is largely composed o the suractants hydrophobic groups;
this means that the surace essentially has low surace energy. As a
consequence o the low surace energy, the surace area is easier to
expand to a film. Tis means that the system is easier to oam, since
aqueous oams really consist o water films with entrapped gas. I
the oam surace is structured by the adsorbed suractant, then oamstability can be achieved.7
Surfactant Micelles
Relatively large aggregates orm within solution just beyond
the concentration at which the surace becomes saturated with
suractant.8Tese aggregates are surfactant micelles in which
the hydrophobes are segregated within the core o the aggregateand the hydrophilic groups are located on the surace where they
interact strongly with water.9For a given system, micelles initially
orm at the precise concentration at which the driving orce or
surace adsorption becomes equal to the driving orce or aggregate
ormation. Tis driving orce is the chemical potential o the
suractant species. Te lowest concentration at which micelles orm
is named the critical micelle concentration(CMC). Te aggregates arelarge; or example, micelles o sodium dodecyl sulate at the CMC
contain about 100 molecules and the thickness o the head group
layer is about 0.4 nm.10
Suractant micelles have liquid centers. Tey effectively solubilize
hydrophobic substances only when the temperature o the system is
above the Kraf point. Kraf ound this phenomenon in 1895, and
68 years later Shinoda explained that the Kraf point corresponds to
the melting point o the hydrated solid suractant.11
Micelles have different shapes. Te simplest shape is the
spherical micelle that was postulated by Hartley in 1936. Te
shape o a micelle can be explained on the basis o the principle
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o opposing orces (see Figure 1). wo or three amphipathic
molecules alone cannot orm a stable micelle because micellization
is essentially a cooperative process that requires the participation
o many amphipathic molecules bound together by hydrophobic
interaction. However, i hydrophobic interaction accounted solely
or the ormation o micelles, then the association would continue
until phase separation occurred, as in oil separating rom water.
Tereore, there must be a orce that opposes the hydrophobic
association and controls the size o the micelles. Tis orce is the
repulsion between the head groups that could arise rom ion-ionrepulsion and/or hydration o the head groups.12Teoretically,
the repulsive surace terms are difficult to handle rom a
thermodynamic perspective but the presence o micelles has been
validated experimentally.
I micelle structure was determined solely by thermodynamics,
spherical micelles would always be avored over other shapes.
However, real micelles are not restricted to a spherical shape;
spherical structures account or only a small minority o micelles.
Te shapes o suractant molecules and the way they can be packed
Figure 1.The shape of a surfactant micelle is determined by
the balance between the mutual repulsion between hydrophilic
groups at the micelle surface and the cohesion due to hydrophobic
interaction. This has been dubbed the principle of opposing forces.
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also plays an important role in determining micelle shape. Although
thermodynamics and packing geometries are inextricably linked,
by considering the limits o possible packing arrangements we can
obtain insight into the shapes o micelles and the transormation
rom one shape to another as physical and chemical conditions
are changed. In this context, the many shapes o micelles, arising
rom the principle o opposing orces, can be appreciated by
considering Packing Factor Teory (Figure 2).13First, consider a
spherical micelle. In this instance the micelle radius, R, the volume
o the hydrophobic core, v, and the surace area o the amphipathicmolecule at the hydrophobe/water interace, a, are related by:
Eq. 1
Te radius o a micelle, R,cannot exceed the ully extended
length, l, o the hydrophobe chain o the suractant molecule. Tis
gives the critical condition or the ormation o spherical micelles:
Eq. 2
Figure 2.The packing factor of a surfactant molecule is the volume of
the tail group divided by the volume of the cylinder subtended by the
head group to the length of the tail group.
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Te raction, v/al, is known as the packing actor (Figure 3).
When the packing actor has a value o 1/3, the suractant molecule
can be approximated by a conical shape and the molecules pack into
a sphere (Figure 4).
When the packing actor has a value o , the micelles become
cylinders (Figure 5), and when the packing actor has a value o
1, the suractant molecules pack as planar bilayers in a so-called
lamellar structure (Figure 6).
For ionic suractants, the area per head group can be decreased
by adding soluble salt to the solution to lessen the ionic repulsion
between the head groups. (Salt also enhances the hydrophobic
interaction.14) Increase in salt and/or suractant concentration causes
spherical micelles to transition to rods and then to long worm-like
micelles.15Te wormlike micelles behave like polymers in solution.16
Figure 3.Surfactant molecules with a packing factor of 1/3 have a
shape that can be approximated by a cone.
Figure 4.These conical molecules pack naturally into a sphere.
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Tese micelles also orm branched as well as linear structures, and
above a certain concentration (the critical overlap concentration, C*)
they entangle just like polymer molecules17and display viscoelastic
rheology.18-20Tis behavior is depicted in Figure 7as it was
explained by Candau in 1993.21An increase in salt concentration
causes spherical or elliptical micelles to transition into rods, then
to worms then to branched worms. As the suractant concentration
increases, the micelles orm entangled networks. Consumers desire
Figure 5.Surfactant molecules with a packing factor
of pack naturally into cylinders.
Figure 6.Surfactant molecules with a packing factor of 1 pack
naturally into bilayer planes.
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thicker shampoos, in part because they are easier to apply, but
also or aesthetic reasons; a thicker ormula is generally perceived
as being more-luxurious. Te desired rheology is achieved rom
ormulations that contain worm-like micelles.
Wormlike micelles do, however, show non-polymeric behavior
at certain shear rates when the shear stress becomes independent o
the shear rate and the relaxation time becomes monodisperse.22Tis
behavior has been explained on the basis that the entanglements
can be broken and reormed as the rod-like micelles disassemble
and then reassemble upon passing through each other.23-24Systemslike these have been dubbed phantom networks by Cates to
signiy that one micelle flows through another just as we imagine a
phantom would pass through a wall. Te phantom network behavior
may explain why shampoos can show viscoelasticity without the
stringiness observed in entangled polymer solutions.
At higher concentrations, the rod-like micelles mutually repel,
and this avors alignment into a nematic phase. At still higher
concentrations the aligned rods pack in a hexagonal array to orm
hexagonal phase liquid crystals (Figure 8). Te hexagonal phase
has the properties o a clear ringing gel that is bireringent in
polarized light.
Figure 7.Ionic surfactant micelles change shape as a function of ionicstrength and surfactant concentration.
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As the suractant concentration is increased urther and/or
dissolved salt concentration is increased, the surace o the micelles
becomes less curved until the large planar aggregates o the lamellar
phase are ormed (Figure 9). Modern shampoos consist essentially
o entangled worm-like micelles and conditioners are usually in the
orm o the lamellar phase.
In summary, shampoo and conditioner ormulation essentially
involves the preparation o suractant mixtures that possess the
Figure 8.Rod-like micelles can pack into hexagonal liquid crystal phase.
Figure 9.Increase in surfactant concentration causes micelles to transition from
spheres to rods to hexagonal phase to lamellar phase to inverse hexagonal
phase to inverse micelles.
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aorementioned structures, while also being esthetically pleasing.
Te hair care ormulation scientist has an ever-increasing variety
o suractants available in the ormulation toolbox, and so these
structures can be obtained via a wide range o concoctions.
Nonetheless, attaining such stable structures is not a trivial task,
due to the presence and interactions o so many ingredients in
the typical ormulation. Tereore, with historical knowledge
involving many established ingredients already being relatively
well-understood, it is a brave ormulation chemist that opts to cut a
new pathway. Moreover, it is also probably prudent to arrive at thesestructures in the most cost-effective manner. For these reasons, it
is imperative to understand how the suractant structure, together
with interactions with other molecules alters the nature o the
aggregate structures.
Oily Soil Removal Mechanisms
Te principal unction o a shampoo is to remove oily soil romthe hair. Tere are several principal detergency mechanisms or
removing oily soils: roll-up,25emulsification, penetration, and
solubilization.
In the roll-up mechanism, the detergent solution causes a steady
increase in the contact angle o the oil at the oil/fiber/aqueous
interace (Figure 10).
Te oil droplet is rolled up on the surace, and when the contact
angle reaches 180degrees, the interacial orce that is holding it to
the surace is overcome by the wetting tension o the oil and aqueous
solutions on the fiber surace. Roll-up is avored by fibers that are
Figure 10. In this mechanism the oil contact angle at the oil/water/fiber interface
steadily increases until it rolls up and floats off of the solid surface. This
mechanism was first reported by N. K. Adams.
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oleophobic and hydrophilic.26Te removal o oily soil by detergent
compositions is not necessarily predictable due to the wide variation
o the surace properties o hair that arise rom prior treatments
and weathering. Moreover, the transport o the detergent solution
to the fiber surace can occur by three different routes: (i) along the
fiber surace, (ii) through a previously applied permeable surace
treatment, or (iii) through the body o the fibers (Figure 11).
Roll-up o oily drops on fibers occurs when the contact angle
exceeds a critical value and this causes the oily drop to adopt an
unstable axially asymmetric attachment on one side o the fiber.27
Te rate o roll up depends also on the viscosity o the oily soil,
and mechanical action is oen necessary to dislodge viscous oily
soils rom the fiber surace. In some cases, the oil orms a viscous
emulsion when contacted by the detergent composition, and theresulting viscous soil can be difficult to remove rom the fiber.
Perect hair is covered by a covalently attached monolayer o
18-methyleicanosoic acid (18-MEA), which coners hydrophobicity
on the hair. Modern grooming techniques and weathering removes
this layer o 18-MEA.28Removal o the layer o 18-MEA results
in hair becoming macroscopically hydrophilic.29Te roll-up
mechanism, thereore, should be expected to become more
prominent on damaged rather than pristine hair.
Initially i the fiber is completely coated in oil, or i the fiber itsel
is hydrophobic, the detersive solution cannot easily reach the oil/fiber
interace, and the soil will be removed by emulsification (Figure 12).
Figure 11. In the roll-up mechanism, the detergent solution can be transported
to the fiber/oil interface along the fiber surface, through a permeable coating
on the fiber, or through the fiber itself.
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Emulsification is avored by low oil/water interacial tension that
allows the oil surace to be expanded into an emulsion droplet.30
In the penetration mechanism o oily soil removal, suractant-
rich phases penetrate the oil at the interace. Tis results in an
interacial liquid crystalline phase that swells and is broken off
to reveal a resh soil interace, and then the process is repeated
again and again.31Te penetration mechanism occurs with polar
soils and/or phase separated coacervates o nonionic suractants
above the lower critical solution temperature (LCS). Spontaneousemulsification, in the absence o detersive suractant, has been
observed or non-polar-polar soil mixtures like sebum.32Te
penetration mechanism can occur with anionic suractants that
orm coacervate phases in the presence o calcium salts.33
Solubilization is the process o incorporating a water-insoluble
hydrophobic substance in the internal hydrophobic core o micelles.
Direct solubilization can occur in the presence o an excess osuractant micelles with respect to oily soil.34Te rate o exchange
o suractant molecules between micelles is important because the
micelles must re-assemble around the soil to solubilize the soil by
encompassing it inside the micelle.
Foam/Lather
One essential attribute o a shampoo is its ability to produce
a rich lather or oam. Te important elements o a oam are
the lamellae and the Plateau border. Te micrograph in Figure
13depicts these structural eatures o a oam. Te lamellae are
stabilized by suractants adsorbed at the air-water interace.
Figure 12. Emulsification can remove the soil if the interfacial tension between the
oily soil and the surfactant solution is low.
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Foams lose stability by two main mechanisms: draining o the
liquid and puncture o the lamellae. Te oam lamellae are the
junctions between two oam bubble cells and the plateau border issituated at the triple-cell junction. Te Laplace pressure in the liquid
components o the oam is inversely proportional to the curvature
o the interace. Te higher curvature o the plateau border results
in a lower pressure in that region and this causes the liquid in the
oam to drain preerentially rom the lamellae to the plateau borders.
Based upon this reasoning, it can be understood that drainage can
be hindered in two ways, namely by blockage o the lamellae or byblockage at the plateau border. About two decades ago, Des Goddard
careully measured the drainage rom oam films and deduced
that polyquaternium-24 adsorbed across the lamellar interace and
hindered the drainage o liquid rom the oam. In addition, about
thirty years ago, Stig Friberg concluded that certain liquid crystals
blocked the plateau border region and delayed oam drainage and
conerred longer-term stability on suractant oams. In the case o
cationic polymers, hindered drainage o the lamellar liquid could be
caused by adsorption o the cationic entities at the lamellar surace
with the nonionic and/or anionic blocks in the lamellar liquid.
Figure 13. Micrograph showing surfactant foam structure.
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Alternatively, ormation o phase-separated coacervates between the
cationic polymer and the anionic suractant could result in blockage
o the plateau border. O course, i the interaction o the cationic
polymer was strong enough to orm inverse micellar structures,
then there would be a possibility that the phase-separated particles
could cause a local reversal o the curvature in the lamellae and this
in turn would result in breakage o the lamellar film and subsequent
oam destabilization. Tis type o oam destabilization mechanism
has been extensively reported by Peter Garrett.
Solid Foams
Cationic conditioners
that would normally be
incompatible with liquid
shampoos can be delivered
rom solid oams. Solid
oams also make it possibleto have one scent or the
solid and then to allow
a different ragrance to
bloom when the solid is
wetted by water.35Te
porous solids are made by
mixing the suractants,glycerin as a plasticizer,
and water in the presence
o a water-soluble polymer.
Figure 14shows a solid
oam in which poly(vinyl
alcohol) is the water-soluble
polymer. Aer a heating
and mixing cycle, the
porous solid is ormed by
aeration.
Figure 14. Micrograph showing solid foam structure
(reproduced from US Patent Application 20110195098).
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The Anatomy of a Shampoo Formulation
Shampoos consist essentially o water, a primary suractant,
one or more co-suractants, and soluble salt. Other ingredients
are added or ragrance, preservation, conditioning, and styling
attributes. Cleaning is achieved mainly by the primary suractant,
which is oen an anionic suractant that would adopt a conical
shape i it was present in water alone. Te co-suractant is usually
a nonionic or zwitterionic suractant with a relatively small head
group surace area. Tis molecular shape allows the co-suractant
to serve two roles: (i) it packs between the molecules o the primarysuractant to reduce the curvature and to promote the ormation
o worm-like micelles with their high viscosity and luxurious
rheology; and (ii) it packs between the primary suractant in the
lamellae o the oam to provide good lather that is easily removed
by rinsing. Salt enhances the unction o the co-suractant by
damping down the ionic repulsion between primary suractant
head groups and promoting the ormation o wormlike micelles. Iexcess salt or co-suractant is added, shampoo compositions can
separate into phases that contain co-existing micelles and liquid
crystals. Tese phase-separated compositions oen exhibit thin
viscosities and haziness.
The Primary Surfactant
Te lauryl sulates have been the primary suractant workhorses
o the shampoo industry or decades. Te sulate head groups bear
an anionic charge when dissolved in water. Te long chain alkyl
tail group has an average length o 12 carbon atoms. It is important
to understand that this is an average chain length; commercial
lauryl sulates have a distribution o chain length rom as short as
8 carbons to as long as 18 carbons. Tis chain length distribution
changes rom supplier to supplier and it also changes depending
on the source o raw materials. Formulators should be aware that
changes in the chain length distribution o the suractants can lead
to subtle changes in the properties o the shampoo.
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During the 1970s, triethanolamine lauryl sulate was preerred
as a primary suractant due to its excellent cleaning properties and
luxurious flash oaming capability. However, it was replaced by
laureth sulates or two reasons: the concern over the ormation o
nitrosamines rom secondary amine components and the reduced
eye irritation exhibited by the laureth sulates.
Over the last two decades, the primary suractants o most
shampoos have been sodium laureth sulate, ammonium lauryl
sulate, and sodium lauryl sulate.
Te co-suractantoen called the oam boosterhas mostprominently been selected rom two types o materials: alkylamide
MEA and alkylamidobetaines. Modern shampoos contain primarily
betaines as co-suractants.
Enhancing Mildness
Isethionates are suractants noted or their mildness to skin,
and or at least three decades, they have been the basis o non-soapdetergent bars such as Dove (Unilever). Tey have been making
inroads into shampoos based upon mildness claims. Moreover,
Unilever researchers discovered that the mildness can be enhanced
even urther by including mildness benefit agents that can be
flocculated by cationic polymers present in the ormulation and
delivered as flocs upon dilution o the ormulation.36Te preerred
benefit agent in this case is petrolatum; the cationic polymersare well known polymers like polyquaternium-10 and guar
hydroxypropyltrimonium chloride. Tis could orm the basis o
shampoos that are mild to the skin.
Certain non-cross-linked linear acrylic copolymers can lower
the irritation potential o suractants and provide products that are
clear and highly oaming.37Te preerred polymers interact with the
suractant and effectively shiing the CMC to higher concentrations,
while lowering the critical aggregation concentrationthe latter
being the concentration at which the suractant selectively interacts
with the polymer rather than adsorbing at the liquid surace
(Figure 15). It is postulated that ree suractant molecules and
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ree suractant micelles are responsible or irritation o skin and
eyes and that binding o the suractant to the polymer effectively
reduces the concentration o ree micelles. A measure o mildness
is the delta CMC, which is defined as the difference between the
CMC o the suractant alone and the higher CMC o the suractant
in the presence o the polymer. Larger values o delta CMC or a
particular suractant are apparently correlated with lowering o the
irritation potential. Te delta CMC provides a measure that is useul
or selecting, comparing, and optimizing polymers that reduce the
irritation potential o selected suractant systems. Carbomer andacrylates copolymer have been identified as polymers that exhibit a
satisactory delta CMC.
Conditioning Shampoos
odays conditioning shampoos are expected to coner wet-hair
attributes o hair soness and ease o wet-combing, and the dry hair
attributes o good cleansing efficacy, long-lasting moisturized eel,
and manageability with no greasy eel.
Te origin o conditioning shampoos can be traced to the
balsam shampoos o the 1960s ollowed by the introduction o
polyquaternium-10 by Des Goddard38,39 in the 1970s and 1980s in
which he introduced the concept o polymer-suractant complex
coacervates that phase-separate and deposit on the hair during
Figure 15. Plot of surface tension vs. surfactant concentration for
surfactant alone and for surfactant in the presence of polymer. The
difference in the CMC induced by the presence of the polymer is
claimed to be related to the effect of the polymer in enhancing themildness of a shampoo.
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rinsing. Te first two-in-one shampoos depended on a complex
coacervate being ormed between anionic suractant and the
cationic hydroxyethylcellulose, polyquaternium-10. Tis complex
was solubilized in excess suractant and it phase-separated as a
coacervate liquid phase upon dilution during the rinsing cycle.
Later guarhydroxypropyltrimonium chloride was introduced as
an alternative cationic polymer that worked on the same principle
as polyquaternium-10. Tese two polymer types continue to
dominate the compositions o conditioning shampoos.40Guar is a
galactomannan and it is interesting that, in recent years, recentlya new cationic galactomannan hydrocolloid, cationic cassia,
has been claimed to coner conditioning shampoo benefits.41,42
Polygalactomannans consist o a polymannan backbone with
galactose side groups. In guar gum, there is a pendant galactose
side group or every two mannan backbone units. Tese galactose
groups sterically hinder the substitutable C-6 hydroxyl unit,
limiting the extent o possible cationic substitution on guar gum.In cassia, however, there is less steric hindrance o the C-6 hydroxyl
group and, consequently, higher degrees o cationic substitution
are possible with cassia (60% or cassia relative to 30% or guar).
Cationic cassia can be used as a conditioning polymer in shampoos
and conditioners to impart cleansing, wet-detangling, dry-
detangling, and manageability.
Te mechanism o conditioning shampoos depends upon theormation o polymer/suractant coacervates that phase-separate
during rinsing (Figure 16). Polyions in aqueous solution are
surrounded by an electrical double-layer o counterions, and the
location o the counterions with respect to the polyion is determined
by a balance between chemical potential and electrochemical
potential, called the Donnan Equilibrium. Suractant ions contain a
large hydrophobic group that makes them intrinsically less soluble
in water than inorganic ions such as chloride or bromide. When
suractant ions interact with an oppositely charged polyion, they
bind strongly and displace the water-soluble inorganic ions rom
the polyion; that is, they ion-exchange. Once the suractant ions
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bind, hydrophobic interaction between the hydrophobic suractant
tails causes the polymer-suractant complex to phase separate at
concentrations below the suractant critical micelle concentration.
Above the CMC, the suractant concentration is sufficiently high
to orm micelles or hemi-micelles along the polyion chain, and the
polyion/suractant complex is solubilized. Conditioning shampoos
are ormulated within the range o suractant concentrations that
correspond to this solubilized regime. When these shampoos are
diluted to a concentration that is in the vicinity o the CMC, then thecomplex coacervate phase-separates. Te separated phase is deposited
on the hair during rinsing, and it can co-deposit other additives such
as silicone conditioning agents or anti-dandruff agents. Maximum
coacervate deposition occurs at precise ratios o cationic polymer to
anionic suractant, but the optimum ratio or coacervation might not
coincide with the best ratios or cleaning and oaming.
Cationic guar has been a known additive or 2-in-1 shampoos
or more than three decades. However, it has now been shown that
improved post-shampoo detangling times are achieved by including
a small degree o hydrophobic substitution in the cationic guar
derivatives.43
Figure 16. A schematic phase diagram that explains the mechanism of coacervate
formation in 2-in-1 shampoos.
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Synthetic copolymers o acrylamide and a riquat monomer are
postulated to provide improved deposition on hair and improved
conditioning perormance with respect to wet combing.44
Silicones have become standard ingredients in many conditioning
shampoos or the smooth, silky hair eel that they coner. Silicones
were introduced to shampoos as 2-in-1 conditioning agents in
the 1980s. Te introduction o silicones needed to overcome two
substantial deficiencies: (i) silicones are well known deoamers, and
(ii) silicones are incompatible with typical shampoo compositions
and they tend to separate due to their low specific gravity. Initialattempts to stably suspend the silicone included the use o water
miscible saccharides such as corn syrup.45Later products comprised
xanthan gum in the shampoo as a suspending agent and acceptable
oaming attributes were conerred on the shampoos by ormulating
with relatively high levels o alkyl sulates as the primary suractant,
cocamide MEA as the co-suractant, and ethylene glycol distearate
as a suractant structuring agent.46In the actual application, thereis a technical contradiction involved in the deposition o silicone
conditioning components rom a detersive, cleansing system;
the detersive system is designed to remove oil, grease, dirt, and
particulate material rom the hair, and the conditioning agent
has to be deposited on that same hair in one process. As a result,
large excess amounts o silicone are used to ensure deposition,
and one consequence o this is that large amounts o the expensiveconditioning silicone can be rinsed away rather than deposited on
the hair. Cationic polymer/anionic suractant coacervates enhance
the deposition o silicones on hair and, consequently, increase the
efficiency o conditioning shampoos.47,48
Volatile cyclic siloxanes coner the desired silky initial eel, but
these materials are difficult to ormulate in consistent homogenous
ormulations, Tey tend to spread uncontrollably over the hair and
skin.49Tis effect can be controlled with polymeric silicone gels
ormed in volatile silicones to provide both the initial silky eel and a
high viscosity and smooth eel when dry.50Branched molecules with
a silicone core and hydrocarbon branches, or networks ormed rom
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these branched units, have been disclosed as suitable or improving
sensory eel, while minimizing phase separation and conerring
good shampoo removability.51
Shampoos containing more than one cationic conditioning
polymer and a quaternary silicone give more uniorm deposition on
hair than standard shampoos based on polyquaternium-10 as the
sole conditioning polymer. Tus, a conditioning polymer cocktail
comprising poly(acrylamide-co-acrylamidopropyltrimonium)
chloride, guar hydroxypropyltrimonium chloride, and silicone
quaternium-13 give uniorm deposition on hair. In this instance, theclaims are based upon multiple testing and analysis:52
A multiple attribute consumer assessment study that measured
the attributes o cleanliness, wet-comb, dry-comb, hair soness,
lather amount, and creaminess.
Secondary Ion Mass spectrometry to detect silicon on the hair
surace. Tis method revealed that a standard commercial
shampoo concentrated silicone on the cuticle edges o the hair,whereas the patent application shampoo distributed silicone
more evenly.
X-ray photoelectron spectroscopy (XPS) to measure the thickness
o the silicone polymer layer on hair rom Si:C:O ratios. Tis
method revealed that the commercial shampoo deposited
a significant amount o silicone, and the patent application
shampoo deposited only one or two molecular layers.
Instron ring compression as a measure of combability.
Complex coacervates can also be ormed rom mixtures o
cationic and anionic polymers. Tis could be the underlying
mechanism in shampoos that include an anionic and cationic
polymer that provide sleekness and gloss.53
wo drawbacks o silicones are that they oen destabilize oamand the final compositions are hazy due to light scattered rom
the suspended silicone droplets. Initially, silicone copolyols were
introduced to overcome the insolubility o silicones in shampoo
compositions, but this drastically reduced the amount o silicone
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deposited onto hair and compromised conditioning perormance.
Clear, silicone-containing conditioning shampoos have been
ormulated by adding trideceth-2 carboxamide MEA to reduce the
silicone droplet size.54ransparent conditioning shampoos can be
ormulated by incorporating the silicone as microemulsified droplets,
but the small microemulsion droplets tend to be rinsed away rather
than deposited during the shampooing process. Moreover, coalescence
o the droplets can lead to loss o transparency in the product during
storage. Attempts have been made to overcome these challenges by
including silicone emulsions with high internal viscosities, typicallygreater than 100,000 centistokes, but the high internal phase viscosity
gives deposited silicone that is can be difficult to remove and this
causes buildup with each consecutive shampooing. Such buildup
usually reduces the volume o the desired hair style and causes
droop and flatness. Fortunately, shampoo compositions providing
superior conditioning to hair while also providing excellent storage
stability and optionally high optical transparency or translucency canbe obtained by combining low viscosity microemulsified silicone oil
with cationic cellulose polymers and cationic guar polymers having
molecular weights o at least about 800,000 and charge densities
o at least about 0.1 meq/g.55Conditioning shampoo ormulations
that include a silicone microemulsion in a conditioning shampoo
containing guar hydroxypropyltrimonium chloride and an anionic
detersive suractant have also been reported to be clear.56,57I pre-gelatinized starch, such as hydroxypropyl distarch phosphate, is
included with polyquaternium-10, transparent conditioning shampoos
can be obtained.58
Another way to minimize buildup is to treat the hair with water-
in-water emulsions that can be prepared by including cationic
polymers with soluble salts in suractant compositions.59Tese water-
in-water emulsions provide conditioning benefits with good spread
o the conditioning phase on the hair and less chance o buildup.
Te living ree radical polymerization techniques that have
emerged in the last decade offer the prospect o preparing precise
polymers with unprecedented accuracy in molecular structure and
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variety o chemical types.60Tis technique has enabled synthesis o
a wide diversity o block and gra polymers that were previously
unattainable. Such polymers offer the prospect o conerring
conflicting properties within one molecule, which in turn can lead
to improved compatibilities in the same system while maintaining
stability. Tese conflicting properties could possibly be achieved
by blending different polymers, but different polymers do not mix
readily at the molecular level and phase separation may result.61
Block, gra, and gradient copolymers serve to compatibilize such
compositions and gradient polymers have been proposed or thispurpose. Block copolymers comprising polycationic blocks and
nonionic blocks or surace deposition62and or improved oam
retention63have been claimed, which are desired to deposit on
hair in order to modiy the chemical properties o the surace
or protection or compatibility; to modiy hairs hydrophobic or
hydrophilic surace properties; or to modiy eel or mechanical
properties o the substrate rom two-in-one products. Te polymersdisclosed are block copolymers o polyMAEAMS (methylsulate
[2-(acryloyloxy)ethyl]-trimethylammonium) g/mole) and
polyacrylamide.
Conditioning shampoos can also be ormulated to unction
by mechanisms other than cationic polymer-induced complex
coacervation, such as:
Conditioning can be achieved by including chain extended
silicones in an anionic suractant-based shampoo. Specific
examples o useul silicones include silicone emulsions
containing divinyldimethicone/dimethicone copolymer.64
Shampoos containing polyalkylene oxide alkyl ether particles
givelarger coacervate cohesive flocs (20500 microns) that
resist shear and coner superior deposition efficiency on hair orgood wet conditioning.65
Conditioning shampoos containing a polyester formed from
adipic acid and pentaerythritol provides conditioning or dry
hair (possibly rom reduced hair riction), with no greasy eel.66
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Inclusion of polybutene is thought to increase the deposition
o silicone conditioners and provide improved conditioning
benefits, such as wet and dry eel and combing.
O Lenick disclosed a unique class o alkyl polyglucoside quaternary
suractants possessing all the multiunctional attributes o cleansing,
conditioning, and sel-preserving.67Tis could have the potential o
greatly simpliying the ormulation o multiunctional shampoos.
A conditioning shampoo that contains a conditioning gel
phase in the orm o vesicles is described by Unilever researchers.68
Cationic conditioners are usually incompatible with anionicshampoos, and consequently conditioners based upon cationic
suractants are usually applied as separate post-shampoo products.
Te Unilever researchers prepared a conditioning gel phase by
combining a small amount o water, atty alcohol, a long-chain
secondary anionic suractant (sodium cetostearyl sulate), and
a long-chain cationic suractant (behenyltrimethylammonium
chloride), and subjecting the mixture to high shear to orm a stablevesicular gel phase. Prolonged shear causes the lamellar gel phase to
roll-up into an array o multilamellar vesicles (Figure 17). Te gel
phase was added to a dilute primary suractant solution (sodium
laureth sulate) to orm a conditioning shampoo that conerred good
wet smoothness on hair.
Deposition of Particles on Hair to Confer Styling Benefits
Whereas conditioning shampoos are ormulated to reduce hair
inter-fiber riction, some consumers need an increase in riction in
Figure 17. Lamellar gel subjected to high shear rolls up into vesicles of gel phase that can
be used for conditioning. (Figure reproduced from US Patent Application 20110243870).
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order to achieve styling benefits. Factors that influence hair body
and ullness include hair diameter, hair fiber-to-fiber interactions,
natural configuration (kinky, straight, wavy), bending stiffness,
hair density, and hair length. Increases in riction can be achieved
by depositing particles such as titanium dioxide, clay, pearlescent
mica, or silica on the hair surace. Particles can be deposited or
more purposes than merely increasing inter-fiber riction, e.g., or
conerring color, or slip (spherical particles are best or this), and
or conditioning (hollow silica, hollow polymer particles). Hollow
particles can be included in shampoo to increase hair volume.69,70
Deposited hollow particles that can increase fiber-fiber interaction
include complexes o gas-encapsulated microspheres (such as silica
modified ethylene/methacrylate copolymer microspheres and
talc-modified ethylene/methacrylate copolymer microspheres);
polyesters; and inorganic hollow particles.
It has already been noted that cationic guar enhances
the deposition o conditioning agents. In a like manner, thismacromolecule enhances the deposition o particles on hair.71
Silicones and particulates can be deposited simultaneously. Tus,
enhanced deposition o particulate actives, such as zinc pyrithione
(shown on cadaver skin treated in a Franz diffusion cell), has
been reported72rom shampoos comprising a water-soluble
silicone (such as silicone quaternium-13, cetyltriethylammonium
dimethicone copolyol phthalate, or stearalkonium dimethiconecopolyol phthalate), a cationic conditioning agent (such as
acrylamidopropyltrimonium chloride/acrylamide copolymer, or
guar hydroxypropyltrimonium chloride), a cleansing detergent,
and suspending agents (such as carbomer, hydroxyethylcellulose,
and PVM/MA decadiene cross-polymer) to insure homogeneous
distribution o the insoluble active.
Hydrophobic modification o cationic hydroxyethylcelluloseis claimed to endow better efficacy. Tus, polyquaternium-24,
a hydrophobically modified cationic hydroxyethylcellulose, is
also disclosed as being a preerable thickener or zinc-depositing
compositions.73
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It has been discovered that responsive particles, with two
contrasting polymers adsorbed to the particle core,74can adsorb
to the hydrophilic hair surace and render it hydrophobic, thereby
conerring conditioning attributes to the hair. For example, graing
o aminopropyl-terminated dimethicone and polyethylenimine
on titanium dioxide particles produces responsive particles.
Tese particles orm stable dispersions in water and aqueous
solutions because they are sterically stabilized by expansion o
the polyethylenimine into the aqueous medium. However, when
they are deposited on hair and dried, the polyethylenimine layercollapses and the dimethicone layer expands to render the surace
hydrophobic. Te useulness o these responsive particles is
demonstrated by including them in typical conditioning shampoo
and conditioner ormulations. In the case o the shampoo, inclusion
o the responsive particles results in a higher water contact angle on
the treated hair and the conditioner with particles causes an increase
in the hydrophobicity o the hair. On the other hand, shampooscontaining ethoxylated alcohols have been ound to enhance the
deposition o large particle silicones (52000 microns), and in this
case it is claimed that cationic polymer is not required.75
Two-phase Systems for Visual Attributes:
Tere is esthetic appeal to products that exist as separate phases
in the bottle but which mix during application to provide addedbenefit, such as moisturizing or conditioning, by interaction o the
components o the two phases. Te most obvious way to ormulate
such products is to use the immiscibility o water and oil in
ormulations that are shaken prior to use to produce a metastable
emulsion. However, when a suractant is included in the system such
a visually attractive phase separation can be mixed into an emulsion
due to shear in manuacturing and packing operations. Tere are
known de-emulsifiers, which are widely used in the oil industry,
but these demulsifiers also tend be deoamers that compromise the
lather o shampoos. Neutralized polyacrylate can be added as a non-
emulsiying oam stabilizer to yield phase-separated compositions
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that resist the production difficulties to make phase-separated
shampoos that orm temporary emulsions upon shaking and oam
during use.76 A two-phase shampoo system can also be ormed by
mixing polar lipophilic shampoo components with non-polar lotion
constituents such as mineral oil.77
Under appropriate conditions, phase-separated systems can be
prepared rom polymer solutions or micellar suractant solutions. I
two distinct aqueous phases are desired in a composition, one must
take into consideration the thermodynamics o coexisting phases
and the driving orce or such phase separation that comes directly
rom the chemical thermodynamics o the system. Tis is especially
the case or systems that contain polymers or micelles because the
configurational entropy is reduced as molecules are assembled
into polymers or aggregated into micelles, and mixing can become
unavorable. I the ree energy o mixing is insufficient to maintain
uniorm dispersion, spontaneous phase separation will occur.
Phase separation becomes more likely as the micellar aggregates orpolymers get bigger. Te addition o salts to ionic suractant micellar
systems causes a reduction in the suractant intra-micellar head-
group interaction, and oen an increase in hydrophobic interaction.
Tis can cause a pronounced increase in micelle size and consequent
phase separation into a suractant-rich phase and a suractant-poor
phase. Tis approach has been adopted by adding mineral salt to
induce two distinct layers,78
and by adding the detergent builder,sodium hexametaphosphate, to cause phase separation. In this case,
a thickener is required and the system comprises a suractant, a
thickener, a polyalkylene glycol, and a non-chelating mineral salt.
Te system spontaneously separates into two layers.
A multiphase composition comprising suractant, betaines,
co-suractant (such as an alkyl ether carboxylate, an acylglutamate;
or an acylisethionate), and an appropriate concentration o saltorms a stable multiphase system that becomes temporarily
uniormly dispensed upon agitation.79
Multiphase cleansing products have been introduced that go
beyond mere phase separation insoar as the separate phases can be
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arranged to orm visually attractive patterns inside a transparent
container.80Te phases comprise an aqueous cleansing phase, a
benefit phase, and a non-lathering structured phase. Te aqueous
cleansing phase must be capable o adequate lathering.81Te
benefit phase comprises hydrophobic component(s) or conditioning
components. Tese products are designed at the nanoscale: the
structured phase can be a lamellar-phase ormed by adding sufficient
electrolytes to an appropriate suractant. Structurants such as
starch have been used in personal cleansing ormulations,82but the
suractant itsel can be structured. Tus, lamellar phase does exhibit
a yield stress that is sufficient to stably suspend the benefit phase.
However, the yield stress o lamellar phase can vary dramatically
with temperature, and, in order to overcome this problem, the
cleansing and benefit phases were density matched by adding
microsphere particles to reduce the specific gravity o the cleansing
phase or high density particles to the benefit phase to increase its
specific gravity. In this context, it is interesting that it has beenrecently disclosed that controlled phase separation and deposition
could conceivably be achieved by loading the desired active phase
into hollow-sphere polymer carriers,83and again it has been reported
that certain cationic guar derivatives can enhance the deposition o
conditioning additives and/or solid particle benefit agents.84
Lamellar phase, especially i it is made rom unneutralized long-
chain atty acids, usually displays poor dispersion kinetics and alather that is slow to build up or slow to rinse off. However, it has
surprisingly been discovered that swollen lamellar gels can exhibit
both high product viscosity and ast dispersion kinetics i they are
ormed by combining C16-24 normal monoalkylsulosuccinates
with n-alkyl atty acids o approximately the same chain length.85In
this context, Guth claimed a composition that was low-irritating to
skin and eyes but synergistic in oaming by combining zwitterionicsuractants-atty acid complexes with sulosuccinates,86and Pratley
reported synergistic oaming and mildness rom compositions
with combinations o specific long-chain suractants with specific
short-chain suractants and these included atty acids and
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alkylsulosuccinnates.87Amine-oxide copolymers have also been
claimed as suds-enhancers.88
Concentrated Cleansing Compositions
Most personal care products are based on aqueous compositions
but concentrated cleansing/personal care compositions offer
the benefits o lower transportation costs, less packaging, and
convenience or air travelers. I these products are solid, they
must possess sufficient strength to resist the orces o extrusion
during manuacture, shipping, and handling, but should disperserapidly in water during use. Porous solid particles that are
strengthened by hydrophilic polymers such as poly(vinyl alcohol)
or hydroxylpropylmethylcellulose have been shown to exhibit the
desired properties.89Control o interconnectivity o the porous
network is vital to this application and is described by a star volume,
a structure model index, or a percent open cell content.
Conditioners
Conditioning o damaged hair is commonly achieved by
treatment with aqueous ormulations that contain atty alcohols,
cationic suractants, and (optionally) silicones. Tese components
are considered to adsorb in a hydrophilic head-down, hydrophobic
tail-up conormation that coners hydrophobicity on the damaged
hydrophilic hair surace. Te role o a conditioner is to coner sleek
lubricity and gloss on the hair. Conditioners are usually based
upon cationic suractants, and they most oen are in the orm
o emulsions o multi-lamellar vesicles. Conditioners comprise a
primary cationic suractant, a co-suractant, and dissolved salt.
Conventional conditioner ormulations are based upon lamellar
gels or emulsions using either ceto-stearyl trimethylammoniumchloride or distearyldimethylammonium chloride as cationic
suractants and ceto-stearyl alcohol as co-suractant.
As a primary suractant, the vast majority o conventional
conditioners contain either cetyl/stearyl trimethylammonium
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chloride or distearyldimethylammonium chloride. Te secondary
suractant is most oen ceto-stearyl alcohol.
Cetyl/stearyl trimethylammonium chloride is a conical molecule
according to Ninhams packing actor. On the other hand, ceto-
stearyl alcohol consists o molecules with the approximate shape
o an inverted conical molecule. Te role o ceto-stearyl alcohol
in a conditioner is to pack between the cationic cones and convert
the micellar structure into a lamellar structure with just enough
curvature to orm a vesicle. Distearyldimethylammonium chloride
spontaneously orms vesicles in the presence o salt, and thereore
there is usually no need to add a long-chain alcohol to conditioner
ormulations based upon distearyldimonium chloride.
Tese products orm a gel matrix that coners conditioning
benefits rom rinse-off products. Tey have been the basis o hair
conditioners or the last hal-century, and they provide excellent
detangling, wet- and dry-combing, and good anti-static properties,
but they can leave the hair eeing lank and greasy, and they give along-lasting slippery eel during rinsing which is perceived by some
consumers as an unclean hair eel.
Pristine hair, as it emerges rom the scalp, is coated with a
covalently bound layer o 18-methyleicanosoic acid (18-MEA).90-92
It has been shown that the layer o 18MEA coners hydrophobicity
and boundary lubrication on hair fibers.93Tis discovery has
influenced researchers to seek to include 18-MEA in conditionerormulations.94Pristine hair shows a measured advancing water
contact angle that is high, but a receding contact angle that is
likewise high, and the hair tends to align. However, once the
18-MEA layer is removed, the receding contact angle is low (even
approaching 0degrees), and this corresponds to cuticle edges that
are essentially hydrophilic. Tis means that the major differences
or such 18-MEA deficient hair would be in its drying behaviorrather than its wetting characteristics. Te low receding contact
angle would tend to pin the water to the hair. Tis would
lead to longer drying times during which the capillary orces
imparted by the water between hair fibers would tend to cause
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the hair fibers to clump and entangle. Te inclusion o 18-MEA
in prototype conditioner ormulations that were based upon
stearoxypropylmethylamine, dimethylaminopropylstearamide, and
stearyltrimethylammonium chloride le the conditioner on the
hair surace, and this in turn yielded improvements in inter-fiber
lubricity due to improved deposition at the hair surace.
Conditioning Polymers in Hair Straightening Applications
Te two main processes or relaxing or straightening hair are
hair treatment with a reducing agent to cleave the disulphide cystinebridges (SS) within the hair structure, and treatment o stretched
hair with a strong alkaline agent.
Repeated relaxation treatments can cause significant hair damage,
to both the cuticles and the cortex. Te damage can be assessed by
measuring the porosity o the hair, and the porosity o the keratin
fibers can be measured by fixing 2-nitro-para-phenylenediamine
at 0.25% in an ethanol/buffer mixture (10:90 volume ratio) at pH10 at 37C or 2 minutes. Cationic and amphoteric polymers, such
as polyquaternium-6, polyquaternium-7, and polyquaternium-39,
added to hair relaxer ormulations, mitigate this degradation o the
hair structure. Also, the inclusion o high molecular-weight (>106
g/mole) copolymers o acrylamide and diallyldimethylammonium
chloride, acryloyloxytrimethylammoniumchloride, or
acryloyloxyethyldimethylbenzylammonium chloride in the relaxingormula results in significant reduction in the hair structural
damage caused by alkaline relaxation.
Conditioning Polymers
Cationic conditioning polymers are used to enhance the
conditioning properties, especially to mitigate the effects o extreme
processing that are experienced during hair-straightening. Cationic
polymeric conditioners can improve wet combability and ameliorate
electrostatic charging o the hair (maniested by flyaway).
Many cationic polymers have been developed or the purpose
o conerring conditioning properties on hair. In act, there are
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now more than one hundred polyquaternium ingredients listed in
the INCI dictionary, and this list is still expanding. Te primary
purpose o polyquaternium polymers is to coner good conditioning
benefits. A non-exhaustive list o conditioning polymers is shown in
Table 1.
Table 1. Examples of cationic conditioning polymers
Chitosan
Cocodimonium Hydroxypropyl Hydrolyzed Collagen
Cocodimonium Hydroxypropyl Hydrolyzed Hair Keratin
Cocodimonium Hydroxypropyl Hydrolyzed Keratin
Cocodimonium Hydroxypropyl Hydrolyzed Wheat Protein
Cocodimonium Hydroxypropyl Oxyethyl Cellulose
Steardimonium Hydroxyethyl Cellulose
Stearyldimonium Hydroxypropyl Hydrolyzed Oxyethyl Cellulose
Guar Hydroxypropyltrimonium Chloride
Starch Hydroxypropyltrimonium Chloride
Lauryldimonium Hydroxypropyl Hydrolyzed Collagen
Lauryldimonium Hydroxypropyl Hydrolyzed Wheat Protein
Stearyldimonium Hydroxypropyl Hydrolyzed Wheat Protein
Polyquaternium-4
Polyquaternium-10
Cationic hydroxyethylcellulosePolyquaternium-24
Hydrophobically modified cationic hydroxyethylcellulose
Poly(methacryloxyethyltrimethylammonium methosulfate)
Poly(N-methylvinylpyridinium chloride)
Onamer M (Polyquaternium-1), PEI-1500 (Poly(ethylenimine)
Polyquaternium-2
Polyquaternium-5-poly(acrylamide-methacryloxyethyltrimethylammoniumethosulfate)]
Polyquaternium-6 poly(dimethyldiallylammonium chloride)
Polyquaternium-7
poly(acrylamide-co-dimethyldiallylammonium chloride)
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Polyquaternium-8
Polyquaternium-11
[poly-(N-vinyl-2-pyrrolidone-methacryloxyethyltrimethylammonium ethosulfate)]
Polyquaternium-16 [Co(vinyl pyrrolidone-vinyl methylimidazolinium chloride)
Polyquaternium-17
Polyquaternium-18
Polyquaternium-22
Poly(sodium acrylate dimethyldiallyl ammonium chloride)
Polyquaternium-27
Polyquaternium-28
Polyvinylpyrolidone-methacrylamidopropyltrimethylammonium chloride)
Polyquaternium-31
Poly(N,N-dimethylaminopropylacrylate-N-acrylamidine-acrylamide-
acrylamidine-acrylic acid-acrylonitrile) ethosulfate
Polyquaternium-39
Poly(dimethyldiallylammonium chloridesodium acrylateacrylamide)
Polyquaternium-43
Poly(acrylamide-acrylamidopropyltrimoniumchloride-2-acrylamidopropyl
sulfonate-DMAPA)
Polyquaternium-44
Poly (vinyl pyrrolidone--imidazolinium methosulfate)
Polyquaternium-46
Poly (vinylcaprolactam-vinylpyrrolidone-imidazolinium methosulfate)
Polyquaternium-47Poly (acrylic acid-methacrylamidopropyltrimethyl ammonium chloridemethyl
acrylate)
Polyquaternium-53
Polyquaternium-55
Poly(vinylpyrrolidone-dimethylaminopropylmethacrylamide-lauryldimethylpropy
lmethacrylamido ammonium chloride)
PVP/Dimethylaminoethyl Methacrylate Copolymer
VP/DMAPA Acrylate Copolymer
PVP/Dimethylaminoethylmethacrylate Polycarbamyl
Polyglycol Ester
Table 1. Examples of Cationic Conditioning Polymers (Cont.)
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PVP/Dimethiconylacrylate/Polycarbamyl Polyglycol Ester
Quaternium-80 (Diquaternary polydimethylsiloxane)
Poly(vinylpyrrolidone--dimethylamidopropylmethacrylamide)
VP/Vinyl Caprolactam/DMAPA Acrylates Copolymer
Amodimethicone
PEG-7 Amodimethicone
Trimethylsiloxyamodimethicone
Ionenes
Poly(adipic acid-dimethylaminohydroxypropyldiethylenetriamine)
Poly (adipic acid-epoxypropyldiethylenetriamine) (Delsette 101)
Silicone Quaternium-8
Silicone Quaternium-12
Polyampholytes have been commercially available asconditioning polymers or a considerable time. A prominent
example is polyquaternium-39, which is a copolymer o
diallyldimethylammonium chloride, acrylamide, and acrylic acid.
When this is polymerized in a single batch process, the mismatch
in reactivity ratios between these monomers results in a lack o
compositional uniormity. An improved version o this type o
terpolymer o diallyldimethylammonium chloride, acrylamide, andacrylic acid has been made by a monomer eed method or better
control o molecular weight and composition.95
Copolymers comprising a diallylamine (typically diallyldimethyl
ammonium chloride) and vinyllactam monomers (typically
polyvinylpyrrolidone) are useul film-ormers that coner
conditioning properties such as good wet and dry combability, eel,
volume, and handleability.96
Silicone Conditioners
Silicone quaternaries have long been known as hair conditioning
compounds.
Table 1. Examples of Cationic Conditioning Polymers (Cont.)
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A recent patent application rom Evonik Goldschmidt is
directed to silicone quats that coner conditioning with longer
lasting conditioning through several shampoo cycles. Te premise
is that long-term substantivity to hair requires the conditioning
agent to contain a string o cationic charges. Tis was achieved
by Goldschmidt by polymerizing cationic monomers and
graing them to silicone backbones. In general, water-soluble
monomers polymerized in the presence o silicones yield a
mixture o water-soluble polymers and unsubstituted silicones
because the two ingredients are incompatible and attachmento the polymer chain to the silicone would require appropriate
coupling groups. Te Evonik researchers rose to the challenge
by polymerizing the cationic monomers in the presence o
silicone polyethers. Te ether groups are compatible with the
quat monomers, and they readily chain transer to give gra
copolymers. Once graed, the copolymers are quaternized to
coner permanent positive charges with enhanced substantivityto hair. Te gras are obtained by polymerizing the readily
available monomers, dimethylaminoethylmethacrylate, or
3-trimethylammoniopropyl-methacrylamide.
Leave-on silicone conditioners specifically targeted to non-
shampoo applications coner enhanced and relatively durable
conditioning. Tese contain emulsified vinyl-terminated silicones
applied in combination with a conventional cationic conditioner. Apreerred product type is a mousse. Tese silicone block copolymers
can achieve excellent conditioning at relatively high viscosities (100
KPa/s-1).
Improved conditioning that coners surprisingly reduced riction
on hair can be achieved by including an aminosilicone in which the
aminosilicone has a airly large range o average particle sizes rom
about 550 microns.97
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