interactions of cationic and anionic surf act ants on hair surfaces

8/4/2019 Interactions of Cationic and Anionic Surf Act Ants on Hair Surfaces

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j. Soc.Cosmet. hem., 4, 263-278 (September/October993)

Interactions of cationic and anionic surfactants on hairsurfaces: ight-scatteringnd radiotracer tudiesCHARLES REICH and CLARENCE R. ROBBINS,Colgate-Palmoliveesearchenter, 09 RiverRoad,Piscataway, J08854-1343.

Received arch 10, 1993.

SynopsisLight-scatteringechniques, upplementedy radiotracer tudies,havebeenused n this work to demon-strate ormationon hair surfacesf insoluble omplexes etween omecommon ationicconditioner ctivesandanionic auryland aurethsulfates. hese omplexes, hichwere ound o be verydulling and resistantto cleaningby C 12-based etergents,wereshown o form in tress reatments nd also n treatments f fullheads of hair.Alkyl ethersulfates avinghydrophobichain engths f 6, 8, or 10 were oundnot to form he above ypesof complexes n hair and were shown o be superior or use n cleaningconditioners.n experiments ithconditioner ctives,contributionso buildupwere found rom both conditioner nd detergentdeposition.In the case f commercial onditioners, uildupwasobservednlyasa resultof excessetergent epositionin the presence f conditioner. n both cases, ormationof insolublecomplexesed to greatly reducedcleaningby lauryl or laurethsulfate-basedhampoos.

INTRODUCTIONIn a previous aper, Reichand Robbins 1) describedhe useof light-scatteringech-niques o follow cleaningand soilingof the hair surface.Using the demonstratedechniques, longwith dyestainingmethods, t wasshown hatcomplexesould orm on hair betweenPolyquaternium-10 ations nd myristateanionswhen these wo species eredeposited n the hair from differentshampoos. ormationof thesecomplexes asshown o havea negative ffectsince he resultantdepositswerevery dulling and quite resistant o removal rom the fiber surface.In work previous o the above, Robbins et al. (2) demonstrated he formation of adifferent type of complexon hair, betweencationicstearalkonium hloride SAC) orcetrimoniumchloride CTAC) particlesand conventional, nionicshampoo etergents.The former two species re conditioner ctivescommonly ound in many commercialconditioners.Because f the natureof the techniques sed n reference to establish omplex orma-tion, dye staining and radiotracers,t was not possible o say much concerning heeffectson hair of complex ormation. n addition, although he possibilityof complex

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264 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTSformationwas nvestigatedor a largenumberof detergents,he relativeefficacy f mostof thesedetergentsn cleaningconditioner oil wasnot established.In this paper, t is shown hat the light-scatteringechniques escribedn referencecan be used o rapidlyand conveniently nswer he abovequestions oncerning ondi-tioner/detergent nteractions n hair.As in reference1 for shampoocomplexes, t is shown, using light scattering, hatconditioner:detergentomplexesormed on the hair are very dulling and difficult toremovewith commondetergents.These effectsare shown o be readily measured nsingle ibers, on hair tresses, nd evenon full headsof hair.Following his, surfactantsot exhibiting ormationof insoluble omplexesn hair arepresented, nd the relativeconditioner leaning fficienciesf a large numberof sur-factants is determined.The abovemeasurementsre performedwith both conditioner ctives nd fully formu-lated conditioners. he results rom both typesof experiment re confirmed nd sup-plementedwith more detailedradiotracer xperimentshan were run in the previouswork.The results n this papershow hat light scattering anbe used o rapidlyand quanti-tatively measurehe practicaleffectson hair of manyhair careproducts.As wasstatedpreviously 1), much of this type of informationwould be difficult or impossibleoobtain using other techniques.

EXPERIMENTALTRESS PREPARATION

All tresses erepreparedwith three gramseachof humanhair purchasedrom DeMeoBrothers,New York. In order o minimize scatteringrom the interiorof the hair, onlyvirgin, Oriental hair wasused 1).Permed resseswere preparedby perming 60-gram bundlesof hair with a standardcommercial ermingproduct.After the initial perm, the hair waswashed wice with a20% solution f SODS, a detergent onsisting f 45% sodiumocteth- sulfate nd 55%sodiumdeceth-1sulfate Vista ChemicalCo., Austin, TX). Followingthis treatment,the hair was permedand washedagain, and then divided into three-gram resses.TRESS TREATMENTS

For all comparisoneries, minimum of three resses aspreparedor each reatment.In addition, three control resses,reatedonly with 20% SODS and representing cleanhair," were prepared or each series.When carrying out a comparison xperiment,succeedingressesn a series eceiveddifferent reatmentsso that any particular reat-ment was staggeredhroughout he entire series.For stearalkonium hloride SAC)/detergent xperiments,resses eresubjectedo twoprewashes,ollowedby three treatmentcycles. n commercial onditioner/detergentexperiments, he numberof treatmentswas ncreasedo five.


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SURFACTANT INTERACTIONS 265

Prewashes ereperformed y applying5 ml of 20% SODSto a tress, ubbing by handfor oneminute, and then rinsing or oneminute under unning ap water at a temper-ature of 100 F.Treatmentcyclesor SAC/detergent xperimentsonsisted f treatmentwith 2 ml of 1%SAC in a 30:70 ethanol/watermixture, rinsing, treatment with 0.5 ml of a 20%solutionof a test detergent,and then another inse.Each reatmentsolutionwas ubbedinto he ressoroneminute,whileeach insewas arried utunder100 F running apwater for one minute.Commercial onditioner/detergentxperiments ere run in the same ashionas above,except that treatment quantitieswere increased o 5 ml of conditionerand 2 ml ofdetergent.

HALF-HEAD TESTS

Half-head tests were carried out by parting a panelist'shair down the middle andsubjectingeachhalf to differenttreatments.All treatmentsamplesn each est wererubbed into the hair for one minute, while the duration of all rinseswas also one minute.All half-head estswere begunby washingeachside of the headwith 5 ml of the testshampoodetergent)o be usedon that side. This wasperformedwice, followedby arinse each time.Following the above,both sidesof the headwere treatedwith either 15 g of 6% SACin a 30:70 ethanol/watermixture or 15 g of a commercial onditioner.This treatmentwas ollowedby a water rinse, after which eachsideof the headwas reatedwith 5 mlof either 20% SODS or 20% triethanolamine auryl sulfate TEALS) and then rinsedagain. The entire conditioner/surfactantyclewasrepeatedhree imes.For SAC experiments, 0-40 hairswere taken from eachsideof the headafter the lastshampoo nd put aside or light-scatteringmeasurements. he hair was then blow-dried, combedas straight as possible o avoid orientationartifacts,and evaluatedsub-jectively.All subjective valuations erecarriedout in a darkened oomunderan overhead ointsourceamp (Smith-Vicker ffi710 amp; Sylvania BD, 500-watt bulb) by four to sixtrained evaluators.Note that, of the evaluators, nly the hairdresser new which treat-ment each side had received.For commercialconditionerexperiments, he procedure ollowedwas the sameas theabove,except hat, in most cases, amplingand subjective valuationwere carriedoutafter both the last conditionerand the last detergent reatments.RADIOTRACER EXPERIMENTS

[14C]SAC,14C]CTAC,35S]ammoniumauryl ulfateALS), 35Sisodiumeceth-2sulfateSDES-2),nd 35Sisodiumeceth-3ulfateSDES-3)ere llsynthesizedn theradiotracer aboratories t Colgate. The precursor lcohols or the last two surfactantsnthe preceding ist were providedby Vista ChemicalCo., Austin, TX.


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266 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTSThe above adiolabeledompounds erediluted n their non-radioactiveounterpartsothat the final activitieswere between .1 and 0.3 microcuries er gram of solution.Wool swatches7.6 x 11.4 cm woolchallis,TestFabrics,nc., Middlesex, J) werepreparedor radiotracer xperiments y overnight mmersionn a 1:1 mixtureof acetoneand ethanol.Followingovernightdrying, the cleaned watches erecut with pinkingshearsnto0.14-gsegmentsaving reasfapproximately.4 cm . At leastiveofthecut segmentswere prepared or each reatmentunderstudy.In all experiments, ut swatches erewettedwith tap water, excess ater squeezed ut,and the swatchaid on a stainlessteelwire gauzeplaced vera beaker.Following his,either0.3 or 0.15 ml of a test materialwasapplied o the swatch sevenlyaspossible.The wool was then rubbed or one minute between wo lengthsof rubber ubingmountedon stainless teel rollersespecially onstructedn our laboratories.After rubbing, swatches ere rinsed n a beakerof tap waterfor 45 seconds,ollowedby a 15-secondinse n a second eaker.After the latter rinse,very little radioactivematerialcouldbe removed rom the swatchesnd a final rinsewasperformedor oneminuteunder100 F running ap water.Dependingupon the particularexperiment,after the above reatment, wool swatcheswere either hung up to dry overnightor treatedagainafter excess aterwassqueezedout using ubber ubing placedover he endsof crucible ongs.Following reatment nddrying, woolswatches eredissolvedy placingeach n a glasscounting ial, adding1 ml of 2M NaOH, andheating n an oven t 80C for 1.5 hours.Threereferenceialswerealsopreparedn whicha woolswatchwasdissolvedollowingaddition of a known amount of radioactive material.After cooling, approximately12 ml of Aquasol-2LSC cocktailwas added o eachvial,followedby addition of 0.25 ml of concentrated erchloric cid. The vials were thenshaken igorously, esulting n a clearsolution eady or counting.All measurements ith radiotracers ere run using only one radiolabeled ubstance ta time. Thus, for example, n experimentsn which both conditioner nd detergentdepositionwere measuredor a given treatmentseries, he serieswas run twice, oncewith radiolabeled etergentand oncewith radiolabeled onditioner.LIGHT-SCATTERING MEASUREMENTS

The useof a goniophotometero carryout light-scatteringmeasurementsasdescribedin reference. In the currentwork,all goniophotometriceasurementsereperformedusinga MurakamiGP-1R automatic oniophotometerurchasedrom Hunter Associ-atesLaboratory,Reston,VA.The GP-1R, whichemploys ollimatedight from a tungsten alogenamp, hasseveraladvantages ver the Brice-Phoenix hotometer mployed n the previouswork (1).Among hese re he fact hat it is a doublegoniometernstrument o hat the samplecanbe turned o anyangledesiredwith respecto the incident ight. In addition, t hasa large samplecompartment ermitting the sensitive teppingmotors o run scansrom0 to 75 (or a full 360 if sodesired). inally, he instrumentccuracys quitehigh,with a specifiedcan epeatabilityf ---0.2%, an angleaccuracyf ---20', anda pho-tometric accuracy f ---0.5%.


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As in the previouswork (1), for all light-scatteringexperiments,polarizershavingdirectionsof polarizationperpendicularo the plane of incidencewere placedbetweenthe light source nd the sampleand between he sample nd the light detectorof thegoniophotometer.n the currentexperiments, Glan-Thompson rism was used nfront of the sample,while a sheetpolarizerwasplacedbefore he light detector.Figure la shows he bottomplate of the GP-1R sampleholderused or mountinghairfibers.The diameterof the opening n this plate is 7.3 cm, while the raisedplastic ingis 2-mm high and2-mm thick. In order o accommodatep to 40 hair ibers, he plasticring contains 0 grooves, .635 mm apart, cut at opposite ndsof the ring. In allexperimentsn this work, only one hair fiber was usedper scan.These ibers weremountedon the bottomplateunder he constantension upplied y a 2-g alligatorclipand held in placeby a coverplate secured ith two stripsof magnetic ape. Figure lbshows he complete ampleholderwith a single iber mounted.All tressmeasurementsere madeby taking 21 hairs rom a treated ress,scanning

Figure l a. Photographf the bottomplateof a GP-1R hairsample older.Note the fourcircularmagnetsset n the bottomplate and the two holeson eitherside.Theseare used o mount the sampleholderon thevertical mount in the light-scattering nstrument.


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268 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

Figure lb. Photograph f hair sampleholderwith onehair mountedand top plate n place.Note that theholder s mounted n the GP-1R with the hair fiber in a horizontal osition.Also, becausef the magnetictape on the bottom plate, the useof the four fastenerss optional.

themoneat a time, asstated bove,rom0to 75, andaveraginghe results. he timefor a singlescanwas 75 seconds.All SAC experiments ere run with the hair fibersat an incidentangleof 30 andorientedso that the directionof incident ight was towardthe tip of the hair [RERorientation (3)]. All experiments nvolving commercialconditionerwere run at anincident ngleof 45 in order o comparehe resultso previousmeasurementsun onthe Brice-Phoenixhotometer,n nstrument nwhichscansrom0 to 75couldonlybe run at 45 incidence.In the Brice-Phoenixxperiments,or an RER orientation t 45 incidence,eflectionfrom the back walls of hair fibers was found to interfere with the estimate of diffusescattering t 75 (1,3). All the former45 measurementsn the Brice-Phoenixnstru-ment, and also he currentGP-1R 45 measurements, ere therefore un with the hairfibers in an REL orientation.


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The output from the GP-1R was sent to a Bascom-Turner 120T electronic ecorder(Bascom-Turnernstruments,Norwood, MA) that digitized the 75 scan nto 500points. Thesepointswere then sentto an IBM PC computer or processing.MEASUREMENT OF SHINE

All shinevalueswerecalculatedrom ight-scattering arameters, sing he previouslydeveloped xpression1),L = S/DW(V2) (Eq. 1)

whereL is shine,or luster,W(V2) is the width of the spectral eakat half height, andS and D are the integratedspecular nd diffuse eflectances,espectively. detaileddescription f the foregoingermsalongwith a discussionf hair shinecanbe found nthe previouswork (1).All shinevaluescalculated sing equation1 were averagesaken from a minimum ofthree tressmeasurements. inceeach ressmeasurement as, in turn, averaged ver 21hairs, eachshinevaluerepresentsn average aken from at least63 hairs.STATISTICAL TREATMENT OF DATA

All light-scattering nd subjective valuations erformed n the half-head estswereanalyzedusing a sign test.All measured hinevaluesof treated resses nd all deposition alues rom radiotracerexperiments ereanalyzed y means f a one-way nalysis f varianceANOVA) test.In the following ables,measuredaluesof tressesnd swatches ot significantly if-ferent rom eachother at a 95% level of confidence)re connected y vertical ines.

RESULTS AND DISCUSSIONSTEARALKONIUM CHLORIDE/DETERGENT TRESS EXPERIMENTS

Table I lists the shine values esulting rom a large seriesof SAC/detergent ressexperiments. hose ressesreatedonly with SODS (cleanhair) had the highestshinevaluesand thus the greatest hine.Clean ressesreatedwith SAC, on the other hand,were ound to have oweredshinevalues.This dulling is a resultof deposition f SACparticles n the surface f the hair (1,4,5).An attempt was made to cleanSAC-treated resses ith 20% TEALS. Sincepreviousexperimentsn which clean resses erewashedwith TEALS resulted n shinevaluessimilar to thoseobtainedwith SODS, it was expected hat removalof someof thedeposited onditioner y the TEALS detergentwould cause he measured hinevaluesto increaseoward that of cleanhair. In Table I it is seen hat the shinevaluesdid not,in fact, increase ponwashingSAC-treatedresses ith TEALS but, rather, decreasedby a further42%.As was he casewith interactions f substantivehampoongredients1), sucha decreasein shine mplies that the anionicTEALS detergentwas not very effective n cleaningSAC from the hair surface, ut instead nteractedwith the deposited ationicconditioner


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270 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTSTable ISACTress xperiments

Treatment No. tresses reated ShineSODS 18 1.72 (0.23)SAC 3 1.15 (0.07)SAC/TEALS 6 0.67 (0.12)SAC/SODS 18 1.47 (0.27)SAC/SDES-2 3 1.53 (0.07)

Shine alues onnectedy a verticalinewerenotsignificantlyifferent.Numbersn parenthesesrestandard eviations.to form an insolublecomplex hat was more dulling to the hair than the originaldeposited oil.That sucha complexwasactuallybeing ormedwasconfirmed y dye-staining xper-iments, suchaswere performed n reference , in which it wasshown hat the anionicdye, Red 80, couldnot stain hair or wool swatchesreatedwith SAC and then washedwith TEALS. Since he light-scattering esultsshowed hat SAC still remainedon thesurfaceof theseswatches, hese results ndicate that the cationic SAC was unavailable forbinding to Red 80 because f complexationwith lauryl sulfateanion.The above ype of complex formationoccurson the surfaceof hair because f theinsolubilityof the SAC:laurylsulfate nteraction roduct. t was herefore easonednreference that changing he chain engthof the detergentmight render he interactionproductmore soluble; ucha detergent ould hen effectively lean he SAC from thehair surface ather than form an insoluble omplexwith it.This reasonings shown o be correctby the results n Table I. The shinenumbersofSAC-treated tresseswashed with the shorter-chain surfactants SODS (C8 and C10mixture)andSDES-2wereobservedo increasen value,becoming lmostasgreatas hevalue for clean hair. This indicates hat these wo detergents,unlike TEALS, wereeffectiven removingSAC from the hair surface.We therefore oncludehat, asa resultof shortening he detergentchain length, SODS and SDES-2 did not form insolublecomplexes ith SAC, thus leading o improvedcleaningof conditioner.CONDITIONER/DETERGENT RADIOTRACER EXPERIMENTS

In order to test the above ight-scattering onclusions,nd also o compare he shinevalues n Table I to relative conditioner/detergentepositions, seriesof radiotracerexperimentswas run measuringdepositionon wool swatches fter variousSAC anddetergent reatments.The resultsof thesemeasurements re tabulated in Table II. Note that ALS (ammoniumlauryl sulfate) ather han TEALS wasemployedn the measurementsn Table II. Thiswasconsideredo be an acceptableubstitute, incebothTEALSandALS producedhesame ight-scatteringresultswith SAC.The data n Table II show hat, aswasconcludedbove,SDES-2 s superioro laurylsulfatedetergentsn cleaningSAC deposits. fter washingSAC-treated watches, LSremovedonly 31% of the deposited onditioner s 62% for SDES-2. In addition, it is


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Table IIDepositionromDetergent leaning f SAC:Radiotracereasurements'2Treatment SACpergramwool mg) Detergentergramwool mg) Totaldeposit

1% SAC 6.68 (0.40) -- 6.68 (0.40)5% ALS -- 1.94 (0.18) 1.94 (0.18)1% SAC/5% ALS 4.58 (0.72) 4.09 (0.57) 6.73 (0.94)5% DES-2 -- 1.860.22) 1.860.22)% SAC/5% SDES-2 2.52 (0.47) 2.12 (0.33) 2.78 (0.57) Numbersn parenthesesrestandardeviations.2 Measuredaluesonnectedy a verticalinewerenotsignificantlyifferent.3 0.3 ml of each reatment asapplied.4 Totaldepositsorconditioner/detergentashesrecalculatedysummingonditionerlus etergentdepositsminus he detergent eposits n cleanwool.seen hat ALS depositionon conditioner-treatedwatches as more than twice that oncleansubstrates. his confirms hat lauryl sulfateanions nteractwith cationicSAC toform an insolublecomplex. n the caseof SDES-2, binding to cleanor conditioner-treatedswatches asvirtually the same,proving,aswas ndicatedby light scattering,that SDES-2 doesnot interactwith SAC to form insolublecomplexes n keratin sub-strates.

The last column n Table II lists the total amountof deposit ound on swatches fterdifferent treatments. For SAC-treatedswatcheswashedwith ALS, it can be seen hat nonet cleaningoccurred: lthoughsomeconditionerwas removedby ALS, this was re-placedby detergentbinding to the remainingSAC. In the caseof the SDES-2wash,onthe otherhand, the net effectwas o remove 0% of the originaldeposit, husagaindemonstratinghe superiorityof SDES-2 n cleaningconditioner.It shouldbe noted n Table I that the amountof total depositmeasuredfterwashingconditioner-treated ool with detergentwas adjustedby subtracting hat amount ofdepositmeasured fter washingcleanwool. This doesnot mean to imply that thesubtracted etergentwasnot part of the conditioner/detergentomplex,but wasdonesimply to emphasizehe excess f deposit esulting rom washingconditioner-treatedwool over that resulting rom washingcleanwool alone.Table III shows he resultsof radiotracer xperimentsn which CTAC wassubstitutedfor SAC. The results in this case were similar to those obtained with the latter condi-tioner. Almost three times as much ALS bound to CTAC-treated swatches s SDES-2,

Table IIIDepositionromDetergent leaning f CTAC:RadiotracereasurementsTreatment CTAC ergramwoolmg) Detergentergramwoolmg)

1.7% CTAC 7.13 (0.58)1.7% CTAC/20% ALS 4.25 (0.13)1.7% CTAC/5% ALS --1.7% CTAC/20% SDES-2 2.88 (0.33)1.7% CTAC/5% SDES-2 --

4.30 (0.63)1.47 (0.15)

Numbersn parenthesesrestandardeviations.0.3 ml of eachreatment as pplied.


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272 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

indicating, as with SAC, that while CTAC doesnot interactwith SDES-2 to form aninsoluble omplex, t does orm suchcomplexes ith ALS on the wool surface.Becauseof this complex ormation,only 40% of deposited TAC was removed rom woolswatches y ALSvs 60% by SDES-2.Total deposits ouldnot be directlycalculatedbecause ifferent concentrations f detergentwere used in different experiments. tseems lear rom the data, however, hat, aswith SAC, washingCTAC-treatedswatcheswith ALS would result in little or no net cleaning.SURFACTANT SERIES EXPERIMENTS

The preceding adiotracer xperiments onfirmed hat light scattering an be used oevaluate leaningof conditioners y surfactants. sing this methodology,he condi-tioner cleaningefficiency f a series f alkyl ether sulfates avingcarbonchain engthsof 6, 8, 10, and 12 and degrees f ethoxylation f 1, 3, and 5 was evaluated.Table V presentshe results or thosedetergents avinga degree f ethoxylation f one.The resultsndicate hat alkyl (lEO) ethersulfates ith carbon hain engthsof 6, 8,and 10 are all effective n removingSAC from hair. The samewasnot found o be truefor the C12 detergent,SLES-1EO,which, like TEALS, dulled the hair as a result ofcomplex ormationwith SAC.The light-scatteringesults or the 3EO and 5EO detergentsestedwere found o besimilar to thoseobtainedwith the correspondingEO species. his indicateshat, atleastup to 5EO, formation f insoluble etergent:conditioneromplexess determinedprimarilyby the lengthof the hydrophobicortionof the detergentather hanby thedegreeof ethoxylation.CLEANING OF SAC/TEALS COMPLEXES

The precedingmaterial showed hat shorter-chainlkyl ether sulfateswere superior oconventional, 12-based etergentsn cleaning ACand CTAC, becausehey do notform he nsoluble onditioner:detergentomplexesn hair that are ormedby the attersurfactants.The above-mentionedxperiments aveno indication,however,of the effectivenessf

Table IVShine f SAC/Detergent-TreatedairTreatment Shine2

SODS 1.72 (0.23)SAC/C6-EO3 1.79 (0.22)SAC/C8- EO 1.57 (0.09)SAC/C 10- EO 1.58 (0.16)SAC/C12- lEO 0.88 (0.07)SAC/TEALS 0.67 (0.07)

Shine alues onnectedy a verticalinewerenotsignificantlyifferent.2 Numbersn parenthesesrestandardeviations.3 This s a sodium exyl ther ulfate ubstitutedithoneethoxy roup. he ollowingurfactantsn thecolumnare all alkyl (lEO) ether sulfateswith the designated arbonchain engths.


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shorter-chainurfactantsn cleaning he insolubleSAC:detergent omplexeseft on hairby the useof conventional etergents.This was tested by performing ight-scatteringmeasurements n tresses hat werewashedwicewith SODSor TEALS ollowingdeposition f a TEALS/SAC omplex nthe surface.n Table V, it is seen hat attempting o remove he TEALS/SACcomplexwith TEALS did not result n significantcleaning, eaving tresseshat were still sub-stantiallydulled. The SODS reatment,on the otherhand, restoredmostof the originalshine, ndicating hat the complexwaseffectively leaned.We conclude, herefore, hatdetergents uch as SODS are superiorcleaners,not only of conditioner,but of theinsoluble conditioner:detergent omplexes eft on hair as a result of washing withconventionaldetergents.Half-head ests.n additionto testson singlefibersand on tresses,ight-scatteringresultscan be obtained rom experiments n actual headsof hair. In order to testdetergent/conditionernteractions nder conditions s closeas possible o actual con-sumer use, therefore, a series of half-head tests was run in which SAC/TEALS andSAC/SODS reatmentswere compared.Table VI lists he results f these reatments n ten panelists.A plussign n the columnlabeledsubjective hinemeans he SODS-washed ide was judged shinier by the eval-uators,while a positivevalue n the delta shinecolumn ndicateshat the SODS-treatedsidehad the larger measured hinevalue.In all ten cases, he SAC/SODS-treated alf of the headwas found to have the greatermeasuredhinevalue,while in only onecasewas he SAC/TEALS-treatedide udgedto have he greatersubjective hine.Applicationof a simplesign test to these esultsindicates difference etween he TEALS- andSODS-treated ides t a greater han 99%level of confidence.This confirms hat the dulling effectsarising from formation ofinsoluble omplexes anbe easilyobserved nderconditions imilar to actualconsumeruse.

The one discrepancybove,between nstrumental nd subjective valuations,s prob-ablyan orientation ffect.Shine s observed henan objectscattersmuchmore ight ina particulardirection han in otherdirections1). Thus, even f individualhairs n anarrayareveryshiny, he lessparallel heyare o eachother he less heywill reflect ightin the samedirection, resulting n a decreasen perceived hine. The hair in half-headtest 6 was quite curly, so it is reasonableo assumet would be more sensitive oorientationeffectsof this type.Note that the largest differencesn measured hine were observedwith permed or

Table VSAC/TEALSomplex xperimentsTreatment Shine2

SODS 1.72 (0.23)Complex SAC/TEALS) 0.67 (0.12)Complex/TEALS 0.87 (0.11)Complex/SODS 1.43 (0.23)

Shine alues onnectedy a verticalinewerenotsignificantlyifferent.Numbersn parenthesesrestandardeviations.


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274 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTSTable VI

SAC Half-Head Tests. (SODS vs TEALS)Testno. Subjectiveshine Delta shine

13 q- 0.262 + 0.123 + 0.114 + 0.385 + 0.506 - 0.4474 q- 0.8085 + 0.389 + O.63104 q- 0.80

A positiveignmeans ODS-treatedideudged hinier.2 This s hedifferenceetweenhine alues easuredorSODS ndTEALS-treatedides. positivealuemeansSODS sidehad greatershine.3 Tests -3 were erformedn hesame oman.4 These omen adpermedair.5 Tests and9 wereperformedn samewoman efore ndafterapplicationf a hair-straighteningtreatment.

straightened air. This is not surprising incechemically reatedhair has a greaternumberof negative harges n the surface ndwouldbe expectedo bind morecationicconditioner.This is confirmedby the observationrom radiotracer xperimentshatpermedhair binds2.3 times moreSAC than virgin hair (6).Cleaning f commercialonditioners.he preceding xperiments ealt for the most partwith SAC, a conditioner ctive ound n manycommercial roducts.Experiments erealso performedwith conditionerA, a commercial onditioner ontainingSAC andceteth-2, in order to determinewhether he results eported or SAC would alsobeobservedwith commercialproducts.Tresses treated with conditioner A and then washed with TEALS were found to exhibitmuch essdulling than wasobserved henwashingSAC-treatedresses. his is prob-ably the resultof solubilization f the SAC by the ceteth-2oil. In order o increasehesensitivity f the experiments,herefore,measurementseremadeusingpermed resseswhich, aswasnoted n the preceding ection, dsorbmoreconditionerhandoes irginhair.Table VII tabulateshe light-scatteringesults rom a typicalpermedhair experiment.In this case t is seen hat, aswasobservedor SAC-treated air, washing onditionerA-treated hair with TEALS resulted in duller tresses than those washed with the shorter-chainsurfactantsomprising ODS.This wasconfirmed y panelists ho subjectivelyevaluatedresses ccordingo the methods escribedn reference .These esultsndicate hat, although he dullingeffect s smaller, ormation f insolublecomplexes etweenTEALS and SAC still occurswith commercial onditioners.Note that the shine values in Table VII were obtained at 45 incidence and thus cannotbe comparedirectlywith the 30 ncidencehine aluesisted n the previousables.The reasonor this s that speculareflectionncreasesith increasingngleof incidence(Fresnel's quations, eference ).


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Table VIICommercial Conditioner Treatments of Permed Hair '2Treatment Shine3

SODSConditionerA4/SODSConditioner A/TEALS

2.57 (0.28)2.58 (0.06}2.08 (0.05)

Shine alues onnectedy a verticalinewerenotsignificantlyifferent.Theangle f incidencen these xperimentsas45Numbersn parenthesesrestandardeviations.This s a commercialonditionerontainingACandceteth-2.Commercialonditioneralf-headests.A series f half-head estswasrun with conditionerA to determine if the treatment differences noted for tresses could be observed on headsof permedhair. In theseexperiments,ollowingconditioner reatment, one sideof thehead was washed with TEALS while the other side was washed with SODS.Overall, a total of 26 half-head estsevaluating leaningof conditionerA wererun. Themostconsistentubjective ifferencesound n these estswereassociatedith shineandthe existence of a coated feel to the hair on one side of the head.In 23 of the 26 half-head tests, the evaluatorschose he SODS-treated half of the headasbeing he cleaner ide. n the threecases here hiswasnot true, the TEALSsidemayhave been chosenbecause f the previouslymentionedorientationeffects.Even dis-counting his possibility,however, tatistical nalysisndicates difference etween heTEALS and SODS sidesat a greater han 99% level of confidence.The greatershineof the SODS-washedair wasalsosupported y the light-scatteringresults. Table VIII lists those half-head tests for which instrumental measurements wereperformed.For 10 of the 11 measurements,he SODS sidehad the higher shinevalue,while for the eleventh est, the shinevalueswere essentially qual.

Table VIIICommercial onditionerConditioner ) Half-HeadTests. (SODSvs TEALS)Testno. Subjectiveshine Delta shine

11 + 0.74114 q- 0.50124 - 0.7413 + 0.1514 + 0.37144 + 0.88154 + 0.61164 + 0.26174 + 0.23184 + -- O.07194 + 0.23

Theangle f ncidencen these xperimentsas 5.All subjectsadpermedair.2 A positiveignmeans ODS-treatedide udged hinier.3 This s hedifferenceetweenhine alues easuredorSODS ndTEALS-treatedides. positivealuemeansSODS side had greatershine.4 Conditionerasast reatmentrior o viewingndhairsampling.


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276 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTSThese esultsconfirm hat for commercial roducts s well as for SAC, the superiorcleaningof conditioners y shorter-chain urfactantsuchas those ound n SODS canbe observed under conditions similar to actual consumer use.Commercialonditioner/detergentadiotracerxperiments.s wasdonewith conditioner c-tives, adiotracerxperimentsere unwithconditionerdoped ith 4C]SACLnorder to confirm the light-scatteringresultsand also to obtain an idea of relativeamountsof deposition.The resultsof theseexperiments retabulated n Tables X and X. Unlike the casewithconditioner ctives, t is seen hat bothALS and SODSare equallyeffectiven cleaningSAC deposited rom conditionerA. In addition, the amount of SAC left on the hair isapproximatelyhe same fter oneor two treatmentcycles, ndicating hat, at least n thislimited case,SAC did not build up on the surface f the swatch.Interaction between ALS and the SAC in conditionerA still occurs,however. This isindicatedby the fact that binding of ALS to conditionerA-treatedswatches asmorethan three imesgreater han binding o cleanswatches. uchdeposition,eplacing sit does,cleaned onditioner,greatlyreduceshe net cleaningby ALS. This situation smade worseby buildup of ALS with repeated reatment:after three conditioner/washcycles,ALS depositionwas 28% greater han after one cycle.The increased inding of ALS to conditioner-treatedwatches as not exhibitedbySDES-3. n Table X it is seen hat the same mountof SDES-3wasdeposited n cleanswatches s on conditionerA-treatedswatches,ndicating,as was seen n the light-scattering experiments, that SDES-3 does not interact with conditioner A to forminsoluble omplexes n keratin surfaces.Table IX also lists the resultsof experiments n which the conditionerA/SDES-3treatmentcyclewasapplied o swatcheshree imes. No increasen SDES-3deposition

Table IXDepositionromDetergent leaning f Commercialonditioner:adiotracereasurements'2Treatment SAC per gram wool (mg) Detergentper gram wool (mg) No. cycles

Conditioner A 3 --Cond. M5% SODS3Cond. M5% hLS3 --Cond. M5% SODS3 --Cond. M5% ALS3 --5% ALS 1.18 (0.08)Cond.M5% ALS 3.57 (0.13)Cond.M5% ALS 3.79 (0.18)Cond.M5% ALS 4.58 (0.19)5% SDES-34 1.11 (0.19)Cond.A/5% SDES-34 1.08 (0.08)Cond.A/5% SDES-34 1.17 (0.30)Cond.M5% SDES-34 0.98 (0.31)

4.27 (0.59)1.83 (0.67)1.67 (0.24)2.05 (0.56)2.03 (0.55)

-

-

-

-

-

__

-

-

Numbersn parenthesesrestandardeviations.Measuredaluesonnectedy a verticalinewere otsignificantlyifferent.0.3 ml of eachreatment asapplied.0.15 ml of eachreatment as pplied.


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Table XDepositionromShampooleaningf Commercialonditioner:adiotracereasurementsTreatment SACpergramwool mg) TEALSpergramwool mg) Totaldeposit

Conditioner A 3.17 (0.19) -- 3.17 (0.19)Shampoo4 1.37 0.10) 1.37 0.10)Cond.A/Shampoo 1.66 (0.25) 3.09 (0.52) 3.28 (0.59) Numbersn parenthesesrestandardeviations.2 0.15 ml of each reatment asapplied.3 Totaldepositor heconditioner/shampooreatment as alculatedysummingheSACandTEALS ndsubtracting he TEALS deposits n cleanwool.4 This s a TEALS-containingommercialhampoo.

wasobserved ith repeatedreatment, ndicating hat, unlike ALS, SDES-3doesnotbuild up on conditioner-treatedwatches.Table X shows he resultsof experimentsn which shampooB, a TEALS-containingcommercial hampoo,wasused o washconditionerA-treatedswatches. s was he casewith SACand TEALS alone, he shampoo xhibited ncreasedepositionn the presenceof conditioneras a result of SAC/TEALScomplex ormation. Because f this increaseddeposition, o net cleaningwasobserved:he total deposits efore ndaftershampooingwerecomparable. his indicateshat for fully formulated ommercial roducts s wellas or the active ngredients,ormationof insoluble omplexesetween ationiccondi-tionersand anionicdetergents an occuron hair.

CONCLUSIONS

In this paper, light-scatteringmeasurements,upplemented y radiotracerechniques,wereused o demonstratehe formationon hair surfacesf dulling, insoluble omplexesbetweencommonconditioner ctives nd the lauryl and laureth sulfatedetergents sedin virtually all commercial hampoos.Washingdeposited onditioner ctivewith the aboveC12 detergentswas shown oresult n little net cleaningas a resultof buildup of both conditioner nd detergentonthe hair surface.Detergentswith hydrophobic hain engths ess han 12 wereshown obe superioro laurethsulfatesn cleaning onditioner ecausef the absence f complexformationand alsobecause f their ability to solubilize nypreviouslyormedcomplex.In the case f commercial onditioners, uildupwasobserved nly from C 12 detergents,rather han from detergent nd conditioner. his led to lessdulling; however, noughincreasedepositionrom detergentwasobservedo occur, o again eadto little netcleaningby commercial hampoos.Theabove-documenteduildup romconditioning,hampooyclesould ea contrib-uting factor o the common onsumerelief hat the cleaning ffectivenessf anyparticularhampooecreasesver ime.A better nderstandingf hepossibleausesordecreasesn cleaning ith repeatedse,such sthe interactionsocumentedn thepresent ork,could esultn productshatwould ommand ore onsumeroyalty.


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278 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTSACKNOWLEDGMENTSWe wish to thank Mr. Andrew Charig, who synthesizedmost of the radiolabeledmaterials sed n this work. We wishalso o thank Ms. DonnaHartnett, who synthe-sized 35SISDES-3.The bulk of the tressstudieswere performedby Ms. Donna Hartnett and Ms. JudyMcKendrick. Ms. Hartnett and Ms. LoisCastrovinceerformedmostof the radiotracermeasurements.We are grateful o Mr. FrankSchebeceor valuable iscussions.

REFERENCES(1) C. Reich and C. R. Robbins,Light-scatteringnd shinemeasurementsf humanhair: A sensitive

probeof the hair surface,. Sac.Cosmet.hem., 4, 221-234 (1993).(2) C. Robbins,C. Reich, and J. Clarke, Dyestaining nd the removalof cationicsrom keratin:Thestructure nd the influence f the washing nion, . Sac.Cosmet.hem., 0, 205-214 (1989).(3) R. F. Stamm,M. L. Garcia,andJ. J. Fuchs,The opticalproperties f humanhair. I. Fundamentalconsiderationsnd goniophotometerurves, . Sac.Cosmet. hem.,28, 571-599 (1977).(4) B. J. Tighe, "SubjectivendObjective ssessmentf Surfaces,"n Polymerurfaces,. T. ClarkandW. J. Feast,Eds. JohnWiley & Sons,Chichester,978),pp. 269-286.(5) D. B. Judd and G. Wyszecki,Colorn Business,cience,nd ndustry, nd ed. (JohnWiley & Sons,New York, 1963), p. 381.(6) C. Reich and R. Heck, unpublished esults.

interactions of cationic and anionic surf act ants on hair surfaces

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