Tuning theProperties Polyetherof Alkyl Urea Derivatives as ...

ABSTRACT Polyether alkyl urea derivatives were synthesized and theirproperties as gelators in solvents commonly used in cosmetic formulationssuch as Labrafac cc isopropyl myristate and isododecane wereinvestigated A solvent-free larger-scale (up to 70 g) hydrophobicfunctionalization of the polyetheramines was carried out by one-stepreaction with alkyl or aryl-containing isocyanates which resulted in theformation of urea-functionalized polyethers Systematic structural studieswere conducted by varying the nature and molecular weight of thepolyether backbone and the length of the linker and the side chain Thegels obtained have an appearance varying from opaque to transparent andtheir properties were characterized by rheological measurements andsmall-angle X-ray scattering (SAXS) studies Rheological analysisindicated the dependence of the gel properties on the hydrophobicityof the alkyl end groups and the type of polyether backbone SAXSmeasurements revealed a topological description of the network structures of these materials wherein the gels obtained in Labrafaccc form defined structures from the fiber bundles while those in isopropyl myristate produce clusters The results obtained in thisstudy offer potential applications in perfume and cosmetic formulations

KEYWORDS polyetheramines polyether alkyl urea rheology modifier cosmetic solvents small-angle X-ray scattering

INTRODUCTION

The high demand for personal care products has rapidly andcontinuously increased over the past years1 The fast growth inthe consumption of cosmetic products has led to thedevelopment and advancement of new and effective ingre-dients for formulations Polymeric additives both syntheticand natural have been widely utilized in personal careproducts as emollients emulsifiers thickeners and rheologymodifiers2minus5 The broad interest in the use of polymers in theproduct formulations is mainly due to easy manipulation andtailoring of their physical and chemical attributes viamodifications such as cross-linking and copolymerization6

The most common examples of bio-based natural polymersused in cosmetic products are chitin alginates carrageenanpectin and xanthan gums7minus9 They serve mainly as emulsifiersthickeners emollients andor antibacterial agents10 Poly-acrylates11 and polyurethanes3 on the other hand are amongthe most extensively investigated classes of synthetic polymersSimilar to biopolymers they also function as thickenersrheology modifiers emulsifiers moisturizers and disper-sants3512 and are able to facilitate the controlled release ofactive compounds2 The flexibility in the structural mod-ification of synthetic polymers is one advantage that they haveover most natural materials13

Polyetheramines are mono- di- or triamine terminatedpolyether derivatives commercialized under the trademarkJeffamine1415 Their backbone is generally derived frompropylene oxide ethylene oxide or a combination of bothJeffamine polyetheramines have been reported to find wideapplications as new materials in many different fields Forinstance they have been used as an epoxy-curing agent16 asadditive for industrial and decorative coatings and paints andas corrosion inhibitor17minus19 In addition chemical modificationsof Jeffamine derivatives have enabled tuning of their propertiesto specific and directed applications Thermoresponsivehydrogels that are based on chemically modified polyether-amines were reported to have potential applications in drugdelivery and biomaterial science20minus24 Porous materials thatwere derived from Jeffamines functionalized with surfactantshave been demonstrated to show potential utility in the field ofcatalysis25minus27 Polymeric networks that are Jeffamine and

Tuning the Properties of Polyether Alkyl Urea Derivatives as Rheology Modifiers in Cosmetic SolventsMonissa C Paderes Craig James Scott A Jamieson Anh Hung Mai Juan Hermoso Limon Marc Dolatkhani Susana Fernandez-Prieto Wim M De Borggraeve and Emiliano Fratini

lithium-based were also developed as highly conductivematerials2829 The wide range of molecular weights availableas well as the composition of the repeating units of theJeffamine products make these polymeric materials attractiveand advantageous to useThe personal care market is predominantly driven by skin

care products1 Despite some major breakthroughs in thecosmetic industry there is still a challenge to produce stableproducts that provide the desired performance Thus thereremains a continuous need to further develop innovative andhigh-performing materials which satisfy different productrequirements Therefore the main objective of this study isto identify polymeric rheology modifiers for solvents that arecommonly used in cosmetic formulations A rheology modifieris an important component of a liquid composition used tomodify its flow behavior provide stability and improve theaesthetics of the system3031 The choice of the most effectiverheology modifier is dependent on several factors such as thetype of flow needed and the nature and characteristicperformance of the formulationIn this study it was found that the properties of Jeffamine

polymer derivatives can be tuned by introducing hydrophobicfunctionalities Our group has successfully transformed thesecompounds into efficient rheology modifiers for hydrophobicsystems such as cosmetic solvents by providing suspensionpower via gel formation32 In this work the solvents used forgelation investigation are synthetic oils such as triglycerides(capryliccapric triglycerides or Labrafac cc) isopropylmyristate and isododecane (Figure S1 Supporting Informa-tion) These are common organic solvents used for a numberof beauty products such as creams cosmetic foundations andmany others because of their availability low price andemollient property33 To the best of our knowledge this is thefirst report that uses urea-functionalized polyetheramines as arheology modifier for solvents used in cosmetic formulations

EXPERIMENTAL SECTIONGeneral Procedure for the Synthesis of Polyether Alkyl

Urea Derivatives General Experimental Information All chem-icals reagents and solvents used for synthesis were purchased fromSigma-Aldrich and used as received The solvents (Labrafac ccisopropyl myristate and isododecane) for gelation studies were usedas supplied by PolymerExpert For lab-scale synthesis 1H NMRspectra were recorded on a Bruker Avance spectrometer operating at300 MHz Spectra are reported in parts per million (ppm) relative toresidual chloroform (726 ppm) A Bruker Vertex 70 spectrometerwas used for IR spectroscopic analysis All the samples were

characterized in powder form The OPUS software package is usedto analyze the FTIR spectra The average and number-averagemolecular weight (Mw and Mn respectively) and the molecular weightdistribution (PDI) were determined by gel permeation chromatog-raphy (GPC) GPC was performed on a Shimadzu apparatus (UV andRI detection) with a PLgel D column and THF as the eluent at 303 Kcalibrated with linear polystyrene standards

Lab-Scale Synthesis Jeffamine and dry solvent (THF or CH2Cl2)were added to a two-neck 100 mL round-bottom flask equipped witha magnetic stirrer under N2 atmosphere (balloon) Then theisocyanate was added at room temperature via an airtight syringeAfter the reaction was stirred for 16 h precipitates were observedwhich were filtered off by gravity filtration The filtrate was dried invacuo by using a rotary evaporator followed by drying under vacuumto obtain the desired product The polyether alkyl urea derivative wasused without further purification

Larger-Scale Synthesis Jeffamine was dried in a 250 mL three-neck round-bottom flask under vacuum at 80 degC for 2 h Then theisocyanate was added dropwise to the reaction flask (over 1minus15 h)via an addition funnel while stirring at 80minus85 degC under N2atmosphere The reaction was monitored by FTIR spectroscopy Ifa small amount of isocyanate still remained after about 2 h of stirringa small amount of Jeffamine was slowly added to the reaction mixtureuntil its FTIR spectrum showed no more isocyanate The reaction wascooled to room temperature The polyether alkyl urea derivative wasused without further purification

Gelation Studies Gelation studies were performed using an 8 mLscrew cap glass vial by heating the polyether alkyl urea derivatives to80 degC in the desired solvent (Labrafac cc isopropyl myristateisododecane) using an oil bath or a heating block For 5 wt 50 mgof polyether alkyl urea derivatives was dissolved in 950 mg of solventThe solution was heated until all the solids were dissolved after whichit was cooled to room temperature by quenching with either runningwater or with a dry iceacetone solution Gelation was confirmed byvial inversion For consistency the gelation tests were performedinitially at 5 wt The concentration was further lowered by 05 wt decrements for those that successfully formed gels to find theminimum gel concentration

Rheological Characterizations All rheological measurementswere performed using a controlled-stress rheometer DHR I from TAInstruments Rheological data were obtained using 40 mm diameterplateminusplate geometry with a 1 mm gap To determine the linearviscoelastic (LVE) range and the crossover point of the gels (GPrime gtGprime) oscillatory amplitude sweep tests (γ = 01minus1000) were carriedout at a fixed angular frequency of 628 rads Samples at aconcentration of 3 wt in Labrafac cc or isopropyl myristate wereprepared approximately 24 h before the analysis to complete thegelation process All samples were maintained at 20 degC for 2 minbefore testing The sample was placed directly onto the surface of therheometer and frequency sweep tests were performed between 001and 100 Hz at a constant strain of 1

Scheme 1 General Scheme for the Lab-Scale Functionalizationa

a(A) Polyether bis-amine polymers where R = alkyl or aryl-containing group Reaction conditions polyetheramine (1 equiv) and R-NCO (205minus21 equiv with respect to amine) in dry solvent (CH2Cl2 or THF) stirred for 16 h at room temperature under N2 atmosphere (B) Polyethermonoamine with alkyl diisocyanate Reaction conditions polyether monoamine (205 equiv) and OCN(CH2)nNCO (1 equiv) in dry solventstirred for 16 h at room temperature under N2 atmosphere

Data analysis of the rheological measurements was performed usingGraphPad Prism 8 software to obtain the average and standarddeviation of two sets of dataSAXS Measurements All small-angle scattering measurements

were performed using a HECUS S3-Micro system This Kratky-typecamera is equipped with a position-sensitive detector comprising 1024channels which are 54 μm in width Cu Kα radiation with awavelength (λ) of 1542 Aring at a power of 50 W was obtained using anultrabrilliant point microfocus X-ray source (GENIX-Fox 3D XenocsGrenoble)A sample-to-detector distance of 281 mm (calibrated using silver

behenate) provided a measurable q-range between 001 and 054 Aringminus1

(where q the scattering vector is given by q = 4πλ sin θ and 2θ isthe scattering angle)Samples at a concentration of 3 wt in Labrafac cc or isopropyl

myristate were placed into demountable cells containing Kapton filmwindows giving a sample thickness of 1 mm Measurements wereperformed under vacuum to reduce scattering from air and at atemperature of 25 degC Raw scattering curves were corrected for thescattering of the cell Data acquisition time was set at 2 h

RESULTS AND DISCUSSIONChemical Modifications of Polyetheramine Deriva-

tives Two types of hydrophobic modifications wereperformed on a series of readily available polyetheramines(1) grafting of alkyl and aryl-containing urea groups at the N-terminus of the polyetheramines (Scheme 1A) and (2)coupling of polyether monoamines with alkyl and aryl-containing diisocyanates (Scheme 1B) The first type ofchemical modification was easily accomplished in one step viatreatment of polyetheramines with alkyl or aryl-containingisocyanates using anhydrous CH2Cl2 or THF as solvent underinert conditions resulting in the formation of alkylaryl ureapolyether derivatives Scheme 1A shows the general procedurefor the functionalization of polyether bis-amine compounds Asimilar procedure was followed for the modification of mono-and triamine polyethersThe other type of modification was performed by the

reaction of polyether monoamine with alkyl and aryl-containing diisocyanates as shown in Scheme 1B The reactionwas also performed under inert conditions using dry CH2Cl2 orTHF as the solvent Using 1H NMR FTIR spectroscopy andGPC successful functionalization of the polyetheramines wasconfirmed The Mn Mw and PDI of the functionalizedpolymers were determined using GPC (Supporting Informa-tion section III) The PDI values obtained range from 10 to109Gelation Studies Gelation studies commenced with the

chemically modified poly(ethylene glycol) (PEG) alkyl bis-urea 1aminusd and 2aminuse (Table 1) The solvents used for gelationtests were Labrafac cc isopropyl myristate and isododecanewhich are good model systems for formulations used incommercial cosmetic products33 The results showed that thistype of modified polymer is an effective gelator for Labrafac ccwhen the Mw of the starting PEG bis-amine polymer is low(Mw asymp 1500 see entries 2minus4) It is also apparent thatincreasing the length of the aliphatic side chain (ie from C6to C12) improves the gelation ability of the modified polymers(compare entry 1 to entries 2minus4) This result is consistent withpolymers that serve as associative thickeners wherein thiseffect is thought to be due to the ability of longer alkyl groupsto form a network as well as the hydrodynamic radius of thechains34 The effect of increasing the molecular weight of thestarting polymer backbone was also investigated Unfortu-nately the modified poly(ethylene glycol) (PEG) alkyl bis-urea

2aminuse (Mw gt 3000 entries 5minus9) failed to form a gel in Labrafaccc under analogous conditions These modified polymers werealso found to form a precipitate in isopropyl myristate whencooled to room temperature and were insoluble in isodecaneeven when heated to higher temperatureThese studies revealed that at concentrations gt3 wt

compounds 1bminusd formed gels in Labrafac cc that are stable formore than 1 week Stable gels are those that did not showprecipitation or phase separation and did not flow upon vialinversion In addition they have successfully formed gels at 2wt (Table 1 entries 2minus4) however they exhibit vialinversion stability of less than a week (2minus3 days) These resultsprompted us to further investigate other polymer backbonesAnother polymer backbone that was examined is the

diamine terminated poly(propylene glycol) (PPG) marketedas Jeffamine D The gelation test results using the modifiedPPG alkyl bis-urea 3aminusd were disappointing as they failed toform gels in any of the solvents tested (Table 2) Theincorporation of the methyl substituents in the polymerbackbone increases the solubility of the functionalizedpolyether alkyl bis-ureaThe importance of the nature of the polymer backbone was

further assessed by studying the Jeffamine ED polymers Theseare polyether diamine derivatives composed of mixtures ofPEG and PPG The hydrophobically modified Jeffamine EDalkyl bis-urea compounds proved to be highly effective gelatorsof Labrafac cc and isopropyl myristate (Table 3) Thesecompounds displayed a trend similar to the PEG alkyl bis-ureacompounds (Table 1) wherein those with longer aliphatic sidechains perform better as a gelator than those with shorterchains The effect of the longer alkyl group is morepronounced for this type of compound as stable gels can beformed at lower concentrations (Table 3 compare entry 1 toentries 2 and 3) Based on the gelation test results there is no

Table 1 Gelation Studies of PEG Alkyl Bis-ureaCompounds

entryb gelator Labrafac cc isopropyl myristate isododecane

1 1a P P I2 1b G (20) P I3 1c G (20) P I4 1d G (20) P I5 2a P P I6 2b P P I7 2c P P I8 2d P P I9 2e P P I

aMw (Da) refers to the average molecular weight of the startingpolyetheramine bGelation tests were performed at 5 wt Pprecipitates upon cooling G gel I insoluble number in parenthesesis the minimum concentration in wt at which a gel is formed

obvious change on the behavior of compounds with R =C16H33 and C18H37 alkyl side chains both in Labrafac cc and

isopropyl myristate which was also supported by rheologicalanalysis (vide inf ra) Generally the gels formed at theminimum concentration exhibit a vial inversion stabilitygreater than 1 monthIn contrast when aryl-containing group (R = benzyl (Bn))

was incorporated with Jeffamine ED polymers (compounds 4dand 4k) either dissolution or precipitation occurs in thesolvents tested (entries 4 and 11) These compounds were alsofound to be ineffective gelators of isododecaneNext we investigated the use of Jeffamine T series which are

branched polymers (Table 4) As expected the low-Mw

modified polymers were more efficient in gelling both Labrafaccc and isopropyl myristate (entries 1minus3) The high-Mwmodified compounds were observed to cause an increase inthe viscosity of Labrafac cc solution (entries 4minus5) by visualinspection These compounds are also not compatible withisododecane forming a precipitate in this solventGenerally these polyether alkyl urea derivatives afford gels

that are opaque Representative examples of the gels preparedin 5 g scale are shown in Figure 1ATable 5 shows the gelation test results for Jeffamine M alkyl

monourea compounds Only compound 6b formed a weak gelin Labrafac cc at 5 wt Although we cannot directly comparethese results with the modified polyether alkyl bis- and tris-urea compounds because the polymer composition and Mw arenot entirely the same it can be concluded that the formershowed superior gelation behavior over the monoureacompounds based on the gelation test resultsThe polyether bis-urea compounds shown in Table 6 were

functionalized by coupling of diisocyanates with Jeffamine Mpolymers Similar trends were observed wherein thosecompounds with low Mw polymer backbone and longer alkyl

Table 2 Gelation Studies of PPG Alkyl Bis-ureaCompounds

entryb gelator Labrafac cc isopropyl myristate isododecane

1 3a D D P2 3b D D P3 3c D D P4 3d D D P

aMw (Da) refers to the average molecular weight of the startingpolyetheramine bGelation tests were performed at 5 wt D staysdissolved even after cooling P precipitates upon cooling

Table 3 Gelation Studies of Jeffamine ED AlkylAryl Bis-urea Compounds

entryb gelator Labrafac cc isopropyl myristate isododecane

1 4a G (20) G (30) P2 4b G (15) G (20) P3 4c G (15) G (20) P4 4d D D P5 4e G (30) G (30) P6 4f G (15) G (20) P7 4g G (15) G (20) P8 4h P P P9 4i G (20) G (20) P10 4j G (20) G (20) P11 4k P P P

aMw (Da) refers to the average molecular weight of the startingpolyetheramine bGelation tests were performed at 5 wt G gel Pprecipitates upon cooling D stays dissolved even after coolingnumber in parentheses is the minimum concentration in wt that agel is formed

Table 4 Gelation Studies of Jeffamine T Alkyl Tris-ureaCompounds

entryb gelator Labrafac cc isopropyl myristate isododecane

1 5a G (30) G (40) P2 5b G (20) G (20) P3 5c G (20) G (20) P4 5d V P P5 5e V P P

aMw (Da) refers to the average molecular weight of the startingpolyetheramine bGelation tests were performed at 1 and 5 wt Vviscous P precipitates upon cooling G gel number in parentheses isthe minimum concentration in wt that a gel is formed

chain work better in Labrafac cc and isopropyl myristate(entries 1 and 2) In addition the aryl-containing substituentie compound 7c is detrimental to the gelating ability as itfailed to form gel in isododecane and precipitated upon cooling(entry 3) Interestingly the gels formed using thesecompounds are transparent one important quality of acommercial cosmetic product Figure 1B shows examples oftransparent gels formed in Labrafac cc and isopropyl myristate

Rheological Characterizations Rheological analyseswere conducted to gain further insights on the properties ofthe gels The rheological parameters of the frequency sweeptests in the LVE region of the polyether alkyl urea compoundsin Labrafac cc and isopropyl myristate at 3 wt aresummarized in Table 7 and the rheology plots are shown in

Figures S12minusS14 (Supporting Information) The data reported

are the average of two independent measurements of the

Figure 1 (A) Examples of gels formed in Labrafac cc (a) 4c (c) 4j and (e) 5c and in isopropyl myristate (b) 4c (d) 4j and (f) 5c at 3 wt (B)Transparent gels formed from 7b in (a) Labrafac cc and (b) isopropyl myristate at 3 wt

Table 5 Gelation Studies of Jeffamine M Alkyl UreaCompounds

entryb gelator Labrafac cc isopropyl myristate isododecane

1 6a D D P2 6b G P P

aMw (Da) refers to the average molecular weight of the startingpolyetheramine bGelation tests were performed at 5 wt G gel Dstays dissolved even after cooling P precipitates upon cooling

Table 6 Gelation Studies of Jeffamine M AlkylAryl Bis-urea Compounds

entryb gelator Labrafac cc isopropyl myristate isododecane

1 7a G (30) G (40) P2 7b G (15) G (10) P3 7c D D P4 7d D D P5 7e D D P

aMw (Da) refers to the average molecular weight of the starting polyetheramine bGelation tests were performed at 5 wt G gel D staysdissolved even after cooling P precipitates upon cooling number in parentheses is the minimum concentration in wt that a gel is formed

Table 7 Rheology Data of Gels Obtained in Labrafac cc andIsopropyl Myristate at 3 wt

Labrafac cc isopropyl myristate

gelatora Gprime (Pa) GPrime (Pa) tan δ Gprime (Pa) GPrime (Pa) tan δ

4b 8483 496 0058 418 36 00864c 8384 743 00894g 6682 506 00764i 1955 202 01034j 2905 217 00755b 549 45 0082 2470 240 00975c 622 37 00597b 413 86 0208 129 16 0124

aValues of Gprime and GPrime were taken at a frequency equal to 1 Hz

storage (Gprime) and loss (GPrime) moduli (Tables S1 and S2Supporting Information)All the gels tested in both solvents showed similar

rheological profiles wherein the storage modulus (Gprime) isgreater than the loss modulus (GPrime) throughout the LVEregion demonstrating a solid-like behavior (Table 7) Thisproduces small values of loss factor defined as tan δ (tan δ =GPrimeGprime) and represents the physical behavior of the gels Thetan δ is less than 1 for all samples which suggests the elasticnature of the gels In Labrafac cc the gels of 4b and 4cexhibited the highest Gprime value (sim8400 Pa) indicative of theformation of physically robust gels whereas the smallest valueobserved was from 7b with less than 500 Pa The long aliphaticgroups C16H33 and C18H37 did not show significant effect onthe rheological properties of the polyether alkyl ureacompounds as evidenced by the comparable moduli values(Gprime and GPrime) obtained ie for compounds 4b and 4c 5b and5c Gels obtained from compounds 5 generally exhibit modulivalues less than those from 4 indicating that linear polymerbackbone is favored over branchedSimilarly gels obtained in isopropyl myristate also exhibit

viscoelasticity (Table 7) Noteworthy is that the gel formedfrom the branched polyether showed higher Gprime values inisopropyl myristate than Labrafac ccSmall-Angle X-ray Scattering Scattering studies were

conducted to gain a better understanding of the networkformation and structure for the functionalized polyetheraminesand how the Mw and nature of the polymer backbone mightaffect the morphology and dimensions at the nanoscale Gelsformed in both Labrafac cc and isopropyl myristate wereexamined to identify any differences due to the choice ofsolvent The samples included in the SAXS studies are 4bc4fg 4ij and 5bc Representative examples of SAXS profilesare shown in Figure S15 (Supporting Information)SAXS data were modeled using a correlation length model

comprising a modified Lorenztian term to account forscattering arising from a polymer network This network ischaracterized by a correlation length that described the so-called ldquoblobrdquo size (comparable to the network mesh size) asseen in semidilute polymer and gel systems (eq 1)35

ξ=

[ + ]+I Q

IQ

bkg( )(0)

1 ( )mL

(1)

ξ is the correlation length describing the blob size and IL(0) isthe network scattering intensity at q = 0 The Lorenztianexponent m describes the fractal dimension of the scatteringobject A Lorenztian exponent equal to 2 describes anoverlapping polymer chains in a semidilute system ie coil-like while a value of 3 shows a more defined although fuzzyinterface 4 shows the maximum allowed for this model for awell-defined smooth interface ie a globular structure36

The model fitting for the scattering provides informationabout the polymer interface for the fibers in the network Basedon the values obtained from the model (Table 8) it can beassumed that the network is highly disordered and is notaffected by a linear scaling of molecular size or solvent typeFor the gels formed in Labrafac cc the Lorentzian exponent isclose to or equal to 4 suggesting that there are definedstructures present in the short-range system In contrast thegels formed in isopropyl myristate show a range of values from2 to 4 for the Lorentzian exponent The network structuresfound in the gels formed in isopropyl myristate are less

consistent and more variable in morphology compared tothose in Labrafac ccThe model fitted to the SAXS curves obtained for the gels in

this study defines the correlation length ξ (Table 8) which is ameasure of the average spacing between phase regionsassuming smooth interfaces between the phases In thesesystems the correlation length can be considered as theaverage size of the mesh with respect to Mw of the polymerThe results from the modeling of compounds 4 did not suggesta relationship between the Mw of the polymer and thecorrelation length with the highest values achieved for 4c inLabrafac cc and 4i in isopropyl myristate The majority of thegels showed a higher ξ value in isopropyl myristate howeverthe similarity between each solvent suggests that there is nodefined connection between the molecular weight andcorrelation length

Scale-up Synthesis of Modified PolyetheraminesLab-scale functionalization of the Jeffamine derivatives involvesthe use of an anhydrous solvent (eg dichloromethane THF)With large-scale synthesis the use of these solvents is notdesirable for a number of reasons (a) low mass transfer (lowconcentration of reaction medium approximately 5 wt ) (b)toxicity (eg dichloromethane is suspected of causing cancer)(c) cost efficiency (expensive anhydrous solvent and requiresextra workup) (d) possible side products Therefore synthesisof several promising compounds which possess highlyinteresting gelating properties (eg 4c and 5c) were optimizedat large scale (up to 70 g) in which solvent-free conditionswere applied By taking advantage of the high reactivities of theisocyanate and primary amine the reactions were performed inwhich the Jeffamine derivatives acted as both reactant andsolvent The reactions were carried out in a short period oftime (2minus3 h) at a temperature higher than the melting point ofthe products (eg 80 degC) Prolonging the reaction time leadsto the formation of a product with a darker color Theproducts obtained using this protocol have rheologicalproperties comparable to those prepared using the conven-tional lab-scale synthesis

CONCLUSIONSNew polyether alkyl urea derivatives were readily synthesizedin large scale These polymeric materials were identified to beeffective structurants for cosmetic solvents such as Labrafac ccand isopropyl myristate The properties of these compoundsare found to be dependent on the Mw and the nature of the

Table 8 Correlation Length ξ (Aring) and LorentzianExponent m of Functionalized Polyetheramines

Labrafac cc isopropyl myristate

gelatora

correlationlength ξ[plusmn2 Aring]

Lorentzianexponent m

correlationlength ξ[plusmn2 Aring]

Lorentzianexponent m

4b 443 4 526 24c 113 37 874 314f 394 4 722 44g 736 33 881 234i 425 35 103 34j 234 4 107 365b 381 4 531 365c 411 4 237 4

aAll calculations performed in IGOR Pro using NIST package for datareduction and analysis37

polymer as well as the length of the alkyl groups Generally forthe modified polyether bis- and tris-urea compounds (eg 4band 5b respectively) a Mw of the starting polymer backbonewith lt2000 Da exhibits the best rheological properties It isalso clear that the elasticity of the gels is highly dependent onthe chain length of the end groups By increasing the alkyl sidechain from 6 to 16 or 18 carbons the gelating ability of thesecompounds significantly improves Rheological analysisshowed that in Labrafac cc the modified compounds withthe Jeffamine ED series (Mw asymp 1000minus3000 Da) a linearpolymer backbone showed the highest viscoelastic moduli (ie4b Gprime = 8483 Pa GPrime = 496 Pa) However in isopropylmyristate both linear and branched polymer backbones (ieJeffamine T-403) can be effective gelators Unfortunately noneof the modified polymers form a gel in isododecaneFurthermore a change in physical appearance of the gels wasobserved from opaque to transparent when the hydrophobicalkyl group is at the center of the polymeric material (ie 7b)From SAXS measurements a clear connection between theMwof compounds 4 and the correlation length was not observedHowever the Lorenztian exponent suggests the formation ofdefined structures from the fiber bundles in Labrafac cc and amore variable network formation in isopropyl myristateCurrently the focus of this research is exploring the potentialapplication of these compounds to commercial perfume andcosmetic formulations These materials could provide aninteresting and more affordable alternative to commercial skincare products The straightforward solvent-free and industri-ally scalable synthesis together with the viscoelastic propertiesof these compounds make them good candidates as rheologymodifiers for formulations in the cosmetics market

ASSOCIATED CONTENTsı Supporting InformationThe Supporting Information is available free of charge athttpspubsacsorgdoi101021acsapm0c00416

Representative examples of synthesis of polyether alkylurea derivatives and their characterization supplemen-tary data on rheology and SAXS (PDF)

AUTHOR INFORMATIONCorresponding AuthorMonissa C Paderes minus Department of Chemistry Division ofMolecular Design and Synthesis KU Leuven 3001 LeuvenBelgium Institute of Chemistry University of the PhilippinesDiliman Quezon City 1101 Philippines orcidorg0000-0002-4042-4153 Email mcpaderes1upeduph

AuthorsCraig James minus Department of Chemistry and CSGI Universityof Florence 50019 Sesto Fiorentino Florence Italy

Scott A Jamieson minus Department of Chemistry and CSGIUniversity of Florence 50019 Sesto Fiorentino Florence Italy

Anh Hung Mai minus PolymerExpert 33600 Pessac FranceJuan Hermoso Limon minus Procter amp Gamble 1853 Strombeek-Bever Belgium

Marc Dolatkhani minus PolymerExpert 33600 Pessac FranceSusana Fernandez-Prieto minus Procter amp Gamble 1853Strombeek-Bever Belgium

Wim M De Borggraeve minus Department of Chemistry Divisionof Molecular Design and Synthesis KU Leuven 3001 LeuvenBelgium orcidorg0000-0001-7813-6192

Emiliano Fratini minus Department of Chemistry and CSGIUniversity of Florence 50019 Sesto Fiorentino Florence Italy

orcidorg0000-0001-7104-6530

Notes

The authors declare no competing financial interest

ACKNOWLEDGMENTSThe authors gratefully acknowledge the financial support of theresearch project ISSFLOW-PIAAP-GA-2013-612330 spon-sored by the FP7-PEOPLE-2013-IAPP UE Programme andthe UP System Balik PhD Program (OVPAA-BPhd-2017-05)

REFERENCES(1) Owh C Chee P L Loh X J A Global Analysis of thePersonal Care Market In Polymers for Personal Care Products andCosmetics Loh X J Ed Royal Society of Chemistry CambridgeUK 2016 pp 1minus17(2) Lochhead R Y The Role of Polymers in Cosmetics RecentTrends In Cosmetic Nanotechnology ACS Symposium SeriesAmerican Chemical Society 2007 Vol 961 pp 3minus56(3) Patil A Ferritto M S Polymers for Personal Care andCosmetics Overview In Polymers for Personal Care and CosmeticsACS Symposium Series American Chemical Society 2013 Vol1148 pp 3minus11(4) Schulz D N Glass J E Polymers as Rheology Modifiers ACSSymposium Series American Chemical Society 1991 Vol 462 pp2minus17(5) Lochhead R Y The Use of Polymers in Cosmetic Products InCosmetic Science and Technology Sakamoto K Lochhead R YMaibach H I Yamashita Y Eds Elsevier Amsterdam 2017 pp171minus221(6) Patil A Sandewicz R W Cosmetic Science and PolymerChemistry Perfect Together In Polymers for Personal Care andCosmetics ACS Symposium Series American Chemical Society 2013Vol 1148 pp 13minus37(7) Yin X L Loh X J Polymers for Personal Care minus NaturalProtein-Based Polymers In Polymers for Personal Care Products andCosmetics Loh X J Ed Royal Society of Chemistry CambridgeUK 2016 pp 18minus36(8) Zheng Y J Loh X J Natural Rheological Modifiers forPersonal Care In Polymers for Personal Care Products and CosmeticsLoh X J Ed Royal Society of Chemistry Cambridge UK 2016pp 60minus89(9) Chan S Y Choo W S Young D J Loh X J Pectin as aRheology Modifier Recent Reports on its Origin StructureCommercial Production and Gelling Mechanism In Polymers forPersonal Care Products and Cosmetics Loh X J Ed Royal Society ofChemistry Cambridge UK 2016 pp 205minus226(10) Heng H Y J Loh X J Antibacterial Polymers In Polymers forPersonal Care Products and Cosmetics Loh X J Ed Royal Society ofChemistry Cambridge UK 2016 pp 90minus107(11) Benderly D Zolotarsky Y Beyond Thickening minus Use of AlkylAcrylate Crosspolymer in Personal Care Formulations In Polymers forPersonal Care and Cosmetics ACS Symposium Series AmericanChemical Society 2013 Vol 1148 pp 205minus218(12) Lochhead R Y A Review of Recent Advances in the PolymericDelivery of Attributes in Cosmetics and Personal Care Products InPolymeric Delivery of Therapeutics ACS Symposium Series AmericanChemical Society 2010 Vol 1053 pp 3minus22(13) Paderes M Ahirwal D Fernandez Prieto S Natural andSynthetic Polymers in Fabric and Home Care Applications PhysicalSciences Reviews 2017 2 1minus20(14) Abdollahi H Salimi A Barikani M Zeynizadeh B NewSynthesis Processes of Polyetheramines Comparison of Three

Different Developed Amination Routes Mater Manuf Processes 201732 1296minus1303(15) Amey R L Polyetheramines Compositions IncludingPolyetheramines and Methods of Making US8765904B2 July 12014(16) Klein H P Burton B L Forkner M W Alexander D CRenken T L Godinich C E Polyether Polyamine Agents andMixtures Therefor US7550550B2 June 23 2009(17) Sanchez Garcia A M Step E N Sawrey J S Nguyen L HPreneta J B Oxidized Carbon Blacks Treated with Polyetheraminesand Coating Compositions Comprising Same US20150087764A1March 26 2015(18) Flosser D Garcia P Corley L S Erdem B Lucy P CuringAgent for Epoxy Coatings US20170137664A1 May 18 2018(19) Yao H Hang J Sun X Jin L Shi L Zhang J Preparationand Anticorrosive Behavior of Epoxy-Polysiloxane Hybrid CoatingsModified by Polyetheramines J Adhes Sci Technol 2014 28 1103minus1116(20) Jalageri M D Puttaiahgowda Y M Parambil A MVaradavenkatesan T Synthesis and Fabrication of Highly Function-alized Jeffamine Antimicrobial Polymeric Coating Polym AdvTechnol 2019 30 1616(21) Mocanu G Nichifor M Picton L About-Jaudet E Le CerfD Preparation and Characterization of Anionic Pullulan Thermoas-sociative Nanoparticles for Drug Delivery Carbohydr Polym 2014111 892minus900(22) Dulong V Mocanu G Picton L Le Cerf D Amphiphilicand Thermosensitive Copolymers Based on Pullulan and JeffamineregSynthesis Characterization and Physicochemical Properties Carbo-hydr Polym 2012 87 1522minus1531(23) Mocanu G Souguir Z Picton L Le Cerf D Multi-responsive Carboxymethyl Polysaccharide Crosslinked HydrogelsContaining Jeffamine Side-chains Carbohydr Polym 2012 89578minus585(24) Agut W Brulet A Taton D Lecommandoux SThermoresponsive Micelles from Jeffamine-b-poly(l-glutamic acid)Double Hydrophilic Block Copolymers Langmuir 2007 23 11526minus11533(25) Riachy P Lopez G Emo M Stebe M-J Blin J LAmeduri B Investigation of a Novel Fluorinated Surfactant-BasedSystem for the Design of Spherical Wormhole-like Mesoporous SilicaJ Colloid Interface Sci 2017 487 310minus319(26) May-Masnou A Pasc A Stebe M J Gutierrez J M PorrasM Blin J L Solubilization of Decane into Gemini Surfactant with aModified Jeffamine Backbone Design of Hierarchical Porous SilicaMicroporous Mesoporous Mater 2013 169 235minus241(27) May A Pasc A Stebe M J Gutierrez J M Porras MBlin J L Tailored Jeffamine Molecular Tools for OrderingMesoporous Silica Langmuir 2012 28 9816minus9824(28) Vancaeyzeele C Nguyen G T M Michan A L ViallonM Michal C A Vidal F Lithium-based Oligomer Ionic Liquid forSolvent-free Conducting Materials Polymer 2018 142 337minus347(29) Aldalur I Zhang H Piszcz M Oteo U Rodriguez-Martinez L M Shanmukaraj D Rojo T Armand M JeffamineregBased Polymers as Highly Conductive Polymer Electrolytes andCathode Binder Materials for Battery Application J Power Sources2017 347 37minus46(30) Clarke T M Rheological Properties of Cosmetics andToiletries In Cosmetic Science and Technology Series Laba D EdMarcel Dekker Inc New York 1993 Vol 13 pp 55minus152(31) Schramm G A Practical Approach to Rheology and Rheometry2nd ed Gebrueder Haake Karlsruhe Germany 1994(32) Fernandez-Prieto S Dolatkhani M De Borggraeve W MPaderes M C Hydrophobically Modified Urea Ethers as Structurantsfor Hydrophobic Systems US10092489B2 October 9 2018(33) Kirilov P Le C A K Rabehi H Rum S Villa C HaftekM Pirot F Organogels for Cosmetic and Dermo-CosmeticApplications minus Classification Preparation and Characterization of

Organogel Formulations - Part 1 Household Pers Care Today 201510 15minus19(34) Fonnum G Bakke J Hansen F K Associative ThickenersPart I Synthesis Rheology and Aggregation Behavior Colloid PolymSci 1993 271 380minus389(35) Hammouda B Ho D L Kline S Insight into Clustering inPoly(ethylene oxide) Solutions Macromolecules 2004 37 6932minus6937(36) Beaucage G Small-Angle Scattering from Polymeric MassFractals of Arbitrary Mass-Fractal Dimension J Appl Crystallogr1996 29 134minus146(37) Kline S R Reduction and Analysis of SANS and USANS DataUsing IGOR Pro J Appl Crystallogr 2006 39 895minus900