Analysis and Testing of Bisphenol A—Free Bio-Based Tannin Epoxy-Acrylic Adhesives

14 Pages·2016·3.67 MB·English

polymers
Article
Analysis and Testing of Bisphenol A—Free
Bio-Based Tannin Epoxy-Acrylic Adhesives
ShayestehJahanshahi1,2,AntonioPizzi2,3,*,AliAbdulkhani1andAlirezaShakeri4
1 DepartmentofWoodandPaperScienceandandTechnology,UniversityofTehran,
31585-43414Karaj,Iran;[email protected](S.J.);[email protected](A.A.)
2 Laboratoired’EtudeetdeRecherchesurleMateriauBois(LERMAB),UniversityofLorraine,
Epinal88000,France
3 DepartmentofPhysics,KingAbdulazizUniversity,Jeddah21589,SaudiArabia
4 DepartmentofChemistry,UniversityofTehran,6455-14155Tehran,Iran;[email protected]
* Correspondence:[email protected];Tel.:[phone]
AcademicEditor:FrankWiesbrock
Received:20January2016;Accepted:11April2016;Published:15April2016
Abstract: Atannin-basedepoxyacrylateresinwaspreparedfromglycidylethertannin(GET)and
acrylicacid. Theinfluenceofthereactionconditionforproducingtanninepoxyacrylatewasstudied
byFT-MIR,13C-NMR,MALDI-TOFspectroscopyandshearstrength. Thebestreactionconditions
forproducingtanninepoxyacrylateresinwithoutbisphenolAwasbyreactionbetweenGETand
acrylicacidinthepresenceofacatalystandhydroquinoneat95˝Cfor12h. FT-MIR,13C-NMRand
MALDI-TOFanalysishaveconfirmedthattheresinhasbeenpreparedundertheseconditions. The
jointsbondedwiththisresinweretestedforblockshearstrength. Theresultsobtainedindicated
thatthebeststrengthperformancewasobtainedbythebioepoxy-acrylateadhesiveresinpreparedat
95˝Cfora12-hreaction.
Keywords: tannin; biosourced adhesives; epoxy resin; glycidylation; acrylic acid; adhesives;
MALDI-TOF;FT-MIR;13C-NMR
1. Introduction
Epoxyresinsrepresentanimportantclassofpolymersprimarilyduetotheirversatility, high
degreeofcrosslinkingandeaseofuse. Thus,theyareverywidelyusedinmodernindustry,suchas
foradhesives,coatingsandpaints,substratesforprintedcircuitboardsandencapsulatingmaterials
formicroelectronicdevices[1]. Theycontainmanyhydroxylgroups,andthenatureoftheinterchain
bondsgivescuredepoxiesmanydesirablecharacteristics[2]. Thesecharacteristicsincludeexcellent
adhesiontomanysubstrates,highstrength,chemicalandmoistureresistance,lowthermalshrinkage
and high dielectric properties, fatigue resistance, corrosion resistance and electrical resistance [3].
Epoxyresinshavetheabilitytotransformtheirliquid(orthermoplastic)statetotough,hardthermoset
solids. Thishardeningisaccomplishedbytheadditionofachemically-activecuringagent[4]. Epoxy
resinswerealsoproducedbythereactionofthecorrespondingbiobasedpolyolsandpetroleum-based
epichlorohydrin[5–8]. Commercializedformorethan50years,bisphenolA(BPA)isthemostcommon
phenol derivative used in epoxy resin formulations to produce adhesives, laminates, structural
composites,protectivecoatingsandmanyotherproducts. BPA-basedresinsarealsoencounteredin
humanhealthapplications,suchasfillingmaterialsorsealantsindentistry. However,thesepolymers
aresensitivetohydrolysisandleachingofBPA,leadingtowidespreadhumanexposureasrevealed
byanumberofstudies[9,10]. TheyaremostlyderivedfromBPA,acompoundclassifiedasCMR
(carcinogenic,mutagenicandreprotoxic). Moreover,highBPAlevelsinvarioushumanfluidsand
tissueshavebeendetected,whichmayberesponsibleforhealthdamages[11].
Polymers2016,8,143;doi:10.3390/polym8040143 www.mdpi.com/journal/polymers
Polymers2016,8, 143 2of14
RecentawarenessofBPAtoxicitycombinedwiththelimitationandhighcostoffossilresources
impliesnecessarychangesinthefieldofepoxyresins. Epoxyligninhasalsobeenstudied,theresults
showing that epoxy resin can be cured by lignin, and the curing temperature for the blends can
be reduced by the introduction of a polyamine cure agent [12]. The reactivity of catechin toward
epichlorohydrintoformglycidyletherderivativeshasalsobeenstudied. Theglycidyletherofcatechin
(GEC) thermal properties showed that these new synthesized epoxy resins displayed interesting
propertiescomparedtothecommercialdiglycidyletherofbisphenolA(DGEBA)[5–8]. Majorissues
today are to find both alternatives to the typical synthesis route for epoxy resins and substitutes
forBPA.
Thegrowinginterestintheutilizationofrenewableresourcesasanalternativetopetroleum-based
polymershasfocusedmuchattentiononthedevelopmentofpolymericmaterialsfromvegetables
andrenewableresources. Amongtherenewable,biosourcedphenoliccompoundsbeingstudiedare
condensed flavonoid tannins. Their source is from forestry or viticulture by-products, thus not in
competitionwithfoodcrops. Resinsderivedfromfunctionalizednaturalcompoundspossessthermal
andmechanicalpropertiescomparabletothoseofconventionalfossilfuel-derivedresins,suchasthe
diglycidyletherofBPA[5–8]. Tocureepoxyresins,hardeners,suchasanamineoranaldehyde,are
usuallyneeded. However,becauseinthiswork,ahardenerisnotused,itwaspreferredtoconcentrate
on acrylate epoxy resins. The acrylate epoxies are a category of resins prepared with unsaturated
carboxylic acids and in the presence of transesterification catalysts that renders the esterification
reactionbetweenthecarboxylgroupoftheacidontheepoxidegroupsoftheepoxyresintoformvinyl
esterbondspossible.
Epoxy-acrylicresinshavebeenparticularlydevelopedforself-stratifyingcoatings,thuscoatings
thatdonotneedtobeappliedinsuccessivelayers. Itisthepresenceofsuchaconcentrationgradient
inthelayerappliedtoasurface,thustheeliminationofinterlayersboundaries[13],thatpresentssome
interestalsofortheapplicationofthesematerialsasadhesives. Thisissobecauseeliminationofthe
interlayers;boundary,whichisapotentialsiteofweaknessandfailure,maybeofbenefittoadhesives
whentheseareappliedinasinglelayer,singleface. Furthermore,thelackoftheneedtouseanepoxy
hardenerisofadditionalinterest,astheepoxyacrylicsarefastercuringthanepoxiesalone,andthis
characteristicisofinterestforadhesives,aswell.
Inthispaperisdescribedthesynthesisofanovelbioepoxyresinbasedonaglycidylethertannin
(GET)[6]reactedwithacrylicacid,andthetimeandtemperaturereactionconditionsofpreparation
areinvestigated,aswellasthederivedresinproperties.
2. MaterialandMethods
2.1. Materials
Mimosa(Acaciamearnsii,formerlymollissimadeWildt)barktanninextractwasprovidedby
Silva Chimica (San Michele Mondovì, Italy). It contained 80%–82% actual flavonoid monomers
and oligomers, 1% of amino and imino acids, the balance being composed mainly of oligomeric
carbohydrates,mainlyhemicellulosefragments,andsomecarbohydratemonomers. Theflavonoid
partofmimosatanninextractiscomposedinthemajorityofrobinetinidinandfisetinidin,butalso
includes 10%–15% of catechin and delphinidin (Figure 1), each of these monomers forming the
repeatingunitsofthetannin,theunitsbeinglinked,respectively,C4–C6orC4–C8[14]. Thetannins’
enchainmentsformedbytheseunitsarecalled,respectively,prorobinetidin,profisetinidin,procyanidin
andprodelphinidin. Theaveragenumberofunitsvariesfrommonomerstooctamerswithanaverage
degreeofpolymerization(DPn)between4and5[15].
AlloftheotherchemicalmaterialwerepurchasedfromSigma-Aldrich(St. Louis,MO,USA).
Sodium hydroxide (98%), epichlorohydrin and acetone were used as reagents in the epoxidation
reaction. Acrylicacid(99%),hydroquinone(99%)and1,4-diazabicyclo[2,2,2]octane(97%)wereused
forproducingthebioepoxyresin.
Polymers2016,8, 143 3of14
Polymers 2016, 8, 143 3 of 14

FFiigguurree 11.. TThhee ffoouurr mmaaiinn ssttrruuccttuurreess iinn ccoommmmeerrcciiaall ffllaavvoonnooiidd ttaannnniinnss..
22..22.. SSyynntthheessiiss ooff GGllyycciiddyyll EEtthheerr TTaannnniinn
Tannin was epoxidized with epichlorohydrin. Glycidyl ether tannin was obtained with
Tannin was epoxidized with epichlorohydrin. Glycidyl ether tannin was obtained with
eeppiicchhlloorroohhyyddrriinn aatt aa rreeaaccttiioonn tetemmppeerraatuturere oof f8800 °C˝C anadn da arartaioti oofo tfantanninn itno tNoaNOaHO H(20(%20 %solsuobllueb ilne
ethanol) of 1:1.5, respectively. Epichlorohydrin (15 g) was dissolved in water (10 g) at room
in ethanol) of 1:1.5, respectively. Epichlorohydrin (15 g) was dissolved in water (10 g) at room
temperature under mechanical stirring for 30 min. Subsequently, the mixture solution was placed in
temperatureundermechanicalstirringfor30min. Subsequently, themixturesolutionwasplaced
a 100-mL three-neck round-bottomed flask equipped with a reflux condenser with tannin (3 g) and
in a 100-mL three-neck round-bottomed flask equipped with a reflux condenser with tannin (3 g)
haneadtehde attoe d80to °8C0 u˝Cnduenr dmerecmheacnhicaanli csatilrsrtiinrgri.n Ag.nA anquaqeouueos ussodsoiudmiu mhyhdyrdorxoidxied seosloultuiotino nofo faa 2200 wwtt %%
concentration (4.5 g) was added dropwise using a dropping funnel while continuing to stir. The
concentration (4.5 g) was added dropwise using a dropping funnel while continuing to stir. The
reaction was continued for 3 h to allow the reaction to occur. After reaction completion, the solution
reactionwascontinuedfor3htoallowthereactiontooccur. Afterreactioncompletion,thesolution
was diluted to 200 mL with acetone. The salts released as by-products in the reaction medium were
wasdilutedto200mLwithacetone. Thesaltsreleasedasby-productsinthereactionmediumwere
ffiilltteerreedd ououtot veorvaer1 -µa L1g-lµasLs -figblaesrsfi-flitbere.rT hfieltaecre. toTnhee, waacteetroanned, nwonat-erera catendd exncoenss-roefaectpeidch leoxrocehsysd roinf
wepeircehleovraophoyrdartiend wuesrine gevaarpootararyteedv uapsionrga tao rroatta9ry0 ˝eCvaupnodraetrorre adtu 9c0e d°Cp ruenssduerre .reTdhuecereda pctrieosnsuprreo. dTuhcet
wreaascttihonen prreoddiuscsot lwveads tihneanc reetdoniseso(4lv0emd Lin) ,aficeltteorneed (o4v0 emrLa)1, -fµilLtergeldas os-vfiebr ear 1fi-lµteLr ,galansds-tfhibeefir lftirltaetre, wanads
tehvea pfioltrraatteed wunasd eervvaapcouruatmeda tu9n0d˝eCr vuancdueurmre daut c9e0d °pCr eussnudreer. Trehdisuclaesdt sptreepsswuares.r eTpheisa tleadstt wstiecpe. wThaes
repeated twice. The remaining product was glycidyl ether tannin (GET). The appearance of GET was
remainingproductwasglycidylethertannin(GET).TheappearanceofGETwasalightbrown-colored
a light brown-colored liquid. Its viscosity was measured with a Brookfield RV viscometer (Harlow,
liquid. ItsviscositywasmeasuredwithaBrookfieldRVviscometer(Harlow,UK),yieldingaviscosity
UK), yielding a viscosity of 760 centipoises with spindle No. 5 and a 60 rpm rate; the pH was 10.3,
of 760 centipoises with spindle No. 5 and a 60 rpm rate; the pH was 10.3, and the epoxy index
and the epoxy index was 7.2% [6].
was7.2%[6].
22..33.. SSyynntthheessiiss TTaannnniinn EEppooxxyy AAccrryyllaattee
BBiioo ttaannnniinn--bbaasseedd eeppooxxyy rreessiinn wwaass ssyynntthheessiizzeedd ffrroomm GGEETT aass tthhee ccoorree ooff tthhee mmoolleeccuullee aanndd aaccrryylliicc
aacciidd,, ccaattaallyysstt aanndd hhyyddrrooqquuiinnoonnee.. HHyyddrrooqquuiinnoonnee iinnhhiibbiittss tthhee sseellff--rreeaaccttiioonn ooff aaccrryylliicc aacciidd.. TThhee ccaattaallyysstt
wwaass uusseedd ttoo aacccceelelerraatete ththe ereraecatciotino.n F.orF oprropdruocdiuncgi nthge tbhieo-btaion-ntainn neipnoxeyp oaxcyryalactrey lraetseinr,e ascinry,laicc raycliidc
(a1c.i5d m(1L.5) wmaLs) dwisassoldviesdso ilnv ehdydinrohqyudinrooqnue in(0o.n04e g(0) .0a4ndg )1,a4n-ddia1z,4a-bdiciayzcalob[i2c,y2c,2lo]o[2c,t2a,n2e]o (c0t.a0n6e g()0. .0A6ftge)r.
Athfoteroruthgholryo umghixlyinmg ixaitn gamatbiaemntb iteenmtpteemraptuerrea,t utrhee, thmeixmtuixretu rweaws apslapcleadce dini naa 110000--mmLL tthhrreeee--nneecckk
rroouunndd--bboottttoommeedd ffllaasskk wwiitthh aa mmaaggnneettiicc ssttiirrrreerr,, tthheerrmmoommeetteerr aanndd GGEETT ((44 gg)).. TThhee rreeaaccttiioonn mmiixxttuurree wwaass
hheeaatteedd uunnddeerr ttwwoo vvaarriiaabbllee rreeaaccttiioonn ttiimmeess aanndd rreeaaccttiioonn tteemmppeerraattuurreess.. TToo ddeetteerrmmiinnee tthhee mmoorree ssuuiittaabbllee
rreeaaccttiioonn ppaarraammeetteerrss,, tthhee ccoonndditiitoionnss uusesedd wwereer ea acocmombibniantaiotino nofo tfwtow toemtepmepraetruartuesr,e ns,anmaemlye 8ly0 8a0nda n9d5
°9C5,˝ aCn,da tnwdot wreoacrteioacnt itoimnetsim, neasm,nealym 8e laynd8 a1n2 dh.1 T2hhe. fTinhieshfiendi sphreoddupcrtosd wuecrtse wobetraeinoebdta aisn evdiscaosuvsi sdcaoruks-
bdraorwk-nb rloiqwunidlsi.q Tuhide sv.aTrihaeblveasr oiaf bthlees soyfntthheessiys notfh tehseisseo bfioth-beasesebdi ota-bnansiend eptaonxnyi naceryploaxtey raecsriynlsa wteerrees tihnes
w4 ereresitnhse p4rerepsainresdp rreepspaerecdtivreeslyp eactt i8v0e l°yCa fto8r0 1˝2C hf o(rre1s2inh E(Tre1s)i,n aEt T810) ,°Cat f8o0r ˝8C hf o(rET82h),( EaTt 29)5, a°Ct9 f5o˝r C12f ohr
1(E2Th3()E aTn3d) 9an5 d°C9 5fo˝rC 8f ohr (8ETh4()E. TT4h)e. Tehpeoxeyp oinxydeinx d(eepxo(expidoex iedqeueivqaulievnatl/ekngt /okf greosfinre)s wina)sw daestedremteirnmedin bedy
cbhyecmhiecmali caanlaalynsailsy usissinugs ian gmaetmhoedth dodescdreisbcerdib iend thine tlhiteerlaitteurraet u[1re6][.1 W6]h. eWn heepnoxeipeos xairees parreespernets ienn tthine
reaction media, the addition of HBr leads to opening of the epoxy groups. When all of the epoxy
Polymers2016,8, 143 4of14
thereactionmedia,theadditionofHBrleadstoopeningoftheepoxygroups. Whenalloftheepoxy
groupsareopenedbyHBr,thefurtheradditionofHBRresultsintheblue-greenendofthecrystal
violetindicator. Theepoxyindexisthencalculatedas:
Epoxy% “ pvˆnˆ1.6q{W (1)
m
wherevisthetitrationsolutionconsumed,nisthenormalizedvalueandW istheamountofglycidyl
m
ether tannin. For the four resins, the epoxy indexes were: resins at 80 ˝C for 12 h (ET1) (epoxy
index=6.4),at80˝Cfor8h(ET2)(epoxyindex=7.2),at95˝Cfor12h(ET3)(epoxyindex=4.8),and
95˝Cfor8h(ET4)(epoxyindex=5.6).
Theresinssynthesiswasalsofollowedbytitration. TheresinwasweighedinanErlenmeyerflask
anddissolvedinethanol. Additionally, twodropsofphenolphthaleinwereadded. A0.1MKOH
solutionwasusedtotitrate. Theendpointwastakenwhenthesolutionturnedfrompinktoyellow.
Theacidvaluewascalculatedas:
AcidValue “ V ˆKOHnormality{massofsample (2)
titre
Theacidvalueoftheresinswas10–12.
2.4. FTIRAnalysis
AllofthebiotanninepoxyacrylateresinswereanalyzedwithaPerkinElmerFrontierAttenuated
TotalReflectance-FourierTransform-MidInfraRed(ATR-FT-MIR)spectrometer(Waltham,MA,USA)
providedbyanATRMiraclediamondcrystal. Theliquidsampleswereplacedonthediamondeye
(1.8mm)oftheATRequipment,andthecontactforthesamplewasensuredbytightlyscrewingthe
clampdevice. Eachresinwasscannedregisteringthespectrumwith32scanswitharesolutionof4
cm´1 inthewavenumberrangebetween600and4000cm´1. Eachsamplefromthetannin-based
epoxyresinwasscannedfivetimes,andtheaverageofthesespectraaftervectornormalizationand
baselinecorrectionwasstudiedinthefingerprintregionbetween1800and600cm´1.
2.5. 13C-NMRSpectroscopy
13C-NMR DEPT spectra were recorded on a Bruker MSL 300 spectrometer (Bruker France,
Wissembourg, France) at a frequency of 75.47 MHz. Chemical shifts were calculated relative to
tetramethyl silane (TMS). The rotor was spun at 12 kHz on a double-bearing 4-mm Bruker probe
(BrukerFrance,Wissembourg,France). Thespectrawereacquiredwith5-srecycledelays,a90˝pulse
of5µsandacontacttimeof1ms. Thenumberoftransientswas3000. Thespectrawererunwiththe
suppressionofspinningsidebands.
2.6. MALDI-TOFMassSpectrometry
The spectra were recorded on a KRATOS AXIMA Performance MALDI instrument (Kratos
Analytical,Shimadzu,Manchester,UK).Theirradiationsourcewasapulsednitrogenlaserwitha
wavelengthof337nm. Thelengthofonelaserpulsewas3ns. Themeasurementswerecarriedout
usingthefollowingconditions: polaritypositive, flightpath-linear, mass-high(20-kVacceleration
voltage),100–150pulsesperspectrum. Thedelayedextractiontechniquewasusedapplyingdelay
timesof200–800ns. Thesamplesweredissolvedinacetone(4mg/mL).Thesamplesolutionswere
mixed with an acetone solution (10 mg/mL acetone) of the matrix. As the matrix, 2,5-dihydroxy
benzoicacid(DHB)wasused. Fortheenhancementofionformation,NaClwasaddedtothematrix.
Thesolutionsofthesampleandthematrixweremixedinequalamounts,and0.5–1µLoftheresulting
solutionwereplacedontheMALDItarget. Afterevaporationofthesolvent,theMALDItargetwas
introducedintothespectrometer. ThereisnointerferencenoticeableoftheDHBonthespectrum,
becausethisshouldresultat154+23Da(Na+),andtheMALDIweredonewiththeiongateat200Da.
Polymers2016,8, 143 5of14
Thiseliminatesanylowermolecularweight. Theuseoftheiongateisappliedtobesuretoidentify
theoligomersformedwithoutinterferencefromlowermolecularweightspecies.
2.7. PreparationoftheAdhesiveMixturesandBondingofWoodSpecimens
Priortobonding,allofthebeechwoodblocks,ofdimensionsof150ˆ20ˆ5mm3,wereplanned
inordertoensurefreshly-cut,smoothandflatsurfaces. Thebeechwoodhadbeenpreconditionedat
8%moisturecontentfor6weeksbeforethetests. Thewoodblockswerethenbondedtogethertwoby
twowiththedifferentadhesives. Eachoftheadhesiveswasappliedbymeansofaroller,usingan
applicationrateof200g/m2. Theblockswerepressedtogethereachbymeansoftwoclampstohave
self-equilibrationoftheamountofresinusedandtohaveclosecontactgluelinesofď0.1-mmthickness
accordingtoEuropeanNormEN12765(2002)[17]. Thetanninepoxy-acrylate-bondedsampleswere
curedat60˝Cfor24hinanoven.
2.8. BlockShearStrengthTest
The shear strength of the specimens bonded with bio tannin-based epoxy acrylate resin was
determinedbythetestdefinedinEuropeanNormEN12765:2002[17]. Theuniversaltestingmachine
usedwasaconstant-rate-of-traversemachine. ItwasanINSTRON-4467(Instron,HighWycombe,UK).
Fivebondedsamplesforeachresintypewerecutintospecimensforthesheartestaccordingtothe
standard. Thedimensionsoftheshearareasweremeasuredforallofthespecimens,andthestrength
inNewtonspersquaremillimeter(N/mm2)wascalculatedusingEquation(3):
F F
max max
τ “ “ (3)
A l ˆb
2
where
F =theappliedmaximumforceinNewtons(N);
max
A=thebondedtestsurfaceinsquaremillimeters(mm2);
l =thelengthofthebondedtestsurfaceinmillimeters(mm);
2
b=thewidthofthebondedtestsurfaceinmillimeters(mm).
3. ResultsandDiscussion
3.1. SynthesisoftheTannin-BasedBioepoxyAcrylateResin
AsshowinFigure1,intheepoxidationreaction,thehydroxylgroupsontheringofthetannin
reactedwithepichlorohydrintoobtainglycidylgroupsunderalkalinereactionconditions.
Sinceepoxygroupsareunstable,byopeningtheepoxyring,andinthepresenceofacatalyst,
reactionensueswithacrylicacid. Thereactionschemeofglycidylationoftannin(GET)withacrylic
acidisshowninFigure2. TheGETcanreactwithacrylicacidthroughthefollowingthreereactions:
I.Additionalesterificationofepoxyandacidgroups.
II.Condensationesterificationofsecondaryhydroxylgroupsintheepoxychainwithproductsof
thereactionoftheacidandepoxyandacidgroups.
III.Etherificationofepoxygroupsandsecondaryhydroxylsintheepoxychainwithproductsof
reactionacidandepoxyandacidgroups.
Forthesynthesisofepoxyacrylates,onlythefirstreactionisdesired. Undercontrolledreaction
conditions(temperatureandreactiontime)andcondensingandreturningthewatervaporformed
tothereactionsystem,itwasexpectedthattheunwantedreactions(TypesIIandIII)didnotoccur
duringtheresinsynthesis. TheadditionalesterificationreactionofGETgroupsandacrylicacidgroups
led to the loss of epoxy groups and the formation the carbonyl ester bond (links to vinyl bonds)
andsecondaryhydroxylgroups. Thespectroscopymethodswereusedtomonitorthedecreaseand
Polymers2016,8, 143 6of14
eliminationofepoxygroupsandtheformationhydroxylgroupanddouble-bondesterfunctionsafter
Ptholeymfoerrsm 20a1t6i,o 8n, 1o43f theepoxytanninacrylate. 6 of 14

FFiigguurree 22.. FFTTIIRR ssppeeccttrruumm ooff tthhee EETT33 ttaannnniinn eeppooxxyy aaccrryylliicc rreessiinn ssaammppllee..
33..22.. FFTT--MMIIRR AAnnaallyysseess ooff TTaannnniinn EEppooxxyy AAccrryyllaattee RReessiinn
FFiigguurree 22 sshhoowwss tthhee FFTT--MMIIRR ssppeeccttrruumm ffoorr tthhee EETT33 rreessiinn.. AAnnaallyyssiiss ooff tthhiiss FFTTIIRR ssppeeccttrraa ssuuggggeesstteedd
tthhaatt tthhee pprroodduucctt ffoorrmmeedd dduurriinngg tthhee rreeaaccttiioonn.. TThhuuss,, eeppooxxiiddee ssiiggnnaallss dduuee ttoo rriinngg vviibbrraattiioonnss aappppeeaarreedd
aatt 880000––990000 aanndd 11004444––11229955 ccmm´−11. .TThhee ssuubbsstrtraatete ((tatannnninin) )sshhoowweedd ttyyppiiccaall aabbssoorrppttiioonn ffoorr aarroommaattiicc aanndd
aalliipphhaattiicc hhyyddrrooxxyyll ggrroouuppss ssttrreettcchhiinngg oovveerr 33330000,, 11440000––22000000 aanndda annootthheerra att1 1335599c cmm´−11 ccoorrrreessppoonnddiinngg ttoo
aarroommaattiicc OOHHd edfeofromrmatiaotnio.nT.h eThmee tmhyeltghryolu pgroofump etohfy lmoxeitrhaynleomxiroaienteie smsoigientailessa psipgenaarlesd aapt2p9e6a0recdm ´a1t .
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cohxairraancteerriisntgico onf etphoex oidxiizraednefl raivnogn oonid sepwoexriedifzoeudn dflatovobneoiindas pwreervei ofuosunstdu dtoy abte 9i0n5 aa npdre8v3i5oucms s´t1ud[6y] .
aOt n90t5h eanFdT 8IR35s cpmec−1t r[u6]m. Oinn tFhige uFrTeIR2, stpheecsterutmw oinb Faingdusreh 2a,v teheosnee twdios abpapnedasr headvaen odneth deisoatphpeeraornede a(tnhde
t8h3e5 octmh´er1 )oanlem (othste d8i3s5a pcpme−a1r)e adlm(cof.stth deisbalapcpkeaarrreodw (cifn. tFhige ubrleac2k). aTrarbolwe 1ins hFoigwusrteh 2e)i.n Ttearbplere 1ta sthioonwosf tthhee
ipnetaekrpsroeftathtieonsp oefc tthrae fpoeratkhse oEfT t3het asnpneicntreap fooxry thaec rEyTla3t etarnensiinn. epoxy acrylate resin.
TTaabbllee 11.. AAssssiiggnnmmeenntt ooff ggrroouuppss iinn tthhee FFTTIIRR ssppeeccttrruumm ooff tthhee EETT33 ttaannnniinn eeppooxxyy aaccrryyllaattee rreessiinn..
Band (cBman−1d) (cm´1) AsAsisgsnimgnemntent
3,300 –OH stretching
3,300 –OHstretching
2,960 2,960 C–HC s–trHetscthreitncghi nogf –oCf–HC2H in imnmetehtyhlyoloxxiriarannee ((eeppooxxyy))
2
1,702 1,702 CO sCtrOetscthreitncgh iinng aincrayclriycl iaccaidci d
1,616 1,616 C=C Cst=rCetscthreintcgh iinng ainroamroamtiact ircinrign g
1,507 C–Cstretchingofaromaticring
1,507 C–C stretching of aromatic ring
1,359 Aromatic–OH
1,359 Aromatic –OH
1,295 Stretchingofcyclicether(epoxy)
1,295 1,044 StretCch–Oin–gC oeft hceyrcslisct reetthcheirn (gepoxy)
1,044 905 C–OO–Cxi reatnheer(esp sotxreyt)cghrionugp C–Ostretching
835 C–O–Cinoxiranegroup
905 Oxirane (epoxy) group C–O stretching
835 C–O–C in oxirane group
Polymers2016,8, 143 7of14
Polymers 2016, 8, 143 7 of 14
33..33.. 113P3CoCl-y-NmNeMrMs 2RR0 1A6A, n8n,a a1l4lyy3s siiss 7 of 14
TT3.hh3.ee 1 311C33CC-N NNMMMRR RA nsspapleyecsctitsrr aa wweerree ddoonnee aass ddiissttoorrttiioonn eennhhaanncceemmeenntt bbyy ppoollaarriizzaattiioonn ttrraannssffeerr 113355°˝ ((DDEEPPTT))
spectra indicating that several groups have formed in the reaction of tannin with epichlorydrin under
spectrainTdhicea 13tCin NgMthRa tspseevcterraa wlgerreo duopnseh aasv deisftoorrmtioend einnhtahnecermeaecntti obny poofltaarniznaitnionw tirtahnesfpeirc 1h3l5o°r y(DdEriPnTu) nder
the conditions indicated. Scheme 1 indicates the sites numbering of a flavonoid unit. The NMR
the csopnedctirtaio inndsicinatdinicga ttheadt .seSvcehraelm greou1pisn hdaivcea tfoersmthede isni tthese rneuacmtiobne roifn tganonfina wflitahv eopnicohidloruyndirti.n uTnhdeerN MR
ssppeecctttrrhuuemm c ooonffd EEitTTio33n tstaa innnnndiiinnca eeteppdoo. xxSyyc haaeccmrryyell ii1cc rrineedssiiinnca iitsse sss hhthooeww snnit eiinsn nFFuiiggmuubrreeer i33n..g TT ohhfee amm foloassvtto iinnnoddidiicc aauttniivvitee. Tppheeeaa kkN ssMhhRooww iinngg
tthhaatt eespppooexcxtyyru ggmrro oouufp pEssTt 3hth ataatnth nhaiavnv eeepb boeexenye naf ocfrroymrlmiecd eredas niandn idhs ashhvaoevwreen ar eicnat ecFdtiegwdu riweth 3it.th hT ehtheoe pm eoonpsietn nignindaignc daatnifvuder tfphueerartkhr seehra ocrwteiaoincngtii osnth ies
athbes eanbthcseaetno ecfpeto hoxeyf ptghereoa ukppeasat tk4h 6aa.tt4 h4pa6vp.4em bpefpoemnr t ffhoorerm –teChdeH a –nC-deH phao2-vxeeyp rogexaroyctu egpdr owauniptdh a tthnheed oatpphepen eaianprgpa aennacdrea fonufcrtethh oeerf 4 rt6eh.ae5c -t4,i6o4n.65 .-i6s, - 4a6n.6d-
2
4an6.d8 -4pth6pe.8m a-bppspeemnack eps oebfa etkhlose n bpgeeialnokgn agtt oi4n6tg.h4 e tpo–p CmthH efo –rg CtrhHoeu 3– pCgsHrof2ou-erppmso exfdyo rgfmrrooeumdp ifatrn.odNm to hinet .ea Npopfoetnaherea onofct eht hoefre tchooetnh 4fie6rr.5 mc-,o i4nn6gf.6irp-m eainkgs
3
peaksa ndde t4e6r.m8-pinpemd pine aak sp rbeevloionugisn ign tvoe sthtieg a–CtioHn3 gorfo GupEsT f [o6r]m inedd ifcraotmin igt. tNheo nper eosfe tnhcee o othf earn c eopnofixrmy irnign g are
determinedinapreviousinvestigationofGET[6]indicatingthepresenceofanepoxyringarepresent,
peaks determined in a previous investigation of GET [6] indicating the presence of an epoxy ring are
present, further confirming its further reaction.
furtherconfirmingitsfurtherreaction.
present, further confirming its further reaction.
'
22'' 3'3 '4O'OHH
HHOO77 A8A8 99 OO11 22 11'' BB6'6' 45'5O'HOH
33
66
55 1100 44 OOHH
SSccShhceehmmemee e11 ..1 SS. Siittieetesss n nnuuummmbbbeeerrriiinnnggg ooof ffa aa f lfflalvaaovvnooonnioodii uddn uuitnn. iitt..
TPIRATNP.I0R0A2N.e.0s0p2.esp 46.61 6.61
1.0 4
1.0
2
0.5 0.8
malized Intensity 0.5Normalized Intensity212.110211.79 212.11211.79 171.47167.82171.47167.70167.82167.46167.70167.46 150.58150.58 132.91132.91132.62132.62130.8213 67.6066.4867.6066.1566.4863.8963.6966.1561.9663.8963.6958.2561.9646.8358.2546.5146.8335.3931.3446.5131.0635.3930.9631.3430.5731.0630.1830.9629.8030.5730.1829.80
Nor 0 -0.5 131128.86128.86128.67128.67 116.99116.99 73.2972.5073.2970.687269.6770.6869.67 18.49 18.49
.4 .5
4 70
1
-0.5 1 .37
3
200 180 160 140 1 120 100 80 60 40 20
.44Chemical Shift (ppm) 7
1
.3
FiguFirgeu3r.e 133.C 13-CN-NMMRRs pspeeccttrruumm ooff tthhee EETT33 tatnanninni nepeopxoyx aycrayclaryte7l arteesirne. sin.
200 180 160 140 120 100 80 60 40 20
Chemical Shift (ppm)
TheT1h31e .143-p1.p4-mpppme apkeabke bloelnognsgst otot hthee ––CCHH2–– ggrroouupps sofo efitehiethr ear –aO––COH–2C–CHH–OCHH–COHH3 –gCroHup gtor oau pto
2 2 3
–O–CH2–CHOHF–iCgHur2–e 3b.r i1d3Cg-eN. TMhRa ts bpoetchtr uofm t hoefs teh eex EisTt3 i st ainnndiinca etpedox byy a tchrey lfaatier lrye ssimn.a ll –CH3 peak at
a–O–CH –CHOH–CH –bridge. Thatbothoftheseexistisindicatedbythefairlysmall–CH peak
31 pp2m, the probabi2lity of the –O–CH2–CHOH–CH2– bridge linking two flavonoids or flavonoi3d
at31ppm,theprobabilityofthe–O–CH –CHOH–CH –bridgelinkingtwoflavonoidsorflavonoid
Tolhigeo 1m3e1r.s4 -hpapvming p aelareka dbye lboenegns ptroo vtheen 2–inC aH p2–re gvrioouusp is2n voefs etiigthateior na o–nO G–ECTH [26–]C, hHoOwHev–eCr, Hto3 bger othuep to a
oligomers having already been proven in a previous investigation on GET [6], however, to be the
dominant one. This indicates a phenolic site of the flavonoid where an epoxy group got attached and
–O–CH2–CHOH–CH2– bridge. That both of these exist is indicated by the fairly small –CH3 peak at
domitnhaant thaosn feu.rTthheirs rienadctiecda tbeys oappehneinngo tlhice seipteoxoifdteh aenflda evvoenn ofuidrthwehr erreeacatinnge pwoixthy agnrootuhper gfloatvaotntoaicdh teod and
31 ppm, the probability of the –O–CH2–CHOH–CH2– bridge linking two flavonoids or flavonoid
thathbarisdfguer athnder lirneka cthteed twboy. openingtheepoxideandevenfurtherreactingwithanotherflavonoidto
oligomers having already been proven in a previous investigation on GET [6], however, to be the
bridgeanTdhlei npkeathk eattw 7o0..7 ppm is the shift of the –CH2– group of the same –O–CH2–CHOH–CH3 or
dominant one. This indicates a phenolic site of the flavonoid where an epoxy group got attached and
T–Oh–eCpHe2a–kCHatO7H0–.C7Hp2p–m witihs tthhee psehaikfst aotf 6t6h–6e7– pCpHm2 b–eignrgo tuhpe soigfntahles osfa tmhee C–HO g–rCoHup2s– oCfH thOe Hsa–mCeH. 3 or
that has further reacted by opening the epoxide and even further reacting with another flavonoid to
–O–C H –CHOH–CH –withthepeaksat66–67ppmbeingthesignalsoftheCHgroupsofthesame.
2 2
bridge and link the two.
The peak at 70.7 ppm is the shift of the –CH2– group of the same –O–CH2–CHOH–CH3 or
–O–CH2–CHOH–CH2– with the peaks at 66–67 ppm being the signals of the CH groups of the same.
Polymers 2016, 8, 143 8 of 14
Polymers2016,8, 143 8of14
Polymers 2016, 8, 143 8 of 14
The peak at 130.8 belongs to the CH group of acrylic acid attached to the C=O group and the peak at
131.4 ppm to the CH2= group of acrylic acid. However, its shift at 131.4 ppm rather than the expected
The peak at 130.8 belongs to the CH group of acrylic acid attached to the C=O group and the peak at
133 pTphme ipnedaikcaatets1 3th0a.8t tbheel oancgrysltico athciedC dHougbrloeu bponodf ahcarsy loipceanceidd aatst aac choendsetoquthenecCe= oOf ag rreoaucptioann.d Tthhee
Cp13=e1Oa.k4 o apft pu1mn3r 1et.oa4 ctphteepd mC aHctro2y=lt ighcre oaCcuipHd o2is=f fagocurroynuldipc a aotc f1id7a.1c H.r4y olpiwcpemavc.ei Tdr,h. ietHs p osehwaikfetsv a eatrt ,1 73i1t1s–.47s 3hp ippftpmam tr a1pt3ah1ret.r4i ctuphlpaanmr ltyhr aee tvehixdepreentchtt aeindn
133 ppm indicates that the acrylic acid double bond has opened as a consequence of a reaction. The
rtCeh=seiOne xEopfT eu3c nbtereedlao1cnt3ge3 drpe aspcpmreyclitincivd aeicclyiad tt eoiss t fthoheua –tnCtdhH aet2a –1c 7gr1yr.ol4iuc ppapsc mildin. dkTeohdue btpolee aab k–osOn a–dt o7hf1a –bs7oo3tph pe opnfme tdh peaa osrrtaiigccuionlnaasrl elCyq Hueve2=nid gceernootu fipna
orerefev astiichdnteei oE nanTtc.3irnTy blhrieecel soCainnc=gidOE r Teao3sffptbeuerenc lotroiepvnaeegcnltyerien dtsogap tcoehrfcye tt lih–ivceCea lHdycoi2dt–uo ibgstlhrefooe buu–opnCnsdH dlai nat–kn1ge7dd1r oo. 4tufo ppt ahps e–ml Oi–n.–CTk Hehodef2 –bpto oegtaarhko –souOfap tt– ha7oet1tf –oab7rc3oihgtepihdnpoa mtlfo Ct phtHhaere2to= i–cr gOiugrl–oian uroalpyfl
the opened epoxy ring, both being the consequen2ce of the reaction of the acrylic acid with the
CofH th=e gacroryulpico afctihde aafcterry loicpeanciidnga fotef rthoep ednoiunbgleo fbtohnedd aonudb loefb tohned –aCnHd2o–f gthroeu–pC aHtta–cghreodu tpo atthtae c–hOed– otof
epox2y ring. 2
the opened epoxy ring, both being the consequence of the reaction of the acrylic acid with the
the–O–oftheopenedepoxyring,bothbeingtheconsequenceofthereactionoftheacrylicacidwith
All of the above indicates that a number of different species obtained by the reaction of the epoxy
epoxy ring.
theepoxyring.
ring of GET with the acrylic acid does occur and coexist.
All of the above indicates that a number of different species obtained by the reaction of the epoxy
Alloftheaboveindicatesthatanumberofdifferentspeciesobtainedbythereactionoftheepoxy
Oligomers, such as already identified in previous work [6], also still subsist in the reacted
ring of GET with the acrylic acid does occur and coexist.
ringofGETwiththeacrylicaciddoesoccurandcoexist.
mixture, such as the one shown in Scheme 2:
Oligomers, such as already identified in previous work [6], also still subsist in the reacted
Oligomers,suchasalreadyidentifiedinpreviouswork[6],alsostillsubsistinthereactedmixture,
mixture, such as the one shown in Scheme 2:
suchastheoneshowninScheme2: OH HO
HO O OOH HOO O OH
HO O OH O OH O HO O OH

OH OH
HO

Scheme 2. Epoxy tannin oligomers as previously identified.
Scheme2.Epoxytanninoligomersaspreviouslyidentified.
Scheme 2. Epoxy tannin oligomers as previously identified.
All of these coexist with unreacted flavonoid oligomers. Thus, the peaks at respectively
167.4–167.8 ppm (C7), 150.6 ppm (C3′/C4′), 132 ppm (C1′), 116.99 ppm (C2′), 108.6 ppm and 102 ppm
AAllll oofft htehseesceo ecxoiestxwisti thwuitnhr eaucntreedaflctaevdo nfolaidvoonliogiodm oerlisg.oTmhuerss,.t hTehpuesa,k sthaet repsepaekcst ivaetl yre1s6p7e.4c–t1iv6e7l.y8
ap1r6pe7m .c4h–(a1Cr6a77c).,t8e 1rp5ips0tm.i6c (opCfp 7fm)l,a 1v(5oC0n3.o61/ ipdCps4 mb1)e ,(iCn1g332′,/ Crpe4sp′p)m,e 1c3(tiC2v 1pe1lp)y,m, 1t 1h(C6e. 19C′9)3, ′p1/C1p64m.′9, 9t(h Cpe2p 1Cm),1 (′1 Ca0n28′.d)6, t1ph0pe8 m.C6 2pa′.pn Fmdig 1au0nr2de p140p s2mh popwamrse
tcahhreea 1rc3aChca-tNrearMcistteRirc issoptfiecflc toarfvu ofmlna ovoiofd ntshobeid eEsinT bg3e ,sirnaemgs,p prelecest piovefe ctltayinv,ntehliyne, Cetph3oe1/x CCy3 4a′1/c,Crty4hl′e,a ttCeh 1er1 eCasin1n′d .a tnhde tCh2e1 .CF2i′g. uFriegu4rseh 4o wshsotwhes
1th3Ce -1N3CM-NRMspRe scptreucmtruomft hoef tEhTe3 EsTa3m spalmepolfet aonf ntainnneipno expyoaxcyry alcartyelraetsei nre.sin.
3.4. MALDI-TOF Mass Spectrometry
3.4. MALDI-TOFMassSpectrometry
3.4. MMAALLDDII--TTOOFF M maasss sS pspecetcrtormometreyt ry was used to ascertain if the expected reactions between GET
and acrylic acid did occur and if the expected oligomers were formed. This analysis confirmed the
MMAALLDDII--TTOOFF mmaasssss sppeecctrtorommetertyryw wasasu suesdedto taos caesrctearitnaiinf tihf ethexep eexcpteedctreeda crteioacntsiobnestw beeetwneGeEnT GaEnTd
1aa3Cncrd yN laiMccrayRcl iicda nadacilidyds odisci cdbu yor caicnnuddr iciafanttdhin eigfe txthhpeae tec xttepadnecnotilenidg-b ooamlsigeerdosm eweperosrx ewyf oearrcemr fyeoldram.teTesh dwi.s Tearhneia s playrnseiapslaycrsoeinsd fi.c roTmnhfeeidr mttyhepdee 1 t3hoCfe
products expected and the reactions involved are shown in Figures 4 and 5.
N13CM NRManRa lyasniaslbyysisin bdyic aintidnigcathtiantgt atnhnaitn t-abnanseind-bepasoexdy aepcroyxlyat eascrwyelarteeps rwepearree dp.rTephaerteydp. eTohfep rtyodpeu cotsf
epxrpodecutcetds aenxpdetchteedre aancdti othnes irnevacotlivoends ainrevoshlvoewdn arine sFhigouwrnes in4 aFnigdu5r.es 4 and 5.
Reaction 1:
Reaction1:
Reactio n 1:
OH
HO O OH (NaOH)
OH
+ CL O
HO O 8 (0N oaCO, H3h)
OH OH
+ CL O
OH
80 oC, 3h
Tannin OH Epichlorohydrin
OH
Tannin Epichlorohydrin
O
O
O O
O O
O
O O O O O O OH
O O + O
O O O O O OH
OH O + OH O
O O O
OH OH
O O
O O (2)
(1)
O O (2)
FFiigguurree 44.. RReeaaccttiioonn sscchheemmee ffoorr t(th1h)ee eeppooxxiiddaattiioonn ooff ttaannnniinn.. FFoorrmmaattiioonn ooff eeppooxxyy ggrroouuppss oonn ddiiffffeerr eenntt ssiitteess
ooff ttaannnniinn’’ss ffllaavvoonnooiidd uunniittss..
Figure 4. Reaction scheme for the epoxidation of tannin. Formation of epoxy groups on different sites
of tannin’s flavonoid units.
Polymers 2016, 8, 143 9 of 14
Reaction 2:
Polymers2016,8, 143 O 9of14
O
PolymerOs 2016, 8, 143 9 of 14
O
O O
RReeaaccttiioonn 22:: O Hydroquinone
OO ++ H2C CH C OH
OH O catalyst
O
O O
O O
O Acrylic acid Hydroquinone
O ++ HC CH C OH
2
OH
O catalyst
O
GET Acrylic acid
O

O
GET
O
O
OH
HO
O O O
O
O O O
O OH O
HO
O OH O
OH O
O O O
O O
OH OH OH O
O O O
OH

O O
Figure 5. Reaction scheme of glycidylation of the tannin with acrylic acid (tannin-based epoxy

acrylate).
Figure5.Reactionschemeofglycidylationofthetanninwithacrylicacid(tannin-basedepoxyacrylate).
Figure 5. Reaction scheme of glycidylation of the tannin with acrylic acid (tannin-based epoxy
The products of Reaction 1 in Figures 4 and 5 and similar oligomers have already been observed
acrylate).
in prevTiohuesp wroodrukc [t6s]o, fwRheialcet iiot nw1asin hFoipgeudre tso4 parnedpa5raen pdrsoidmuilcatrs osilimgoilmare rtos hwahvaeta ilsr esahdoywbne einn oRbesaecrtvioedn 2.
inpInre tvhieo uMsAwLorDkI [s6p],ewcthriulemi tinw aFsighuorpee d6, tao npurempabreer porfo mduocntsomsimeri laanrdto owlihgaotmisesrh sopwencieins Rofe aac tdioifnfe2r.ent
The products of Reaction 1 in Figures 4 and 5 and similar oligomers have already been observed
nature Icnanth beeM obAsLeDrvIesdp,e tchterusem bieninFgig liusrteed6 ,ina nTuambleb e2r; tohfums,o (ni)o fmlaevroannodido lmigoonmoemresprse,c siuescho faas fdiisfefetirneindtin,
in previous work [6], while it was hoped to prepare products similar to what is shown in Reaction 2.
catneacthuirne/craonbibneetoibnsiedrivne adn,tdh egsaellboeciantgeclihsitned, ainndT aubnlere2a;cthteuds ,f(lia)vfloanvooindo didimmeornso, msuecrhs, assu cthhea sspfiesceiteinsi dati n6,38
In the MALDI spectrum in Figure 6, a number of monomer and oligomer species of a different
Dac;a (tiei)c heipno/xriodbiizneedti fnliadvionnaoniddsg arellaocctaetdec whiinth,a ancdryulincr eaaccidte; danfldav (oiini)o fildavdoimnoeirds, msuocnhoamsethrse esppeocxiiedsiazted63, 8but
nature can be observed, these being listed in Table 2; thus, (i) flavonoid monomers, such as fisetinidin,
noDtc ayat;ee(tci hri)eineapc/rtooexbdiid nwiezitetihdn iafldcairnvy oalnincod ai dgcsiadlrl,eo ascucatcteehdc ahwsin itt,hh aean scdpr yeulcnicireeasac ricdetep;daren fsdlaev(nioitien)dofl ibadvy do tnihmoeie dprsem,a skounsc oahmt a3es8r t4sh,e e4p 7sop6x eiDdciaiez,s et dha,te b 6mu38to st
pronDboata;b y(ieliet) rseetpraoucxtceitdduirzwee idoth ff lwaacvhroyinclihoci aidscs i( drSe,cashcuetcemhde aw s3i)tt:hh e ascpryelciice sacriedp;r aensedn (tieiid) fblayvtohneopidea mksoanto3m84er,s4 7e6poDxaid,tihzeedm, boustt
probablestructureofwhichis(Scheme3):
not yet reacted with acrylic acid, such as the species represented by the peaks at 384, 476 Da, the most
probable structure of which is (Scheme 3):
OH
OH
O
OH
O O
OOH
O
O
O O
OH
O
O O
O OH
O
Scheme3.MoOstprobablestructureofthe476DaMALD Ipeak.
Scheme 3. Most probable structure of the 476 Da MALDI peak.
and654Da(Table2),thisSclahtetmereo 3n. eMboesit npgroabapbrleo tsotrnucattuerde ocfa ttheec h47in6 Dora rMoAbiLnDeIt ipneiadki.n dimerwithoneepoxy
and 654 Da (Table 2), this latter one being a protonated catechin or robinetinidin dimer with one
group,suchasinScheme4:
epoxy group, such as in Scheme 4:
and 654 Da (Table 2), this latter one being a protonated catechin or robinetinidin dimer with one
epoxy group, such as in Scheme 4:
Polymers2016,8, 143 10of14
Polymers 2016, 8, 143 10 of 14
PPoollyymmeerrss 22001166,, 88,, 114433 1100 ooff 1144
OH
OOHH
HO O
HHOO OO OH
OOHH
OH O
OOHH O OO
OH OO
OOHH
HO O
HHOO OO OH
OOHH
OH
OOHH
OOOHHH
SScchheemmee 44.. CCaatteecchhiinn ddiimmeerr wwiitthh oonnee eeppooxxyy ggrroouupp rreepprreesseennttiinngg tthhee 665544 DDaa MMAALLDDII ppeeaakk..
SScchheemmee 44.. CCaatteecchhiinn ddiimmeerr wwiitthh oonnee eeppooxxyy ggrroouupp rreepprreesseennttiinngg tthhee 665544 DDaa MMAALLDDII ppeeaakk..
oooorrrr aaaa rrrroooobbbbiiiinnnneeeettttiiiinnnniiiiddddiiiinnnn----ggggaaaallllllllooooccccaaaatttteeeecccchhhhiiiinnnn ddddiiiimmmmeeeerrrr wwwwiiiitttthhhh oooonnnneeee eeeeppppooooxxxxyyyy ggggrrrroooouuuupppp,,,, ssssuuuucccchhhh aaaassss iiiinnnn SSSScccchhhheeeemmmmeeee 5555::::
OH
OOHH
OH
OH OOHH
OOHH
HO HO O O
HHOO HHOO OO O OO
OO
HO OH
HHOO OOHH
O OH
OO OOHH
OOOHHH
Scheme5.Robinetinidin-gallocatechindimerwithoneepoxygroupequallyrepresentingthe654Da
Scheme 5. Robinetinidin-gallocatechin dimer with one epoxy group equally representing the 654 Da
MSSccAhheeLmmDeeI p55e.. aRRkoo.bbiinneettiinniiddiinn--ggaallllooccaatteecchhiinn ddiimmeerr wwiitthh oonnee eeppooxxyy ggrroouupp eeqquuaallllyy rreepprreesseennttiinngg tthhee 665544 DDaa
MALDI peak.
MMAALLDDII ppeeaakk..
Performance
PDSDSPDSaaehhaehttriitrimmaafmafoo:::aa ra rmEEmEdddTTTzzazauu44u4nn ccBBiiBieooeoiii nn nooo tttgggeeeaaaccchhtthteee AA A 222xxx000iiimm00m0DDDaaaaaa PPP00000ee0e00rr0rfff11oo1o..rr.rGGmmGm111aaa777nnn[[[cccccceee]]] 222222999...999 AAA...333ppp...22rr2r 00220211001011111100550566 6 111222111444:::::33:3 MM22M2 ooCCoCdddaaaeeelll::: LLLtttoooiiinnnfff eee222aaa999rrr ,,,AAA PPPpppooorrr www222ee00e0rr11r1::: 55 5888 001101,,11,1 BB::B:000lll999aaa nnnkkkeeeddd,,, PPP...EEExxxttt... @@@ 222000999444 (((bbbiiinnn 777555)))
%Int. 415 mV[sum= 414675 mV] Profiles 1-1000 Unsmoothed
%%IInntt.. 441155 mmVV[[ssuumm== 441144667755 mmVV]] PPrrooffiilleess 11--11000000 UUnnssmmooootthheedd
305.74
100 330055..7744
11090050
9955 205.39
90 220055..3399
9900
85
8855
80
8800
75
7755
70
7700
65
6655
60
6600
55
5555
555000 444777888...000000
45
4455
40
4400
333555 333000444...777777
30
11223112211223050500505505050505 222000666...222222222999111...333111222444444...222222222555111666999111.....44.4444222888777777888...777555333000333666111...333777555222111...111555...555222000 333888333...777777 444444444777777888666999000.....99.9...444000333000999555111333...777777 666666666333333333777888999........44.4446646444444665565999444...333444 888111333...888999 999777666...000111
00 222000000 222555000 333000000 333555000 444000000 444555000 555000000 555555000 666mmm000///00zz0z 666555000 777000000 777555000 888000000 888555000 999000000 999555000 111000000000111[[[ccc]]]...GGG111
Figure 6. MALDI-TOF spectrum of the ET3 sample of tannin epoxy acrylate resin.
FFFiiiggguuurrreee 666... MMMAAALLLDDDIII---TTTOOOFFF ssspppeeeccctttrrruuummm ooofff ttthhheee EEETTT333 sssaaammmpppllleee ooofff tttaaannnnnniiinnn eeepppoooxxxyyy aaacccrrryyylllaaattteee rrreeesssiiinnn...