ChemistryofMaterials /cm ChemistryofMaterials /cm Article#—1354IHEMISTRYOFMATERIALSA/cmArticleSelf-HealingMultimodalFlexibleOptoelectronicFiberSensorsXiaochunWang,#GuangxueChen,#KailiZhang,Ren’aiLi,ZihanJiang,HongyouZhou,JiulinGan,*andMinghuiHe*ReadOnline^^CiteThis:Chem.Mater.2023,ReadOnlineACCESS lililACCESS lililMetrics&More畫ArticleRecommendations@SupportingInformationABSTRACT:Fiber-opticsensorsareattractingattentionbecauseoftheirhighsensitivity,fastresponse,largecapacity-transmission,andanti-electromagneticinterferenceadvantages.Nevertheless,rigidopticalfibersareinevitablydamagedorevenfracturedinapplicationsinvolvinglargetensileorbendingstrains(e.g.,humanbodymonitoring,softrobotics,andbiomedicaldevices)andthepositionofthefractureisdifficulttolocateandrepair.Therefore,opticallyself-healingfiberopticsensorsarehighlydesirable.Here,wereportadesignstrategyforincreasingthepolymersegmentalmobilityandreversiblenon-covalentbonddensityofpoly(polymerizabledeepeutecticsolvent)(PDES)tocontinuouslyfabricateacore-claddingpoly(PDES)opticalfiber(CPOF)withsignificantoptical,electrical,andmechanicalself-healingabilities.Italsopossesseslowopticalpropagationattenuation(0.31dBcm_1),widetemperaturetolerance(—77—168°C),andexcellentbiocompatibility.Moreover,CPOFshavebeenvalidatedforgesturerecognition,subcutaneousself-healing,andpressure—temperaturedetection,owingtotheirabilitytotransmitdualoptical-electricalsignalsinrealtime,andarepromisingforvariousapplicationsinindustrialandtechnologicalfields.INTRODUCTIONThenextgenerationofwearablesmartsensorsisexpectedtobeintegrateddirectlyintosoftskin,possessbiocompatibility,andbestableinvariousenvironmentstoenablethemonitoringofthestatesandactivitiesofthehumanbody,1—3andfibershapedsensorsandwovenfabricsensorswillfacilitatethelongworkinghoursofdevicesandreducediscomforttohumanskinduetotheirhighbendingelasticity,lightness,andbreath-ability.4—7Previousresearcheffortsfocusedonelectricalsignalbasedsensors,butapplicationsincertainenvironments(e.g.,industrialandunderwaterenvironments)werelimitedbecauseofsusceptibilitytoelectromagneticinterferenceandpoorelectricalsafety.8—13Fiber-opticsensorshavebeendevelopedtoaddresstheseissues.BasedonfiberBragggratingandlightintensitytechnologies,silica-basedopticalfibershavebeenappliedtomonitorthedeformationofbridges,buildings,andotherfacilitiesaswellaschangesinphysiologicalparameterssuchasheartrateandbloodpressure.14—17However,rigidopticalfibers,suchassilica-basedandpoly(methylmethacrylate)(PMMA)-basedopticalfibers,aresusceptibletofracturewhensubjectedtostressorbendingatlargeangles,anditisextremelycomplicatedtodetectandfusethefractures.18,19Therefore,somehighlytransparent,stretchablethermoplasticpolymersandhydrogelshavebeenpreparedforflexiblefiber-opticsensors.Yunandco-workersdemonstratedanalginate-polyacrylamidehydrogelopticalfiberwithlowattenuationcoefficient(0.45dBcm—1),20butthehydrogelfiberstendedtolosewaterandfreeze,reducingsensingstabilitywithchangesinambienttemperatureandhumidity.Kolleetal.selectedcommercialpolystyrenepolymersandfluorinatedpolymerswithdifferentrefractiveindicesascoreandcladdingmaterials,respectively,andstretchableopticalfiberswerefabricatedbyacoextrusionprocessaftermeltingandutilizedasstrainsensors.21However,itisnoteworthythatfewreportshaveproposedthespontaneousfusionofbrokenopticalfiberviatheself-healingabilityofsupermolecules.Comparedtoelectricalandmechanicalself-healingability,theachievementofopticalself-healingismuchmorechallenging,especiallyforthermallystableopticalfibers,becausetheminorstructuralvariationsduetoincompletehealingofthefracturecanincreaseopticalloss,22whichrequiresexcellentphysicalmobilityofmolecularsegmentsinthevicinityofthefractureregiontoallowsufficientreorganizationofdynamiccovalentornon-covalentbonds,i.e.,tocreateadequatefreevolumeinthepolymernetworks.23—26Therefore,itisofgreatsignificancetodevelopastretchableopticalfiberwithanopticalself-healingfunctionandthermalstability.Polymerizabledeepeutecticsolvent(PDES),akindofenvironmentallyfriendlyionicliquidformedbytwoormorecomponentsinsolid—liquidorevensolid—solidstatethroughReceived:November11,2022Revised:January7,2023WACSPublications?2023AmericanChemicalSocietyWACSPublications?2023AmericanChemicalSociety1345H-bondinggsrcocMT-Qt-cNEOOOOOOOOOOOoooooooddodsign(h)r(a.u.)Figure1.Designandpreparationofacore-claddingpoly(PDES)opticalfiber.(a)SchematicillustrationoftheUV-initiatedcuringspinningprocessandsupramolecularnetworkinpoly(PDES).(b)Color-filledRDGplots(iso-value=0.5)ofPDES(AAmH-bondinggsrcocMT-Qt-cNEOOOOOOOOOOOoooooooddodsign(h)r(a.u.)Figure1.Designandpreparationofacore-claddingpoly(PDES)opticalfiber.(a)SchematicillustrationoftheUV-initiatedcuringspinningprocessandsupramolecularnetworkinpoly(PDES).(b)Color-filledRDGplots(iso-value=0.5)ofPDES(AAm-ChCl-Gly)andRDGvssign(X2)pforPDES(AAm—ChCl—Gly)wherethesign(X2)prangesfrom—0.05to0.05.Onlyonestructuralunitwasconsideredinthecalculationstoqualitativelycomparetheintermolecularinteractions(withoutchlorideion).(c)Side-viewopticalmicroscopicimagesoftheCPOF(thefibercorewasdyedwithrhodamineB,scalebar,200林m).Thevelocityratiointhefigurewastheratiooftheprecursoroffibercoretotheprecursoroffibercladding,andthediameterofthefibercoreincreasedastheratioincreased.(d)Opticalimageofa3mCPOFwoundonthespoolofawinder(thefibercorewasdyedwithrhodamineB,andthefibercladdingwasdyedwithmethylviolet,scalebar,1cm).Inthiswork,glycerol(Gly)wasintroducedasasecondhydrogenbonddonorintohard-typeacrylamide(AAm)/cholinechloride(ChCl)PDES(PDES(AAm-ChCl)).TheadditionofGly,anaturalnontoxicpolyol,significantlyincreasedthehydrogenbonddensityofthePDES,whichwasconfirmedusingdensityfunctionaltheory(DFT)calculations.Basedonthisdesignstrategy,theUV-initiatedpolymerizationmethodwaschosentorapidlyfabricateastepindexcore-claddingstructurepoly(PDES)opticalfiber(CPOF)insuccession(Figure1a).Actingasalubricant,Glyevenlyfilledthepolymernetworks,increasingthefreevolumeandreducingthefrictionbetweenthepolymerchains.ThesegmentalmobilitywasfurtherfacilitatedbythefluidmotionduetothestronghydrogenbondingbetweenGlyandthepolymerchains,whichreconstructedthedamagedareasandenabledtheCPOFtoachieveopticalself-healing.Inaddition,theCPOFexhibitedlowopticalattenuation(0.31dBcm—1),widetemperaturetolerance(—77—168°C),andbiocompatibility.ThestablesignalchangesoflightattenuationandresistanceduringstretchingandbendingallowtheCPOFtobeimplementedforgesturerecognition.Furthermore,thepotentialapplicationoftheCPOFasasubcutaneousmultimodalself-healingsensorwasdemonstratedbasedonthedifferenceinsensitivityofopticalandelectricalsignalstopressureandtemperature.EXPERIMENTALSECTIONMaterials.ChCl(>98%),AAm(>99%),Gly(>99%),and4-methoxyphenol(>99%)werepurchasedfromMacklinCo.Poly-(ethyleneglycol)diacrylate(PEGDA,averageMw~200)waspurchasedfromShanghaiAladdinReagent.2-Hydroxy-4-(2-hydrox-yethoxy)-2-methylpropiophenone(photoinitiator2959,>98%)wasobtainedfromTianjinJiuriNewMaterialsCo.SynthesisofPDES.ChClwasdriedundervacuumat105°Cfor1h,andAAmwasdriedundervacuumat65°Cfor5hbeforeuse.Twocomponents(AAm—ChCl)orthreecomponents(AAm—ChCl—Gly)weremixedwithPEGDA,photo-initiator2959,and4-methoxyphenolintheratiorequiredinthepaper,andthemixturewasthenstirredat65°Cuntilaclearandtransparentliquidwasformed.FabricationoftheCPOF.ThemolarratioofAAm,ChCl,andGlywas2:1:1.5.Thedosagesofphoto-initiator2959and4-methoxyphenoltotheprecursorforfibercorepreparationwere0.5and0.1wt%,respectively,andthedosagesofphotoinitiator2959,PEGDA,and4-methoxyphenoltotheprecursorforfibercladdingpreparationwere0.1,0.5,and0.1wt%,respectively.Theprecursorswerecentrifugedat8000rmin—1for10minandinjectedintoadouble-layercoaxialspinningheadconnectedtoacommercialsiliconetube(Oupli)with10mLsyringes.The1mmdiameterCPOFwascontinuouslyextrudedandcollectedbyUVirradiation(lightintensity~20mWcm-2,Runwing,RW-UVA-①200U).FabricationofthePoly(PDES)Film.Theprecursorwasinjectedintoa2X2X0.5mmsiliconemoldandsandwichedbetweentwoglassplates.TheywereplacedintheUVcuringmachinefor15stopreparethepoly(PDES)film.

FabricationoftheHydrogelFiber.2.04gofAAmaswellas0.008gofPEGDA,photo-initiator2959,and4-methoxyphenolwereaddedto1.98gofdeionizedwater.AfterstirringatroomtemperatureuntilAAmwasfullydissolved,thesolutionwasvacuumdegassedandtheninjectedintoasiliconetube.Thehydrogelfiberwasobtainedbyremovingitfromthesiliconetubeafter80sofphotopolymerizationintheUVcuringmachine.Characterizations.Fouriertransforminfrared(FTIR)spectrawerecollectedonaBrukerVertex33FTIRspectrophotometer.Testsolutionswereinjectedintoa1X1X0.5mmsiliconemoldandsandwichedbetweentwoslidesintheUV-irradiatedareaforinsitureal-timeFTIRtestingusingaNicolet6700spectrometerinthewavelengthrangeof400-7000cm-1.Thetimeintervalofdataacquisitionwas0.84s.The1Hnuclearmagneticresonance(1HNMR)spectra(400MHz)werecarriedoutonaBrukerspectrometerAVANCEIIIHD400.Dimethylsulfoxide-d6(C2D6SO)wasusedastheexternalreference.Thetotalsoluteconcentrationswereall0.1M.TheamorphousphasewasanalyzedviaX-raydiffraction(XRD,BrukerD8ADVANCE).ViscositymeasurementswereconductedusingaCAP2000+viscometer(Brookfield)at25°C.Thermogravimetryanalyses(TGA)wereperformedonaTG209F3(NETZSCH)viascanningatemperaturerangefrom30to700°CunderN2(heatingrate=10°Cmin-1).Differentialscanningcalorimetry(DSC)measurementswerecarriedoutusinga214Polyma(NETZSCH)withaheatingrateof10°Cmin-1from-150to100°Cinanitrogenatmosphere.Tensiletestswerecarriedoutonauniversalmechanicaltestmachine(Instron,3300)atatensilespeedof50mmmin-1,unlessotherwiseindicated.Dynamicmechanicalanalysis(DMA)measurementswereperformedusingaTAQ800deviceintensilemodefrom1to100Hz.Thetransmittanceswererecordedwithanultraviolet-visible(UV-vis)spectrophotometer(Agilent,Cary60).Scanningelectronmicroscopy(SEM)imageswereacquiredusingafieldemissionscanningelectronmicroscope(ZEISS,Merlin)withanacceleratingvoltageof10kV.Opticalmicroscopicimageswerecapturedbyametallurgicalmicroscope(Motic,BA310MET)oradigitalmicroscope(Linglingxing).OpticalimagesweretakenbyaNikonDigitalSightDS-Fi1camera.MTTassaywasusedtoevaluatetheeffectofmaterialsonthecytotoxicityofNIH-3T3cells.TheNIH-3T3cellswerefirstresuscitated,andthematerialswereirradiatedwithUVlightfor30mintosterilize.Next,wecollectedNIH-3T3cellsinthelogphase,performedcellcounting,adjustedthecellsuspensionconcentration,andplatedthecellstobetestedto2X104cells/well(500代Lofcellsuspensionperwell).Cellsandmaterialswereco-culturedfor24hat37°Cwith5%CO2.Then,NIH-3T3cellswerewashedwithphosphate-bufferedsaline,and500林LofMTTsolution(0.5mgmL-1)wasaddedtoeachwell.Afterincubationfor4h,themediumandMTTsolutionwereremoved.400林Ldimethylsulfoxidewasaddedandshakenfor10min.Subsequently,theliquidwasaspiratedintoa96-wellplateand150林Lwasaddedtoeachwell.Theabsorbancevalueat570nmwasmeasuredwithanenzymemarker(BioTek,Epoch2).Thecellswithoutanytreatmentwereusedasthecontrolgroup,andthecellviabilityofthecontrolgroupwassetat100%.Finally,thesamplecellsweresubjectedtolive/deadstainingexperimentsandtheresultswereexaminedwithalaserconfocalmicroscope(Leica,TCSSP8).Thecalceinexcitationwavelengthwaschosentobe488nm,andtheexcitationwavelengthofthedye-DNAcomplexwas552nm.n2(X)=1+取242—C(1)Refractiveindexesweremeasuredbyaprismcoupler(Metricon,2010/M)atwavelengthsof633,1309,and1533nm.TheSellmeierdispersionmodeldescribingtheempiricalrelationshipbetweenrefractiveindexandwavelengthwasusedtofitthedispersioninthe400-1600nmspectralrange,andtheSellmeierequationwassimplifiedduetothelimitedamountoftestdata(n2(X)=1+取242—C(1)AttenuationMeasurementoftheCPOFSensor.A532nmlaser(opticalpower~0.5W,Thorlabs)wascoupledintotheCPOFthroughapigtailedPMMAopticalfiber,andtheoutputopticalpowerfromtheotherendoftheCPOFwasmeasuredwithapowermeter(Thorlabs,PM100D).WhentheCPOFunderwentdeformation,attenuationwascapturedandcalculatedusingeq2.S=T01%!(2)whereSistheattenuation,P1istheinitialopticalpower,andP2isthereal-timeopticalpower.(2)CutbackTechniquetoMeasureOpticalTransmissionAttenuation.The532nmlaserwascoupledintotheCPOFthroughapigtailedPMMAfiber.TheopticalpowersweremeasuredattheotherendoftheCPOFwiththelengthoftheCPOF,whichwasshortenedbycuttingfromtheendwithscissorsbyabout10mmeverytime.Theprocesswasrepeated,andthecorrespondinglengthsandopticalpowerswererecorded.Opticaltransmissionattenuationswerecalculatedusingeq2,whereSistheattenuation,P1isthelastmeasuredopticalpower,andP2istheopticalpowerwithcuttingpermeasurement.RESULTSDesignandCharacterizationofPDESAAm-ChCl-Gly.Theloweringofthemeltingpoint(Tm)aftermixingandtheformationofaclearandtransparentliquidarethemostvisualproofsofthesuccessfulsynthesisofPDES.ThemeltingpointsofAAmandChClare82and302°C,respectively,whiletheTmofPDESAAm-ChClwasreducedto32°C,35andtheadditionofGlyfurtherreducedtheTmofPDESAAm-ChCl-Glyto30.5°C(FigureS1a).TheFTIRspectrashowedthattheC=CpeakofAAmremainedat1675cm-1inPDESAAm-ChCl-Glyandthecharacteristicpeakscorrespondingtoeachmonomercanbeidentifiedinthe1HNMRspectrum,whichprovedtheformationofPDESbyintermolecularhydrogenbonding,ratherthanchemicalreaction(FigureS1b-d).PDESAAm-ChClandPDESAAm-ChCl-GlywerecomparedtoverifythebeneficialeffectofGlyintroductiononPDES.ThestretchingvibrationoftheN=HpeakofAAmintheFTIRshiftedfrom3518cm-1toalowerwavenumber(3468cm-1)(FigureS2a).Thepeaksatnear6.26ppminthe1HNMRofPDES(AAm-ChCl)areattributedtoHinthe=CHgroup(Ha)ofAAm,andthepeakatabout3.18ppmrepresentsHinthe=。印group(Hb)ofChCl.InFigureS2b,thecorrespondingpeaksinPDESAAm-ChCl-Glyallshowedatendencytoshifttolowerchemicalshifts.Furthermore,DFTmodelingwasusedtosimulatethenon-covalentinteractionsinthemixture(Figure1b)andthecalculatedbindingenergyofPDESAAm-ChCl-Glywasaslowas-36.79kcalmol-1.AlloftheaboveresultsindicatedthattheadditionofGlysignificantlyincreasedthehydrogenbonddensityofthesystem.FabricationofCPOFandPolymerizationKinetics.ThelowerviscosityofPDESAAm-ChCl-Glymaybeowingtotheinter-componentinteractionsthatattenuatetheintermo-lecularinteractionsofGly,conferringhighprocessabilitytoPDES(FigureS3).Comparedtothestep-indexcore-claddingstructureopticalfiber,thesingle-coreopticalfiberrequireseffectiveopticalwaveguidingthroughtotalinternalreflectionatthematerial-mediuminterface,whichisdependentontherefractiveindexoftheenvironmentalmediumandusuallyresultsinlargeandunstableopticalloss.Therefore,byadjustingtheamountofphoto-initiatorandcrosslinkeradded,

CutTouchHealedd4□Original△0hFigure2.Self-healingofthepoly(PDES)opticalfibercore.(a)Schematicillustrationoftheself-healingprocessofthefibercore.Whenthefibercorethathadbeencompletelycutwastouched,themoleculeswereinterconnectedbyhydrogenbondingandtheexcellentmobilityofthepolymersegmentspromotedcompleteincisionhealing.(b)Opticalmicroscopicimagesofthefractureat25°Cwithdifferenthealingtimes.Scalebar,500林m.(c)Opticalmicroscopicimagesoftheself-healingprocessofthefibercore.After2hofself-healingat25°C,crackslargelydisappearedunderillumination,resultinginlowerlightattenuationattheincision.(d)Opticalpropagationattenuationsoforiginal,touched,andhealedfibercoresweremeasuredbythecutbacktechnique.(e)Thechangesinresistancevalueofthefibercoreduringthreeconsecutivecut-touchprocessesdemonstratedexcellentelectricalhealingability.(f)Typicalstress-straincurvesoftheoriginalfibercoreandhealedfibercoresfordifferenthealingtimesatroomtemperature.Areaof

incisionthePDESprecursorssuitableforpreparingahighindexfibercoreaswellaslowindexcladdingarescreenedandinjectedintoadouble-layercoaxialspinningheadtofabricatetheCPOFcontinuouslybyUVirradiation,andthecore/claddingradiusratiocanberegulatedbychangingthevelocityratio(Figure1c,d).TheSEMimagedemonstratedthatGlyuniformlyfilledthepolymernetworkswithoutmacroscopicphaseseparationandagglomerationofcomponents(FigureS4).Moreover,wecomparedthepolymerizationprocessesoffoursolutions(PDESAAm-ChCl,PDESAAm-ChCl-Gly,AAmaqueoussolution,andAAmGlysolution)andthedosagesofeachcomponentarelistedinTableS1.DuringUV-initiatedpolymerization,real-timeFTIRwasconductedtorecordtheconversionratiosoftheC=CbondwiththeUVirradiationtime(FigureS5a).PDESAAm-ChCl-Glyexhibitedanextremelyshortinductiontime(<1.71s),ultrafastpolymerizationrate(^pmax=27.39%s-1),andahighC=Cbondconversionratio(~98%)(FigureS5b—d),indicatingthesuperiorityofPDESAAm-ChCl-Glyinpolymerizationkinetics.CutTouchHealedd4□Original△0hFigure2.Self-healingofthepoly(PDES)opticalfibercore.(a)Schematicillustrationoftheself-healingprocessofthefibercore.Whenthefibercorethathadbeencompletelycutwastouched,themoleculeswereinterconnectedbyhydrogenbondingandtheexcellentmobilityofthepolymersegmentspromotedcompleteincisionhealing.(b)Opticalmicroscopicimagesofthefractureat25°Cwithdifferenthealingtimes.Scalebar,500林m.(c)Opticalmicroscopicimagesoftheself-healingprocessofthefibercore.After2hofself-healingat25°C,crackslargelydisappearedunderillumination,resultinginlowerlightattenuationattheincision.(d)Opticalpropagationattenuationsoforiginal,touched,andhealedfibercoresweremeasuredbythecutbacktechnique.(e)Thechangesinresistancevalueofthefibercoreduringthreeconsecutivecut-touchprocessesdemonstratedexcellentelectricalhealingability.(f)Typicalstress-straincurvesoftheoriginalfibercoreandhealedfibercoresfordifferenthealingtimesatroomtemperature.Areaof

incisionSelf-HealingofthePoly(PDES)OpticalFiberCore.Thesupramolecularpropertygivesthepoly(PDES)opticalfiberstrongnon-covalentinteractionsbetweenmolecules,andGlyfurtherincreasesthefreevolumerequiredforthemobilityofpolymersegmentstohealfracturesseamlessly(Figure2a).Afterseveringmethylred-stainedaswellasunstainedfibercoresandsplicingthecutfiberscrosswise,thehealedfibercorecanstilltoleratebendingandstretching(FigureS6).Inordertomorevisuallydemonstratethefractureremodelingcapabilityofthefibercoreresultingfromsupramolecularself-healing,wepreparedthepoly(PDES)film,anditwasobservedfromtheopticalmicroscopeimagesthatthecracksgraduallyfadedasthehealingtimeincreasedandthecrackscompletelydisappearedafter2hofhealingat25°C(Figure2b).Importantly,theexcellentfractureremodelingcapabilityenablesthefibercoretofeatureopticalself-healing,whichisexpectedtofundamentallyovercomethecomplexfracture500 600 700Wavelength(nm)pu-3>!t5e4=￡1stcycle10thcycle50thcycle100thcycle?0.5 0-120 -80 -40 0 40Temperature(℃)Figure3.Opticalandmechanicalproperties,thermalstability,andbiocompatibilityofthepoly(PDES)fiber.(a)X-raydiffraction(XRD)spectraofthefibercoreandcladding.(b)Ultraviolet-visiblespectraofthefibercoreandcladding.Theinsetshowstheaveragelighttransmittanceinthevisiblerange.(c)Opticaldispersionofthefibercoreandcladding.(d)Typicalstress-straincurvesofthefibercore,fibercladding,andCPOF.(e)Cyclicstress-straincurvesoftheCPOFwithdifferentstrains.(f)Cyclicstress-straincurvesoftheCPOFforthe1st,10th,50th,and100thcyclesat100%strain.Differentialscanningcalorimetriccurve(g)andthermogravimetricanalysiscurve(h)ofCPOF.(i)Fluorescentmicrographtakenafter24hofcultureofNIH-3T3cellswiththeCPOF.Livecellsareshowningreen.Scalebar,200林m.detectionandfusingprocesswhenthefibercorebreaks.Afterthefibercorewascompletelycut,lightscatteredattheincisionwhenthecutfibercorefirsttouched,resultinginhigheropticallossintheareaofincisionwithnoimpactontheopticalwaveguideinotherareasofthefibercore.After2hofselfhealingat25°C,theincisionswerealmostinvisibletothenakedeyeunderilluminationandthelightattenuationintheareaofincisionreturnedtoalmosttheinitialvalue,demonstratingthattherewasalmostnoadditionallightlossduetomacro-ormicrostructuralchangesattheincision(Figure2c,d,MovieS1).Moreover,thepoly(PDES)opticalfibercorealsopossessedexcellentelectricalandmechanicalself-healingability.Whenitwascut,theresistancedriftedupwardtoinfinityandtheiontransportpathwastheninstantlyconnectedwhentheincisionwasconnected.Afterrepeatingthecut-touchcyclethreetimes,theresistanceofthefibercorewasalmostunchanged(Figure2e).Figure2fshowsthetypicalstress-straincurveofthefibercorewithdifferenthealingtimes.Asthefigureindicates,thetensilestrainandstrengthafterhealingfor24hwereclosetothatoftheoriginalfibercoreandthemechanicalself-healingefficiencyreachedabout63%(FigureS7).BasicPerformanceCharacterizationofthePoly-(PDES)OpticalFiber.TheXRDresultsshowedabroaddiffractionpeakat23ofabout21°(Figure3a),illustratingtheamorphouscharacteroftheCPOF,inwhichthelightpropagationwouldnotprovokelightscatteringbetweentheamorphousandcrystalinterfaces,makingthepoly(PDES)fibersuitableforflexibleopticalfibers.ThehightransparencyoftheCPOFwasillustratedbytheultraviolet-visible(UV-vis)spectrum,wheretheaveragetransmittanceofthe1mmlengthfiberwasabove90%inthevisiblewavelengthrange(400-800nm)(Figure3b).TherefractiveindicesofthefibercoreandcladdingweretestedandfittedbytheSellmeierdispersionmodelseparat