Development of Polymeric Coating for Alkali-Free Thin GlassMuhammad Risyad Hasyim1,2

,Dr. Michael Lanagan1,3, and Dr. Ramakrishnan Rajagopalan1,31Department of Engineering Science and Mechanics, Penn State University; 2Department of Chemical Engineering, Penn State University;

3Materials Research Institute, Penn State University

Introduction- Alkali-freethinglasses,suchasAF-45Schottglass,hasshowntohavehigh

breakdownstrength,makingitasuitablematerialforhighenergycapacitors1- Varioustypesofcoatingsontotheglasssurfacecanprovideselfhealing

capabilitiesaswellasimproveddurability2- A3-stepsurfacepolymerization,basedonastudyofmodifyingthesurfaceof

Au-coatedSiwafer3,isexploredasamethodtosynthesizeuniformsubmicroncoatingonalkali-freethinglasses.

SilanizationStrategies

OverallSynthesisScheme

1. Silanization:modificationofglasssurfacebycouplingagentsknownassilanes.Thisisdonebyusingasolutionof3-cyanopropyltriethoxysilanemixedina90%EtOH(pH=4)at2,4,and10vol%.Thesolutionsareappliedontotheglasswithvariousstrategiesoutlinedbelowanddriedat100oC.

2. Catalystanchoring:apalladiumcomplexisusedasthepolymercatalystandanchoredontothesilanelayerbyligandexchangewiththenitrile(-C≡N)group.Thisisdonebyimmersingasilane-coatedglassinacatalystsolution(nitromfor12– 24h.

3. Polymerization:glassisimmersedfrom12– 24hinamonomer(norbornene)solutionwherereactionbetweenmonomersmayoccur.

- Silanizationprovestobethemostchallengingstepsincede-wettingprocesslimitsuniformityofcoating.

- Dewettingreferstothebreakageofthinliquidfilm,formingdropletsonthesurface

- Variousstrategieswereexploredtoensurethatthisdewetting processisminimized.

- Longbathing:acleanedglassisimmersedinasilanesolutionfor24h,andtakenouttobedriedintheoven

- Thisisthebasemethodforotherstrategies.

- Optionally,itcanberinsedwithwaterpriortodrying

- Dipcoating+blowdry:acleanedglassisdippedinsideasilanesolutionatashortperiodoftimeanddriedbyusingablowdryer.

- Blowdryingisusedtospeedupthedryingandminimizede-wettingprocess

- Dipcoating+papermethod:acleanedglassisdippedinasilanesolutionandthenplacedbetweentwoweighingpapersbeforebeingdriedintheoven

- Theweighingpapershelpcreateathinliquidinterfacethatsticksontheglass,preventinganyde-wettingprocess

Figure1:aqualitativeillustrationoftheglasssurfaceatthemolecularlevelforeachstepinthedevelopmentofpolymericcoating.

Figure2:Illustrationofatypicalglasscoatedwithsilanesolutionbefore(left)andafterdrying(right).Darkbluemarksindicatehardenedsilanedroplets

Figure3:illustrationsofvarioussilanizationstrategies:Longbathing,dipcoating+blowdry,and dipcoating+papermethod

ATR-IRResults- ATR-IR(Attenuatedtotalreflectance– infraredspectroscopy)isamolecular-

levelspectroscopymethodthatmeasurestheresponseofasample’ssurface(0.5to2μm) withaninfraredlight.

- Informationobtainedistheabsorptionofinfraredlightbycertainchemicalfunctionalgroupsduetovibrationstheyexperienceafterabsorbinginfraredlight.

1.Longbathing

2.Dipcoating+blowdry

3.Dipcoating+papermethod

4.Polymerizedglassresult

Acknowledgments- TheauthorswouldliketoacknowledgethePPGResearchFoundationandMaterials

ResearchInstituteforfundingandsupportofthisresearch.References1 T.Murata,P.Dash,E.Furman,C.Pantano,M.Lanagan,JournaloftheAmericanCeramicSociety 2012,95.2M.Lanagan,C.Pantano,H.Lee,R.Rajagopalan,N.Smith,SelfHealingHighEnergyGlassCapacitors,2013,US

8542475B2.3 K.Dronavajjala,R.Rajagopalan,S.Uppili,A.Sen,D.Allara,H.Foley,J.Am.Chem.Soc. 2006,128.

Conclusion- A3-steppolymerizationwasimplementedonanalkali-freethinglassusing

norbornene asthebasemonomer.- Silanization stepdictatesthelevelofuniformity,withdipcoating+paper

methodasthemostsuccessfulstrategytoapplysilanes ontotheglass.

- IRdatashowsvariousglasssampleswithdifferentvolumepercent.

- Withoutrinsing,non-uniformityexistsalthoughsilanescanbeeasilydetected.

- Withwaterrinsing,silanescouldnotbedetected.Itispossiblethateithersilaneswerenotattachedoritexistasanundetectablemonolayer

- IRdatashowsasingleglasssample using4vol%silane,

- Formationofdropletsareminimized,althoughsmalleronesstillexist(shownontheleftfor1and2)

- Silanescouldnotbedetectedontransparentregions.Plasiblecausessimilartoalongbathedandrinsedglasses

- IRdatashowsasingleglasssampleusing2vol%silane.

- Uniformityismoreeasilycontrolledandallowslittletonodropletsformingontheglasssurface.Whiteresiduescouldstillform.

- Similarly,therearetransparentregionswheresilanescouldnotbedetected.

- Surfacesofvariousglassescanbepolymerized.A‘naked-eye’exampleisthe10vol%longbathedglass(left),althoughthere’slittleuniformityonthesurface.

- Areaswithhardeneddropletshavemorepolymerthanotherareas.

(1)

(3)

(2)

Aliphatic

Aliphatic

Aliphatic