DUT Chimie
22233
Alexandre DELANGUE Juline TRICHET Promotion 2010
Technische Hochschule Wildau [FH] Bahnhofstr. 1 15745 Wildau
Internship from 01/04/10 to 30/06/10
Synthesis of graphene and DCANP
French tutor Mr Ahmed Mazzah
German tutor Mr Sigurd Schrader
Acknowledgment
We!want!to!thanks!our!German!supervisors!Mr!Schrader!and!Mr!Grimm,!our! French!supervisor!Mr!Mazzah,!and!all!the!people!who!helped!us!during!this!project,! especially!Mr!Beyer,!and!all!the!team!from!which!we!could!learn!very!much!for!their! friendly!welcome.!
Outline ! ! Introduction.................................................................................................................................................!
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I)Presentation!of!the!university!.................................................................................................................. !!!!!! 2 II)Synthesis!of!graphene!............................................................................................................................. !!!!!! 7 1)Synthesis!of!graphene!by!the!chemical!way!...............................................................................!
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2)The!aim!of!this!synthesis!............................................................................................................!
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3)Our!results!..................................................................................................................................!
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III)Synthesis!of!DCANP!................................................................................................................................!
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1)General!presentation!.................................................................................................................!
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2)Tests!...........................................................................................................................................!
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Personal!conclusion!....................................................................................................................................!
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Summary.........................................................................................................................................................! 31 Bibliography!................................................................................................................................................!
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! ! ! !
Introduction At!the!beginning!of!our!internship,!we!had!to!work!on!plasma!technology.!But,!after! a!short!introduction!period!we!were!asked!to!work!on!the!synthesis!of!graphene!which!is!a! chemical! subject.! After! debate,! we! had! chosen! to! work! on! graphene! because! it! is! a! very! interesting!subject!and!because!we!already!knew!graphene.! ! During!our!work,!we!tried!to!prepare!graphene!from!graphite.! Graphene! is! a! flat! monolayer! of! carbon! atoms! in! two! dimensions.! There! are! only! sp2" bonded!carbon!atoms!in!graphene.! ! In!2004!scientist!from!the!University!of!Manchester!found!a!way!to!isolate!individual! graphene! sheets.! Since! this! discovery,! the! graphene! investigation! increased! all! over! the! world.! ! Graphene!is!a!natural!compound!which!can!be!found!in!the!crystalline!graphite.!In! the!crystal!of!graphite,!there!are!many!graphene!sheets!stacked!together.! There!are!3!different!ways!to!produce!graphene:! "Epitaxial! graphene! from! silicon! carbide! SiC! heated! to! 1300°C! under! vacuum.! The! silicon!carbide!is!reduced!to!form!graphene.! "Graphene!can!also!be!obtained!by!mechanical!exfoliation!from!graphite.! "We!can!make!graphene!thanks!to!the!oxidation!of!graphite!and!after!the!reduction! of!graphite!oxide.!Thereby,!graphene!oxide!flakes!are!detached!from!the!graphite!crystal.! During! our! internship! we! worked! on! the! last! method! which! is! the! formation! of! graphene!by!the!chemical!way.! ! A! second! task! during! our! internship! was! the! synthesis! of! the! 2"docosylamino"5" nitropyridin! (DCANP),! an! amphiphile! with! high! second"order! hyperpolarisability.! This! compound! can! be! used! to! prepare! photonic! devices! for! electro"optic! or! for! opto"optic! application.!There!are!only!a!few!reports!in!literature!about!this!material.!The!challenge!is! to!synthesize!this!product!and!then!to!purify!it.!! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! 1
I) Presentation of the university In!the!University!of!Applied!Sciences!Wildau!(Technische!Hochschule!Wildau![FH]"TH!Wildau)! are!about!4000!students.!It’s!one!of!the!biggest!universities!of!the!Federal!State!of!Brandenburg.! TH!Wildau!is!a!forward"looking!and!an!oriented!through!the!future!university.!It!is!one!of!the!five! universities! of! applied! sciences! in! the! Federal! State! of! Brandenburg! and! enjoys! a! preferential! location:!very!closed!to!Berlin,!the!station!railway!is!just!near!the!university.!(Fig.!1)! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Fig.!1!:!Location!of!the!city!of!Wildau,!University!of!Applied!Sciences!Wildau ! ! TH!Wildau!offers!14!degree!programs!and!is!active!in!research!and!development.!It!became! an!important!center!of!sciences!and!a!great!economic!factor.! ! Previously,! this! place! was! a! factory! which! manufactured! ! locomotives! (see! at! fig.! 2).! In! 1991,! therefore! TH! Wildau! was! ! founded! as! TFH! Wildau,! and! is! a! young! university.! A! ! characteristic! of! TH! Wildau! is! the! practical! application! of! ! science! and! economic! courses,! with! a! large! part! of! internship! ! and!high!level!equipment.! ! ! ! ! ! Fig.!2!:!Technical!monument! ! ! In!2009,!the!university!at!the!entrance!of!the!!University!of!Applied!Sciences!Wildau!could! successfully! approve! its! system! of! education! and! management.! TH! Wildau! was! certified! as! “Familienfreundliche! Hoschule”! (family! friendly! university).! The! university! enjoys! close! links! to! important!companies.!! The!three!main!faculties!at!the!university!are:!! Business!informatics/management!! Economy,!administration!and!right! Engineering! ! 2
Faculty!of!Engineering!/!Engineering!Management!(Fig.3)! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
Fig.3:!House!15,!location!of!some labs
! The!department!offers!bachelor!and!master!degrees.! ! There!are!7!different!bachelor!degrees!in!this!department!in!several!areas:! ! *!Biosystems!Engineering!/!Bioinformatics! *!Engineering!(including!dual!degree!system)! *!Engineering!(including!dual!degree!system,!Engineering!Physics! *!Logistics! *!Aeronautics!/!Aviation!Logistics! *!Telematics! *!Industrial!Engineering! ! For!example,!during!the!Engineering!Physics!study!the!most!important!areas!of!work!are:! ! *!Micro!and!Nanotechnology! *!Laser!and!Plasma!Technology,! *!Photonics!and!Technical!Optics,! *!Measurement!and!Sensor!Technology,! *!Renewable!Energy! ! There!are!also!5!different!master!degrees!in!this!department:! ! *Biosystems!Engineering!/!Bioinformatics! ! ! !*Aeronautics!/!Aviation!Logistics! ! !*Photonics! !*Technical!Management!and!Logistics!(first!enrolment!2010)! !*Telematics!
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There!are!several!laboratories!for!research!in!the!above!mentioned!areas:! *!Inorganic!Chemistry!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! *!Materialography!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! *!Organic!Chemistry!/!Instrumental!Analysis! *!Laboratory!of!Chemical!Engineering! *!Biosystems!Engineering!!!!!!!!!!!!!!!!!!!!!!!!!!!! *!Bioprocess! *!Bio"Analytics! *!Molecular!Biology! *!Computational!Biology!and!Biomedical!
*!Transport!Logistics! *!Production!Logistics! *!Factory!Planning! ! *!Process!and!plant!automation! *!Laser!and!Plasma!Technology! *!Surface!Treatment! ! ! *!Scanning!electron!microscopy!!!!!!!!!!!!!!!!!!! *!Treatment!and!Recycling!!!!!!!!!!!!!!!!!!!!!!!!!!! *!Basic!Physics!/!Renewable!Energy!!!!!!!!!!!!
!!!!! ! !We! worked! in! laboratories! for! the! Optical! Technologies,! Laser! Technology,!
Plasma!Technology,!and!Photonics:!! ! *Laser! Laboratory:! There! are! different! lasers! available! for! applications! such! as! laser! cutting! and! laser! marking! as! well! as! equipment! for! the! training! of! students,! about! e.g.! Michelson! interferometer,!holography!etc.! !! *Plasma! Laboratory:! The! focus! is! on! the! sputter! coating,! and! plasma! enhanced! chemical! vapour! deposition!and!physical!vapour!deposition.! ! !*Photonics! Laboratory:! equipment! for! the! production! and! characterization! of! optical! and! optoelectronic!materials,!components!and!parts.! ! !!*Materialography:! The! focus! is! on! the! metallography.! There! are! various! devices! for! sample! preparation! and! examination! of! samples! available.! In! addition,! a! well"equipped! chemistry! laboratory!is!available.! ! We!worked!in!the!Materialography!laboratory!during!our!internship!(Fig.4)! ! ! ! ! ! ! ! ! ! ! !
Fig.4:!Materialography!laboratory,!chemistry!division
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! Our!group!made!research!on!photonics,!laser!and!plasma!technologies.! The!work!group!for!photonics,!laser!and!plasma!technologies!at!the!University!of!Applied!Sciences! Wildau!under!the!direction!of!Prof.!Dr.!Sigurd!Schrader!represents!the!working!areas!of!photonics,! optical! technologies,! laser! and! plasma! technologies! both! in! teaching! and! in! applied! research! in! close!cooperation!with!partners!from!industry!and!science.! ! ! There!are!18!staff!members!in!our!research!group:! ! Head! ! !!!!*!Prof.!Dr.!rer.!nat.!habil.!Sigurd!Schrader! ! Scientific!Staff! ! !!!!*!Dipl.!Phys.!Harald!Beyer! !!!!*!Dr.!rer.!nat.!Martin!Burger! !!!!*!Dipl.!Ing.!(FH)!Torsten!Dohler! !!!!*!Dr.!rer.!nat.!Bernd!Grimm! !!!!*!Dr.!Ing.!Heinrich!Friedhelm! !!!!*!Dr.!rer.!nat.!Mandy!Hofmann! !!!!*!Dipl.!Phys.!Viachaslau!Ksianzou! !!!!*!Dr.!rer.!nat.!Viktor!Lisinetskii! !!!!*!Dipl.!Ing.!(FH)!Kurt!Meiner! !!!!*!Dipl.!Krist.!Ronald!Ries! !!!!*!Dipl.!Phys.!Hans"Henning!Witzmann!! ! Technical!Staff! ! !!!!*Dipl.!Ing.!Volker!Korn! ! Research!assistants,!students,!interns! ! !!!!*!Daniel!Biniok! !!!!*!Benjamin!Dubrau! !!!!*!Benjamin!Polomski! !!!!*!Klaus!Villinger! !!!!*!Martin!Bauer! ! During! our! internship,! we! were! supported! by! our! supervisor! Dr.! Bernd! Grimm! who! is! responsible!for!the!chemistry!research!in!this!group.! !
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! Currently,!there!are!several!running!research!projects!in!this!group:!! ! *Elster! Electrically!switchable!and!adjustable!diffractive!optical!elements!based!on!novel!liquid!crystal" polymer!materials.! ! *OMEGA! Materials!and!concepts!for!optical!modulators!based!on!electro"optic!switching!processes!for!the! gigabit!data!transfer!and!related!applications.! ! *SiliconLight!! Novel!light!sources!and!components!for!the!silicon!photonics.! !
*IQ!Level!! Innovative!high!quality!level!meter.! !
*Carbon!Functional!Layers! Carbon!based!functional!layers!for!electronics!and!photonics.! !
*Arc!Spray!Technology! Modified!arc!spraying!for!selected!systems!in!gas!turbines!and!jet!engines.! ! ! TH! Wildau! has! many! partners! e.g.! in! Spain,! France,! UK,! Italy,! Sweden,! Australia,! Netherlands,!Switzerland,!Israel,!Ukraine,!Poland.! ! ! In!2006,!the!Joint!Research!and!Training!Centre!of!TH!Wildau!was!established).!The!research!of!the! Jointlab!is!the!development!of!novel!silicon"based!device!concepts!and!technologies!for!high"speed! electronics!and!photonics.!Another!key!area!of!work!is!the!common!realisation!of!practical!training! courses.! ! ! ! ! ! ! ! !
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II. Synthesis of graphene 1)Synthesis!of!graphene!by!the!chemical!way! ! There!are!4!main!steps!to!produce!graphene!by!the!chemical!way.! ! ! First!step:!generation!of!graphite!sulfate! ! To!obtain!graphite!sulfate,!graphite!has!to!be!blend!with!a!concentrated!acid!such!as!sulfuric! acid! H2SO4! and! with! an! oxidant! like! K2Cr2O7! [1].! The! reaction! is! slow! so! the! reactive! compounds! have!to!react!during!1!week!at!room!temperature.! !
! Second!step:!Oxidation!of!the!graphite!sulfate! ! The!oxidation!of!graphite!sulfate!can!be!made!with!a!powerful!oxidant!such!as!KClO3!or!KMnO4! at!room!temperature.! ! Graphite! oxide! (Fig.6)! is! composed! of! ! Carboxylic! acids! ("COOH)! carbonyl! (=CO),! ! hydroxyl! ("OH),! phenol! groups! attached! to! ! both!sides.!The!detailed!structure!is!still!not! ! understood! due! to! the! strong! disorder! and! ! irregular!packing!of!the!layers.! ! ! ! Fig.6:!A!three"dimensional!molecular!model!of!graphite!oxide! ! ! The!graphite!oxide!is!soluble!in!water!because!of!all!his!different!groups!such!as!hydroxyl!groups.! !
! Third!step:!production!of!layer!(Fig.7)! !
This! step! is! the! most! important! and! difficult! step.! Layers! have! to! size! around! 1! nm! on! a! substrate!like!SiO2.!Layers!can!be!formed!with!the!dip"coating!which!is!a!simple!method.! ! ! ! ! ! ! ! ! ! ! ! ! ! Fig.7:!Scheme!of!the!dip"coating!
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To!prepare!the!solution!for!the!dipping!we!just!have!to!dissolve!the!graphite!oxide!in!water! (around!1mg/mL)! But!to!have!a!continuous!and!homogeneous!film!which!is!necessary!we!must:! – Use!different!polar!solvent!such!as!DMF!or!EtOH.! – Use!a!preheated!substrate!at!80°C.! ! In! this! case,! when! the! preheated! substrate! is! taken! off,! the! solvent! is! evaporated! and! continuous!graphite!oxide!sheets!appear.! !
! Fourth!step:!reduction!of!layers! ! Graphite!oxide!can!be!reduced!by!hydrazine!vapour!at!80°C![2,!3].!In!this!situation,!the!graphite! oxide!will!be!reduced!but!sheets!will!be!not!continuous!because!the!water!will!condense!with!the! hydrazine!and!it's!a!big!problem.! To! resolve! this! difficulty,! we! must! use! hydrazine! vapour! under! a! flow! of! helium! to! avoid! the! condensation!of!water!on!the!substrate.! ! After! these! 4! steps,! we! have! a! continuous! film! of! graphene! on! a! substrate.! But! to! see! if! the! reaction!is!completed!and!if!all!films!are!uniform!we!can!make!3!tests.!
! ! Electric!test! ! Unlike!graphite,!graphite!oxide!is!a!good!conductor!which!enables!a!higher!resistance.! ! ! With!the!measurement!of!the!influence!of!! the!voltage!according!to!the!intensity(!Fig.8).! ! We!can!demonstrate!that!the!resistance!of! Graphene graphite!oxide!(G.O)!is!~!1x1010#.! ! R=U/I=0.1/10"11=1010#! G.O. ! ! We!can!also!prove!the!resistance!of! graphene!is!~!1x106#.! ! R=U/I=0.1/10"7=106#! Fig.8:!Current!(Id)"voltage!(Vds)!plots!taken!on!graphite! ! oxide!films!before!(G.O)!and!after!(Graphene)!reduction! ! reveal!a!10000"fold!decrease!in!sheet!resistance.! ! The!conductance!increases!by!a!factor!104!after!the!reduction.! !
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! Raman!spectroscopy! ! The!Raman!spectroscopy!(Fig.9)!can!also!be!used!to!show!if!the!reaction!worked.! !
! ! !
! Fig.9:!Scheme!of!the!Raman!spectroscopy!
When!light!is!scattered!from!an!atom!or!a!molecule,!most!photons!are!elastically!such!as!that! the!scattered!photon!have!the!same!energy!as!the!incident!photons.!However,!a!small!fraction!of! the! scattered! light! is! scattered! by! an! excitation,! with! the! scattered! photons! having! a! different! frequency!and!usually!lower!than!the!frequency!of!the!incident!photons.!And!with!this!different!of! energy!we!can!deduce!some!chemical!properties!of!the!molecule.! ! !
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2) The!aim!of!this!synthesis! !
"At!first,!this!kind!of!graphene!material!can!be!used:! ! ! in!silicon!technologies!such!as!to!make!very!small!transistor!which!are!very!efficient.! ! ! ! ! ! ! On! this! ! AFM! picture! (Fig.10),! we! can!see!a!transistor!with!graphene! ! sheet!on!the!surface!(1nm)! ! ! ! ! ! ! ! ! ! ! Fig.10:!The!graphene!sheets!appear!as!thin!platelets!between! ! the!somewhat!grainy!gold!electrodes!as!imaged!by!AFM.! ! ! ! as!a!component!integrated!circuit.! ! "Secondly,!graphene!has!very!interesting!properties!like:! ! ! a! very! high! mechanical! resistance! (42! Newton! per! square! meter).! Graphene! is! 200! times! stronger!and!6!times!lighter!than!steel.!We!can,!for!example,!add!graphene!is!a!polymer!to! increase!its!hardness!and!its!stability.! ! "For!some!scientists!graphene!could!substitute!silicium!because!electrons!move!at!1000km$s"1! (30! times!faster!than!in!silicon).!And!graphene!has!useful!properties,!it!doesn't!warm!up!which!is!very! important!for!transistors.! ! ! ! ! ! ! ! !
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1. Our!results! ! At!the!beginning,!we!tried!with!3!different!kind!of!graphite!(Fig.11):! ! graphite!powder!!!!!!!!!!!!!!!!!!!!!!!graphite!suspension!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!graphite!fluid! !! ! ! ! ! ! ! ! ! ! ! ! ! Fig.11:!picture!of!the!3!different!graphite!materials! ! ! But! rapidly! we! stopped! the! investigation! with! the! graphite! suspension! because! there! was! too! much!water!in.! ! ! First!of!all,!we!started!the!generation!of!graphite!sulfate.!! ! We!added!the!2!different!kinds!of!graphite!in!a!solution!with!1g!of!K2Cr2O7! which!is!an!oxidant! and! sulfuric! acid! at! different! concentrations:! 96%,! 90%,! and! 85%.! And! we! stirred! a! little! bit! to! homogenize!the!solutions.! ! We!kept!these!solutions!during!1!week.!After!this!period!the!solutions!were!green!because!of! the!reduction!of!the!cation!Cr!6+!(orange)!in!Cr3+!(green).! ! Then!we!filtrated!the!solution!on!a!special!filter!because!particles!of!graphite!sulfate!were!very! small,!and!we!washed!with!concentrated!H2SO4.! ! After! the! filtration! we! stopped! the! investigation! with! the! graphite! fluid! because! it! was! too! difficult!to!filtrate.! ! So! we! made! the! same! experimental! procedure! with! a! pure! graphite! powder! 99%! (Fig.12)! (generation!of!sulfate!and!filtration).! ! ! ! ! ! ! !
Fig.12:!picture!of!the!pure!graphite!99%!
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! Then,! we! continued! with! the! oxidation! of! the! graphite! sulfate! with! two! different!powerful!oxidants:! "KMnO4! "KClO3! We!read!in!the!literature!that! the!solutions!form!a!gel!and!must!turn!in!a!blue!colour!with! KMnO4!and!in!a!dark!green!colour!with!KClO3.! !
We!already!know!that!the!reaction!is!almost!complete!according!the!concentration!of!acid.! ! "With!a!96%!in!H2SO4,!there!is!generation!of!graphite!oxide!with!some!graphite.! "With!a!90%!in!H2SO4,!there!is!generation!of!graphite!oxide!with!a!few!amount!of!graphite.! "With!an!85%!in!H2SO4,!there!is!only!generation!of!graphite!oxide.! ! Table!1:!Colours!from!the!oxidation!with!KMnO4! KMnO4!
Graphite!powder!
%!H2SO4!
96%!
90%!
Pure!graphite!powder! 85%!
90%!
85%!
Colours! Violet! Dark!green! Dark!blue! Black! Black! ! ! ! ! ! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! ! ! As! we! presumed,! the! best! results! we! got! with! the! solution! with! 85%! of! H2SO4! because! it! was!blue.! The!pure!graphite!powder!solution!is!black!maybe!because!the!particles!were!very!small!and!form! a!suspension!in!the!solution.! ! Table!2:!Colours!from!the!oxidation!with!KClO3! KClO3!
Graphite!powder!
%!H2SO4!
96%!
90%!
85%!
90%!
85%!
Colours! ! ! ! ! ! ! ! !
Dark!green!
Dark!green!
Dark!green!
Dark!green!
Dark!green!
Pure!graphite!powder!
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! ! The!solution!from!the!oxidation!with!KClO3! was!green!with!a!formation!of!gel.!That's!mean! the!reaction!worked!very!well.! ! To!be!sure!that!the!reaction!worked!we!made!some!analyses!in!Raman!spectroscopy!and!X"RAY! spectroscopy.! !
! Raman!spectroscopy! ! We!have!sent!the!samples!in!another!laboratory!in!IHP!to!make!our!analysis!because!we!didn't! have!this!device.! ! We!obtained!these!spectrums!(see!the!spectrum!1,!2,!3):! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Spectrum!1:!graphite!powder!in!Raman!spectroscopy! ! ! As!we!can!see!on!this!graph,!there!are!3!typical!peaks!on!the!graphite!spectrum.! The! first! one! (around! 1300cm! "1)! shows! that! the! graphite! is! not! a! perfect! organized! crystal! that! means!there!not!only!sp2!carbon.!The!second!one!(around!1600cm!"1)!is!the!peak!of!graphite.!That! means! there! is! graphite! in! our! sample.! The! last! one! (around! 2700cm! "1)! shows! the! thickness! of! graphite!or!the!number!of!graphite!sheets.! ! ! ! ! ! ! !
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! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Spectrum!2:!Graphite!oxide!in!Raman!spectroscopy!on!glass! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Spectrum!3:!Graphite!oxide!in!Raman!spectroscopy!on!silicon!! ! The!spectrum!of!graphite!oxide!shows!no!typical!peak.!We!can!just!notice!that!the!peak!of! graphite!is!less!clear!than!at!the!beginning.!That!means!a!big!amount!of!graphite!has!reacted!to! form!graphite!oxide.! ! There! are! two! other! peaks! on! the! second! spectrum! around! 2900cm"1! which! show! that! a! silicon!substrate!has!been!used.! ! We!don't!have!more!details!about!the!devise!because!these!spectrums!were!made!in!another! laboratory.! ! !
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! X"RAY!spectroscopy! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Spectrum!4:!Theoretical!spectrum!of!graphite!oxide!in!X"RAY!spectroscopy!on!glass.! ! This! peak! can! move! between! 6! and! 12! A°! according! to! the! amount! of! water! in! the! sample! (spectrum!4).! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Spectrum!5:!Spectrum!of!our!sample!on!X"ray!spectroscopy!on!glass.! ! The!spectrum!of!graphite!and!the!green!one!are!very!different,!and!we!can!find!the!typical! peak!of!graphite!oxide!near!10!A°!(spectrum!5).! One!more!time,!we!have!the!proof!that!the!reaction!worked.! We!don't!have!more!details!about!the!devise!because!these!spectrums!were!made!in!another! laboratory!too.!
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! !
! Formation!of!layers.! ! Then! we! tried! to! make! layers! with! the! graphite! oxide.! For! that! we! wanted! to! have! graphite! oxide!powder!and!not!in!solution.! We!made!the!first!test!on!the!solution!oxidized!by!KCO3!with!the!pure!graphite!powder.! ! ! We! had! problem! for! the! filtration! because! particles! of! pure! graphite! powder! were! too! small.! So! Na2CO3! was! added! in! the! solution! to! have! a! neutral! solution.! Sulfuric! acid! was! reacted! with!sodium!carbonate!by!this!reaction:! ! ! ! H2SO4!!+!!Na2CO3!!=>!!Na2SO4!!+!H2O!+!CO2! ! After!this!reaction,!graphite!oxide!was!in!suspension!in!neutral!solution.!So!we!filtrated!and! washed!very!carefully!wish!water.! ! To!make!layers,!we!solved!the!graphite!oxide!in!water!thanks!to!a!sonic!bath!during!2!hours.! We!tried!with!methanol!too.! ! Then,!we!made!the!dipping!on!a!quartz!substrate!and!on!a!preheated!quartz!substrate.! !
AFM!(atomic!force!microscope)!is!used!to!see!the!thickness!of!the!layer.! ! ! The!AFM!consists!of!a!cantilever!with!a!sharp!tip!! At!its!end!that!is!used!to!scan!the!surface.!! The! cantilever! is! typically! silicon! or! silicon! nitride! with! a! tip! radius! of! curvature! on! the! order! of! nanometres!(Fig.13).! ! ! ! !! ! Fig.13:!The!cantliver!of!the!AFM! ! ! When!the!tip!is!brought!into!proximity!of!a!sample!surface,!forces!between!the!tip!and!the! sample!lead!to!a!deflection!of!the!cantilever!according!to!Hooke's!law.!Depending!on!the!situation,! forces!that!are!measured!in!AFM!include!mechanical!contact!force,!van!der!Waals!forces,!capillary! forces,! chemical! bonding! etc.! Along! with! force,! additional! quantities! may! simultaneously! be! measured!through!the!use!of!specialized!types!of!probe.!Typically,!the!deflection!is!measured!using! a!laser!spot!reflected!from!the!top!surface!of!the!cantilever!into!an!array!of!photodiodes.! ! ! !
16
! This!scheme!sums!up!in!an!easier!way!the!working!of!this!device!(Fig.14).! !
!
!
! Fig.!14:!Scheme of!the!AFM!spectroscopy ! ! ! At!first,!we!made!analyses!with!the!quartz!substrate!to!see!how!its!look!on!the!AFM!(Fig.15).! ! ! ! ! ! The!quartz!substrate!is! uniform.!
Fig.15:!3D!picture!from!AFM!of!quartz!substrate
17
! Fig.16:!Height!profile!from!AFM!of!quartz!substrate! ! This!picture!(Fig.16)!shows!that!the!roughness!of!the!quartz!substrate!is!very!small!(1.177nm)! ! After!that,!the!quartz!substrate!with!graphite!oxide!is!analysed!on!AFM!to!see!the!thickness!of!the! graphite!oxide!(Fig.17).! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Fig.17:!3D!picture!from!AFM!of!graphite!oxide!on!quartz! ! 18
!
! ! Fig.18:!Height!profile!from!AFM!of!graphite!oxide!on!quartz! ! ! Graphite!oxide!makes!some!high!peaks!(0.7503µm,!0.1065µm)!and!doesn't!form!a!homogeneous! film!(Fig.18).! ! All!these!results!mean!that!the!dipping!didn't!work!as!well!as!we!could!imagine.! ! ! ! ! !
19
Then,!the!preheated!quartz!substrate!with!graphite!oxide!is!also!analysed!on!AFM!(Fig.19,!20).!
Fig.19:!3D!picture!from!AFM!of!graphite!oxide!on!preheated!quartz!substrate! !
!
Fig.20:!Height!profile!from!AFM!of!graphite!oxide!on!preheated!quartz!substrate!
20
! With! the! preheated! substrates,! there! is! more! graphite! oxide! on! the! substrate.! Although! graphite! oxide! makes! a! lot! of! peaks;! they! are! smaller! than! those! with! substrate! without! preheating.! We! can! say! that! we! have! better! results! with! the! preheated! substrate,! although! it! is! not! a! continuous!graphite!oxide!sheet.! ! We! stopped! our! results! and! our! investigation! here! for! the! report! but! we! will! continue! in! July!to!improve!the!formation!of!layers!and!the!reduction!of!graphite!oxide.!
21
III) Synthesis of DCANP !
1) General!presentation! !" #$!%&'()**
Synthesis!of!DCANP!can!be!carried!out!by!condensation!of!amine!and!a!bromocompound!(Fig.21),[6].*
* * * * * * * * * * * * * * * * * * * * * * * * *
Fig.21!:!Scheme of!the!reaction
The!DCANP!is!very!interesting!as!a!material!with!nonlinear!optical!properties!for!optical! computers!and!optical!telecommunication!and!for!applications!which!need!molecules!with!a!non" centrosymmetric!arrangement!in!thin!layers!created!with!the!Langmuir"Blodgett!technology![4,!5].! !
* * * * * * * * *
1-Bromodocosan
2-Amino-5-nitropyridin
Fig.22:!Picture!of!the!starting reagents
22
*
b.!Chromatography:!! ! We!chose!the!thin!layer!chromatography!to!analyze!and!column!chromatography!to!purify! the!product.! ! A!chromatography!is!a!physical!technique!of!separation.!It!is!based!on!the!different!speeds! of!migration!of!products.!A!chromatography!is!always!composed!of!a!stationary!phase!(fixed!phase)! and!a!mobile!phase,!which!moves!through!the!stationary!phase.!The!chromatography!is!based!on! the!migration!of!the!sample.!The!speed!of!migration!depends!on!the!nature!of!the!two!phases!and! on!the!nature!of!the!compounds.! ! !
! Thin!layer!chromatography!(TLC)!to!analyze.! The!aim!is!to!separate!products!and!identify!them.!The!stationary!phase!is!a!layer!of!absorbent,! and!the!mobile!phase!(eluent)!is!a!liquid!which!doesn’t!react!with!the!latter.! This!kind!of!chromatography!can!be!used!to!monitor!a!reaction,!to!identify!a!composition!of!a!mix! or!to!check!the!purity!of!a!component.! ! Stationary!phase:!! ! The! TLC! plates! are! generally! a! stand! of! glass,! aluminium! or! plastic,! and! these! sheets! are! coated!with!silica!gel!or!aluminium!oxide.!The!thickness!of!the!layer!is!in!the!order!of!0.1"0.25!mm.! Generally,!the!adsorbent!is!mixed!with!a!fluorescent!pigment!to!make!the!UV!detection!easier.!This! pigment!emits!a!green!colour!under!an!UV!light!except!where!a!product!adsorbs!in!the!UV!so!spots! appears.! ! General!procedure!(Fig.23):!! ! Preparation!of!the!TLC!plate:!A!line!is!drawn!about!1cm!from!the!base.!On!this!line,!small! spots!of!the!sample!and!the!reference!are!applied.!! ! Preparation!of!the!eluent:!In!an!enclosed!container,!the!eluent!is!added!for!5mm!high.!We! have! to! let! the! container! enclosed! for! 5"10! min,! to! let! the! vapours! of! the! eluent! fill! up! the! container.! ! The! plate! is! dipped! into! the! eluent,! which! migrates! through! the! plate! by! capillary! action.! When! it’s! at! the! top,! the! chromatography! is! ended! and! a! line! is! drawn,! where! the! eluent! is! stopped.!This!eluent!is!evaporated!before!the!detection.! Detection;! with! a! UV! lamp:! when! the! adsorbent! is! mixed! with! a! fluorescent! pigment! or! for! the! aromatic!components;!with!iodine:!in!a!beaker,!some!crystals!of!iodine!are!placed!with!the!plate! and!then!the!beaker!is!closed.!Iodine!and!organic!components!form!yellow/brown!spots.!!
Fig.23:!Scheme!of!the!thin!layer!chromatography!
23
*
! Column!Chromatography!to!separate:!!
The!aim!is!to!separate!compounds!from!a!mixture.!The!stationary!phase!is!a!solid!(silica!gel!or! aluminium! oxide).! This! chromatography! works! by! gravity.! The! products! go! down! with! different! speeds!(as!the!TLC),!the!speeds!depend!on!the!affinity!with!the!eluent!and!on!the!interaction!with! the!stationary!phase.! ! Procedure!(Fig.24):!! ! Preparation!of!the!column:!A!column!with!a!tap!is!used.!It!is!necessary!to!block!the!column! with!cotton!when!there!is!no!sintered!glass.!! There!are!two!ways!to!fill!the!column:!the!dry!method!and!the!wet!method.!For!the!dry!method,! the!column!is!filled!with!the!powder!and!then!the!eluent!is!added.!For!the!wet!method,!a!slurry!of! the!eluent!and!the!powder!is!prepared.!Then,!a!part!of!the!eluent!is!put!into!the!column!and!with!a! funnel,!the!slurry!is!added.!It!is!ended!when!the!supernatant!is!clear.!The!filling!of!the!column!must! be!done!carefully:!the!stationary!phase!must!be!homogeneous.! ! Depot!of!the!sample:!The!sample!must!be!homogeneous!and!have!a!small!volume;!perhaps! a! filtration! or! evaporation! is! needed.! The! eluent! must! be! at! the! same! high! level! as! the! gel.! The! sample!is!added!slowly!and!carefully!with!a!pipette.! ! At!the!top!of!the!column,!an!eluent!reservoir!is!placed,!because!the!gel!doesn’t!have!to!be! dry.!The!eluent!is!slowly!passed!into!the!column,!with!a!flow!of!1!drop!all!the!5sec.!Every!20mL,!a! fraction!is!collected!and!analyzed!with!a!TLC.! * * * *
Fig.24:!Scheme of!the!column!chromatography
24
*
! IR!spectroscopy!(FTIR)! !
This! spectroscopy! is! based! on! the! adsorption! of! an! infra! red! radiation! by! a! material.! We! can! analyze! the! chemical! compounds! through! the! detection! of! the! characteristic! vibration! of! the! chemical! bonds.! When! the! wavelength! of! the! light! approaches! the! vibration! energy! of! the! molecule,!the!molecule!adsorbs!the!radiation,!and!then!we!can!see!a!diminution!of!the!intensity.! All! the! vibration! don’t! give! an! adsorption,! it! depends! on! the! geometry! of! the! molecule! and! its! symmetry.!Every!adsorption!band!characterizes!a!group,!thanks!to!the!Group!theory.! ! The!analysis!is!made!with!the!Fourier!transform!infrared!spectroscopy.!The!light!goes!through! an!interferometer!and!is!modulated.!The!modulated!beam!is!reflected!by!two!mirrors!toward!the! sample!then!it!is!arrived!on!the!detector!to!be!turned!into!an!electric!signal.!After!an!application!of! the! Fourier! transform,! we! obtain! the! same! spectrum! as! a! conventional! infrared! spectroscopy! (Fig.25).! * * *
* *
Fig.25:!Picture!of!the!device!
25
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