Sol Gel Lezione Bari

Solsaredispersionsofcolloidalpar.clesinaliquid.

Colloidsaresolidpar.cleswithdiametersof1‐100nm

Agelisainterconnected,rigidnetworkwithporesof

submicrometerdimensionsandpolymericchainswhose

averagelengthisgreaterthanamicrometer.

Interestinthesol‐gelprocessingofinorganicceramicandglassmaterialsbeganasearlyasthemid‐1800swith

Ebelmanl,andGraham’sstudiesonsilicagels.Theseearlyinves.gatorsobservedthatthehydrolysisoftetraethyl

orthosilicate(TEOS),Si(OC2H5),underacidiccondi.onsyieldedSiO2 intheformofa"glass‐likematerial”.Fibers

could be drawn from the viscous gel, and even monolithic op.cal lenses or composites formed. However,

extremely long drying 5mes of 1 year ormore were necessary to avoid the silica gels fracturing into a fine

powder,andconsequentlytherewasliQletechnologicalinterest.

…Royandcoworkersrecognizedthepoten.alforachievingveryhighlevelsofchemicalhomogeneityincolloidalgels

andusedthesol‐gelmethodinthe1950and1960stosynthesizealargenumberofnovelceramicoxidecomposi.ons,

involvingAI,Si,Ti,Zr,etc.,thatcouldnotbemadeusingtradi.onalceramicpowdermethods.Duringthesameperiod

Iler's pioneering work in silica chemistry led to the commercial development of colloidal silica powders, Du Pont's

colloidalLudoxspheres.Stoberetal.extended Iler'sfindings toshowthatusingammoniaasacatalyst for theTEOS

hydrolysisreac.oncouldcontrolboththemorphologyandsizeofthepowders,yieldingtheso‐calledStoberspherical

silicapowder.

Thefinalsizeofthesphericalsilicapowderisafunc.onoftheini.alconcentra.onofwaterandammonia,thetypeof

silicon alkoxide (methyl, ethyl, pentyl, esters, and alcohol (methyl, ethyl, butyl, pentyl) mixture used, and reactant

temperature.

Xerogelfilm

Sol

Densefilm Aerogel DenseCeramics

Uniformpar.cles

Ceramicfibres

Extrac.o

nof

solven

t

PrecursorSolu/ons

WetGel

Densefilm Aerogel DenseCeramics

Uniformpar.cles

Ceramicfibres

Furnace

Xerogel

Heat

Heat

Coa.ng

Hydrolysis,polimeriza.on

Sol‐GelTechnologies

3Finalproduct

amorphous,nanocrystalline,crystalline

Mainstepof

THESOL‐GELROUTE1

Solu.onofprecuros:

alkoxide,salts,complexessolvent,addi.ves

2Gel

porousandamorphoussolid

1 2 3Hydrolysis

Condensa/on

Densifica/on

Hydrolysisandcondensa.onofSiliconCompound

Genera.onofreac.vespecies:hydrolysis

Networkforma.on:condensa.on

‐ Kindofcatalyst(pH)‐ Kindofmolecularprecursor

‐ Water:ORra.o

‐ Solvent‐ Temperature

‐ Addi.ves(e.g.electrolytes,surfactants,complexingagent)

‐ Precursorconcentra.on‐ Rela.veconcentre.onoftheprecursorsinmul.‐componentsystems

Influenceofthecatalyst

Acidiccondi.ons

Alkalinecondi.ons(similarF‐)

Hydrolysisreac.ons: X=R Y=H

Condensa.onreac.ons: X=RorH; Y=Si

Alcoholexchange: X=R, Y=R’

pHdependenceofhydrolysisandcondensa.on

Hydrolisisandcondensa5on

occurconcomitantly!

O R O R S i

R O R O

O H O H S i

R O R O

O R O H S i

H O H O

O R O H S i

R O R O

O H O H S i

H O H O

O H S i

R O R O

O R O S i O R O R

O R S i

R O O R

O S i O R O R O R S i

R O R O

O O S i O R O R

O R S i

R O R O

O R O S i O R O R

H 2 O c a t .

O H S i

R O R O

O R O S i O R O R

O R S i

R O O R

O S i O R O R O O H S i

R O R O

O H S i R O

O S i

O R O R

O O S i

R O R O

R O S i

R O

R O O S i O

O R

R O O R O R

O O S i O R O R

H O R O

R O O S i O R O R

O S i

R O O R

O S i O R O R O O H S i

R O R O

S i O R R O R O

Hydrolisis

Condensa.on

InfluenceoftheSubs.tuents

Stericandelectronicinfluenceof–ORgroups:

Reac.onRate Si(OMe)4>Si(OEt)4>Si(OnPr)4>Si(OiPr)4

Electrondensity@Silicon

Acidcatalysis: reac.onratesdecreasefromleltoright

Basecatalysys: reac.onratesincreasefromleltoright

AcidityofSi‐OHgroups

Lowest

Higest

pHandNetworkStructure

Alkalinecondi.ons

X=RorH; Y=Si

NucleofilaQack@themostcondensedSiatoms

pHandNetworkStructure

Acidiccondi.ons

Reac5ons@theleastcondensedSiatoms

Alkoxygroup/H2Ora.o

Theore.cally

Rw=2 Si(OR)4 → SiO2

Rw=1 Si(OR)4 → Si(OH)4 without condensation

In practice:

More H2O (lower Rw) favors the formation of Si-OH over Si-O-Si (hydrolitic depolimerization)

Even with Rw > 2 only mixtures of [SiOx(OH)y(OR)z]n (2x+y+z = 4) are obtained

MetalOxide‐basedsystems

Si(OR)4vs.M(OR)n

Reac.vity

Si(OiPr)4<<<Ti(OiPr)4<Zr(OiPr)4<Ce(OiPr)4

StrongerLewisacidthansiliconalkoxides:

NucleofilicaQackisfavoured

Strongincreaseofhydrolysisrates

HydrolysisTi(OR)4ca.100.mesfasterthanThatofSi(OR)4

i)  Catalystisnotrequiredii)  Modera.onofmetalalkoxidesreac.vity

Strongmetal‐anioninterac5onmayinfluencesol‐gelprocessing

‐ sol‐gelreac.onsmayproceeddifferentlywhendifferentsaltof

thesamemetalareemployed

‐ Strongcoordina.onofthecounter‐ionblockscoordina.onsitesthusleadingtotoasmallerdegreeofcondensa.on

‐ Thecompleteremovalofthecounter‐ionfrommaterialsmaybedifficultor

mayrequirespecialpost‐synthesisprocedure

ORGANIC‐INORGANICHYBRIDSOL‐GELMATERIALS

ItisaQrac.vetocombine,forexample,aninorganicglasswithan

organicpolymeronamolecularlevel

Itisequallyself‐evidentthatthecondi.onsrequiredforprocessinga

glassareen.relyincompa.blewiththemuchlowerprocessing

temperaturesneededforpolymers

Thisallchangedwiththerealiza.oninthe1980sthatorganic

componentscouldbecombinedwithinorganicglassesusingthesol‐gel

process

Oneofthefirstwellknownexampleoforganic‐inorganicmaterial:

inorganicpigmentorfillersdispersedinorganiccomponent(solvents,

surfactant,polymers,…)–paintandpolymerindustries–op.calor

mechanicalproper.esimprovement

ORGANIC‐INORGANICHYBRIDSOL‐GELMATERIALS

Organicorbioac.vecomponentscanbecombinedin

nanomaterialsthroughsol‐gelchemistry,thanksto:

‐thesol‐gelsolinorganicchemistryprocess

(‘chimiedouce’):hydrolysisandcondensa.on

reac.onsoccuratT<200°C

‐thegreatstabilityoftheSi‐Cbond

Classification on the base of the nature of the chemical links

(interface) between organic and inorganic component

CLASSIHYBRIDS:onlyweakinterac.onsarepresentbetweenorganicand

inorganiccomponents(Hbonds,vanderWaals,π−πinterac.ons)

CLASSIIHYBRIDS:organicandinorganicpartarelinkedthroughstongchemical

bonds

Func.onalmolecule:organicdye(linearornonlinearop.calproper.es),

complexes,polimerizablegroups….

Rhodamine6G

RhodamineB

Rapidgelforma.onbyfilmdeposi.on

Fastevapora.onofthesolventfromathingellayer

Xerogel

Filmbysol‐gel

Whichmaterialcanbecoated?

Glasses

Ceramics

Metals

Polimers

Coa.ngmaterials:

Inorganic

Hybridinorganic‐organic

nanopar.cles

Principalcoa.ngtechniques:

Dipcoa.ng

Spincoa.ng

Spraycoa.ng

Flowcoa.ng

Dipcoa.ngtechnique:thesubstrateisimmersedinaliquidandthenwithdrawnatwell‐definedspeedundercontrolledCondi.ons(temperature;humidity…)

Dipcoa.ng

dipping wetlayerforma.on

solventevapora.on

Applica.onofcoa.ngsolu.on

Spreadingofthefilm

Solventevapora.on

Inthespincoa.ngprocess,thesubstratespinsaround

anaxiswhichshouldbeperpendiculartothecoa.ngarea

07/05/09 10:13SCHOTT AG - Color Effect Glass

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Color Effect Glass

NARIMA™ color effect glass

from SCHOTT

Reference objects

NARIMA™ - The living glass

This dichroic color effect glass from SCHOTT produces dazzling variable color effects

with spectacular depth effects depending on the position, reflection and transmittance.

Extremely thin layers are applied to the glass

using the SOL-GEL dipping process. The coated

glass subsequently consists of multiple optical

interference layers that account for the various

intentional color effects.

The predominantly oxidic layers are hard and

highly resistant to both scratches and

chemicals.

A combination of highly refractive and low-

refractive layers results in a rainbow effect.

Different colors result depending on incident

solar radiation, the viewing angle and the

background.

NARIMA™ - The living glass (product range)

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NARIMA™ on float glass

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07/05/09 10:05Evonik Degussa Silanes - Sol-Gel Modular System

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Silane Contacts

Breaking New Ground:

A World First from Evonik Degussa: Modular Sol-Gel System for Coating Metals

Whenever conventional coating systems containing standard organic binders reach the limits of their

capabilities, sol-gel systems are used. Up to now, these have had the disadvantage of being

technically difficult to handle. But things are about to change, thanks to the specialists of Evonik

Degussa's Aerosil & Silanes Business Unit. The modular system consists of various water-based sol-

gel components comprising a water-based binder and other water-based additives. For the first time

ever, formulators and developers of coating systems are being offered a simple method for producing

sol-gel coatings with specific properties and good storage stability— thanks to Evonik Degussa's new

SIVO® SOL technology. Both hard and flexible SIVO® SOL technology is a novel, modularly

organized, water-based sol-gel system that is particularly suitable for metal pretreatment and metal

coating applications. The additives have been specially designed for compatibility with the new sol-gel

binder Dynasylan® SIVO 110. The modular concept allows an unusually high degree of flexibility in

the formulation of water-based scratch- and abrasion-resistant sol-gel coatings, which can also be

given anticorrosive or easy-to-clean properties if required. In addition to Dynasylan® SIVO 110, the

new sol-gel system consists of three additives: the neutralizing agent SIVO 111, the anti-fingerprint

and oleophobizing additive SIVO 112, and the hydrophobizing additive SIVO 113 for improved

weathering stability.

The main applications center on metal coatings as used in metal pretreatment, corrosion-protection

primers, and anti-fingerprint finishes. The additives are mixed into the base component in various

concentrations, depending on the field of application, to achieve the required properties in the coating.

The coating films obtained are hard and resistant to abrasion as well as to chemicals and solvents, yet

possess surprising flexibility. SIVO® SOL technology is particularly suitable for aluminum, steel,

galvanized steel, and other pretreated metal surfaces.

The system is usually applied to the substrate by spraying or dipping. It significantly improves the

corrosion properties of metal surfaces. Other possible applications SIVO® SOL technology can be

used for topcoats on metals, glass, and ceramic materials. It is also suitable for the manufacture of

easy-to-clean and anti-graffiti surfaces. Inorganic silane-based coatings are significantly harder than

traditional organic binders. They also react chemically with the metal surface and have the ability to

improve adhesion of further coating films. Acting as barriers to water and salts, they inhibit corrosion

and generally show outstanding weathering resistance. However, systems of this type have so far

suffered from the disadvantage that the coatings could be obtained only via high-solvent formulations.

With the new Dynasylan® SIVO class of products, Evonik Degussa has overcome this traditional

drawback. SIVO® SOL technology is a water-based modular system for the formulation of inorganic

sol-gel coating materials that are virtually solvent-free and are stable in storage.

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Evonik Degussa Dynasylan® - Welcome Silane Innovations Market Expansion Sol-Gel Modular System

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Multifunctional Silane

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These are designed to fulfill

even the most demanding

requirements of the adhesives

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more

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Imagination with Silanes!

Organofunctional silanes, most

commonly called silanes can

make a huge impact on

coatings even in small

amounts.

more

Here you find our other

brands in the internet:

Protectosil® Building

Protection - Europe and

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07/05/09 10:07Evonik Degussa Silanes - Market Expansion

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Silane Innovations


Market Expansion



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Silane Contacts

Evonik Degussa is the Number 1 in the Global Silanes Business

And this is why our Market Expansion Team is continuously screening for brand new innovative

solutions for You!

Novel Sol-Gel Systems:

Corrosion

Protection:

(left Standard

Primer,

right SIVO SOL®

Technology)

Wood Protection Systems:

... and a lot more. Come and visit us more often!

We identify and evaluate new market and business opportunities for our specialty silanes. Together

with you we develop new business ideas and partnerships. Hence, we are always happy to hear your

suggestions and queries.

Please get in touch with us at [email protected]



Evonik Degussa Dynasylan® - Welcome Silane Innovations Market Expansion

Degussa is now Evonik.

As of September 12, 2007, what was Degussa isnow the Chemicals Business Area of the newEvonik Industries. For further information on this





Silane Contacts


Systems™





more

Solutions beyond






amounts.

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ROW


Protection - NAFTA




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07/05/09 10:06Evonik Degussa Silanes - Impregnating Agent for Wood Surfaces

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Dynasylan® SIVO 121 - Evonik Degussa's New Solvent-Free and

Permeable Protective Impregnating Agent for Wood Surfaces

Evonik Degussa GmbH will shortly be launching on the market a new protective impregnating agent for

wood surfaces under the brand name Dynasylan® SIVO 121.

According to Dr. Burkhard Standke of Evonik Degussa Technical Service, Dynasylan® SIVO 121 has

several advantages over commonly available commercial products: "The water- and dirt-repellent

properties are particularly impressive. This means that attack of the wood surfaces by microorganisms

such as molds is significantly reduced. Dynasylan® SIVO 121 is suitable for both untreated and

impregnated woods. In contrast to the oils and waxes currently used for the purpose, it is odorless.

It is also non-toxic and solvent-free, and therefore not subject to labeling regulations under German

chemicals legislation." Standke adds: "The lower thickness of the applied layer means that the product

is virtually invisible. But it has extraordinarily high weathering resistance and, depending on the

concentration, is effective for up to three years."

Evonik Degussa, the global market leader in specialty chemicals, will supply the new water-based

impregnating agent initially to producers and formulators of wood preservatives and to wholesale

manufacturers of, for example, garden furniture. Dynasylan® SIVO 121 is suitable for both untreated

and impregnated woods as well as for weathered surfaces of originally glazed, waxed, or varnished

woods. The new wood preservative from Degussa does not affect the expansion and contraction

behavior of the treated wood.

This makes it suitable also for woods without ground contact in exterior applications. Organofunctional

silanes with the Dynasylan® brand name are used in a broad range of applications. In addition to the

application described here, they are used, for example, in adhesives and fillers, in foundry resins, in

insulation materials, as additives in paints and coatings, and in the electronics industry.

In addition, Protectosil®, another product group from the Silanes Business Line, protects buildings

against graffiti and saves on the considerable cost of its removal. The Aerosil & Silanes Business Unit

employs a total of about 1,900 people at nine sites in Europe, the U.S., and Asia. Based on 60 years

of experience, the products of the Aerosil & Silanes Business Unit occupy leading global positions. To

ensure that this remains so, research focuses on continual development of customer-specific solutions;

innovative products for building protection, electronics, and high-performance ceramics open up new

fields of application.

please get also much more information here: www.specialchem4coatings.com/tc/silanes/

Dynasylan® SIVO 121 is unfortunately currently not available in NAFTA market.



Evonik Degussa Dynasylan® - Welcome Silane Innovations Market Expansion Impregnating Agent for WoodSurfaces





Silane Contacts


Systems™





more

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amounts.

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Core‐shellcapsuleforcarryingfunc.onalcontent

CommercialIsomersSunscreenSPF20withUVPearls®

Bibliography

L.L.HenchandJ.K.West,TheSol‐Gelprocess,ChemicalReview,1990,90,33‐72

A.Pierre,Introduc.ontoSol‐gelProcessing,Springer1998

N.Hüsing&U.Schubert,SynthesisofInorganicMaterials,WileyVCH(2000)

C.J.Brinker&G.W.SchererSol‐GelScience:ThePhysicsandChemistryofSol‐GelProcessing

AcademicPressInc.:SanDiego,1990

C.Sanchez,B.Julián,P.Belleville,M.Popall,JournalofMaterialsChemistry,2005,15,3559

G.Kickelbick,HybridMaterials:Synthesis,Characteriza.onandApplica.ons,WileyVCH(2006)

Sol Gel Lezione Bari

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