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  • Silicon Symposium

    New Hydrophilic Polymeric Coupling Agents Derived from Epoxy Functional Monomers

    Ferdinand Gonzaga, Jonathan Goff and Gerald L. Larson

    Gelest, Inc.

    Gelest - Enabling Your Technology

    PresenterPresentation Notes

    ----- Meeting Notes (8/15/11 07:00) -----This talk is about expanding the use of silicones in organic polymers or modifying siloxanes to achieve structural properties more consistent with organic polymers. The total output of synthetic polymers is 300 billion kg/year. Silicones are about 1%. Incorporate silicones at 1% and we've doubled the total ouput of silicones.Traditional incorporation of siloxanes as comomonomrs in organic polymers have only been successful in high value, low volume niche markets

  • Coupling Agents

    Molecules which have the ability to create a durable bond between organic and inorganic materials.

    Silane coupling agents: Model structure:

    (CH 2 ) n

    R

    Si

    X X X

    R: organofunctional group

    Spacer

    X: Hydrolyzable groups: Alkoxy Acyloxy Halogen Amine (cyclic azasilanes)

  • Properties of Coupling Agents

    Control and tailor surface or interfacial properties of inorganic materials

    Properties:

    Wettability: Hydrophilicity Hydrophobicity Omniphobicity

    Adhesion Ordering (monolayers) Reactivity Refractive Index

    Substrates:

    Siliceous materials: Silica Glass

    Aluminium oxides Zirconium oxides Tin, Nickel Oxides Titanium oxides Boron, Iron and Carbon oxides

  • B. Arkles, Chemtech, 7(12), 766,1977.

    Bonding Mechanism Hydrolysis Condensation

    Hydrogen Bonding

    Bond Formation

  • Coating Degradation Hydrolytic stability of the oxane bond between

    silane and substrate

    Application in an aggressive environment (acidic/basic/saline)

    (CH 2 ) n

    R

    Si

    X X X Conventional Silane

    Gelest solution: dipodal silane coupling agents

  • Improved Stability from Dipodals

    40

    60

    80

    100

    120

    0 20 40 60 80 100 120 140 160 180

    Stat

    ic W

    ater

    Con

    tact

    Ang

    le ,

    ()

    t (days in 6 M HCl)

    SiOC2H5

    OC2H5OC2H5

    Si SiOCH3

    OCH3

    OCH3OCH3H3CO

    Tighter networks Up to X105 greater hydrolytic resistance

  • Multipodals coupling agents?

    Dipodals synthesis: Synthetic challenges Time consuming Cost

    Polymerization of available monomers Mild, tolerant to functional groups Simple, cost-effective

    Polymeric, multipodal coupling agents?

    Polymerization of Epoxides

    SiX3 SiX3 SiX3

    R R

    R R

  • Ring Opening Epoxide Polymerization Anionic ROP:

    Cationic ROP:

    Lewis Acid Catalyzed (Coordination catalyst):

    No strong nucleophile/electrophile No formal charge No hydrolytic conditions

  • Tris(pentafluorophenyl) Borane Active at very low loadings Robust and easy to handle (Air, Moisture) Commercially available

    Widely used in Silicon chemistry:

    Dehydrogenative coupling of silanes and alcohols Hydrosilylation of ketones Piers-Rubinsztajn reaction

  • Proof of Principle Polymerisation

    SIG5820.0

    Conditions: Initiator (methallyl alcohol): 1 equiv. Monomer: 10 equiv. Catalyst: 0.8 mol% Slow monomer addition

    Results: Mw:2,600g/mol Mn:1,702 Mw/Mn: 1.49 Yield: 96% Complete conversion (1H NMR)

    Exotherm!

  • SIG5820.0

    Conditions: Initiator (methallyl alcohol): 1 equiv. Monomer: 20 equiv. Catalyst: 0.8 mol% Slow monomer addition 2nd charge of catalyst required

    Milder exotherm

    Proof of Principle (2)

    Results: Mw:2,391g/mol Mn:1,440 Mw/Mn: 1.66 Yield: 93%

  • Copolymerization with Trialkoxysilanes

    Conditions: Initiator (methallyl alcohol): 1 equiv. Monomer: 20 equiv. (9:1 ratio) Catalyst: 0.8 mol% Slow monomer addition

    Results: Mw:4,388g/mol Mn:2,334 Mw/Mn: 1.88 Yield: 85%

    9 1

    Triethoxysilyl groups unaffected during process

  • PEG as Polymerization initiator

    Conditions: Initiator (methallyl alcohol): 1 equiv. Monomer: 6 equiv. (2:1 ratio) Catalyst: 0.8 mol% Slow monomer addition

    Results: Mw:2,464 g/mol Mn: 1,388 Mw/Mn: 1.78 Yield: 86%

    4 2

    Access to functional block-copolymers

  • NMR Analysis

    a

    a b

    b

    c

    c

    d d

    e, e, h, h

    e

    e e

    f

    f

    g

    f, f

    g

    g, g

    h

    h e

    i

    i

    j

    j

  • Epoxy-PEG monomers

    Conditions: Initiator (methallyl alcohol): 1 equiv. Monomer: 20 equiv. (1:1 ratio) 60C, Catalyst: 5 mol%

    Results: Mw: 4,152 g/mol Mn: 1,269 Mw/Mn: 3.27 Yield: 78%

    Need to optimize reaction conditions

    10 10

  • Synthesis Conclusions Epoxides efficiently polymerized by B(C6F5)3 Polymerization orthogonal to Alkoxysilanes

    Access to various architectures/functionalities:

    Reaction sensitive to experimental conditions:

    Moisture Induction time and exotherm variability Discrepancy calculated/experimental MW

  • Polymeric Coupling Agents Efficiency

    Objective: assess wetting behavior of 3 PCA thin films. Plan of Action:

    Design experimental procedure for surface modification Treat BoroSilicate glass with PCA (3) Analyze efficiency using Contact Angle measurements

    PCA-TMS mPEG-PCA PCA-(PEG)m PCA-TMS

  • Experimental Procedure

    Borosilicate glass slide cleaning: Ethanol wash / Nitrogen dried Acid Etch:

    1. Glass slides dipped for 45minutes in 4% aqueous HCl 2. Rinse (DI / Ethanol / Acetone) 3. Nitrogen dried Coating:

    1. Glass slides dipped for one hour in reactive formulation (90% Ethanol, 5% Deionized Water, 5% PCA, 0.05% Acetic Acid) 2. Rinse (Ethanol) / Dry (N2) 3. Cure (80C; 1 hour) 4. Cool down (dessicator) Contact Angle measurement

  • Results

    PCA-TMS mPEG-PCA

    57

    24

    41

    2121

    30

    0

    10

    20

    30

    40

    50

    60

    PCA-TMS mPEG-PCACoupling Agent

    Con

    tact

    Ang

    le (D

    egre

    es)

    WaterDiiodomethaneHexadecane

  • PCA-(PEG)m

    Results

    ( 6 measurements averaged, 6 slides)

    57

    24

    5

    0

    10

    20

    30

    40

    50

    60

    PCA-TMS mPEG-PCA PCA-(PEG)n

    Coupling Agent

    Cont

    act A

    ngle

    (Deg

    rees

    )

    Water

    Super-wetting coupling agent

  • Conclusions / Future Work

    New synthetic route to polymeric coupling agents Mild, versatile process

    Access to various architectures/functionalities

    Future work:

    Improve experimental conditions Extend methodology to new monomers / initiators Formulate new coatings Durability tests

    New Hydrophilic Polymeric Coupling Agents Derived from Epoxy Functional Monomers Ferdinand Gonzaga, Jonathan Goff and Gerald L. LarsonGelest, Inc.Coupling Agents Slide Number 3Slide Number 4Slide Number 5Improved Stability from Dipodals Multipodals coupling agents? Ring Opening Epoxide Polymerization Tris(pentafluorophenyl) Borane Proof of Principle Polymerisation Proof of Principle (2) Copolymerization with Trialkoxysilanes PEG as Polymerization initiator NMR Analysis Epoxy-PEG monomers Synthesis Conclusions Polymeric Coupling Agents Efficiency Experimental Procedure ResultsSlide Number 20Slide Number 21