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Transcript of Phosphazenes as Fire Retardants in Aircraft Interiors Aircraft Interiors Harry Allcock, Catherine...

  • Phosphazenes as Fire Retardants in Aircraft Interiors

    Harry Allcock, Catherine Ambler, Jonathan Taylor, Thomas Hartle, Clay Kellam, Robbyn Prange, Michael

    McIntosh, Michael Coleman. Department of Chemistry and Materials Science and

    Engineering The Pennsylvania State University

    University Park, PA 16802 Support, FAA (Dr. Richard Lyon)

  • Outline

    • Why Phosphazenes for Fire Retardance? • Fire-proofing Polyurethanes • Block and Graft Copolymers for Fire-Resistant

    Blends with Commercial Organic Polymers – Block copolymers – Polystyrene with pendent phosphazene units – Fire-resistant polynorbornenes by ROMP – Cyclolinear polyalkenes by ADMET – Polymers with phosphate side groups

    • Conclusions and Future Directions

  • Why Polyphosphazenes?

    • Side groups and skeletal architecture easily tailorable – wide range of properties

    • Function through vapor and/or condensed phase fire retardance mechanisms

    • Phosphorus plus nitrogen increases char yield

  • Three Types of Phosphazene Structures for Fire Retardance

    • Cyclic, small-molecule phosphazenes covalently bonded to an organic polymer

    • Linear, high polymeric phosphazenes – Stand-alone use – Blends with conventional polymers

    • Block Copolymers

  • Small-Molecule Cyclic Phosphazenes

    N P

    N P N

    P

    OR ORRO

    RO

    OROR NaOR

    N P

    N P N

    P

    Cl ClCl

    Cl

    ClCl

    RNH2

    • Highly tailorable side groups, including functional groups for linkage to organic polymers

    • Thermo-oxidatively stable • Applications include use as additives,

    pendent functionalities, monomers for cyclolinear polymers

    N P

    N P N

    P

    NHR NHRRHN

    RHN

    NHRRHN

  • Polyphosphazene Synthesis

    N P

    Cl

    Cl N

    P N

    P

    N P

    Cl

    ClCl

    Cl

    ClCl

    N P

    OR

    OR

    N P

    NHR

    NHR

    250 °C

    n

    N P

    OR

    NR2

    n n n

    RO - Na+

    HNR 2H NR

    2

    RO - Na+

  • Living Cationic Polymerization

    P N PCl3 +PCl6

    --

    Cl

    Cl

    Cln Cl3P=NSiMe3 2 PCl5

    n

    • Polymerization of phosphoranimines • Molecular weight control through stoichiometry • Narrow polydispersities • Undergoes macromolecular substitutions • Living polymerization • Allows for synthesis of blocks, dendrimers, grafts, etc

  • Thermal Analysis Testing

  • Prototype Fire Resistant Materials

    Oxygen Index (OI)Polyphosphazene

    26

    24

    18

    N P

    nOC3H7

    OC3H7

    N P

    nOC 4H 9

    OC 4H 9

    N P

    nOC5H11

    OC5H11

  • Prototype Fire Resistant Materials

    32

    43

    46

    59

    Oxygen Index (OI)Polyphosphazene

    N P OCH2CF3 OCH2(CF2)3CF2H

    n

    N P O Cl O Cl

    Cl

    n

    N P O O Cl

    Cl

    n

    N P O O

    n

  • Phosphazene–Urethane Copolymers

    +

    - CO2

    N=P O

    O

    n

    COOH

    COOH

    N=P O

    O

    C O

    N N H

    C O

    N H

    n

    H

    COOH

    OCN N H

    C O

    N H

  • Thermal Analysis

    5 10 12 20 30

    20 20 20 21.5 23

    0 0.5 1.0 1.9 2.9

    0 5 10 20 30

    Char at 600o CLOI% Phosphorus% Phosphazene

  • Cyclic Phosphazene - Polyurethane Copolymers

    P N

    P

    N P

    N

    OPhOHRO

    OPhOH

    OR

    RO

    HOPhO

    + OCNPh(OCH2CH2)nPhNCO

    R = Ph, EtOEt,

    P N

    P

    N P

    N

    OPhORO

    OPhO

    OR

    RO

    OPhO

    C

    C

    C

    O N

    O NO

    N

    Ph

    Ph H

    H Ph

    H

  • Cyclic Phosphazene-Polyurethane Copolymers

    • Increased crosslinking ability

    • Covalently bound, non-migrating

    • Side group tailorablity

    • Low cost

  • Thermal Analysis

    Polyurethane + [NP(OPhOH)(OEtOEt)]3

    0% 10%

    20%

  • Phosphinimine Chemistry

    • Phosphinimine linkage -P=N-P- – Synergistic effects

    • Polymerization of diphenyl-p-styrylphosphine – Free radical – Anionic – Wide range of copolymers possible

    • Tailorability of phosphazene

  • Pendent Phosphazenes

    N

    P N

    P

    N P

    OR

    ORRO

    RO

    ORN

    P

    P

    P

    Toluene, AIBN

    - N2

    R = CH2CF3 R = C6H5

    N

    P N

    P

    N P

    OR

    ORRO

    RO

    ORN3

  • Acyclic Diene Metathesis (ADMET)

    • Intermolecular metathesis of dienes

    • Ethylene elimination favors high polymers

    • Catalyst selection, reaction conditions very reactivity and polymer molecular weight

  • ADMET for Cyclolinear Phosohazenes

    P N P

    N P N

    Cl R

    Cl R

    R R

    P N P

    N P N

    RR

    R R

    Na+ -O+

    O O

    O CH2OR =

    P N P

    N P N

    Cl Cl

    Cl Cl

    Cl Cl

    O CH2Na + -O+

  • Ring Opening Metathesis Polymerization

    • Ring Opening Metathesis Polymerization – ROMP

    • Metathesis of strained cyclic olefins

    • Living polymerization

    • Wide range of monomers available

  • Norbornene-Phosphazene Copolymers

    N

    P N

    P

    N P

    OR

    ORRO

    O

    ORRO

    N

    P N

    P

    N P

    OR

    ORRO

    RO

    ORO

    Grubbs Catalyst

    n

    R = CF3CH2- (17) EtOOCPh- (18) CH3CH2- (19) Ph- (20)

  • Thermal Analysis

  • Thermal Analysis

  • Phosphorylated Phosphazenes

    N P x

    O

    O

    P

    O

    OR O

    RO

    P

    O

    OR

    O RO

    • Improve fire resistance of polyphosphazenes

    • Immobilize fire retardant additive onto polymer backbone

    • Functionalize side groups with phosphate derivatives

  • Prepolymer Synthesis

    N P

    Cl

    Cl

    N P

    O

    O

    n n

    N P

    O

    O

    n N P

    O

    O

    n

    O

    O

    OH

    OH

    Na+-O O

    - NaCl

    BBr3

    CH2Cl2

    BBr3

    CHCl3

    Na+-O OCH3

    OCH3

    OCH3

    - NaCl

  • Phosphorylation

    Cl P

    O

    O O

    N P

    O

    O

    x

    OH

    OH THF

    NEt3, CuCl

    N P

    P

    O

    O O

    P

    O

    O O

    x

    O

    O O

    O

  • Polystyrene Additives

    P N P NPN

    OO

    O

    O O

    O

    O O

    O

    O

    O

    O

    P P

    P

    P

    P

    P

    O

    O

    O

    O

    O

    RO RO

    RO RO

    OR OR

    OR OR

    OR OR

    RO RO

    O

    Trimer 2 R = Ph

    Trimer 1 R = Et

  • Thermal Analysis

    1 1 2

    22 24 28

    10 20 30

    7 12 17

    19 20 21

    10 20 30

    4 8 15

    24 26 25

    10 20 30

    Trimer 2

    Triphenyl Phosphate

    Trimer 1

    1180---------- % Char at 500 oCLOIWt %Additive

    R = Et

    R = Ph

  • Phosphazene Poly(ethylene oxide) Block Copolymers

    R' (CH2CH2O)n CH2CH2NH2 + Br P R

    R NSiMe3

    R' = NH2 or CH3O R = OCH2CF3

    -HBr

    R' (CH2CH2O)n CH2CH2N(H)(R2P=NSiMe3)

    CH2Cl2PCl5

    R' (CH2CH2O)n CH2CH2N(H)[R2P=NPCl3 +]PCl6

    -

    R' = NH(R2P=NSiMe3) R' = CH3O

  • Block Copolymers, Continued

    R' (CH2CH2O)n CH2CH2N(H)[R2P=NPCl3 +]PCl6

    -

    Cl3P=NSiMe3 CH2Cl2

    R' (CH2CH2O)n CH2CH2N(H)R2P[N=PCl2]m

    NaOCH2CF3 dioxane

    R' (CH2CH2O)n CH2CH2N(H)R2P[N=PR2]m

    R = OCH2CF3

  • Phosphazene-Styrene Block Copolymers

    P N

    R

    R

    P

    R

    R

    P N

    Cl

    Cl

    PCl3] +P N[Cl3

    (Ph)2P=N

    PPh2 P(Ph2)=NSiMe3

    N P(Ph)2

    n-Bu n-Bu

    n-Bu n-Bu

    1. nBuLi 2. Ph2PCl

    x

    N3SiMe3

    x x

    2) NaR

    1) 1/2

    R = OCH2CF3

    n-2

    [PCl6] -

    n

    x x

  • Conclusions and Future Directions

    • Phosphazene rings and polymer chains are highly effective fire retardant species

    • They function by both vapor phase flame quenching and char formation

    • A variety of options have been developed for the incorporation of phosphazene units into polymers both for stand-alone polyphosphazenes and material for blends and IPNs with normal organic polymers

    • Future work will involve evaluati