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Odian Book Chapter 7

Odian Book Chapter 7. Ring-opening Polymerization (I). Ring-opening Polymerization. Anionic Cationic Ring Opening Metathesis Polymerization (ROMP) . Commercially Important ROP. cationic. Tg Tm -82 181. cationic anionic. -41 66. cationic. -84 (57). PTMO.

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Odian Book Chapter 7

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  1. Odian Book Chapter 7

  2. Ring-opening Polymerization (I)

  3. Ring-opening Polymerization • Anionic • Cationic • Ring Opening Metathesis Polymerization (ROMP)

  4. Commercially Important ROP cationic TgTm -82 181 cationic anionic -41 66 cationic -84 (57) PTMO

  5. Commercially Important ROP cationic anionic TgTm -60 67 Poly(caprolactone) 53 230 cationic anionic Poly(caprolactam) -124 -50 cationic anionic D4, D3, Di

  6. Ring-opening Polymerization kP kdp linear cyclic • X = ; ; ; ; • Heteroatom provide site for coordination w/ appropriate anionic, • cationic or coordinating initiator (kinetic accessibility) Keq= kP / kdp = 1 / [Monomer]e G= - R T ln Keq= R T ln [M]e

  7. Ring Strain of Cycloalkanes CYCLOALKANE (kcal/mole) (kJ/mole) Cyclopropane 27.6 115 Cyclobutane 26.4 110 Cyclopentane 6.5 27 Cyclohexane 0.0 0 Cycloheptane 6.4 27 Cyclooctane 10.0 42 Cyclononane 12.9 54 Cyclodecane 12.0 50 Cyclopentadecane 1.5 6

  8. Ring Strain Ring Size 3,4 5,6,7 8

  9. Free Energy G= H -TS

  10. Ring Opening Pzn Types of Ring Compound Propagating Species Mx detected up to x = Cycloalkenes Cyclic Ethers Caprolactam Cyclic Siloxanes 14 9 5 400 Metal Carbene THF w/ CF3SO3H Anionic Anionic KOH • Series of Ring Sizes • Concentration Distribution • % Cyclics  w/ decreasing [M]

  11. Cyclic Ethers polymerization difficult (substituents usually will prevent it) unreactive tertrahydropyran dioxane

  12. Cyclic Ethers 1) Ethylene Oxide Living Polymerization (DMSO) PEO

  13. Cyclic Ethers 2) Propylene Oxide Monomer is usually a racemic mixture of enantiomers

  14. Poly(propylene oxide) Initiation Propagation Soft segments in polyurethane Avg Mn limited to ~5,000 g/mol Limited by CT to monomer acidify Termination 1o & 2o

  15. Chain Transfer to Monomer Proton abstraction 200 oC Leads to imperfect networks with “dangling ends” fast allylic structure f = 1 Allylic end group

  16. Functionality Control Polyhydroxy compounds  CTA (CTA) networks fAVG ~ 2.5 f = 3

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