Polymer Synthesis CHEM 421 Odian Book Chapter 7
Polymer Synthesis CHEM 421 • Odian Book Chapter 7
Polymer Synthesis CHEM 421 Ring-opening Polymerization (I)
Ring-opening Polymerization Polymer Synthesis CHEM 421 • Anionic • Cationic • Ring Opening Metathesis Polymerization (ROMP)
Commercially Important ROP cationic Polymer Synthesis CHEM 421 Tg -82 Tm 181 -41 66 -84 (57) cationic anionic cationic PTMO
Commercially Important ROP cationic anionic Polymer Synthesis CHEM 421 Tg Tm -60 67 Poly(caprolactone) cationic anionic 53 230 Poly(caprolactam) -124 -50 cationic anionic D 4, D 3, Di
Ring-opening Polymerization Polymer Synthesis CHEM 421 k. P kdp cyclic X= ; ; linear ; ; • Heteroatom provide site for coordination w/ appropriate anionic, cationic or coordinating initiator (kinetic accessibility) Keq= k. P / kdp = 1 / [Monomer]e G= - R T ln Keq= R T ln [M]e
Ring Strain of Cycloalkanes CYCLOALKANE Cyclopropane Cyclobutane Cyclopentane Cyclohexane Cycloheptane Cyclooctane Cyclononane Cyclodecane Cyclopentadecane Polymer Synthesis CHEM 421 (kcal/mole) (k. J/mole) 27. 6 26. 4 6. 5 0. 0 6. 4 10. 0 12. 9 12. 0 1. 5 110 27 42 54 50 6
Ring Strain Ring Size 3, 4 5, 6, 7 8 Polymer Synthesis CHEM 421
Free Energy G= H -T S # atoms in Ring 3, 4 H S G [M]e Polymer Synthesis CHEM 421 ext. of pzn @ Equil
Ring Opening Pzn Types of Ring Compound Mx detected up to x = Polymer Synthesis CHEM 421 Propagating Species Cycloalkenes 14 Metal Carbene Cyclic Ethers 9 THF w/ CF 3 SO 3 H Caprolactam 5 Anionic 400 Anionic KOH Cyclic Siloxanes 1) Series of Ring Sizes 2) Concentration Distribution 3) % Cyclics w/ decreasing [M]
Cyclic Ethers Polymer Synthesis CHEM 421 polymerization difficult (substituents usually will prevent it) unreactive tertrahydropyran dioxane
Cyclic Ethers 1) Ethylene Oxide Living Polymerization (DMSO) PEO Polymer Synthesis CHEM 421
Cyclic Ethers 2) Propylene Oxide Monomer is usually a racemic mixture of enantiomers Polymer Synthesis CHEM 421
Poly(propylene oxide) Polymer Synthesis CHEM 421 Initiation Propagation Termination Soft segments in polyurethane acidify Avg Mn limited to ~5, 000 g/mol Limited by CT to monomer 1 o & 2 o
Chain Transfer to Monomer 200 o. C Polymer Synthesis CHEM 421 Proton abstraction fast Leads to imperfect networks with “dangling ends” allylic structure f=1 Allylic end group
Functionality Control (CTA) Polymer Synthesis CHEM 421 Polyhydroxy compounds CTA f. AVG ~ 2. 5 networks f=3
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