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Cationic Polymerization: Commercial Significance and Polymer Types

This chapter explores cationic polymerization, focusing on commercial and technological significance. It provides detailed information on various cationic polymers, including Polyisobutylene (Vistanex, Oppanol), Hydrin rubber, and Polyoxymethylene (Delrin). It discusses the specifics of cationic polymerization processes like priming, initiation, and propagation, as well as the roles of Bronsted and Lewis acids as initiators. The chapter highlights the unique properties and applications of different cationic polymers, emphasizing their importance in adhesives, sealants, and elastomers, particularly in automotive and industrial applications.

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Cationic Polymerization: Commercial Significance and Polymer Types

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  1. Odian Book Chapter 5-2

  2. Cationic Polymerization

  3. Cationic Polymers Commercial and Technological Significance Chemical NameTrade NameFormula • Polyisobutylen Vistanex, Oppanol • Isobutylene-isoprene copolymer • and chlorinated copolymer ~98% ~2% Butyl Rubber and Chlorobutyl Delrin Celcon • Polyoxymethylene • Trioxane-epoxide copolymer ~2%

  4. Cationic Polymers Commercial and Technological Significance Chemical NameTrade NameFormula Hydrin Rubber • Polyepichlorohydrin Lycra or Spandex • Poly(THF) or Poly(tetramethylene oxide) • Polybischloromethyl Oxetane Penton

  5. Cationic Polymerizations R = electron releasing group Poly(isobutylene) R, R’=

  6. Cationic Polymerization …Also cyclics Hydrin Rubber Poly(oxymethylene) Delrin

  7. Cationic Polymerization 1) Priming 2) Initiation Step

  8. Cationic Polymerization 3) Propagation 4) CM

  9. Initiators A) Bronsted Acids ionic A  can not be too nucleophilic  HCl is not very good covalent Methanesulfonic acid

  10. Initiators B) 1)Lewis Acids SnCl4, AlCl3, TiCl4, BF3 R3Al, R2AlCl, RAlCl2 2) Co initiator

  11. Auto Ionization Bone dry

  12. Chain Transfer More Important in Cationic than in Anionic 1) To Monomer

  13. Chain Transfer 2) Ring Alkylation on Solvent

  14. Chain Transfer 3) Ring Alkylation on Polymer

  15. Chain Transfer 4) Hydride Abstraction from Polymer

  16. Poly(isobutylene) Low MW(Mn<50,000 g/mol) Liquids  adhesives caulking sealants motor oils -  important Tpzn= 0 to – 40 oC w/AlCl3

  17. Poly(isobutylene) High MW(Mn= 50,000-5,000,000) Elastomeric Tpzn= –100 oC w/ AlCl3 w/ 1-5 % isoprene (to vulcanize) Methylchloride as solvent  Slurry

  18. Butyl Rubber Advantages • Lower Temp Capability • -50 oC NO TM • -70 oC = TG • More Resistant to Ozone • Very Low Gas Permeability  inner tire tubes

  19. Temperature Dependence _ Xn 1/T

  20. Temperature Dependence TerminationandCT  As T  Break  change in mode of CT  [ions] vs [ion pairs]

  21. Complications 3-methyl-1-butene  As T  , % isomerization 

  22. Complications 3-methyl-1-butene Temp%isomerization -130 oC 100 % -100 oC 70 %

  23. Isomerization

  24. Cationic Living Polymerization

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