1. Odian Book
Chapter 5-2

2. Cationic Polymerization

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

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

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

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 1) To Monomer
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
As T 
Termination  and CT 
Break
 change in mode of CT
 [ions] vs [ion pairs]

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

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

23. Isomerization

24. Cationic Living Polymerization