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New epoxide initiators for the controlled synthesis of functionalized polyisobutylenes
Author(s) -
Puskas Judit E.,
Michel Armin
Publication year - 2000
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/1521-3900(200010)161:1<141::aid-masy141>3.0.co;2-k
Subject(s) - epoxide , sn2 reaction , carbocation , isobutylene , isomerization , polymer chemistry , polymerization , chemistry , materials science , photochemistry , copolymer , polymer , organic chemistry , catalysis
The mechanism of initiation was investigated in isobutylene (IB) polymerizations initiated by epoxidized α‐methylstyrene (MSE) and 1,2‐epoxy‐2,4,4‐trimethylpentane (TMPO) in conjunction with TiCl 4 . The proposed mechanism predicts primary OH head groups and tertiary Cl end groups in the PIB. Model studies conducted with MSE/TiCl 4 and diisobutylene lead to ring closure yielding a substituted furanyl structure. Real‐time fiber‐optic refractive index monitoring was used to follow the initiation with the TMPO/TiCl 4 system. It was found that the cleavage of TMPO proceeds simultaneously by S N 1 and S N 2 mechanisms as proposed. The carbocation forming by the S N 1 route is proposed to initiate the polymerization of IB, but it was shown that excess TiCl 4 relative to TMPO was necessary for propagation. Isomerization and polyether formation by the S N 2 pathway lead to side reactions, reducing the initiating efficiency.