Journal of Polymer Science Part A: Polymer Chemistry, Vol.38, No.2, 310-320, 2000
Asymmetric anionic polymerization of maleimides bearing bulky substituents
Asymmetric anionic homopolymerizations of N-substituted maleimide (RMI) bearing bulky substituents [R = benzyl, diphenylmethyl (DPhMI), 9-fluorenyl (9FIMI), triphenylmethyl, (diphenylmethyloxycarbonyl)methyl, (9-fluorenyloxycarbonyl)methyl] were carried out with complexes of organometal compounds (alkyllithium, diethylzinc) with six chiral ligands to obtain optically active polymers. The chiroptical properties of the polymers were affected strongly by the substituents on nitrogen in the maleimide ring, the organometal and chiral ligands. Poly(DPhMI) initiated by an n-butyllithium/(-)-sparteine (Sp) complex showed a positive specific rotation ([alpha](435)(25) +60.3 degrees). Poly(9-FlMI) prepared with a florenyllithium/Sp complex exhibited the highest specific rotation (+65.7 degrees). The specific rotations of the poly(RMI) obtained were attributed to different contents between the stereogenic centers (S,S) and (R,R) based on threo-diisotactic structures of the main chain.
Keywords:N-substituted maleimide;asymmetric polymerization;bulky substituent;optically active polymer;anionic polymerization