ANIONIC-POLYMERIZATION OF N-SUBSTITUTED MALEIMIDE .6. EFFECTS OF COUNTER CATION ON THE ANIONIC-POLYMERIZATION OF N-PHENYLMALEIMIDE WITH ALKALI-METAL TERT-BUTOXIDES

Effects of counter cation on the anionic polymerization of N‐phenylmaleimide (N‐PMI) were investigated with alkali metal tert‐butoxides. N‐PMI was more rapidly polymerized in the polymerization system with a larger size of counter cation (K+ > Na+ > Li+, e.g., 100% for K+, 20 min, and 2.7% for Li+, 90 min, in THF at −72°C). A significant temperature effect was observed for lithium tert‐butoxide as at 0°C the polymer yield was increased to 89% in THF. On the solvent effect, the overall polymerization rates for the every system initiated with alkali tert‐butoxide were lowered in toluene compared to those in THF. The polymerization system with sodium as counter cation showed the unique solvent effect that the fairly high polymerization rate in THF comparable to that observed in the system with potassium cation was drastically reduced in toluene to the almost same rate as that with lithium cation. The influences of crown ethers and common salt were also investigated. The molecular weight distribution of the poly(N‐PMI) was also influenced by the counter cation size. The polymerization system with lithium cation gave the narrowest molecular weight distribution and it became broader as the size of counter cation was increased. Copyright © 1990 John Wiley & Sons, Inc.