ABSTRACT
Copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503 19.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504 References and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505
The polymerization of nonconjugated dienes to form polymers and copolymers that incorporate recurring units of cyclic moieties in the polymer or copolymer backbone is well known.1,2 While it had been initially presumed that the polymerization of nonconjugated dienes produces only crosslinked polymers, the cyclopolymerization of diallyl quaternary ammonium salts to noncrosslinked polymers was first reported by G. B. Butler in 1947.3 A polymerization mechanism involving alternating intramolecular-intermolecular chain propagation was proposed to account for the linear cyclopolymers. The proposed cyclic structures in the polymer backbone were substantiated by degradation of representative polymers. Since then, a large variety of nonconjugated dienes have been reported to undergo cyclopolymerization. Later studies have shown that in numerous cases, cyclic structures are derived by propagation through the less stable intermediate, that is, the reactions are under kinetic rather than thermodynamic control.3
