|125. Königsmann, H.; Jüngling, S.; Müller, A.H.E.: Metal-Free Anionic Polymerization of Methyl Methacrylate Using Bis(triphenylphosphoranilydene)ammonium (PNP+) as Counterion in Tetrahydrofuran, Macromolecular Rapid Communications 21, 758 (2000) -- DOI: 10.1002/1521-3927(20000701)21:11<758::AID-MARC758>3.0.CO;2-8|
Bis(triphenylphosphoranilydene)ammonium (PNP+) triphenylmethanide (Ph3C-) is a new metal-free initiator for the living polymerization of methyl methacrylate (MMA). The kinetics of the polymerization strongly depend on the metal counterion of the initiator precursor. When the initiator is made from the metathesis reaction of Ph3CK and PNPCl, the polymerization follows first-order kinetics up to 0°C with half-lives below 0.1 s. The propagation rate constants are much higher than those obtained with tetraphenylphosphonium (TPP+) cations, indicating a smaller fraction of dormant ylides. When the initiator is synthesized from Ph3CLi, polymerization proceeds much slower and molecular weight distributions of the obtained polymers are broadened indicating that the active species are mostly lithium enolates in this case.