Polymerization of 2‐diethylamino‐1,3,2‐dioxaphosphorinane, 2. Kinetics

Kinetic studies of the anionic polymerization of 2‐diethylamino‐1,3,2‐dioxaphosphorinane were performed in THF solution with (CH3)3SiO−K+ as initiator at temperatures close to r.t. Initiation involves nucleophilic attack of the anion on P atom in the monomer molecule. Breaking of the PO bond leads to an alcoholate anion as the growing species. Polymerization was shown to proceed via macroion‐pairs and to be nearly living; e.g. at r.t. for every 250 propagations there is one termination. Rate constant of propagation k = 3,4 ± 0,31·mol−1·s−1 at 25°C, ΔH = 13,3 kcal·mol−1 and ΔS = −32,2 cal·mol−1·K−1. The ratio k /k was determined by solving a kinetic scheme involving propagation and termination. It was shown that termination consists in the alcoholate anion attack on P in either polymer or monomer molecule with expulsion of (C2H5)2N− anion and formation of a PO bond. The dialkylamide anions cannot reinitiate polymerization. In solving the kinetic scheme it was assumed that termination involving both polymer and monomer proceeds with rate constants equal to each other.