Anionic polymerization of butyl cyanoacrylate by tetrabutylammonium salts, 2. Propagation rate constants

Anionic polymerizations of butyl cyanoacrylate were initiated in tetrahydrofuran (plus a few experiments in 1,2‐dimethoxyethane) by the salts tetrabutylammonium hydroxide, bromide, acetate and three substituted acetates. The hydroxide gives near‐ideal ‘living polymerization’ kinetics, with kp close to 106l·mol−1. s−1 at 20°C. The kinetics of the reactions initiated by the acetates and bromide are analysed by the slow‐initiation‐no‐termination theory, using values of the initiation rate constants evaluated in Part 1. The kp values derived are in the same range as those from the OH‐initiated reactions and those of the zwitterionic polymerizations initiated with covalent bases, i.e., tertiary phosphines and amines. A ca. 4‐fold variation of kp with concentration of active species is given a speculative analysis in terms of dissociation from paired to free ions, yielding tentative estimates for k ≈ 105 and k ≈ 107l·mol−1·s−1 in THF at 20°C. Molecular weights were all high Mn ≈ 106, with Mw/Mn ≈ 2.