Polymerization of α‐methylstyrene by naphthylsodium

Abstract The kinetics of the polymerization of α‐methylstyrene by naphthylsodium at −78°C. in tetrahydrofuran has been studied for elucidating the mechanism of the polymerization. The experimental relationships obtained are accounted for by an assumption that the polymerization proceeds by the “coordination” mechanism and 4 elementary reactions take place: (1) generation of the active centers of polymerization; (2) chain propagation; (3) chain termination; (4) reaction of chain propagation upon the organometal compounds formed as a result of the termination reaction (upon the “living” polymers). This latter reaction proceeds without termination. In solving kinetic equations reduced time φ = ∫0τ m · dτ is introduced here m is the monomer concentration and τ is the time. The apparent values of the constants of elementary reactions are determined from the dependence of the number‐average degree of polymerization \documentclass{article}\pagestyle{empty}\begin{document}$ \[\bar p\] $\end{document} on the initial catalyst concentration n0 and from the dependence of conversion X on reduced time φ. The coincidence of the expected relationship X = F(τ,φ) with those experimentally found was traced with an electronic computer over all the range of X values. Equations are derived for the dependence of the polymerization rate upon the initial concentration of the catalyst and for the molecular weight distribution of the polymer. Experimental points appear to agree with the calculated data. The curve of the molecular weight distribution has 2 maxima.