ANIONIC-POLYMERIZATION OF MONOMERS CONTAINING FUNCTIONAL-GROUPS - 12 - ANIONIC EQUILIBRIUM POLYMERIZATION OF 4-CYANO-ALPHA-METHYLSTYRENE

The anionic polymerization of 4-cyano-alpha-methylstyrene 1 was carrie d out in THF with (diphenylmethyl)potassium (Ph2CHK) as an initiator. At the various temperature ranging from 0 to -78 degrees C, conversion and equilibrium monomer concentration, [M](e), were obtained from the GLC analysis of the residual monomer. From the plot of In [M](e) agai nst reciprocal temperature, the thermodynamic parameters, Delta H and Delta S, and the ceiling temperature, T-c, of the anionic polymerizati on of 1, were determined to be -7.64 +/- 0.5 kcal mol(-1), -25.5 +/- 1 .3 cal mol(-1) K-l, and 27 +/- 3 degrees C, respectively. The apparent rate constant and the activation energy of the anionic polymerization for 1 were determined as follows: In k(p)(ap) = -1.83 x 10(3)/T + 5.7 4 L mol(-1) s(-1) and E-a = 3.6 +/- 0.2 kcal mol(-1), respectively. De polymerization of the living poly(1) proceeded to give a low molecular weight oligomer and starting monomer when the temperature of the poly merization system was raised from -78 to 0 degrees C. The resulting po ly(1)s produced at low temperatures (-30 to -78 degrees C) possessed n arrow molecular weight distributions (M-w/M-n < 1.1) and controlled mo lecular weights based on the molar ratios of monomer to initiator. Ove r -20 degrees C, after the reaction mixture stood for a period of time , the broadening of the MWD of the poly(1) was apparently observed due to the reversible equilibrium polymerization under the thermodynamic conditions.