MESO AND RACEMO ADDITIONS IN PROPAGATION FOR RADICAL POLYMERIZATION OF DIALKYL FUMARATES .1. STEREOREGULARITY OF POLY(DIALKYL FUMARATE)S

The polymerization temperature dependence of the stereochemical configuration of some poly(dialkyl fumarate)s as poly(substituted methylene) was investigated by the use of C-13 NMR spectroscopy in order to clarify the propagation process in radical polymerization of dialkyl fumarates. The probability of meso addition (P(m)) for polymerization of di-tert-butyl fumarate increased from 0.68 to 0.80, when the polymerization temperature decreased from 120-degrees-C to 0-degrees-C. On the other hand, it was revealed that P(m) for dimethyl fumarate and diisopropyl fumarate decreased by the decreasing polymerization temperature, and that it was almost independent of the temperature for methyl tert-butyl fumarate. From the differences in activation enthalpies and entropies for meso and racemo additions, the effect of the ester alkyl groups on the propagation manner was discussed.