4‐(α,α‐dimethylbenzyl)phenyl methacrylate, 2. Polymerization in N,N‐dimethylformamide

Abstract

The polymerization rate of 4-(a,cedimethylbenzyI)phenyl methacrylate in DMF at 70 "C is of the order 1,6 in [monomer] and first order in [AIBN], which deviates from classical kinetics. This could be reconciled by a reaction scheme in which dimeric monomer associates and a spontaneous termination are postulated. The scheme is supported by the dependence of the kinetic chain length, v, on the 1,6-th power in [monomer] and zeroth power in [AIBN]. The degree of polymerization is smaller than v, which indicates some chain transfer. A remarkable feature is the constancy of the dispersion degree, &&,/a,, of the polymers of about 1,4 up to high degrees of conversion.The overall activation energy of the polymerization, E,, is 60,l k J . mol-', and the preexponential factor InA = 15,s (A in (mol . dm-3)-'2s. s-'). The polymer chains seem to have a rod-like character in THF as deduced from the Mark-Houwink exponent of 1,46. In toluene the polymer tends to form associates.