4-(ALPHA,ALPHA-DIMETHYLBENZYL)PHENYL METHACRYLATE .2. POLYMERIZATION IN N,N-DIMETHYLFORMAMIDE

The polymerization rate of 4-(a,a-dimethylbenzyl)phenyl methacrylate in DMF at 70-degrees-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, M(w)BAR/M(n)BAR, of the polymers of about 1,4 up to high degrees of conversion. The overall activation energy of the polymerization, E(a), is 60,1 kJ.mol-1, and the pre-exponential factor in A almost-equal-to 15,5 (A in (mol.dm-3)-1,5.s-1). 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.