Observation of a persistent methacrylate radical in the decomposition of methyl 2,2'-azobis(isobutyrate) and the polymerization of methyl methacrylate

Addition‐Fragmentation Chain Transfer Involving Dimers of α‐Methylvinyl Monomers Studied by ESR Spectroscopy: Competition between Fragmentation and Bimolecular Termination

“…The adduct radical can be readily detected by means of ESR spectroscopy due to its persistent nature. [15][16][17] The ESR spectrum observed during polymerization of St in the presence of MSD exhibits a complex hyperfine structure due to the couplings with the b-and phenyl hydrogen atoms (Figure 1). In order to obtain a simpler spectrum, MSD was replaced by MSD-d 10 (the hfc of deuterium is about 6.5 times smaller than that of a proton [18] ; Figure 1).…”

Chain Transfer and Efficiency of End‐Group Introduction in Free Radical Polymerization of Methyl Methacrylate in the Presence of Poly(methyl methacrylate) Macromonomer

“…The results in Figure 1 thus suggest that the adduct radical formed is not sufficiently long-lived to cause retardation and that no significant fraction of adduct radicals undergo side reactions. Addition of the 2-carbomethoxy-2-propyl radical to the MMA dimer yields a persistent radical which has been detected by electron spin resonance (ESR) in solution, [26] and a similar ESR spectrum has been observed during solution polymerization of MMA in the presence of the MMA dimer or PMMA-CO 2 Me. [14] The results in Figure 1 also suggest that the effect of chain-length dependent termination [27] on the rate of polymerization is not significant in this case.…”

Influence of Mid‐Chain Radicals on Acrylate Free Radical Polymerization: Effect of Ester Alkyl Group

“…[15] Based on the expected persistency of MCR (1 and 2), which are sterically congested tertiary carboncentered radicals, addition of MCR to monomers would be considerably slower than propagation of PRRs. The addition rate constants for the PRRs of methyl a-(carbomethoxyethyl)acrylate (unsaturated dimer of methyl acrylate (MA) : MA-2), methyl a-[2,4-bis(carbomethoxy)butyl]-acrylate (unsaturated trimer of MA : MA-3), and methyl a-[2,4,6-tris(carbomethoxy)hexyl]acrylate (unsaturated tetramer of MA : MA-4) to CHA are extraordinary small, strongly supporting the above prediction.…”