Solvent effects on free‐radical polymerization, 3. Solvent effect on polymerization rate of methyl methacrylate and N‐vinyl‐2‐pyrrolidone

Abstract

The homopolymerizations of methyl methacrylate (MMA) in N-methyl-2-pyrrolidone (NMP) and of N-vinyl-2-pyrrolidone (NVP) in methyl isobutyrate (MiB) were investigated at 60 "C using AIBN as initiator. Reaction rate and dynamic viscosity of the medium were determined as function of monomer dilution. It follows from the estimated monomer exponent n that MMA reacts in NMP faster (n = 0,739) and NVP in MiB slower (n = 1,495) in comparison with reaction rates obtained from the direct proportionality of monomer concentration. The observed deviation was quantitatively separated in partial deviations caused by chain initiation, propagation and termination. It was found that the viscosity effect on chain termination plays a dominant role in the global solvent effect. Chain propagation is influenced by electron donor-acceptor interactions between monomers and solvent.

Dependence of Copolymer Composition in Radical Polymerization on Solution Properties: a Quantitative Thermodynamic Interpretation

“…Also, O’Driscoll et al., to explain the composition effect on the ⟨ k p ⟩ of the Sty/MMA system, postulated the formation of radical-solvent complexes of different stability between benzyl alcohol (BnOH) and growing chains ending in Sty or MMA units. In a series of papers by Czerwinski − on the homo- and copolymerization of MMA and NVP dissolved in their respective saturated analogues, the simultaneous formation of complexes between solvent, growing radicals, and monomers are considered.…”

Solvent Effects on Free-Radical Polymerization. 6. Solvatochromic (LSER) Analysis of the Solvent Effect on the Homopolymerization Rate on the Basis of the Reaction-Solvent Complex Model

“…it Is Imposed « (15) for MMA: log -= -1.137 + rir 0.468( * -0.059(5) + 1.338/3 (13) Monomer responses on solvent properties are very different. Aliphatic and more polar MMA is 3 times more susceptible to solvent polarity than St.…”