Macromolecules, Vol.40, No.1, 47-54, 2007
Deconvoluting the impact of intermolecular and intramolecular interactions on the polymerization kinetics of ultrarapid mono(meth)acrylates
Polymerization studies in the presence of extensive amounts of solvent are used here to deconvolute the effects of intermolecular interactions such as bulk medium polarity, pi-pi stacking, and hydrogen bonding and characterize the contribution of intramolecular conformational effects to monomer reactivity. For that purpose the solution polymerization kinetics of various monomers in the presence of 95 wt % 1, 4-dioxane were measured and compared to bulk polymerization kinetics. The studies revealed that traditional aliphatic acrylates like hexyl acrylate exhibit approximately 2-3-fold reduction upon dilution. Monomers characterized by only hydrogen-bonding features such as hydroxyethyl acrylate exhibit an 8-12-fold reduction upon dilution. Monomers possessing only aromatic ring stacking interactions such as phenyl acrylate exhibit approximately a 5-10-fold reduction upon dilution under similar conditions. Even at a concentration of 5 wt % monomer in 1,4-dioxane, there were approximately 2-5-fold differences in reactivity observed between various acrylates. These reactivity differences between various acrylates, which exist even upon extensive dilution, were inferred to arise solely from intramolecular interactions. The contribution of intramolecular interactions for various monomers was decoupled from the bulk effects, and the impact of various functionalities upon the reactivity of acrylate monomers was quantitatively estimated.