Experimental and computational investigation of structure- reactivity relationship of methacrylates

Abstract

In the first part of this work, a series of alkyl α-hydroxymethacrylates (RHMA) were synthesized and computationally modeled in order to understand the structure-reactivity relationships in their polymerizations. Several factors including H-bonding, π-π interactions and dipole moment were investigated. Experimentally, among the studied monomers, aromatic carbamates containing π-π stacking and H-bonding were found to have highest rate of polymerization. Computationally, the rate constants for propagation kp mimic the qualitative polymerization trends of the monomers modeled and can be used with confidence in predicting the polymerizability behaviors of alkyl α-hydroxymethacrylates. Finally, these studies are expected to be used for the prediction of RHMA monomers prior to synthesis. In addition, RHMA based polymerizable and polymeric photoinitiators were synthesized and evaluated for UV curable coatings. In the second part of this work, glycidyl methacrylate (GMA) derivatives were synthesized and evaluated with respect to their potential to be used as reactive diluents in dental materials. An explanation was also proposed for the cyclopolymerization of methyl α-[(allyloxy) methyl] acrylate via 5-membered rings, while allyl methacrylate (AMA) and allyl 2-cyanoacrylate (ACA) polymerize without ring formation. It has been pointed out that the presence of carbonyl group at C3 in AMA and ACA inhibits the cyclization because of its incompatibility in hybridization with the other unsaturated carbon next to the oxygen. In the last part of this thesis, the effect of solvent on the propagation rate coefficients of acrylic acid (AA) and methacrylic acid (MAA) have been elucidated. Both for MAA and AA it was experimentally found that the propagation rate constants of the monomers increase by more than one order of magnitude in going from the bulk to a highly dilute system. The reactivities of these two monomers have been explained in the bulk and dilute medium by using quantum chemical methods.