Synthesis, Characterization, and Kinetic Studies of Poly(Dimethylacrylamide) Macromonomer

Abstract

<p> The work in this thesis focuses on the search for a system that would allow for the controlled anionic polymerization of N,N-dimethylacrylamide. The resulting polymer would serve as a macromonomer equipped with a chain end functional group originated from diallylamine.</p> <p> Poly(dimethylacrylamide) macromonomers were produced on a laboratory scale by reacting diallylamine with sec-butyllithium initiator, followed by the monomer addition. The synthesis was terminated, the polymer product precipitated in hexane, and dried in a vacuum oven at 45°C. The reactions were performed at 0°C and -77°C in tetrahydrofuran solvent.</p> <p> The polymerization control was achieved as a means of controlling the molecular weight and stereoregularity of the macromonomer, which in turn dictated solubility of the final product in the reaction solvent. The addition of triethylborane coordinating agent allowed for the polymerization of soluble product. The produced macromonomers characterized with atactic and syndiotactic structure were completely soluble in tetrahydrofuran.</p> <p> The molecular weights of macromonomers were evaluated by a gel permeation chromatography, GPC. The best results were obtained by using dimethylformamide as a mobile phase and poly(methylmethacrylate) standards</p> <p> The macromonomer yield was evaluated by 1H NMR and the stereoregularity by 13C NMR. Although the molecular weight of the macromonomer was under good control, the NMR measurements did not show the best yield control.</p> <p> The study of the triethylborane coordinating power showed that varying concentration of this ligand affected the solubility of the polymer in the reaction solvent. The soluble macromonomer was synthesized when triethylborane was in 1.5 molar excess over the initiator concentration. The 13C NMR measurements indicated that 23% of isotactic and atactic structure was required as a borderline for the solubility.</p> <p> The kinetic measurements performed in a batch reactor proved the livingness of the polymerization system with the propagation rate constant kobs equal to 1.9 · 10^-3 [1/s].</p>