Polymerization of β-(Acryloyloxy)-propionamide with Anionic Initiator

Abstract

β-(Acryloyloxy)-propionamide (β-APAm) was prepared using β-propiolactone as a starting material. Two kinds of the propagation step were determined in the anionic polymerization of this monomer, that is, a so called hydrogen transfer (H-Type) polymerization and vinyl (V-Type) polymerization, which were estimated by IR spectra of the polymers. It was found that both H-and V-Type propagation took place with t-BuOK in 0-dichlorobenzene, while only V-Type polymer was formed in dimethylformamide, toluene and chlorobenzene. Poly (β-APAm) polymerized with t-BuOK in o-dichlorobenzene was soluble in dimethyl sulfoxide, partly soluble in formic acid and insoluble in other usual solvents, while poly (β-APAm) initiated with potassium persulfate in water was soluble in water, methanol and insoluble in other usual solvents.
Poly (β-APAm) and poly acrylamide (poly (AAm)) were hydrolyzed with 6N hydrochloric acid and their hydrolyzates were allowed to react with 2, 4-dinitrofluorobenzene. The products were analyzed by UV spectroscopy to determine the quantity of amino-nitrogen in β-amino acids, which were resulted from the sequences formed by H-Type propagation. The degree of H-Type propagation in the polymerization was determined by the (amino-N)/(total-N) ratio in the hydrolysis products of the polymer.
The ratio of the optical density of amide II band (1550cm^-1) to that of amide I band (1670cm^-1) in IR spectrum showed a good correlation with the degree of H-Type propagation determined by the (amino-N)/(total-N) ratio described above. Poly (β-APAm) initiated with t-BuOK in 0-dichlorobenzene had 35% H-Type content at most, while poly (AAm) had 66%. The results indicate that the polymerization of β-APAm proceeded mainly by the intermolecular proton transfer mechanism.