CATALYTIC AMINOLYSIS OF ACRYLIC COPOLYMERS IN SOLUTION AND IN THE MELT .1. MECHANISM AND KINETICS

The aminolysis of poly (styrene-co-methyl acrylate) (SMA) by octadecylamine was studied in solution and in the melt at temperatures around 200-degrees-C. This reaction is rather slow, so several types of catalysts were tested to accelerate it. The most efficient is 2-pyridone, a compound in tautomeric equilibrium with 2-hydroxypyridine. A mechanism of the catalytic reaction is proposed whereby the tautomeric nature of the catalyst plays a key role in a very important step of the reaction, namely the proton transfer. This mechanism is confirmed by the kinetic data determined in a 1,2,4-trichlorobenzene solution and in the melt. In addition, it was found that the kinetic data obtained in both media are very close, indicating no significant difference of local polarity in the two reaction media. Data also show only a minor effect due to differences in viscosity. Finally, the question of the homogeneity of the molten medium is discussed.