Abstract
The homopolymerization of benzylmethacrylate and methylvinylketone was carried out with a Ni(acethylacetonate)(2)-MAO catalytic system. The catalytic efficiency of this complex was almost identical towards ester methacrylic monomers. The yield of polybenzylmethacrylate (84-86%) was not influenced by the bulkiness of the substituent directly attached to the sp(3) oxygen, and in the meantime, it gave a small amount of oligomers (3-16%). The molecular weights of polybenzylmethacrylate obtained by this catalytic system were relatively high ((M) over bar (n) = 1.3-4.3 x 10(4)) and were not practically influenced by the temperature. The polymerization of methylvinylketone (MVK) gave a low polymer yield (8-25%), with low molecular weights ((M) over bar (n) = 2.1-4.4 x 10(3)) and a higher quantity of oligomers (53-67%). This result indicated that the ketone-enol equilibrium of the momoner perturbed highly the polymerization process, which was due to the presence of a methyl group in alpha position of the carbonyl. The polymerization of vinylacetate using the same catalytic system was also investigated in this work. However, the polymerization process was unsuccessful. Ni(acac)(2)-MAO catalyst system was able to initiate the polymerization of various monomers, such as those containing conjugated double bonds C=C-C=C or C=C-C=O, but those containing a donor group in a-position, such as methylvinylketone appeared to give essentially the oligomers. C-13 and H-1 NMR analyses of the polymer revealed that the catalytic system gave a mixture of mr (27.4-46%) and rr (43.8-55.5%) triads in the main chain preferentially. The fraction of triad rr increased when the temperature of polymerization decreased (40% at 80 degrees C and 70% at 0 degrees C). (C) 2009 King Saud University. All rights reserved.