posted on 2005-01-19, 00:00authored byChulsung Bae, John F. Hartwig, Nicole K. Boaen Harris, Rachael O. Long, Kelly S. Anderson, Marc A. Hillmyer
The regioselective functionalization of both model and commercial polypropylenes of varying
tacticity has been conducted by a rhodium-catalyzed functionalization of the methyl C−H bonds of the
polymer with diboron reagents. Rhodium-catalyzed borylation of the polypropylenes, followed by oxidation
of the boron-containing material, produced polymers containing 0.2−1.5% hydroxymethyl side chains. Both
the number-average molecular weights and molecular weight distributions of the polypropylenes were
essentially unchanged after the catalytic and oxidative functionalization process. The efficiency of the
borylation process was affected by the molecular weight of the polymer, the steric hindrance around the
methyl groups, and the ratio of the diboron reagent to the monomer repeat unit. The hydroxylated derivative
of the commercial isotactic polypropylene was used as macroinitiator for the aluminum-mediated ring-opening polymerization of ε-caprolactone to prepare polypropylene-graft-polycaprolactone. This graft
copolymer was an effective compatibilizer for melt blends of polypropylene and polycaprolactone.