The copolymerization of 3-(S)-[(benzyloxycarbonyl)methyl]-l,4-dioxane-2,5-dione (BMD) and L-lactide (LAC) was carried out in bulk at relatively low BMD/LAC feed ratios with stannous 2-ethylhexanoate as the catalyst. The resulting copolymers were subjected to hydrogenolysis at atmospheric pressure in the presence of a palladium on charcoal catalyst to remove the pendant benzyl groups quantitatively. The deprotected copolymers consisted of L-lactic (L), glycolic (G) and L-~-malic acid (M) repeating units, with the copolymer composition being almost identical to the monomer feed composition. ~ 3C n.m.r, spectroscopy revealed that the BMD units (G-M) had been randomly incorporated into the copolymer (L-L). These poly(c~-hydroxy acid)s with pendant carboxyl groups were found to hydrolyse more rapidly than poly(L-lactide), because of the water-absorbing and catalytic activities of the carboxyl moieties. They were allowed to react with p-azidophenacyl bromide in the presence of triethylamine to form photo affinity labelling groups at the carboxyl functionalities. These findings suggested that the malic-acid-containing poly(~-hydroxy acid)s should have a high potential for use as functionalized bioresorbable polymers
Посилання на статтю:
Copolymerization of 3-(S)- [ ( benzylo xyca rbo nyl ) methyl ] - 1,4-d io xane- 2,5-dione and L-lactide: a facile synthetic method for functionalized bioabsorbable polymer / Yoshiharu Kimura*, Kenji Shirotani, Hideki Yamane and Toshio Kitao // Polymer. – 1993. – Vol 34. – P. 1741-1748.