Polymerization of ε-caprolactone initiated through powders of biological and nonbiological glasses

Eight biomedical glasses and three commercial glasses, as finely divided powders, were tested as initiators for the ring-opening polymerization of epsilon-caprolactone in bulk and in vacuo at 185degreesC. All the glass powders were able to initiate the polymerization, along with Pyrex, which was totally inert toward the monomer as the inner surface of a phial. The obtained polymers were examined with Fourier infrared transform spectroscopy and atomic force microscopy. The molecular weights were measured by viscometry in CHCl3. The presence of a fraction of the polymer firmly linked to the glass was quantitatively checked by the determination of the weight loss from the residues of the extrac-tion with CHCl3 after calcination in a kiln at 945degreesC. The molecular weights and weight losses per unit surface were elaborated mathematically so that a possible correlation between these properties and the atomic compositions of the glasses could be better investigated. Two possible initiation mechanisms, induced by the hydroxyls present on the glass surface, were proposed: one for free poly(epsilon-caprolactone) and one for poly(epsilon-caprolactone) linked to the glass. (C) 2002 Wiley Periodicals, Inc.