Biodegradable comb polyesters: Part 1 - Synthesis, characterization and structural analysis of poly(lactide) and poly(lactide-co-glycolide) grafted onto water-soluble poly(vinyl alcohol) as backbone

To overcome discontinuous or polyphasic drug release rates of parenteral delivery systems (PDSs) for peptides and proteins, typical for linear polyesters, novel biodegradable brush-like poly(lactide) and poly(lactide-co-glycolide) (PLG) grafted onto water-soluble poly(vinyl alcohol) (PVA) as backbone were investigated. These polymers were synthesized by ring-opening melt polymerization using stannous octoate as catalyst. The branched PVA-PLGs were characterized by 1D- and 2D-n.m.r. spectroscopy and other methods, such as i.r., g.p.c., d.s.c. and static light scattering. The incorporation of the backbone and the comb structure was demonstrated by H-1- and C-13-n.m.r. spectra, as well as by light scattering studies. The physico-chemical properties, such as molecular composition and architecture, molecular weight, degree of crystallinity, melting point and glass transition point, could be systematically adjusted to the requirements of drug delivery. Therefore, this new class of biodegradable polymers has considerable potential as a PDS. (C) 1998 Elsevier Science Ltd. All rights reserved.