Synthesis and characterization of novel degradable polyesters derived fromD-gluconic and glycolic acids

The ring-opening polymerization of a novel heterocyclic monomer of the 1,4- dioxane 2,5-dione type, namely 3-(1,2-3,4-tetraoxobutyldiisopropylidene)dio xane-2,5-dione (DIPAGYL), derived from glycolic acid and partially protecte d gluconic acid, was investigated. Polymerization of DIPAGYL was carried ou t in the presence of either stannous octoate or antimony trifluoride. The i nfluence of several factors on the polymerization yield and on the molecula r weights of the resulting polymers was evaluated using an experimental des ign. The polymers obtained in the presence of antimony fluoride (polyDIPAGY L-Sb) and stannous octoate (polyDIPAGYL-Sn) had different microstructures a ccording to the distribution of sequences of repeat units as determined by H-1 NMR. The main chain of polyDIPAGYL-Sb was primarily composed of alterna ting g (gluconic) and G (glycolic) units. In contrast, the polymer chain of polyDIPAGYL-Sn resulted from a random distribution of the two comonomer un its. The isopropylidene groups which protected the side chain alcohol group s in polyDIPAGYL chains were partially cleaved by acid hydrolysis to yield hydroxyl-bearing hydrolytically degradable polyesters.