title: Synthesis, characterization, biodegradation, and drug delivery application of biodegradable lactic/glycolic acid oligomers: I. Synthesis and characterization.
abstract: A series of oligomers or low molecular weight polymers of lactic and/or glycolic acid has been synthesized with different molar ratios of lactic to glycolic acid. These oligomers have been characterized with respect to oligomer composition, molecular weight, intrinsic viscosity, crystallinity, melting temperature, and glass transition temperature. The polymerization conditions for the lactic/glycolic acid oligomer syntheses were as follows: 180-220 degrees C, 5 mm Hg, 5 h, and 0.1 wt% of catalyst (antimony oxide) concentration. The polymeric compositions correlated to the feed ratios of lactic to glycolic acid. The molecular weight of the oligomers ranged from 895.8 +/- 48.7 to 1368.0 +/- 0 D with the intrinsic viscosity ranging from 0.0513 to 0.0814 dl g-1. The lactic/glycolic acid oligomers were found to be amorphous. The glass transition temperatures of the lactic/glycolic acid oligomers were lower than physiological temperature.
authors.affiliation: Division of Pharmaceutics and Industrial Pharmacy, Arnold & Marie Schwartz College of Pharmacy and Health Sciences, Long Island University, NY 11201, USA.
authors.forename: N
authors.initials: N
authors.lastname: Wang
authors.forename: X S
authors.initials: XS
authors.lastname: Wu
authors.forename: H
authors.initials: H
authors.lastname: Lujan-Upton
authors.forename: E
authors.initials: E
authors.lastname: Donahue
authors.forename: A
authors.initials: A
authors.lastname: Siddiqui
mesh_terms: D001673:Biodegradation, Environmental; D016503:Drug Delivery Systems; D006016:Glycolates / Q000138:chemical synthesis* / Q000378:metabolism / Q000627:therapeutic use; D019344:Lactic Acid / Q000138:chemical synthesis* / Q000378:metabolism / Q000627:therapeutic use; D016014:Linear Models; D015394:Molecular Structure; D008970:Molecular Weight; D011108:Polymers / Q000138:chemical synthesis* / Q000378:metabolism / Q000627:therapeutic use; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D006016:Glycolates; D011108:Polymers; C031149:glycolic acid; D019344:Lactic Acid