title: Synthesis, characterization, biodegradation, and drug delivery application of biodegradable lactic/glycolic acid polymers: I. Synthesis and characterization.
abstract: A series of lactic/glycolic acid polymers with various molar ratios of lactic to glycolic acid and various molecular weights were synthesized using the ring-opening polymerization method. The polymerization conditions for the lactic/glycolic acid polymer synthesis were as follows: 150 degrees C, 700 microm Hg, 3 h, 0.03 wt% of catalyst (stannous 2-ethyl-hexanoate) concentration. The molecular weight of these polymers was controlled by using a molecular weight controller, lauryl alcohol. The synthesized polymers have been characterized with respect to polymer composition, molecular weight, inherent viscosity, and glass transition temperature. The characterization experiments show a good correlation between the polymer compositions and the feed ratios of lactic to glycolic acid. The molecular weight of the lactic/glycolic polymers, ranging from 10,876 to 166,630 D and the intrinsic viscosity of the polymers, ranging from 0.16 to 0.86 dl g(-1), are controlled by the amount of molecular weight controller used. The effect of the amount of the molecular weight controller on the polymer molecular weight and the polymer inherent viscosity was studied. Results indicate that the molecular weight and inherent viscosity of the polymers have a log-log linear relationship with the amount of molecular weight controller used. The lactic/glycolic acid polymers are amorphous, glassy, and transparent. The glass transition temperature of the polymers range from 21.95 to 51.29 degrees C, depending on the polymer molecular weight and the composition.
authors.affiliation: Division of Pharmaceutics and Industrial Pharmacy, Arnold & Marie Schwartz College of Pharmacy and Health Sciences, Long Island University, Brooklyn, NY 11201, USA.
authors.forename: N
authors.initials: N
authors.lastname: Wang
authors.forename: X S
authors.initials: XS
authors.lastname: Wu
authors.forename: C
authors.initials: C
authors.lastname: Li
authors.forename: M F
authors.initials: MF
authors.lastname: Feng
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D002152:Calorimetry, Differential Scanning; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D016503:Drug Delivery Systems; D019344:Lactic Acid / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008970:Molecular Weight; D011100:Polyglycolic Acid / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid