title: Study of the air-water interfacial properties of biodegradable polyesters and their block copolymers with poly(ethylene glycol).
abstract: It has been reported that the surface pressure-area isotherm of poly(D,L-lactic acid-ran-glycolic acid) (PLGA) at the air-water interface exhibits several interesting features: (1) a plateau at intermediate compression levels, (2) a sharp rise in surface pressure upon further compression, and (3) marked surface pressure-area hysteresis during compression-expansion cycles. To investigate the molecular origin of this behavior, we conducted an extensive set of surface pressure and AFM imaging measurements with PLGA materials having several different molecular weights and also a poly(D,L-lactic acid-ran-glycolic acid-ran-caprolactone) (PLGACL) material in which the caprolactone monomers were incorporated as a plasticizing component. The results suggest that (i) the plateau in the surface pressure-area isotherm of PLGA (or PLGACL) occurs because of the formation (and collapse) of a continuous monolayer of the polymer under continuous compression; (ii) the PLGA monolayer becomes significantly resistant to compression at high compression because under that condition the collapsed domains become large enough to become glassy (such behavior was not observed in the nonglassy PLGACL sample); and (iii) the isotherm hysteresis is due to a coarsening of the collapsed domains that occurs under high-compression conditions. We also investigated the monolayer properties of PEG-PLGA and PEG-PLGACL diblock copolymers. The results demonstrate that the tendency of PLGA (or PLGACL) to spread on water allows the polymer to be used as an anchoring block to form a smooth biodegradable monolayer of block copolymers at the air-water interface. These diblock copolymer monolayers exhibit protein resistance.
authors: School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States.
authors: Hae-Woong
authors: HW
authors: Park
authors: Je
authors: J
authors: Choi
authors: Kimberly
authors: K
authors: Ohn
authors: Hyunsuk
authors: H
authors: Lee
authors: Jin Woong
authors: JW
authors: Kim
authors: You-Yeon
authors: YY
authors: Won
mesh_terms: D000388:Air; D001672:Biocompatible Materials / Q000138:chemical synthesis*; D002208:Caproates / Q000737:chemistry; D019344:Lactic Acid / Q000138:chemical synthesis*; D007783:Lactones / Q000737:chemistry; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000138:chemical synthesis*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011312:Pressure; D013499:Surface Properties; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D002208:Caproates; D007783:Lactones; D011091:Polyesters; D014867:Water; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D011092:Polyethylene Glycols; C121056:caprolactone