title: Phase separation at the surface of poly(ethylene oxide)-containing biodegradable poly(L-lactic acid) blends.
abstract: The surface chemistry and in-depth distribution of the composition of a poly(ethylene oxide) (PEO)-containing biodegradable poly(L-lactic acid) (PLLA) blend matrix system have been investigated using X-ray photoelectron spectroscopy (XPS). This study reports detailed quantitative compositional information using a novel numerical method for determining depth profiles. The PEO system studied is an amphiphilic Pluronic P104 surfactant, PEO-b-poly(propylene oxide) (PPO)-b-PEO. The extent of phase separation is analyzed by determining the surface enrichment of the PEO component via measurement of chemical composition at the polymer-air interface. For this blend system, the combination of the PPO component in the Pluronic surfactants drives the formation of a surface excess of Pluronic in the blends with PLLA. The surface excess profile shows a rapid increase in Pluronic surface composition versus bulk Pluronic mass fractions of 1-5%, but the profile levels off above bulk Pluronic mass fractions of 5%.
authors.affiliation: Department of Chemistry, State University of New York, Buffalo, New York 14260, USA.
authors.forename: Jinxiang
authors.initials: J
authors.lastname: Yu
authors.forename: Christine M
authors.initials: CM
authors.lastname: Mahoney
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Fahey
authors.forename: Wesley L
authors.initials: WL
authors.lastname: Hicks
authors.forename: Robert
authors.initials: R
authors.lastname: Hard
authors.forename: Frank V
authors.initials: FV
authors.lastname: Bright
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Gardella
mesh_terms: D019344:Lactic Acid / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011091:Polyesters; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; D011092:Polyethylene Glycols; C033616:poly(lactide)