title: Porous thin films based on photo-cross-linked star-shaped poly(D,L-lactide)s.
abstract: Self-assembly processes and subsequent photo-cross-linking were used to generate cross-linked, ordered microporous structures on the surfaces of well defined four-arm star-shaped poly(D,L-lactide) (PDLLA) thin films. The four-arm star-shaped PDLLAs were synthesized using an ethoxylated pentaerythritol initiator. Solutions of the PDLLAs were cast in a humid environment, and upon solvent evaporation, ordered honeycomb structures (or breath figures) were obtained. Correlations between molar mass, polymer solution viscosity, and pore dimensions were established. The average pore dimension decreased with increasing polymer solution concentration, and a linear relationship was observed between relative humidity and average pore dimensions. Highly ordered microporous structures were also developed on four-arm star-shaped methacrylate-modified PDLLA (PDLLA-UM) thin films. Subsequent photo-cross-linking resulted in more stable PDLLA porous films. The photo-cross-linked films were insoluble, and the honeycomb structures were retained despite solvent exposure. Free-standing, structured PDLLA-UM thin films were obtained upon drying for 24 h. Ordered microporous films based on biocompatible and biodegradable polymers, such as PDLLA, offer potential applications in biosensing and biomedical applications.
authors.affiliation: Department of Chemistry, Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061,USA.
authors.forename: Afia S
authors.initials: AS
authors.lastname: Karikari
authors.forename: Sharlene R
authors.initials: SR
authors.lastname: Williams
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Heisey
authors.forename: Adam M
authors.initials: AM
authors.lastname: Rawlett
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Long
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry*; D019344:Lactic Acid / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D010777:Photochemistry; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014783:Viscosity
chemical_list: D003432:Cross-Linking Reagents; D008689:Methacrylates; D011091:Polyesters; D011108:Polymers; D012996:Solutions; D019344:Lactic Acid; C033616:poly(lactide)