title: Fine structure and enzymatic degradation of poly[(R)-3-hydroxybutyrate] and stereocomplexed poly(lactide) nanofibers.
abstract: Fiber morphology and crystalline structure of poly[(R)-3-hydroxybutyrate] (P(3HB)) and stereocomplexed poly(lactide) (PLA) nanofibers were investigated by using scanning and transmission electron microscopies and X-ray and electron diffractions. In the P(3HB) nanofibers spun from less than 1 wt% 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solution, planar zigzag conformation (beta-form) as well as 2(1) helix conformation (alpha-form) structure was formed. Based on the electron diffraction measurement of single P(3HB) nanofiber, it was revealed that the molecular chains of P(3HB) align parallel to the fiber direction. From the enzymatic degradation test of P(3HB) nanofiber, it was shown that beta-form molecular chains are degraded more preferentially than alpha-form chains. Stereocomplexed PLA nanofibers were electrospun from 1 wt% poly(l-lactide)/poly(d-lactide) (PLLA/PDLA) solution in HFIP, which contains equal amounts of PLLA and PDLA. While as-spun stereocomplexed PLA nanofiber was amorphous, PLA nanofiber annealed at 100 degrees C contained only racemic crystal. It was supposed that the crystallization behavior of stereocomplexed PLA in the nanofiber is affected by the electrospinning process, which forcibly exerts the strain onto the polymer chains.
authors.affiliation: Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ishii
authors.forename: Won-Ki
authors.initials: WK
authors.lastname: Lee
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Kasuya
authors.forename: Tadahisa
authors.initials: T
authors.lastname: Iwata
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000737:chemistry* / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D049329:Nanostructures; D011091:Polyesters / Q000737:chemistry* / Q000378:metabolism*; D049920:Ralstonia pickettii / Q000201:enzymology*; D014961:X-Ray Diffraction; D000094122:Polyhydroxybutyrates
chemical_list: D002265:Carboxylic Ester Hydrolases; D006885:Hydroxybutyrates; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C033616:poly(lactide); C022417:poly-beta-hydroxybutyrate depolymerase