title: Phase structure and enzymatic degradation of poly(L-lactide)/atactic poly(3-hydroxybutyrate) blends: an atomic force microscopy study.
abstract: Phase structures and enzymatic degradation of poly(l-lactide) (PLLA)/atactic poly(3-hydroxybutyrate) (ata-PHB) blends with different compositions were characterized by using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) thermograms of PLLA/ata-PHB blends with different compositions showed two glass transition temperatures, indicating that the PLLA/ata-PHB blends are immiscible in the melt. Surface morphologies of the thin films for PLLA/ata-PHB blends were determined by AFM. Phase separated morphology was recognized from the AFM topography and phase images. The domain size of the components was dependent on the blend ratio. Enzymatic degradation of the PLLA/ata-PHB blends was performed by using both PHB depolymerase and proteinase K. Either PLLA or ata-PHB domains were eroded depending on the kinds of enzyme. Surface morphologies after enzymatic degradation have revealed the phase structure along the depth direction. Enzymatic adsorption of PHB depolymerase was examined on the surface of PLLA/ata-PHB blends. The enzyme molecules were found on both domains of the binary blends. The larger number of enzyme molecules was found on the PLLA domains relative to those on the ata-PHB domains, suggesting the higher affinity of the enzyme against PLLA domain.
authors.affiliation: Nanoarchitectonics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan. y.kikkawa@aist.go.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kikkawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Suzuki
authors.forename: Takeharu
authors.initials: T
authors.lastname: Tsuge
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kanesato
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Doi
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
mesh_terms: D000327:Adsorption; D002152:Calorimetry, Differential Scanning / Q000379:methods; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D019286:Endopeptidase K / Q000737:chemistry*; D006885:Hydroxybutyrates / Q000737:chemistry*; D008422:Materials Testing; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods*; D008858:Microscopy, Phase-Contrast; D010316:Particle Size; D011091:Polyesters / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D000094122:Polyhydroxybutyrates
chemical_list: D002265:Carboxylic Ester Hydrolases; D019286:Endopeptidase K; D006885:Hydroxybutyrates; D008567:Membranes, Artificial; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C033616:poly(lactide); C022417:poly-beta-hydroxybutyrate depolymerase