title: Biologically Safe Poly(l-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties.
abstract: Although poly(l-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.
authors.affiliation: Department of Chemistry, College of Science, Rikkyo University , 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.|School of Chemical Engineering, Fuzhou University , No. 2 Xueyuan Rd, Minhou Country, Fuzhou 350116, People's Republic of China.
authors.forename: Hideko T
authors.identifier: 0000-0002-7904-7818
authors.initials: HT
authors.lastname: Oyama
authors.affiliation: Department of Chemistry, College of Science, Rikkyo University , 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tanishima
authors.affiliation: Functional Materials Laboratory, Mitsui Chemicals Inc. , 580-32 Nagaura, Sodegaura, Chiba 299-0265, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Ogawa
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D063566:Biodegradable Plastics / Q000737:chemistry*; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008855:Microscopy, Electron, Scanning; D008859:Microscopy, Polarization; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D011091:Polyesters / Q000737:chemistry*; D013718:Tensile Strength; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D063566:Biodegradable Plastics; D010455:Peptides; D011091:Polyesters; C576175:poly(aspartic acid-co-lactic acid); C000624437:poly(malic acid-co-lactide); C033616:poly(lactide)