title: Novel preparation method for poly(L-lactide)-based block copolymers: extended chain crystallites as a solid-state macro-coinitiator.
abstract: A novel synthetic method for poly(L-lactide) (PLLA)-based diblock copolymers was developed by the use of PLLA extended chain crystallites (or crystalline residues) as a solid-state macro-coinitiator. In this study, we showed one example, i.e., a synthesis of diblock copolymer composed of a crystalline PLLA chain and an amorphous poly(DL-lactide) chain by ring-opening polymerization of DL-lactide initiated with stannous octoate (i.e., tin(II) 2-ethylhexanoate) in the presence of PLLA extended chain crystallites. The PLLA extended chain crystallites were prepared by hydrolytic degradation of crystallized PLLA films at 97 degrees C for 70 h. The chains inside the extended chain crystallites are expected to be protected from transesterfication reaction. Gel permeation chromatography, polarimetry, 1H NMR spectroscopy, wide-angle X-ray scattering, and differential scanning calorimetry revealed that the diblock copolymer poly(L-lactide-block-DL-lactide) was successfully prepared without significant transesterification.
authors: Department of Ecological Engineering, Faculty of Engineering, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan. tsuji@eco.tut.ac.jp
authors: Hideto
authors: H
authors: Tsuji
authors: Misato
authors: M
authors: Nishikawa
authors: Yuzuru
authors: Y
authors: Sakamoto
authors: Shinichi
authors: S
authors: Itsuno
mesh_terms: D002152:Calorimetry, Differential Scanning; D002850:Chromatography, Gel; D003460:Crystallization / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D011091:Polyesters / Q000138:chemical synthesis*; D014961:X-Ray Diffraction
chemical_list: D011091:Polyesters; C033616:poly(lactide)