title: Stereocomplex Crystallization of Linear Two-Armed Stereo Diblock Copolymers: Effects of Chain Directional Change, Coinitiator Moiety, and Terminal Groups.
abstract: Two-armed poly(l-lactide) (PLLA)-b-poly(d-lactide) (PDLA) (2-LD) copolymers with a wide-range of molecular weight were synthesized and the effect of coinitiator moiety, which functions as impurity and causes chain directional change in the middle of molecules (Effect A), and/or the additional effect of types of terminal groups (Effect B) on crystallization behavior of 2-LD copolymers were studied, in comparison with that reported for one-armed PLLA-b-PDLA (1-LD) copolymers. Formation of only stereocomplex (SC) crystallites in 2-LD and 1-LD copolymers indicates that neighboring PLLA and PDLA blocks facilitated SC crystallization and neither Effect A nor B affected the crystalline species. Effect A and/or B (both hydroxyl terminal groups) disturbed cold SC crystallization of 2-LD copolymers compared to that of 1-LD copolymers. Crystalline growth morphologies of 2-LD and 1-LD copolymers during cold SC crystallization were spherical and solid sheaf, respectively, exhibiting that crystalline growth morphology was influenced by Effects A and/or B. The melting temperature or crystalline thickness of SC crystallites were determined by number-average molecular weight per one block and not affected by Effect A or B. Maximum radial growth rates of spherulites of 2-LD copolymers compared to those of 1-LD copolymers were largely decreased by Effect A and/or B (both hydroxyl terminal groups).
authors.affiliation: Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology , Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Hideto
authors.identifier: 0000-0001-9986-5933
authors.initials: H
authors.lastname: Tsuji
authors.affiliation: Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology , Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Ogawa
authors.affiliation: Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology , Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Arakawa