title: Stereoblock poly(lactic acid): synthesis via solid-state polycondensation of a stereocomplexed mixture of poly(L-lactic acid) and poly(D-lactic acid).
abstract: Stereoblock poly(lactic acid) consisting of D- and L-lactate stereosequences can be successfully synthesized by solid-state polycondensation of a 1:1 mixture of poly(L-lactic acid) and poly(D-lactic acid). In the first step, melt-polycondensation of L- and D-lactic acids is conducted to synthesize poly(L-lactic acid) and poly(D-lactic acid) with a medium-molecular-weight, respectively. In the next step, these poly(L-lactic acid) and poly(D-lactic acid) are melt-blended in 1:1 ratio to allow formation of their stereocomplex. In the last step, this melt-blend is subjected to solid-state polycondensation at temperature where the dehydrative condensation is allowed to promote chain extension in the amorphous phase with the stereocomplex crystals preserved. Finally, stereoblock poly(lactic acid) having high-molecular-weight is obtained. The stereoblock poly(lactic acid) synthesized by this way shows a higher melting temperature in consequence of the controlled block lengths and the resulting higher-molecular-weight. The product characterization as well as the optimization of the polymerization conditions is described. Changes in M(w) of stereoblock poly(lactic acid) (sb-PLA) as a function of the reaction time.
authors.affiliation: Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Fukushima
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Furuhashi
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Sogo
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Miura
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Kimura
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008970:Molecular Weight; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D011489:Protein Denaturation; D013237:Stereoisomerism; D013696:Temperature; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide)