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Stereocomplexation of solvent‐cast poly(lactic acid) by addition of non‐solvents
Author(s) -
Furuhashi Yukiko,
Yoshie Naoko
Publication year - 2012
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.3190
Subject(s) - crystallinity , crystallization , methanol , solvent , differential scanning calorimetry , chloroform , materials science , acetone , lactic acid , tetrahydrofuran , polymer chemistry , casting , nuclear chemistry , chemical engineering , organic chemistry , chemistry , composite material , physics , genetics , biology , bacteria , engineering , thermodynamics
Abstract Equimolar blends of poly( L ‐lactic acid) (PLLA) and poly( D ‐lactic acid) (PDLA) were obtained by solution casting from chloroform/methanol mixed solvents and analyzed using wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarizing optical microscopy. Chloroform and methanol are a solvent and non‐solvent, respectively, for poly(lactic acid). The WAXD and DSC results showed that stereocomplex crystallization between PLLA and PDLA occurred in addition to homo‐crystallization. On adding methanol to the casting solution, the stereocomplexation was gradually enhanced while the homo‐crystallization was suppressed. When a large amount of methanol was added, the homo‐crystallization was fully suppressed and the degree of stereocomplex crystallinity reached 90%. Similar results were obtained when another non‐solvent, hexane, was added to the casting solution in place of methanol. The effect of the addition of good and poor solvents such as tetrahydrofuran, ethanol, acetone and ethyl acetate was also studied. Copyright © 2011 Society of Chemical Industry