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Hydrogel Formation between Enantiomeric B‐A‐B‐Type Block Copolymers of Polylactides (PLLA or PDLA: A) and Polyoxyethylene (PEG: B); PEG‐PLLA‐PEG and PEG‐PDLA‐PEG
Author(s) -
Mukose Takashi,
Fujiwara Tomoko,
Nakano Junko,
Taniguchi Ikuo,
Miyamoto Masatoshi,
Kimura Yoshiharu,
Teraoka Iwao,
Woo Lee Chan
Publication year - 2004
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200300112
Subject(s) - peg ratio , copolymer , chemistry , polymer chemistry , peg 400 , polyethylene glycol , polymer , organic chemistry , economics , finance
Summary: A mixed suspension of the enantiomeric B‐A‐B triblock copolymers, polyoxyethylene‐ block ‐poly( L ‐lactide)‐ block ‐polyoxyethylene (PEG‐PLLA‐PEG) and polyoxyethylene‐ block ‐poly( D ‐lactide)‐ block ‐polyoxyethylene (PEG‐PDLA‐PEG), was found to induce reversible gel‐to‐sol transition depending on the polymer concentration and temperature. The storage and loss moduli of the gel formed at lower temperature were much higher than those of the gel prepared from the corresponding ABA‐type triblock copolymers because of the higher polymer concentration in the former. Although the stereo‐complexation of the PLLA and PDLA blocks occurred at higher temperature also in the B‐A‐B copolymers, it was not responsible for the gelation of the mixed suspension. The PEG chains, involved in the helix formation of the PLLA and PDLA, should form helices with opposite helical senses to aggregate and lead the gelation of the system.Phase changes of the single dispersion of PLLA‐PEG at 37 °C (a) and 75 °C (b) and the mixed dispersion of PLLA‐PEG and PDLA‐PEG at 37 °C (c) and (d) 75 °C (d).