Immiscibility-miscibility phase transformation in blends of poly(ethylene succinate) with poly(L-lactic acid)s of Different Molecular Weights

E. M. Woo, Ya Ting Hsieh, Wei Ting Chen, Nai Tzu Kuo, Lai Yen Wang

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13 Citations (Scopus)


Using differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and Fourier transformed infrared spectroscopy (FTIR), upper critical solution temperature (UCST) phase behavior with immiscibility- miscibility transformation in blends of poly(ethylene succinate) (PESu) with poly(lactic acid)s (PLAs), such as poly(D,L-lactic acid) (PDLLA), poly(L- lactic acid) (PLLA), poly(D-lactic acid) (PDLA), differing in D/L configurations and molecular weights were investigated. All three binary blends of PDLLA/PESu, PLLA/PESu, and PESu/PDLA exhibit UCST behavior, which means they are immiscible at ambient temperature but can become miscible upon heating to higher temperatures at 240-268 °C depending on molecular weights. The PLLAs/PESu blends at UCST could be reverted back to the original phase-separated morphology, as proven by solvent redissolution. The blends upon quenching from above UCST could be frozen into a quasi-miscible state, where the Flory-Huggins interaction parameter (x12) was determined to be a negative value (by melting point depression technique). The interaction between PDLLA and PESu in blend resulted in significant reduction in spherulite growth rate of PESu. Furthermore, blends of PESu with lower molecular weight PLLA or PDLA (M w of PLLA and PDLA are 152,000 and 124,000 g/mol, respectively), instead of the higher Mw of PDLLA (Mw of PDLLA = 157,000 g/ mol), are immiscible with UCST phase behavior, which are affected by molecular weights rather than the ratio of L/D monomer in the chemical structure of PLAs.

Original languageEnglish
Pages (from-to)1135-1147
Number of pages13
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number11
Publication statusPublished - 2010 Jun 1

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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