Effects of chain configuration on UCST behavior in blends of poly(L-lactic acid) with tactic poly(methyl methacrylate)s

Shu Hsien Li, Eamor M. Woo

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


Chain configuration influences phase behavior of blends of poly(methyl methacrylate) (PMMA) of different tactic configurations (syndiotacticity, isotacticity, or atacticity) with poly(L-lactic acid) (PLLA). Blends system of sPMMA/PLLA is immiscible with an asymmetry-shaped UCST at 250 C. The phase behavior of the sPMMA/PLLA blend is similar to the aPMMA/PLLA blend that has been already proven in the previous work to exhibit similar UCST temperatures (230-250 C) and asymmetry shapes in the UCST diagrams. On the other hand, the iPMMA/PLLA blend remains immiscible up to thermal degradation without showing any transition to UCST upon heating. The blend system with UCST, that is, sPMMA/PLLA, can be frozen in a state of miscibility by quenching to rapidly solidify from the homogeneous liquid at UCST, where the Tg- composition relationship for the sPMMA/PLLA blend fits well with the Gordon-Taylor Tg model with k = 0.15 and the blend's T 0m leads to χ12 = -0.26 for the UCST-quenched sPMMA/PLLA blend. Both parameters (k and χ) as characterized for the frozen miscible blend suggest a relatively weak interaction between the two constituents (sPMMA and PLLA) in the blends. The interaction strength is likely not strong enough to maintain a thermodynamic miscibility when the blend is at ambient temperature or any lower temperatures below UCST.

Original languageEnglish
Pages (from-to)2355-2369
Number of pages15
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number21
Publication statusPublished - 2008 Nov 1

All Science Journal Classification (ASJC) codes

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


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