Crystallization and morphology of stereocomplexes in nonequimolar mixtures of poly(l-lactic acid) with excess poly(d-lactic acid)

Eamor M. Woo, Ling Chang

Research output: Contribution to journalArticlepeer-review

57 Citations (Scopus)

Abstract

Crystallization of nonequimolar compositions of poly(d-lactic acid) with low-molecular-weight poly(l-lactic acid) (PDLA/LMw-PLLA) blends leads to formation of various fractions of stereocomplexed PLA (sc-crystallites) and homocrystallites (PDLA or PLLA). For the PDLA/LMw-PLLA blends within the composition window of LMw-PLLA content between 30 and 50 wt%, only sc-crystal exists and no homocrystal is present. On the other hand, for PDLA/LMw-PLLA blends with excess PDLA, e.g. PDLA/LMw-PLLA = 90/10, atomic-force microscopy (AFM) characterization on various stages of crystallization of sc-PLA crystal with PDLA homocrystal shows a repetitive stacking of excess PDLA on pre-formed sc-PLA crystal serving as crystallizing templates. The crystallization initially begins with string-like (fibril-like) PDLA lamellae, followed with PDLA aggregating on sc-PLA crystal into a bead-on-string crystal, then growing to thicker irregularly-shaped dough-like lamellae. Repetitive growth cycle from strings to bead-on-string lamellae continues on top of the dough-like lamellae as new substrates, until ending impingement of the PDLA spherulites.

Original languageEnglish
Pages (from-to)6080-6089
Number of pages10
Journalpolymer
Volume52
Issue number26
DOIs
Publication statusPublished - 2011 Dec 13

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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