Stereocomplexation Effects Induced by Mixtures of Enantiomeric Polylactides on Hydrolytic Behaviors and Surface Structure

ABSTRACT

The effects of stereocomplexation of enantiomeric polylactide (PLA) mixture films, (l-PLA/d-PLA), on hydrolytic behaviors and surface structure were investigated by Langmuir technique and X-ray photoelectron spectroscopy, respectively. The alkaline hydrolysis rate of stereocomplexed monolayers from equimolar l-PLA and d-PLA was much slower than those of their homopolymers. The (l-PLA-b-PDMS-b-l-PLA/l-PLA, 50/50 by wt.%) mixture film showed the surface segregation of PDMS at the surface layer while the surface composition of PDMS in (l-PLA-b-PDMS-b-l-PLA/d-PLA, 50/50 by wt.%) was similar to its bulk composition. These are likely due to strong interaction between d- and l-lactide unit sequences, which prevents the penetration of water into the bulk and surface segregation of PDMS.

Keywords:

• hydrolysis
• langmuir
• polylactide
• segregation
• stereocomplexation

Acknowledgments

This work was supported in part by grant No. R01-2002-000-00034-0 (2004) from the Basic Research Program of the Korea Science & Engineering Foundation.

Notes

^a Calculated from direct PS calibration of SEC.

^b For as-cast samples.

^c 2.8 mol% of PDMS.