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Surface characterization of poly(L-lactic acid)-methoxy poly(ethylene glycol) diblock copolymers by static and dynamic contact angle measurements, FTIR, and ATR-FTIR
Date
2008-02-05
Author
Mert, Özenç Murat
ERBİL, HÜSNÜ YILDIRIM
Dernir, A. S.
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Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License
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The surface composition and surface free energy properties of two types of amphiphilic and semicrystalline diblock copolymers consisting of poly(L-lactic acid) coupled to (methoxy poly(ethylene glycol) (PLLA-MePEG) having differing block lengths of PEG were investigated by using static and dynamic contact angle measurements, transmission Fourier infrared spectroscopy (FTIR), and attenuated total reflection spectroscopy (ATR-FTIR) and compared with results obtained from PLLA and MePEG homopolymers. The contact angle results were evaluated by using the van Oss-Good method (acid-base method), and it was determined that the Lewis base surface tension coefficient (gamma(-)) of the copolymers increased with an increase of the PEG molar content at the copolymer surface. This result is in good agreement with the transmission FTIR and ATR-FTIR results but not proportional to them, indicating that the surfaces of the copolymers are highly mobile and that the molecular rearrangement takes place upon contact with a polar liquid drop. The dynamic contact angle measurements showed that the strong acid-base interaction between the oxygen atoms in the copolymer backbone of the relatively more hydrophilic PEG segments with the Lewis acidic groups of the polar and hydrogen-bonding water molecules enabled the surface molecules to restructure (conformational change) at the contact area, so that the PEG segments moved upward, whereas the apolar methyl pendant groups of PLLA segments buried downward.
Subject Keywords
Hydrocarbons
,
Contact angle
,
Copolymers
,
Aromatic compounds
,
Homopolymers
URI
https://hdl.handle.net/11511/32310
Journal
LANGMUIR
DOI
https://doi.org/10.1021/la701966d
Collections
Graduate School of Applied Mathematics, Article
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Ö. M. Mert, H. Y. ERBİL, and A. S. Dernir, “Surface characterization of poly(L-lactic acid)-methoxy poly(ethylene glycol) diblock copolymers by static and dynamic contact angle measurements, FTIR, and ATR-FTIR,”
LANGMUIR
, pp. 749–757, 2008, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/32310.