Comparison of the monolayer formation of fluorinated and nonfluorinated amphiphilic block copolymers at the air-water interface.
Series of fluorinated amphiphilic diblock copolymers poly(ethylene oxide)-b-poly(heptafluorobutyl methacrylate) (PEO-b-PHFBMA) and nonfluorinated analogue copolymers poly(ethylene oxide)-b-poly(n-butyl methacrylate) (PEO-b-PBMA) with different lengths of hydrophobic blocks were synthesized. Their interface properties at the air-water interface were investigated using surface pressure and X-ray reflectivity (XR) measurements on the Langmuir trough. The fluorinated species have shown a distinct transition from flat-lying to standing side chains, whereas the nonfluorinated ones have no indication for a significant amount of flat-lying side chains. The water surface is covered by a single layer, which is proved by XR measurements of PEO-b-PHFBMA. The obtained thickness and electron density can be related to the hydrophobic part of the copolymer by a simple consistency check: The total numbers of electrons from the fit of the XR curve should agree with the numbers of electrons in the corresponding block.
Li
Zheng
Z
Institute of Physical Chemistry, Department of Chemistry, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany.
Schön
Volker
V
Huber
Patrick
P
Kressler
Jörg
J
Busse
Karsten
K