An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers.
The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air-water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(ω-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness,Rq. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified.
Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstraße 55, 14513 Teltow, Germany; Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Golm, Germany.
Falko O
FO
Rottke
Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstraße 55, 14513 Teltow, Germany; Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Golm, Germany.
Burkhard
B
Schulz
Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstraße 55, 14513 Teltow, Germany.
Klaus
K
Richau
Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstraße 55, 14513 Teltow, Germany.
Karl
K
Kratz
Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstraße 55, 14513 Teltow, Germany; Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Golm, Germany.
Andreas
A
Lendlein
Langmuir monolayer; ellipsometric mapping; polyester; root mean square roughness; spectroscopic ellipsometry