TY  - JOUR
A1  - Rottke, Falko O.
A1  - Schulz, Burkhard
A1  - Richau, Klaus
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers
JF  - Beilstein journal of nanotechnology
N2  - 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(omega-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, R-q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified.
KW  - ellipsometric mapping
KW  - Langmuir monolayer
KW  - polyester
KW  - root mean square roughness
KW  - spectroscopic ellipsometry
Y1  - 2016
U6  - https://doi.org/10.3762/bjnano.7.107
SN  - 2190-4286
VL  - 7
SP  - 1156
EP  - 1165
PB  - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY  - Frankfurt, Main
ER  -