TY  - JOUR
A1  - Schöne, Anne-Christin
A1  - Richau, Klaus
A1  - Kratz, Karl
A1  - Schulz, Burkhard
A1  - Lendlein, Andreas
T1  - Influence of Diurethane Linkers on the Langmuir Layer Behavior of Oligo[(rac-lactide)-co-glycolide]-based Polyesterurethanes
JF  - Macromolecular rapid communications
N2  - Three oligo[(rac-lactide)-co-glycolide] based polyesterurethanes (OLGA-PUs) containing different diurethane linkers are investigated by the Langmuir monolayer technique and compared to poly[(rac-lactide)-co-glycolide] (PLGA) to elucidate the influence of the diurethane junction units on hydrophilicity and packing motifs of these polymers at the air-water interface. The presence of diurethane linkers does not manifest itself in the Langmuir layer behavior both in compression and expansion experiments when monomolecular films of OLGA-PUs are spread on the water surface. However, the linker retard the evolution of morphological structures at intermediate compression level under isobaric conditions (with a surface pressure greater than 11 mN m(-1)) compared to the PLGA, independent on the chemical structure of the diurethane moiety. The layer thicknesses of both OLGA-PU and PLGA films decrease in the high compression state with decreasing surface pressure, as deduced from ellipsometric data. All films must be described with the effective medium approximation as water swollen layers.
KW  - Brewster angle microscopy
KW  - Langmuir monolayer
KW  - poly[(rac-lactide)-co-glycolide]
KW  - polyesterurethanes
KW  - spectroscopic ellipsometry
Y1  - 2015
U6  - https://doi.org/10.1002/marc.201500316
SN  - 1022-1336
SN  - 1521-3927
VL  - 36
IS  - 21
SP  - 1910
EP  - 1915
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schöne, Anne-Christin
A1  - Schulz, Burkhard
A1  - Richau, Klaus
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Characterization of Langmuir films prepared from copolyesterurethanes based on oligo(omega-pentadecalactone) and oligo(epsilon-caprolactone)segments
JF  - Macromolecular chemistry and physics
N2  - A series of multiblock copolymers (PDLCL) synthesized from oligo(omega-pentadecalactone) diol (OPDL) and oligo(epsilon-caprolactone) diol (OCL), which are linked by 2,2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI), is investigated by the Langmuir monolayer technique at the air-water interface. Brewster angle microscopy (BAM) and spectroscopic ellipsometry are employed to characterize the polymer film morphologies in situ. PDLCL containing >= 40 wt% OCL segments form homogeneous Langmuir monofilms after spreading. The film elasticity modulus decreases with increasing amounts of OPDL segments in the copolymer. In contrast, the OCL-free polyesterurethane OPDL-TMDI cannot be spread to monomolecular films on the water surface properly, and movable slabs are observed by BAM even at low surface pressures. The results of the in situ morphological characterization clearly show that essential information concerning the reliability of Langmuir monolayer degradation (LMD) experiments cannot be obtained from the evaluation of the pi-A isotherms only. Consequently, in situ morphological characterization turns out to be indispensable for characterization of Langmuir layers before LMD experiments.
KW  - brewster angle microscopy
KW  - ellipsometry
KW  - Langmuir layers
KW  - morphology
KW  - polyesterurethanes
Y1  - 2014
U6  - https://doi.org/10.1002/macp.201400377
SN  - 1022-1352
SN  - 1521-3935
VL  - 215
IS  - 24
SP  - 2437
EP  - 2445
PB  - Wiley-VCH
CY  - Weinheim
ER  -