@article{NaolouLendleinNeffe2019,
  author    = {Naolou, Toufik and Lendlein, Andreas and Neffe, Axel T.},
  title     = {Amides as non-polymerizable catalytic adjuncts enable the ring-opening polymerization of lactide with ferrous acetate under mild conditions},
  series = {Frontiers in Chemistry},
  volume    = {7},
  journal   = {Frontiers in Chemistry},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {2296-2646},
  doi       = {10.3389/fchem.2019.00346},
  pages     = {12},
  year      = {2019},
  abstract  = {Sn-based catalysts are effective in the ring-opening polymerization (ROP) but are toxic. Fe(OAc)(2) used as an alternative catalyst is suitable for the ROP of lactide only at higher temperatures (>170 degrees C), associated with racemization. In the ROP of ester and amide group containing morpholinediones with Fe(OAc)(2) to polydepsipeptides at 135 degrees C, ester bonds were selectively opened. Here, it was hypothesized that ROP of lactones is possible with Fe(OAc)(2) when amides are present in the reactions mixture as Fe-ligands could increase the solubility and activity of the metal catalytic center. The ROP of lactide in the melt with Fe(OAc)(2) is possible at temperatures as low as 105 degrees C, in the presence of N-ethylacetamide or N-rnethylbenzamide as non-polymerizable catalytic adjuncts (NPCA), with high conversion (up to 99 mol\%) and yield (up to 88 mol\%). Polydispersities of polylactide decreased with decreasing reaction temperature to <= 1.1. NMR as well as polarimetric studies showed that no racemization occurred at reaction temperatures <= 145 degrees C. A kinetic study demonstrated a living chain-growth mechanism. MALDI analysis revealed that no side reactions (e.g., cyclization) occurred, though transesterification took place.},
  language  = {en}
}
@article{RottkeSchulzRichauetal.2016,
  author    = {Rottke, Falko O. and Schulz, Burkhard and Richau, Klaus and Kratz, Karl and Lendlein, Andreas},
  title     = {An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers},
  series = {Beilstein journal of nanotechnology},
  volume    = {7},
  journal   = {Beilstein journal of nanotechnology},
  publisher = {Beilstein-Institut zur F{\~A}\Prderung der Chemischen Wissenschaften},
  address   = {Frankfurt, Main},
  issn      = {2190-4286},
  doi       = {10.3762/bjnano.7.107},
  pages     = {1156 -- 1165},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}