Advanced tools for molecular characterization of bio-based and biodegradable polymers.

Bio-based and biodegradable materials play a vital role in a sustainable and green economy. These materials must exhibit properties that are similar to or better than the properties of oil- or coal-based materials and require sophisticated synthesis technologies and detailed knowledge of structure-property correlations. For comprehensive molecular structure elucidation, advanced analytical methods, including coupled and hyphenated techniques that combine advanced fractionation and information-rich spectroscopic detectors, are an indispensable tool.

Stereochemical Heterogeneity Analysis of Polylactides by Multidimensional Liquid Chromatography.

A new and robust high-performance liquid chromatography (HPLC) method that separates poly(lactic acid) (PLA) according to its stereochemical composition is presented. Using this method, poly(l-lactide) incorporating trace amounts of -lactide resulting from the racemization is separated from the pristine polymer. To prove this aspect in more detail, a representative poly(l-lactic acid) standard, assumed to be highly homogeneous, was separated using this method.

Iron(ii) carboxylates and simple carboxamides: an inexpensive and modular catalyst system for the synthesis of PLLA and PLLA-PCL block copolymers.

The combination of inexpensive Fe(ii) acetate with low molecular weight aliphatic carboxamides generates an effective catalyst system for the ring opening polymerisation of lactones. PLLAs were produced in melt conditions with molar masses of up to 15 kg mol, narrow dispersity ( = 1.03), and without racemisation.

Connecting the complex microstructure of LDPE to its rheology and processing properties a combined fractionation and modelling approach.

Well-defined mini-plant low density polyethylene samples were fractionated preparatively according to their crystallizability preparative temperature rising elution fractionation and according to molecular weight preparative solvent gradient fractionation (pSGF). Rheology of the fractions was measured in both the small amplitude oscillatory shear (SAOS) and the non-linear extension regimes. The linear and non-linear rheology of the pTREF fractions were dominated by molecular weight effects, while the impact of the higher degree of long chain branching for the pSGF fractions with higher molecular weights was observed in van Gurp-Palmen plots and in strain hardening behavior in the extensional rheology measurements.