TY  - JOUR
A1  - Debsharma, Tapas
A1  - Behrendt, Felix Nicolas
A1  - Laschewsky, Andre
A1  - Schlaad, Helmut
T1  - Ring-opening metathesis polymerization of biomass-derived levoglucosenol
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker
N2  - The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100kgmol(-1) and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 degrees C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment.
KW  - degradable polymers
KW  - metathesis
KW  - ring-opening polymerization
KW  - sustainable chemistry
KW  - thermoplastics
Y1  - 2019
U6  - https://doi.org/10.1002/anie.201814501
SN  - 1433-7851
SN  - 1521-3773
VL  - 58
IS  - 20
SP  - 6718
EP  - 6721
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Naolou, Toufik
A1  - Lendlein, Andreas
A1  - Neffe, Axel T.
T1  - Amides as non-polymerizable catalytic adjuncts enable the ring-opening polymerization of lactide with ferrous acetate under mild conditions
JF  - Frontiers in Chemistry
N2  - 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.
KW  - ring-opening polymerization
KW  - polyester
KW  - catalyst
KW  - iron
KW  - amide ligand
Y1  - 2019
U6  - https://doi.org/10.3389/fchem.2019.00346
SN  - 2296-2646
VL  - 7
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  -