TY  - JOUR
A1  - Peng, Xingzhou
A1  - Behl, Marc
A1  - Zhang, Pengfei
A1  - Mazurek-Budzynska, Magdalena
A1  - Feng, Yakai
A1  - Lendlein, Andreas
T1  - Synthesis of Well-Defined Dihydroxy Telechelics by (Co)polymerization of Morpholine-2,5-Diones Catalyzed by Sn(IV) Alkoxide
JF  - Macromolecular bioscience
N2  - Well-defined dihydroxy telechelic oligodepsipeptides (oDPs), which have a high application potential as building blocks for scaffold materials for tissue engineering applications or particulate carrier systems for drug delivery applications are synthesized by ring-opening polymerization (ROP) of morpholine-2,5-diones (MDs) catalyzed by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane (Sn(IV) alkoxide). In contrast to ROP catalyzed by Sn(Oct)(2), the usage of Sn(IV) alkoxide leads to oDPs, with less side products and well-defined end groups, which is crucial for potential pharmaceutical applications. A slightly faster reaction of the ROP catalyzed by Sn(IV) alkoxide compared to the ROP initiated by Sn(Oct)(2)/EG is found. Copolymerization of different MDs resulted in amorphous copolymers with T(g)s between 44 and 54 degrees C depending on the molar comonomer ratios in the range from 25% to 75%. Based on the well-defined telechelic character of the Sn(IV) alkoxide synthesized oDPs as determined by matrix-assisted laser desorption/ionization time of flight measurements, they resemble interesting building blocks for subsequent postfunctionalization or multifunctional materials based on multiblock copolymer systems whereas the amorphous oDP-based copolymers are interesting building blocks for matrices of drug delivery systems.
KW  - oligodepsipeptides
KW  - ring-opening polymerization
KW  - Sn(IV) alkoxide
KW  - telechelics
KW  - tin(II) 2-ethylhexanoate
Y1  - 2018
U6  - https://doi.org/10.1002/mabi.201800257
SN  - 1616-5187
SN  - 1616-5195
VL  - 18
IS  - 12
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  -