TY - JOUR A1 - Liang, Xiao A1 - Behl, Marc A1 - Lendlein, Andreas T1 - Dihydroxy terminated teroligomers from morpholine-2,5-diones JF - European polymer journal : EPJ N2 - Oligodepsipeptides (ODPs) attract increasing attention as degradable materials in controlled drug delivery or as building blocks for nano-carriers. Their strong intermolecular interactions provide high stability. Tailoring the side groups of the amino acid repeating units to achieve a strong affinity to particular drugs allows a high drug-loading capacity. Here we describe synthesis and characterization of dihydroxy terminated teroligodepsipeptides (ter-ODPs) by ring-opening copolymerization (ROP) of three different morpholine-2,5-diones (MDs) in bulk in order to provide a set of teroligomers with structural variation for drug release or transfection. Ter-ODPs with equivalent co-monomer feed ratios were prepared as well as ter-ODPs, in which the co-monomer feed ratio was varied between 9 mol% and 78 mol%. Ter-ODPs were synthesized by ROP using 1,1,10,10-tetra-n-butyl-1,10-distanna-2,9,11,18-tetraoxa-5,6,14,15-tetrasulfur-cyclodecane (tin(IV) alkoxide) that was obtained by the reaction of dibutyl tin(II) oxide with 2-hydroxyethyl disulfide. The number average molecular weight (M-n) of ter-ODPs, determined by H-1 NMR and gel permeation chromatography (GPC), ranged between 4000 g center dot mol(-1) and 8600 g center dot mol(-1). Co-monomer compositions in ter-ODPs could be controlled by changing the feed ratio of co-monomers as observed by H-1 NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The amount of remaining monomers as determined by H-1 NMR could be kept below 1 wt%. Macrocycles as main sources of byproducts as determined from MALDI-TOF-MS measurements were significantly lower as compared to polymerization by Sn(Oct)(2). Glass-transition temperature (T-g) of ter-ODPs ranged between 59 degrees C and 70 degrees C. KW - Ring-opening polymerization KW - Tin octanoate KW - Morpholindione KW - Depsipeptide KW - Random copolymer KW - Telechel Y1 - 2021 U6 - https://doi.org/10.1016/j.eurpolymj.2020.110189 SN - 0014-3057 VL - 143 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut T1 - Controlled ring-opening polymerization of alpha-amino acid N-carboxyanhydrides in the presence of tertiary amines JF - Polymer : the international journal for the science and technology of polymers N2 - The mechanism of the primary ammonium/tertiary amine-mediated ring-opening polymerization of gamma-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) was investigated. Kinetic analyses revealed that the normal amine mechanism (NAM) together with a dormant-active chain end equilibrium were responsible for the controlled nature of this polymerization pathway, but that the polymerization also proceeded via the activated monomer mechanism (AMM). Mixtures of primary amines (1 equiv) and tertiary amines (0-1.5 equiv) were therefore tested to confirm the co-existence of the NAM and AMM and determine the limits for a controlled polymerization. For tertiary amine molar fractions smaller than 0.8 equiv, the reaction times were greatly reduced (compared to primary amine-initiated polymerization) without compromising the control of the reaction. Hence, the polymerization of NCA can proceed in a controlled manner even when the AMM contributes to the overall chain growth mechanism. (C) 2017 Elsevier Ltd. All rights reserved. KW - Ring-opening polymerization KW - Amino acid N-carboxyanhydride KW - NCA KW - Kinetics KW - Mechanism Y1 - 2017 U6 - https://doi.org/10.1016/j.polymer.2017.07.062 SN - 0032-3861 SN - 1873-2291 VL - 124 SP - 203 EP - 209 PB - Elsevier CY - Oxford ER -