0000000000008247
AUTHOR
Anja Thomas
showing 9 related works from this author
Combining oxyanionic polymerization and click-chemistry: a general strategy for the synthesis of polyether polyol macromonomers
2014
We describe a synthetic pathway to tailor-made amphiphilic macromonomers by a combination of anionic ring-opening polymerization and copper-catalyzed azide–alkyne cycloaddition (CuAAC). Linear polyglycerol and poly(glyceryl glycerol) were synthesized in a controlled manner by anionic ring-opening polymerization of ethoxyethyl glycidyl ether or isopropylidene glyceryl glycidyl ether, respectively, with narrow and monomodal molecular weight distributions (Mw/Mn < 1.20) and molecular weights ranging from 850 g mol−1 to 2500 g mol−1. After end-capping with propargyl bromide and removal of the protecting groups, the hydrophilic precursors were quantitatively clicked to a series of hydrophobic az…
Oligo(glycerol) Methacrylate Macromonomers
2011
Linear, protected ω-methoxy oligo(glycerol) methacrylate (OGly(P)MA) macromonomers are synthesized via anionic ring-opening polymerization of ethoxyethyl glycidyl ether (EEGE) followed by termination with methacrylic acid anhydride (DP(n) = 3-11, PDI < 1.30). The covalently bound methacrylate moiety allows the homopolymerization of OGly(P)MA as well as copolymerization with low molecular weight comonomers. In homopolymerizations, macromonomers are polymerized by atom transfer radical polymerization (ATRP) yielding well-defined graft polymers (M(n) = 20,000-30,000 g mol(-1)). Acidic hydrolysis of the protecting groups releases water-soluble polyhydroxy-functional structures. First results on…
Superconductivity in palladium-based Heusler compounds
2009
This work reports on four more Heusler superconductors: ${\text{Pd}}_{2}\text{ZrAl}$, ${\text{Pd}}_{2}\text{HfAl}$, ${\text{Pd}}_{2}\text{ZrIn}$, and ${\text{Pd}}_{2}\text{HfIn}$. These compounds exhibit superconducting transition temperatures ranging from 2.4--3.8 K as determined by resistivity measurements. According to their behavior in an external magnetic field, all compounds are type II bulk superconductors. The occurrence of superconductivity was predicted for these compounds using electronic structure calculations. The electronic structures exhibit van Hove singularities (saddle points) at the $L$ point. These lead to a maximum in the corresponding density of states and superconduct…
The “Needle in the Haystack” Makes the Difference: Linear and Hyperbranched Polyglycerols with a Single Catechol Moiety for Metal Oxide Nanoparticle …
2014
Multifunctional linear (CA-linPG) and hyperbranched polyglycerols (CA-hbPG) bearing a single catechol unit were synthesized by use of an acetonide-protected catechol initiator for the anionic polymerization of ethoxyethyl glycidyl ether (EEGE) and glycidol, respectively. A key feature for the synthesis of the hyperbranched structures was a selective, partial acetal deprotection step. The single catechol unit among a large number of aliphatic 1,2- and 1,3-diol moieties (i.e., the “needle in the haystack”) in both linear and hyperbranched polyglycerols permits dispersion of transition metal oxide nanoparticles in brine, as demonstrated for manganese oxide (MnO) nanoparticles. Molecular weight…
Supramolecular Linear-g-Hyperbranched Graft Polymers: Topology and Binding Strength of Hyperbranched Side Chains
2013
Complex, reversible hyperbranched graft polymer topologies have been obtained by spontaneous self-assembly. Well-defined adamantyl- and β-cyclodextrin-functionalized polymers were employed to generate linear-g-(linear–hyperbranched) supramolecular graft terpolymers. For this purpose the synthesis of monoadamantyl-functionalized linear polyglycerols (Ada-linPG) and hyperbranched polyglycerols (Ada-hbPG) as well as poly(ethylene glycol)-block-linear polyglycerol (Ada-PEG-b-linPG) and poly(ethylene glycol)-block-hyperbranched poly(glycerol) (Ada-PEG-b-hbPG) block copolymers was established. Isothermal titration calorimetry (ITC) with β-cyclodextrin revealed a shielding effect of hyperbranched …
α ,ω n -Heterotelechelic Hyperbranched Polyethers Solubilize Carbon Nanotubes
2010
The synthesis of novel linear-hyperbranched (linhb) polyether block copolymers based on poly(ethylene oxide) and branched poly(glycerol), bearing a single pyrene or myristyl moiety at the α-position of the linear chain is described. The polymers exhibit low polydispersity (M w /M n < 1.3) and controlled molecular weights (M n = 5 000 g·mol -1 ). The mainly hydrophilic block copolymers with multiple hydroxyl end groups readily dissolve multiwalled carbon nanotubes (MWCNTs) in water by mixing and subsequent sonification, resulting in noncovalent attachment of the linhb hybrid structure to the carbon nanotubes (CNTs). Transmission electron microscopy (TEM) was employed to visualize the solubil…
Tunable dynamic hydrophobic attachment of guest molecules in amphiphilic core–shell polymers
2016
In this study, synthesis and dynamic properties of amphiphilic core–shell polymers are reported as monitored through their interaction with small amphiphilic molecules. Brush-like structures are formed with a hydrophobic core surrounded by a hydrophilic shell utilizing controlled radical addition–fragmentation chain transfer (RAFT) polymerization of macromonomers consisting of linear polyglycerol chains attached to alkylene methacrylate. Continuous wave electron paramagnetic resonance (CW EPR) spectroscopy is employed to study how the amphiphilic, paramagnetic spin probe 16-DSA (16-doxyl stearic acid) interacts with polymers of different alkylene chain lengths in their hydrophobic cores and…
Beyond Poly(ethylene glycol): Linear Polyglycerol as a Multifunctional Polyether for Biomedical and Pharmaceutical Applications
2014
Polyglycerols (sometimes also called "polyglycidols") represent a class of highly biocompatible and multihydroxy-functional polymers that may be considered as a multifunctional analogue of poly(ethylene glycol) (PEG). Various architectures based on a polyglycerol scaffold are feasible depending on the monomer employed. While polymerization of glycidol leads to hyperbranched polyglycerols, the precisely defined linear analogue is obtained by using suitably protected glycidol as a monomer, followed by removal of the protective group in a postpolymerization step. This review summarizes the properties and synthetic approaches toward linear polyglycerols (linPG), which are at present mainly base…
Ligand-Binding Cooperativity Effects in Polymer-Protein Conjugation.
2019
We present an electron paramagnetic resonance (EPR) spectroscopic characterization of structural and dynamic effects that stem from post-translational modifications of bovine serum albumin (BSA), an established model system for polymer-protein conjugation. Beyond the typical drug delivery and biocompatibility aspect of such systems, we illustrate the causes that alter internal dynamics and therefore functionality in terms of ligand-binding to the BSA protein core. Uptake of the paramagnetic fatty acid derivative 16-doxyl stearic acid by several BSA-based squaric acid macroinitiators and polymer-protein conjugates was studied by EPR spectroscopy, aided by dynamic light scattering (DLS) and z…