From organic building blocks to nanomaterials
Modern polymer chemistry allows the precise control over polymer architecture, molecular weights, functionality and many more properties. Beginning with the choice of polymerization technique, suitable monomers are synthesized and polymerized. This, in combination with postpolymerization modifications, such as crosslinking in emulsion or introduction of dyes, drugs or targeting moieties allow the design of desirable properties, e.g. biological recognition, degradability or other properties. By choosing the right reaction conditions we design linear or highly branched materials aiming at the development of fast synthetic access towards different polymer architectures.
Both chain growth (i.e. ionic or radical polymerization) and step growth (i.e. polycondensation and polyaddition) polymerization techniques are applied for the generation of a variety of soluble or cross-linked materials. Polymerization is studied in solution, bulk and in heterogeneous phase. This ranges from special vinyl polymers, like redox-active ferrocene-containing polymers, over smart hydrogels to biocompatible and biodegradable poly(phosphoester)s. The latter can be prepared by either ring-opening polymerization of strained cyclic phosphates or by acyclic diene metathesis (ADMET) polycondensation. ADMET allows us to generate high molecular weight poly(phosphoester)s with a defined number of functional groups along the polymer backbone and to tailor the degradation kinetics. These materials were recently developed in our department and are currently investigated by several coworkers with respect to the inherent characteristics of the main-chain poly(phosphoester)s for bone attachment or flame retardant applications. Water-soluble and degradable PPEs are ideal candidates to substitute non-degradable poly(ethylene glycol) in surfactants or to cover polymeric nanocarriers. We recently elucidated the role of biomolecule-polymer interactions on the so called „stealth effect“, which is the basis for many modern drugs and controls their in vivo blood circulation times. The degradable PPEs are efficient in reducing the protein adsoprtion on the surface of nanocarriers and are currently tested to prepare fully biodegradable nanocarriers for drug delivery.
A precision polymerization technique, such as anionic polymerization, allows us to synthesize block copolymers and random copolymers with tunable solubility or redox behavior, for example. By fine-tuning of the reaction kinetics, sequence-controlled competing anionic polymerization of several monomers becomes feasible. The anionic polymerization of aziridines is the ideal toolbox to control copolymerization behavior by adjusting oft he monomer stucture.
Also protein-polymer conjugates are studied, in order to replace the well-established PEGylation strategy and to improve the pharmacokinetic properties of medically active proteins. Fully degradable protein-PPE conjugates were also prepared. Especially block copolymers with their ability to phase separate into well-defined nanostructures are of great interest for our department. Recently, a synthetic cell-model was developed based on poly(dimethylsiloxane-block-methyloxazoline), which was synthesized via cationic polymerizataion of methyl oxazoline and aggregates into vesicles with a double layer membrane (polymerosomes). These vesicles were then investigated with respect to their uptake behavior for different nanoparticles.
More polymer synthesis? – check out the website of the „Functional Polymers Group“