Soft and Hard Implant Fabrication Using 3D-Bioplotting TM

At the Freiburger Materialforschungszentrum we have developed a new process (3DBioplotting TM) that permits most kind of polymers and biopolymers to be used in 3D scaffold design, including hydrogels (e.g. collagen, agar), polymer melts (e.g. PLLA, PGA, PCl) and twocomponent systems (e.g. chitosan, fibrin). Cells can be incorporated within the construction process, making this an ideal Rapid Prototyping technique for Organ Printing. Tailor-made biodegradable soft or hard scaffolds can so be fabricated in a short time using individual computer-tomography data from the patient. In-vitro tests showed promising results and in-vivo experiments are now under observation.Mechanical Engineerin

Development of Acid-Sensitive Platinum(II) Complexes With Protein-Binding Properties

Four new protein-binding platinum(II) complexes, 10, 11, 21, 22, in which the dichloroplatinum moiety is coordinated either to a carbon-substituted or a nitrogen-substituted ethylene diamino ligand, were prepared in ten-step syntheses. According to pH-dependent stability studies with strictly related compounds, 11 and 22 exhibit acid-sensitive properties

Green Pathways for the Enzymatic Synthesis of Furan-Based Polyesters and Polyamides

The attention towards the utilization of sustainable feedstocks for polymer synthesis has grown exponentially in recent years. One of the spotlighted monomers derived from renewable resources is 2,5-furandicarboxylic acid (FDCA), one of the most promising bio-based monomers, due to its resemblance to petroleum-based terephthalic acid. Very interesting synthetic routes using this monomer have been reported in the last two decades. Combining the use of bio-based monomers and non-toxic chemicals via enzymatic polymerizations can lead to a robust and favorable approach towards a greener technology of bio-based polymer production. In this chapter, a brief introduction to FDCA-based monomers and enzymatic polymerizations is given, particularly focusing on furan-based polymers and their polymerization. In addition, an outline of the recent developments in the field of enzymatic polymerizations is discussed. </p

Organic microcomposites via reactive processing

The in-situ formation of dispersed polyaramide whiskers during melt processing of polymers represents a new route to thermoplastic and elastomeric organic microcomposites. When N-(p-aminobenzoyl)-caprolactam (PAC) is injected into melts of high molecular weight polyamide-6 or dihydroxy-terminated poly(oxytetramethylene) liquid rubber, stable dispersions of polymeric whiskers are formed. At temperatures around 200 °C PAC polymerization takes place exclusively through attack of the PAC amine group at the exocyclic carbonyl group, thus eliminating caprolactam and forming whiskers being composed of highly crystalline poly(p-phenylenebenzamide). With increasing polymerization temperature, the elimination reaction is accompanied by the competing attack of the amine group at the endocyclic carbonyl group of the caprolactam ring system. This side-reaction causes ring-opening, thus incorporating 6-aminocaproic structural units into the polyaramide backbone. Moreover, the condensation reaction of PAC and N-acyl-caprolactam-functional whisker surfaces with hydroxy- or amine-endgroups affords steric stabilization of the dispersions and excellent interfacial adhesion of the microcomposites. This covalent bond formation between matrix polymer and dispersed in-situ formed polyaramide whiskers is the key to unusual property synergisms of such organic microcomposites. In most cases, small amounts of PAC as additives during processing are sufficient to improve stiffness and strength without sacrificing toughness. Morphologies, mechanical properties, and the basic structure/property relationships of in-situ formed polyaramide-reinforced polyamide-6 and of polyurethanes elastomers prepared from novel anisotropic polymer polyol dispersions and diisocyanates are reported as a function of the PAC content and polymerization conditions