Profile
Synthetic degradable biomaterials
- Biodegradable polymers based on synthetic polyether-esters and polyester – building blocks
- Development of polymer systems with tailor made properties
The synthesis of biodegradable polymers for application like tissue engineering is based on comonomers, established in clinical applications as well as on new synthetic strategies.
By the use of a building set, composed of different types of polymers, polymer systems are generated, whose processing properties, hydrolytic degradation behavior and biofunctionality or selectivety diversified by adjustment of specific molecular parameters.
Copolymers based on acrylates
- Acrylic (co)polymers for production of reactive and biostable membrane systems
- Adjustment of polymer properties by control of reaction kinetics
- Application-oriented, economical up-scaling of syntheses
The combination of known building blocks in combination with new synthetic techniques enables tailoring materials for different applications. Polymer synthesis is performed by using free radical polymerisation. The polymers produced via free radical polymerisation are acrylic polymers equipped with reactive groups. The fundamental investigation of the polymerisation kinetics forms the base for the control of molecular parameters in order to reach the favoured profile of properties and for an application-oriented economical up-scaling of syntheses, and allows the production of material up to kilogram amounts.
Stimuli-sensitive polymer systems
- Dual-shape polymers
- triple-shape polymers
- implementation other stimuli than heat
- Polymer systems with tailored mechanical, electrical, and thermal as well as switching functionalities.
- Thermoplastic elastomers, electrical (semi)conducting as well as switchable polymers and polymer network systems.
Thermoplastic elastomers, electrical (semi)conducting poly(p-phenylene ethynylene)s and polymer network systems are synthesised using a combination of polycondensation and polyaddition. Incorporation of certain molecular building blocks enables a stimuli-induced change of shape. Heat or light can be used as stimuli. Polymer composition and synthesis are optimized in such a way, that polymers with the desired mechanical and thermal properties or switching properties respectively are obtained. While in classical one-way dual-shape polymers only one switching phase is present, the inserting of a second switching phase enables triple-shape polymers.
Shape-memory Properties of Polymers
The shape-memory properties can be quantified by cyclic thermomechnical investigations. One cycle includes the programming of the sample and the recovery of its permanent shape. In a typical test program the sample is heated to a temperature above the thermal transition temperature Ttrans, related to the switching phase and is stretched to a certain elongation εm. The sample is cooled at constant stress σn after stretching to εm, fixing the new shape. After reheating to a temperature higher than Ttrans the sample is contracting itself and the original shape is restored. The following series of images shows from left to right the transition from the temporary shape of a stretched rod to the permanent shape of a spiral for a thermoplastic shape-memory polymer. After heating to 60°C the shape recovery process takes 10 s.
