|Title:||Biodegradable thermoplastic polyurethanes for vascular tissue regeneration: synthesis of alternative/new building blocks||Other Titles:||Bioabbaubare thermoplastische Polyurethane für vascular tissue regeneration: Synthese von alternativen Bausteinen||Language:||English||Authors:||Heißenberger, Lukas||Qualification level:||Diploma||Keywords:||Thermoplastic Urethan Elastomers||Advisor:||Liska, Robert||Assisting Advisor:||Dworak, Claudia Lydia||Issue Date:||2015||Number of Pages:||108||Qualification level:||Diploma||Abstract:||
In the last decades cardiovascular diseases have become the number one single cause of death throughout the world. Naturally the demand for substitute materials to replace failing tissue related to these diseases increased as well. Vascular tissue engineering is a promising approach to meet these demands. Although there are synthetic materials available that can replace large diameter blood vessels, small diameter blood vessels of the same materials failed. Compliance and elastic mismatch as well as low hemocompatibility are considered to be the main reasons for failure. Thermoplastic polyurethane materials (TPUs) might offer a new approach for designing small diameter vascular grafts. This type of polymer usually shows good biocompatibility as well as elastomeric properties and usually can be processed from melt as well as from solution. The segmented configuration of these polyurethanes - consisting of a macrodiol, as flexible soft block, and a combination of diisocyanate and chain extender, as a rigid hard block - allows tuning of its final properties, such as mechanical properties and degradation, just by changing the building blocks. The aim of this work was the synthesis of faster degrading TPUs compared to previously developed materials within our working group. These new materials were supposed to show soft block- and hard block degradability as well as suitable mechanical properties for the use in vascular tissue engineering and they should be processed by electrospinning. To ensure highest possible biocompatibility the use of ester-based building blocks, which lead to acidic degradation products that can cause inflammatory reactions within the surrounding tissue, was supposed to be minimial. In order to achieve this goal various polymers with either poly(tetrahydrofuran) or a new PEG-carbonate as soft block and combining them with different chain extenders including bis(2-hydroxyethyl)terephthalate, bis(2-hydroxyethyl)disulfide and newly synthesized thiazolidine compounds, ketals and organophosphates were prepared. As hard block only hexamethylene diisocyanate was used. The higher hydrophilicity due to the ether moieties paired with the higher number of carbonate groups compared to already used polycarbonates and polyether soft blocks in the backbone of the polymer were expected to accelerate degradation with the chain extenders enhancing this effect. The obtained materials were tested towards degradability and mechanical properties and compared to reference materials, to evaluate the most suitable polyurethane for the use in vascular tissue engineering.
|Library ID:||AC12708117||Organisation:||E163 - Institut für Angewandte Synthesechemie||Publication Type:||Thesis
|Appears in Collections:||Thesis|
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checked on Feb 24, 2021
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