engleski

Nanoscale Modified Polyurethanes for Biomedical Application

Polyurethane are used in a large number of commercial applications, including medical devices and artifficial organ production. A variety of performance demands are being placed on polyurethane elastomers (desirable mechanical, thermal, chemical, flow properties and biocompatibility ). Nanoscale modified polyurethane structure are ideally suited to achive this multifunctionality since the best features of different components on nanoscale can be combined to form a new material that has a broad spectrum of desired properties The synthesis of segmented polyurethanes with alternating hard and soft segments, typically result in a microphase separated morphology, which display higly elastomeric behavior that is suitable for variety applications. In general, the hard segments form crystalline region due to strong hydrogen bond associations between the urea or urethane groups, while the soft segments form the continuous phase and remain amorphous.. A one class of polyurethanes with addition branched polyesters are used in biomedical applications. In this paper we are study some characteristic nanoscale phenomena for this class materials. A inovative nanofiber fabric process production, electrospinning are described. Electrospun nanofiber fabrics have several potentially attractive features such as a very soft hand ; the potential of acting as a barrier against microorganisms and fine particulates.The electrospun nonwoven fiber mats possesses a high specific surface area, hierarchical porosity, which lend themselves to a wide-range of applications including filtration devices, vascular grafts, protective clothing, tissue scaffolds. Electrospun of branched polyesters allows control of chain end concentration, reduce viscosity and degradation. Special attention are given to surface phenomena and blood compatibility. The relationship between fiber morphology and processing parameter (applied voltage, flow rate) are developed by numericaiy and experimentaly. However, electrospun nanofiber fabrics have some potential problems in fabricating large quantities at commercial speeds. Mechanical material properties comparison with other polyurethane type production are described. Some nanoscale phenomena characteristic for medical application of this materials are explained.

polyurethane; biomaterials; electrospinning; branched polymers

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