Synthesis and Novel Processing of Polyurethanes

• Main Author: Ahmad, Zeeshan
• Published: Queen Mary, University of London 2007
• Subjects: 668.9
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485558

Polymeric materials have been'' used in a variety of biomedical applications. Although some polymeric materials are more biocompatible than others, there are always some degree of interaction between the material and the host environment. These interactions depend on how the polymers are synthesised and fabricated playing a major role in predicting their long-term behaviour. These factors are directly related to morphological and chemical structUre of these i:.! materials. This study focuses on a class of polymeric material, polyurethanes, and then to prepare a novel materi~l through novel. synthesis routes and electro-spinning, fOf fabricating porous structures from polyurethanes. . A selection of Polyurethanes were synthesised using the two step solvent polymerisation methods without the use, of a catalyst, as catalysts can cause premature degradation of the polymeric chain and act as fungicides· within the biological environment. Characterisation was performed using· Fourier Transform Infrared (FT-IR), Fourier Transform Raman (FTRaman)/ Raman, Differential Scanning Calorimetry (DSC) and Gel Permeation Chromatography (GPC). Degradation profile of the polymers was assessed through simple hydrolytic degradation and tensile properties ofthe materials were also evaluated. A scaffold material was obtained by using Agar as a soft segment, as their hydrolysis ratio can be vaned by changing the hard and soft segments of the resulting polyurethane. Agar has a number of hydroxyl groups within its structure and provides sufficient reaction sites for the isocyanate to react and form urethane linkages. The ratios of reactants were varied and the reaction conditions optimised. A series of co-polymers were also synthesised with Agar molecule. A selection of the polymers prepared from the first section was electrospun to form scaffolds. Prior to electrospinning, polymers were assessed for pH, relative permittivity, viscosity, surface tension, conductivity and density to ascertain the properties of polymers that are required for the electrospinning proces.s. Highly. porous polymeric scaffold materials were obtained, which were analysed under the optical microscope and the scanning electron microscope (SEM).