title: In vitro oxidation of high polydimethylsiloxane content biomedical polyurethanes: correlation with the microstructure.
abstract: The resistance to in vitro metal ion oxidation of a polydimethylsiloxane (PDMS)-containing thermoplastic polyurethane elastomer (Elast-Eon) is compared with that of a polyurethane consisting of the same hard segment chemistry and content, but with aliphatic polycarbonate soft segments (PCU). Scanning electron microscopy and attenuated total reflectance Fourier transform infrared spectroscopy were used to assess changes in surface morphology and chemistry. The extent of bulk degradation was assessed indirectly by dynamic mechanical analysis and small-angle X-ray scattering experiments. The findings indicate that Elast-Eon is more resistant to oxidation than the PCU, because of the presence of the PDMS soft segments as well as its phase separated microstructure. The PCU exhibits a rather high degree of intermixing between hard and soft segments, rendering the hard segments dissolved or trapped in the soft phase more susceptible to oxidative conditions. By contrast, we propose that the existence of a completely phase separated PDMS soft phase in Elast-Eon protects the remainder of the segments from oxidation.
authors.affiliation: Department of Materials Science and Engineering, Pennsylvania State University, Pennsylvania, USA. ruh10@psu.edu
authors.forename: Rebeca
authors.initials: R
authors.lastname: Hernandez
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Weksler
authors.forename: Ajay
authors.initials: A
authors.lastname: Padsalgikar
authors.forename: James
authors.initials: J
authors.lastname: Runt
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011140:Polyurethanes / Q000737:chemistry*; D051381:Rats; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D004129:Dimethylpolysiloxanes; D011140:Polyurethanes; C013830:baysilon