abstract
Graphene oxide (GO) and functionalized carbon nanotubes (f-CNTs) (each in the concentration range of 0.01-1.00 wt/wt%) were investigated as the reinforcing agent in a poly(methyl methacrylate) (PMMA)/hydroxyapatite (HA) bone cement. Mixed results were obtained for the changes in the mechanical properties determined (storage modulus, bending strength, and elastic modulus) for the reinforced cement relative to the unreinforced counterpart; that is, some property changes were increased while others were decreased. We postulate that this outcome is a consequence of the fact that each of the nanofillers hampered the polymerization process in the cement; specifically, the nanofiller acts as a scavenger of the radicals produced during polymerization reaction due to the delocalized pi-bonds. Results obtained from the chemical structure and polymer chain size distribution determined, respectively, by nuclear magnetic resonance and size exclusion chromatography analysis, on the polymer extracted from the specimens support the postulated mechanism. Furthermore, in the case of the 0.5 wt/wt% GO-reinforced cement, we showed that when the concentration of the radical species in the PMMA bone cement was doubled, mechanical properties markedly improved (relative to the value in the unreinforced cement), suggesting suppression of the aforementioned scavenger activity.
keywords
BIOMEDICAL APPLICATIONS; MECHANICAL-PROPERTIES; STEM-CELLS; COMPOSITES; NANOCOMPOSITES; FAILURE; SHEETS; FILMS
subject category
Chemistry; Science & Technology - Other Topics; Materials Science; Physics
authors
Goncalves, G; Cruz, SMA; Ramalho, A; Gracio, J; Marques, PAAP
our authors
Sandra Maria Alves da Cruz
PhD StudentGroups
acknowledgements
This work was co-financed by International Iberian Nanotechnology Laboratory (INL)-Foundation of Science and Technology (FCT-Portugal-FCOMP-01-0124-FEDER-008439). P. Marques thanks the Ciencia 2007 Program and G. Gonclaves thanks INL for a PhD grant. We thank Prof. Dmitry Evtyugin (CICECO, University of Aveiro) for help with SEC analysis and valuable discussions. We especially thank Prof. Alessandro Gandini for valuable and fascinating discussions regarding polymer chemistry.