POLY 610 |
| The aim of this study was to assess whether the introduction of various cations (Ag, Fe (II), Zn, Al, Fe (III), Si or Zr) during the synthesis of amorphous calcium phosphate (ACP) would affect ACP's particle size, its dispersion in the resin and the mechanical performance of composites, without adversely affecting their stability with regard to internal crystalline apatite formation upon aqueous immersion. The median particle diameter of the cation-modified ACPs decreased in the following order: (Si-, Zr-) > (Ag-, Fe (II)-, Al-, Fe (III)-) > Zn-ACP. Fe (II) and Fe (III) compromised the amorphous character of the filler. There were no apparent differences in water content [average 15.5 mass %] or morphology of the cation-modified ACPs. Dissolution tests indicated the potential of Zn, and to a lesser extent Al, to retard ACP's conversion to crystalline apatite. After aqueous exposure, the average biaxial flexure strength (BFS) of Zn-ACP composites (47 MPa) was comparable to the BFS of the similarly exposed unfilled polymer (55 MPa] and superior to the BFS of Al-, Si- or Zr-ACP composites [average 30 MPa]. Zn-ACP appears to be a promising candidate in the future design of composites with improved physicochemical performance. Support: NIDCR (DE13169-07), NIST and ADAF. |
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7th International Biorelated Polymers Symposium
1:30 PM-5:20 PM, Wednesday, 13 September 2006 San Francisco Marriott -- Salon 14/15, Oral
Division of Polymer Chemistry |