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Interphase effects in dental nanocomposites investigated by small‐angle neutron scattering
Author(s) -
Wilson Kristen S.,
Allen Andrew J.,
Washburn Newell R.,
Antonucci Joseph M.
Publication year - 2007
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.30975
Subject(s) - materials science , interphase , small angle neutron scattering , neutron scattering , nanocomposite , small angle scattering , composite material , scattering , neutron , optics , nuclear physics , physics , genetics , biology
Small‐angle and ultrasmall‐angle neutron scattering (SANS and USANS) were used to characterize silica nanoparticle dispersion morphologies and the interphase in thermoset dimethacrylate polymer nanocomposites. Silica nanoparticle fillers were silanized with varying mass ratios of 3‐methacryloxypropyltrimethoxysilane (MPTMS), a silane that interacts with the matrix through covalent and H‐bonding, and n ‐octyltrimethoxysilane (OTMS), a silane that interacts through weak dispersion forces. Interphases with high OTMS mass fractions were found to be fractally rough with fractal dimensions, D s , between 2.19 and 2.49. This roughness was associated with poor interfacial adhesion and inferior mechanical properties. Mean interparticle distances calculated for composites containing 10 mass % and 25 mass % silica suggest that the nanoparticles treated with more MPTMS than OTMS may be better dispersed than OTMS‐rich nanoparticles. The results indicate that the covalent bonding and H‐bonding of MPTMS‐rich nanoparticles with the matrix are necessary for preparing well‐dispersed nanocomposites. In addition, interphases containing equal masses of MPTMS and OTMS may yield composites with overall optimal properties. Finally, the combined SANS/USANS data could distinguish the differences, as a function of silane chemistry, in the nanoparticle/silane and silane/matrix interfaces that affect the overall mechanical properties of the composites. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007