title: Manipulation of nanoneedle and nanosphere apatite/poly(acrylic acid) nanocomposites.
abstract: Colloidal apatitic nanosphere of 2-5 nm in diameter was synthesized in the presence of poly(acrylic acid), PAA. PAA, which has long been recognized as an inhibitor in the synthesis of hydroxyapatite, is used as a structure-directing agent for the synthesis of calcium-deficient apatite (CDHA) in this study. Experimental observation suggests a critical amount of the low-molecular-weight PAA, above which morphological evolution of CDHA nanoparticles from needle to sphere was observed. This reveals that the PAA acts as an inhibitor for the growth of CDHA crystals. Further incorporation of PAA of high molecular weight formed a highly optically transparent nanocomposite, even with the nanospherical apatite loading up to 35 wt %, suggesting no agglomeration. This was further justified through transmission electron microscopy (TEM), where the CDHA nanospheres were uniformly distributed in the PAA-CDHA nanocomposites. No interfacial crevices were visually observed, indicating a highly compatible interface between the inorganic CDHA and organic PAA phase.
authors.affiliation: Department of Materials Science and Engineering, National Chiao Tung University, 1001 Ta-hsueh Road, Hsinchu, Taiwan 300, Republic of China.
authors.forename: Sz-Chian
authors.initials: SC
authors.lastname: Liou
authors.forename: San-Yuan
authors.initials: SY
authors.lastname: Chen
authors.forename: Dean-Mo
authors.initials: DM
authors.lastname: Liu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000838:Anions; D001031:Apatites / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D001709:Biotechnology / Q000379:methods*; D002118:Calcium / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry; D007477:Ions; D008422:Materials Testing; D046529:Microscopy, Electron, Transmission; D008863:Microspheres; D036103:Nanotechnology / Q000379:methods*; D043942:Nanotubes; D014961:X-Ray Diffraction
chemical_list: D000180:Acrylic Resins; D000838:Anions; D001031:Apatites; D001672:Biocompatible Materials; D003102:Colloids; D007477:Ions; C006903:carbopol 940; D017886:Durapatite; D002118:Calcium