title: Calcium Phosphate Mineralization in Cellulose Derivative/Poly(acrylic acid) Composites Having a Chiral Nematic Mesomorphic Structure.
abstract: Calcium phosphate mineralization was conducted by using polymer composites of liquid-crystalline (ethyl)cellulose (EC) or (hydroxypropyl)cellulose (HPC) with poly(acrylic acid) (PAA) as a scaffolding medium for the inorganic deposition. The EC/PAA and HPC/PAA samples were prepared in colored film form from EC and HPC lyotropic liquid crystals of left-handed and right-handed chiral nematics, respectively, by polymerization and cross-linking of acrylic acid as the main solvent component. The mineralization was allowed to proceed in a batchwise operation by soaking the liquid-crystalline films in an aqueous salt solution containing the relevant ions, Ca(2+) and HPO4(2-). The calcium phosphate-deposited EC/PAA and HPC/PAA composites (weight gain, typically 15-25% and 6-11%, respectively) retained the chiral nematic organization of the respective original handedness but exhibited selective light-reflection of longer wavelengths relative to that of the corresponding nonmineralized samples. From X-ray diffraction and energy-dispersive X-ray spectroscopy measurements, it was deduced that the calcium and phosphorus were incorporated inside the polymer matrices in three forms: amorphous calcium phosphate, hydroxyapatite, and a certain complex of PAA-Ca(2+). Dynamic mechanical analysis and thermogravimetry revealed that the inorganic hybridization remarkably enhanced the thermal and mechanical performance of the optically functionalized cellulosic/synthetic polymer composites; however, the effect was more drastic in the EC/PAA series rather than the HPC/PAA series, reflecting the difference in the deposited mineral amount between the two.
authors.affiliation: Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Ogiwara
authors.affiliation: Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Katsumura
authors.affiliation: Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Sugimura
authors.affiliation: Faculty of Applied Biological Sciences, Gifu University , 1-1 Yanagimoto, Gifu 501-1193, Japan.
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Teramoto
authors.affiliation: Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Nishio
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D002413:Cations, Divalent; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D010710:Phosphates / Q000737:chemistry; D058105:Polymerization; D012996:Solutions; D013818:Thermogravimetry; D014867:Water
chemical_list: D000180:Acrylic Resins; D002130:Calcium Phosphates; D002413:Cations, Divalent; D010710:Phosphates; D012996:Solutions; C519480:amorphous calcium phosphate; D014867:Water; C006903:carbopol 940; C013517:ethyl cellulose; D002482:Cellulose; D017886:Durapatite; C008079:hydroxypropylcellulose; D002118:Calcium