Preparation of CaCO3?Polymer Composites by Bio-inspired Control Crystallization

バイオインスパイアード制御結晶化方法による炭酸カルシウム―ポリマー複合材料の調製

2015-03-25

2015-03-25

Natural composite materials produced by living organisms such as teeth, bone, nacre, and eggshells have attracted significant interest over the last few decades because such materials seem to provide new pathways for producing light-weight materials with excellent mechanical properties. In spite of the intensive works, further investigation is still required for understanding the mechanism behind natural biomineralization processes as well as the development novel industrial applications based on the bio-inspired techniques. This thesis describes the bio-inspired control crystallization of CaCO3 under the participation of hydrophilic polymers at the points of the development of novel composite materials as well as the development of novel methods for the morphological control of CaCO3. In a general introduction part, the author has introduced the reviews about biominerallization, CaCO3, crystallography, and the current status of biomimetic approaches, and has described the outline of this thesis. In Part 1 (Chapter 1), poly(p-phenylene-sulfoterephthalamide) (PPST), which has a lyotropic liquid crystalline (LC) nature in water, was used to a template mineralization of CaCO3 for the preparation of CaCO3-all aromatic polyamide composites. The alternate soaking process induced the formation of plate-like calcite mesocrystals at the hydrogel/solution interface, and cubic mesocrystals in the inner space of the hydrogel. The obtained composites are the first example that CaCO3-all aromatic polyamide composites with ordered structures of LC matrix and CaCO3 were prepared through in situ mineralization. In Part 2 (Chapter 2 & Chapter 3), a photoinduced crystallization of CaCO3, which takes advantage of the photodecarboxylation of ketoprofen (KP, 2-(3-benzoylphenyl)propionic acid) in the homogeneous precursor solutions, in which a partially hydrolyzed poly(vinyl alcohol) maintained the homogeneity of the solution by preventing the salt formation of Ca2+ and KP, was investigated. The fundamental concept behind this study concerns the development of the technique controlling the transportation of CO32?. This is the first example of the application of KP in the control crystallization of CaCO3. In Chapter 2, the UV irradiated samples under the alkaline condition at pH 10 were lyophilized. Ca2+ were completely converted to nanometer-to-micron sized calcite in the PVAPS matrix by photodecarboxylation of KP under UV irradiation for 50 min. The present results demonstrate a possibility for the photoinitiated site-selective crystallization of CaCO3 in a polymer matrix to fabricate designable composite materials. In Chapter 3, the UV irradiated samples under alkaline conditions (pH 8.4 and 10) were centrifuged for the preparation of CaCO3 composite particle in single digit micrometer sizes. As the result, spheroidal calcite composites, which contained organic components of about 10 wt%, were obtained at pH 8.4. The comparison of the characteristics of CaCO3 composites obtained at the different alkaline conditions suggests that the aggregation-based crystal growth in the presence of PVAPS seemed to enable the formation of the spheroidal composites of calcite in single digit micrometer sizes.

博士（工学）

京都工芸繊維大学

14303甲第737号

http://hdl.handle.net/10212/2256

en

ETD

Thesis or Dissertation

Thesis