Original Article

Subject Category: Self-assembled Materials

Polymer Journal (2010) 42, 583–586; doi:10.1038/pj.2010.32; published online 5 May 2010

CaCO3/chitin-whisker hybrids: formation of CaCO3 crystals in chitin-based liquid-crystalline suspension

Yuya Yamamoto1, Tatsuya Nishimura1, Tsuguyuki Saito1 and Takashi Kato1

1Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan

Correspondence: Professor T Kato, Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan. E-mail: kato@chiral.t.u-tokyo.ac.jp

Received 16 February 2010; Revised 26 March 2010; Accepted 4 April 2010; Published online 5 May 2010.

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Abstract

CaCO3/chitin-whisker hybrids were prepared using the liquid-crystalline suspension of the chitin whisker. Suspensions of chitin nanowhiskers were obtained by acid hydrolysis of chitin powder. The suspension containing about 5wt% of whiskers exhibited lyotropic liquid-crystalline behavior. The suspension was converted to a gel form when it was exposed to ammonium carbonate vapor. CaCO3 crystals were formed for 30 days in chitin gels as templates. The nucleation of CaCO3 occurred in the liquid-crystalline chitin matrix and the CaCO3 crystals deposited in the chitin gels to form hybrids with an interpenetrated three-dimensional structure. Scanning electron microscopy image of the fractured sample of the hybrid showed that the gel matrix was filled with CaCO3 crystals. Thermogravimetric analysis revealed that the composition of CaCO3/polymer/H2O is about 2:6:2 in weight. This approach inspired by biomineralization may be useful for the development of inorganic/organic hybrid materials.

Keywords:

biomineralization; CaCO3; chitin; hybrid; liquid crystal