title: Petunia-shaped superstructures of CaCO3 aggregates modulated by modified chitosan.
abstract: This paper presents the crystallization behavior of calcium carbonate at the air/liquid interface of aqueous systems of carboxymethyl chitosan (CMCS) using the Kitano method. Although the synthesized CMCS (Mw approximately 100,000) with 1.57 degree of carboxymethyl substitution shows no surface activity, it controls the crystallization of calcium carbonate to form a petunia-shaped superstructure. The shuttlecock-like head of this superstructure strongly supports Colfen's opinion (Rudloff, J.; Colfen, H. Langmuir 2004, 20, 991-996) for the existence of a gas template of CO2 bubbles temporarily captured by polymer molecules, while formation of the stem of this superstructure is provisionally attributed to the presence of the strong electrostatic interactions between calcium ions and the carboxylate groups. The CaCO3 superstructure and its morphology depend not only on the polymer concentration but also on the combined number of calcium ions per CMCS molecule. These results imply that this simple and versatile method expands the morphological investigation of mineralization processes.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Po
authors.initials: P
authors.lastname: Liang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Shen
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Hao
authors.initials: H
authors.lastname: Wei
authors.forename: Ingo
authors.initials: I
authors.lastname: Lieberwirth
authors.forename: Yaping
authors.initials: Y
authors.lastname: Huang
authors.forename: Dujin
authors.initials: D
authors.lastname: Wang
authors.forename: Duanfu
authors.initials: D
authors.lastname: Xu
mesh_terms: D000388:Air; D002119:Calcium Carbonate / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D003460:Crystallization; D010316:Particle Size; D012996:Solutions / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D012996:Solutions; D014867:Water; C077199:O,N-carboxymethylchitosan; D048271:Chitosan; D002119:Calcium Carbonate