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Morphogenetic Control of Calcite Crystal Growth in Sulfonic Acid Based Hydrogels
Author(s) -
Grassmann Olaf,
Löbmann Peer
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200390150
Subject(s) - polyacrylamide , sulfonate , calcite , self healing hydrogels , copolymer , monomer , chemical engineering , ionic bonding , mineralization (soil science) , polymer chemistry , chemistry , sulfonic acid , polymer , materials science , organic chemistry , mineralogy , sodium , ion , nitrogen , engineering
In this paper the mineralization of CaCO 3 in various hydrogel matrices is presented. Sulfonic acid based hydrogels were prepared by introduction of sulfonate‐containing monomers into a polyacrylamide network. The sulfonate content of polyacrylamide‐ co ‐vinylsulfonate and polyacrylamide‐ co ‐allylsulfonate decreases during elution of the copolymers in demineralized water, indicating insufficient linking of the sulfonate‐bearing monomers within the hydrogel. In contrast to this, acrylamidomethylpropanesulfonate (AMPS) effectively copolymerizes with acrylamide (AAm) monomers. To study the influence of spatial arrangement of ionic functional groups within hydrogel networks on the mineralization of CaCO 3 , AMPS copolymers with different degrees of AMPS cross‐linking were synthesized. For the mineralization experiments the copolymers were placed into a double‐diffusion arrangement. Calcite as the thermodynamically stable modification of CaCO 3 was obtained with a particular morphology. The pseudocubic habitus resembles aggregates obtained by mineralization in pure polyacrylamide. However, closer examination of the aggregates by scanning electron microscopy (SEM) shows that the crystal growth in the AMPS copolymers is different from that observed in polyacrylamide. Whereas the morphology of the calcite aggregates could be fine‐tuned by using copolymers with different sulfonate content, the spatial distribution of the ionic functional groups alters the course of crystallization. Calcium ions are locally accumulated due to the heterogeneous distribution of functional sulfonate groups within the copolymer network. Thereby the nucleation of calcite is triggered, resulting in enhanced mineralization.