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Calcium Phosphate Mineralization beneath a Polycationic Monolayer at the Air–Water Interface
Author(s) -
Junginger Mathias,
KitaTokarczyk Katarzyna,
Schuster Thomas,
Reiche Jürgen,
Schacher Felix,
Müller Axel H. E.,
Cölfen Helmut,
Taubert Andreas
Publication year - 2010
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.201000093
Subject(s) - monolayer , copolymer , chemistry , polymer , methacrylate , amphiphile , phosphate , chemical engineering , calcium , transmission electron microscopy , polymer chemistry , colloid , organic chemistry , biochemistry , engineering
The self‐assembly of the amphiphilic block copolymer poly( n ‐butyl methacrylate)‐ block ‐poly[2‐(dimethylamino)ethyl methacrylate] at the air–water interface has been investigated at different pH values. Similar to Rehfeldt et al. ( J . Phys . Chem . B 2006 , 110 , 9171), the subphase pH strongly affects the monolayer properties. The formation of calcium phosphate beneath the monolayer can be tuned by the subphase pH and hence the monolayer charge. After 12 h of mineralization at pH 5, the polymer monolayers are still transparent, but transmission electron microscopy (TEM) shows that very thin calcium phosphate fibers form, which aggregate into cotton ball‐like features with diameters of 20 to 50 nm. In contrast, after 12 h of mineralization at pH 8, the polymer film is very slightly turbid and TEM shows dense aggregates with sizes between 200 and 700 nm. The formation of calcium phosphate is further confirmed by Raman and energy dispersive X‐ray spectroscopy. The calcium phosphate architectures can be assigned to the monolayer charge, which is high at low pH and low at high pH. The study demonstrates that the effects of polycations should not be ignored if attempting to understand the colloid chemistry of biomimetic mineralization. It also shows that basic block copolymers are useful complementary systems to the much more commonly studied acidic block copolymer templates.