Nanosized amorphous calcium carbonate stabilized by poly(ethylene oxide)-b-poly(acrylic acid) block copolymers.
Particles of amorphous calcium carbonate (ACC), formed in situ from calcium chloride by the slow release of carbon dioxide by alkaline hydrolysis of dimethyl carbonate in water, are stabilized against coalescence in the presence of very small amounts of double hydrophilic block copolymers (DHBCs) composed of poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) blocks. Under optimized conditions, spherical particles of ACC with diameters less than 100 nm and narrow size distribution are obtained at a concentration of only 3 ppm of PEO-b-PAA as additive. Equivalent triblock or star DHBCs are compared to diblock copolymers. The results are interpreted assuming an interaction of the PAA blocks with the surface of the liquid droplets of the concentrated CaCO3 phase, formed by phase separation from the initially homogeneous reaction mixture. The adsorption layer of the block copolymer protects the liquid precursor of ACC from coalescence and/or coagulation.
Guillemet
Baptiste
B
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Faatz
Michael
M
Gröhn
Franziska
F
Wegner
Gerhard
G
Gnanou
Yves
Y
D000180:Acrylic Resins / Q000737:chemistry*; D002119:Calcium Carbonate / Q000138:chemical synthesis / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*
D000180:Acrylic Resins; D011092:Polyethylene Glycols; C006903:carbopol 940; D002119:Calcium Carbonate