Nanosized Amorphous Calcium Carbonate Stabilized by Poly(ethylene oxide)-b-poly(acrylic acid) Block Copolymers

• Published in: Langmuir Vol. 22; no. 4; pp. 1875 - 1879
• Main Authors: Guillemet, Baptiste, Faatz, Michael, Gröhn, Franziska, Wegner, Gerhard, Gnanou, Yves
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14-02-2006
• Subjects: Acrylic Resins - chemistry; Calcium Carbonate - chemical synthesis; Calcium Carbonate - chemistry; Chemical Sciences; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Nanoparticles - chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Polyethylene Glycols - chemistry; Polymers; Surface physical chemistry; Water; Acrylic acid; In situ; Carbon dioxide; Coagulation; Precursor; Ethylene oxide polymer; Additive; Carbonates; Diameter; Release; Acrylic acid copolymer; Droplet; Calcium chloride; Hydrolysis; Liquid; Homogeneous reaction; Adsorption; Phase separation; Calcium carbonate; Distribution; Diblock copolymer; Spherical particle; Coalescence; Block copolymer; CRYSTALLIZATION; POLYMERS; MATRIX; SHELL; BIOMINERALIZATION; GROWTH; CACO3; CRYSTALS; NUCLEATION; PROTEINS
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la052419e

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.