Synthesis of poly(methacrylic acid) brushes via surface-initiated atom transfer radical polymerization of sodium methacrylate and their use as substrates for the mineralization of calcium carbonate

This manuscript describes the synthesis of poly(methacrylic acid) (PMAA) brushes via surface-initiated atom transfer radical polymerization (SI-ATRP) of sodium methacrylate (NaMA) and their use as substrates for the mineralization of calcium carbonate. A CuBr/CuBr2/bipyridine catalyst system in aqueous solution at room temperature allowed the synthesis of brushes with thicknesses of up to 300 nm. Using substrates modified with mixtures of an ATRP-initiator modified trimethoxysilane and an "inert" pivaloyl-modified trimethoxysilane to initiate the ATRP of NaMA, a series of brushes with varying chain density could be prepared. Subsequent mineralization experiments revealed that, while low-density brushes promoted the formation of calcite crystals, high-density brushes were covered with a thin layer of amorphous CaCO3 (ACC). This is of interest because ACC can serve as a metastable precursor for different crystalline CaCO3 polymorphs and offers attractive perspectives for the bottom-up fabrication of well-defined CaCO3 crystal architectures. © 2007 American Chemical Society.