PNNL

Abstract

The use of surfaces to promote heterogeneous nucleation of CaCO3 has been extensively studied to better understand natural processes of biomineralization, to develop bioinspired approaches for synthesizing composite materials with diverse functionalities, and as a route towards accelerating CO2 mineralization. Peptoids have emerged as a material of particular interest, because they offer tunable sidechain chemistry while maintaining a constant long-range self-assembled architecture. Here, we investigate the ability of films of self-assembled -NH2 and -COOH terminated peptoid nanotubes to promote the nucleation of CaCO3. Using a combination of atomic force, scanning electron, and optical microscopy, we find that interwoven films of nanotubes formed from peptoids with -NH2 side chains promote the preferential formation of vaterite with the (001) plane parallel to the film and exhibit a lower interfacial energy than that reported for inorganic surfaces. In contrast, the film of -COOH-functionalized peptoid nanotubes is a much stronger promoter, enabling complete coverage of individual peptoid tubes with CaCO3 nanoparticles and enhancing their mechanical properties. Thus, interwoven films of peptoid nanotubes provide a useful platform for investigating the impact of specific chemical groups on nucleation and offer potential application to accelerated mineralization of CO2.