Self-assembly and secondary nucleation in ZnO nanostructures derived from a lipophilic precursor

The influence of organically capped nucleation on morphogenesis of zinc oxide (ZnO) as a technologically important iono-covalent material has been extensively investigated. However, the effect of lipid-lipid interactions on selective adsorption and the mechanism of growth is largely unknown. Here, we demonstrate a novel route toward synthesis of various ZnO nanostructures using zinc stearate, a metal soap, rather than the commonly utilised polar-soluble salts. Study of a variety of amphiphilic ligands suggests that during decomposition, secondary carboxylic acids substitute primary aliphatic tails in the precursor. In this regard, saturated and unsaturated fatty acids appear to influence the rate of progression quite differently. On the other hand, in the early stages of growth, amine adsorbates are inhibited by lipophilic tails of carboxylic acids, leading to a multi-step growth. The subsequent self-assembly of these nanorods into bundles is accompanied by recrystallisation of their stems and formation of planar defects which promote random secondary nucleation.