Graphical abstractAmorphous spherical silica and plane-crystal-shaped zirconia particles were prepared and functionalized with long alkyl chain coupling agents. The effect of the nanoscopic curvature and the co-functionalization with a second coupling agent was investigated.Highlights► Alkyl-chain ordering on curved and plane nanoscopic surfaces. ► Disturbing self-assembled monolayer formation on nanoparticles by co-functionalization. ► Improvement of the dispersion behavior of nanoparticles by co-functionalization of their surface.

ZrO(2) powder (6.6 m(2)/g) was modified using polymerizable phosphorus-based coupling agents (P-CAs) (i.e., phosphonic acid, phosphoric acid, and bis-phosphonic acid), resulting in densely grafted layers as determined by thermogravimetry and elemental analysis (up to 4.2 molecules/nm(2)). The applied P-CAs contained a methacrylate group, which led to the covalent incorporation of a polymerizable moiety into the grafted layer. To direct the ordering of the alkyl chains in the layer, three different approaches were evaluated with respect to their structure-directing ability by means of FT-IR and nitrogen sorption at 77 K: (i) variation of the chain length, (ii) variation of the anchoring group and (iii) comodification with a defined amount of a nonfunctional phosphonic acid (variation of the functional/nonfunctional acid ratio). It was shown that the chain length and anchoring group size have significant effects on the alkyl chain ordering and morphology of the layer.