Aleuritic (9,10,16-trihydroxypalmitic) acid self-assembly on mica

Abstract

Aleuritic (9,10,16-trihydroxypalmitic) acid self-assembly on mica from solution has been studied using AFM, ATR-FTIR and MD simulations. The goal of this study is to define the role of hydroxyl groups in the interaction between molecules as reference data to understand the mechanism of formation of synthetic and natural biopolyesters from polyhydroxylated long chain carboxylic acids. In a confined structure, such as the one imposed by a vertically self-assembled layer on mica, aleuritic acid has a tendency to adopt a monolayer configuration ruled by the lateral interactions between molecules via the two secondary hydroxyl groups. This (2D) growth competes with the multilayer formation (3D), which is conditioned by the terminal primary hydroxyl group. As the self-assembly spatial constraint is relaxed, MD has shown that the structure tends to become an amorphous and crosslinked phase that can be characterized by topographic and friction force AFM data.