Kinetics of solvent supported tubule formation of Lotus (Nelumbo nucifera) wax on highly oriented pyrolytic graphite (HOPG) investigated by atomic force microscopy

Abstract

The time dependence of the formation of lotus wax tubules after recrystallization from various chloroform-based solutions on an HOPG surface at room temperature was studied by atomic force microscopy (magnetic AC mode) taking series of consecutive images of the formation process. The growth of the tubules oriented in an upright fashion follows a sequential rodlet→ring→tubule behavior. The influence of a number of factors, e.g., different wax concentration in chloroform, the additional presence of water, or salts [(NH4)2SO4, NH4NO3] or a mixture of salt/water in the solution on the growth rate and orientation of the tubules is also investigated. Different wax concentrations were found to have no effect on the growth rate or the orientation of tubules in none of the solutions. The presence of water, however, considerably increased the growth rate of tubule formation, while the presence of salt was again found to have no effect on growth rate or orientation of tubules.

Keywords

• AFM
• crystallization
• epicuticular wax
• Lotus
• Nelumbo nucifera
• nonacosanol tubules
• self-assembly
• superhydrophobic