Self-healing on OPA self-assembled monolayers

Controlled scratches on octadecylphosphonic acid self-assembled monolayers were made using atomic force microscopy tips as indenters. Scratch morphological evolution was followed as a function of time, at room temperature, for samples prepared by drip coating and crystal melting methods. Self-healing, ranging from partial to complete, was observed on drip coated samples. However, no substantial healing was observed on crystal melted samples. Such different behaviour is discussed in terms of the scratching mechanism on both sample types.