Recovery dynamics of acrylic coating surfaces under elevated relative humidity monitored by atomic force microscopy

Recovery of indents made at the surface of coatings as observed by AFM. [Display omitted] •Acrylic coating surface recovers under elevated relative humidity.•Recovery dynamics is related to glass transition temperature of polymer and the extent of relative humidity elevation.•Surface recovery is promoted by viscoelasticity change as explained by viscoelastic mechanics theory. Surface recovery of acrylic coatings under elevated relative humidity (RH) is observed in real-time using atomic force microscopy. It is found that the extent and rate of recovery are closely related to the glass transition temperature (Tg) of the polymer and RH. The phenomenon is explained by viscoelastic mechanics theory, in which mechanical characteristics such as elastic modulus and viscosity of the polymer have influence over the dynamics as well as the extent of recovery. The experimental data suggests that the polymer undergoes change in viscoelasticity at elevated RH due to water uptake. It is believed that this behavior may provide new insights in research areas such as controlled repair of coatings, and this experimental approach will help us better understand the mechanical performance of coatings under deviated environmental conditions.