True surface topography and nanomechanical mapping measurements on block copolymers with atomic force microscopy

A quantitative method to obtain nanomechanical mapping data of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) triblock copolymers was studied. The samples were scanned at constant force using an E scanner and triangular Si₃N₄ cantilevers with nominal spring constant of 0.32 N/m. The specific value of periodicity distance determined by fast Fourier two-dimensional-power spectrum was 26.8 ± 2.5 nm. The sample deformation δ was calculated by subtracting the cantilever deflection Δ from the scanner displacement z (δ = z - Δ). The apparent height difference in the tapping mode height image was ~4.5 nm that revealed that the true topography should be the inverse of tapping mode height image.