Published online by Cambridge University Press: 01 February 2011
In this study, a well-controlled humidity system is used to enhance the sensitivity of AFM for characterizing surface chemical heterogeneity of patterned self-assembled monolayers (SAMs) and hydrophilic-hydrophobic polymeric brush specimens. Dependence of the AFM friction contrasts on the surface energy differences between the hydrophilic regions and hydrophobic regions of the chemically heterogeneous samples has been investigated as a function of relative humidity (RH). Effects of RH and surface chemistry on tip-sample adhesion are also investigated. Both AFM image contrast and tip-sample adhesion forces between the hydrophilic and hydrophobic regions significantly depend on RH and follow the similar trend as a function of RH. The results clearly demonstrate that, by using proper RH at the tip-sample environment, chemically heterogeneous regions can be distinguished with the AFM.