Hypothesis: Hydrophobic interaction is crucial in various colloidal phenomena and engineering processes involving air/water/solid systems where polar and nonpolar substances usually mingle with each other. The molecular-level heterogeneity of surface hydrophobicity could potentially disorder the interfacial water molecules and thus influence the hydrophobic interaction strength, but the underlying mechanism is not completely clear. Experiments: The hydrophobic interactions between air bubbles and self-assembled monolayer surfaces bearing methyl and different polar moieties were precisely quantified via bubble probe atomic force microscope coupled with theoretical modeling analysis. Findings: Increasing coverage of surface polar moieties on binary-component surfaces can apparently lower surface hydrophobicity theta(c), but hardly affect hydrophobic interaction's decay length Do. Changing pH has no detectable effect on hydrophobic interactions involving CH3 and CH3/OH-ended surfaces. In contrast, theta(c) and Do decrease monotonically with pH rising for CH3/COOH-ended surface, because high pH tends to dissociate -COOH, enhancing the surface hydrophilicity and weakening the hydrophobic interaction. For CH3/NH2-ended surface, theta(c) and D-0 decrease sequentially with pH declining, because protonation of -NH2 can lower the surface hydrophobicity and weaken the hydrophobic interaction. This work improves the fundamental understanding of hydrophobic interactions in air/water/solid systems and provides useful insights into the interfacial assembly processes in relevant engineering applications. (C) 2019 Elsevier Inc. All rights reserved.