An understanding of the interactions of 2D nanomaterials with pathogens is of vital importance to develop and control their antimicrobial properties. In this work, the interaction of functionalized graphene with tunable hydrophobicity and bacteria is investigated. Polyethyleneglycol-block-(poly-N-isopropylacryl-amide) copolymer (PEG-b-PNIPAM) with the triazine joint point was attached to the graphene surface by nitrene [2+1] cycloaddition reaction. By thermal switching between hydrophobic and hydrophilic states functionalized graphene sheets were able to bind to bacteria. Bacteria were eventually disrupted, when the functionality was switched to the hydrophobic state. On the basis of measuring the different microscopy methods and a live/dead viability assay, it was found that Escherichia coli (E. coli) bacteria is more susceptible to hydrophobic interactions than B. cereus bacteria, in the same conditions. Our investigations confirm that hydrophobic interaction is one of the main driving forces at the presented graphene/bacteria interfaces and promotes antibacterial activity of graphene derivatives significantly.