The variation of the single-chain mechanics of PNIPAM for the entire
range of the methanol molar fraction (χmethanol) (0 ~
100%) in the water/methanol mixed solvent have been studied by AFM-based single-molecule
force spectroscopy at RT. In general, the single-chain mechanics of PNIPAM
shows a reentrant variation upon the change of χmethanol from 0 to
100%. The possible mechanism for the reentrant variation of the single-chain
mechanics is discussed. The current study may cast new light on the design of
novel environmental responsive nano-devices in the future, when χmethanol changes from 16% to 0.
