Abstract: The mechanical properties of polyacrylic acid are investigated on the molecular scale by use of an atomic force microscopy(AFM). Polyacrylic acid was adsorbed onto the glass substrate, then picked up at one point of the chain with an AFMtip and stretched. The elongation of individual molecules was recorded as a function of the applied load. In the force curves of PAA, the monotonically rising forces with the elongation of the polymer chain are observed. After normalization according to their contour lengths, all of the force curves can be superimposed together, and no difference can be found. The superimposion clearly shows that the mechanical properties of polyacrylic acid scale linearly with their lengths and single polyacrylic acid chain is stretched.

Key words: Atomic force microscopy, Single molecule, Nanomechanical properties