We present here the measurement of the single-polymer entropic elastscnx and the single covalent bond force profile, probed with two types of atomic force microscope’ ~AFM on a synthetic polymer molecule: polymethacrylic acid in water. The conventional AFM allowed us to distinguish two types of interactions present in this system when doing force spec~oscopsc measurements: the first interaction is associated with adsorption sites of the polymer chains onto a bare gold surface. the second interaction is directly correlated to the rupture process of a singk covalent bond. All these bridging interactions aliowed us to stretch the single polymer chain and to determine the various factors playing a role in the elasticity of these molecules. To obtain a closer insicht into the bond rupture process. we moved to a force sensor stable in position xx hen measuring atiractix C forces. By optimizing the polymer length so as to fulfill the elastic stability condinons. we were able for the first time to map out the entire force profile associated with the cle.ix age of a single covalent bond. Experimental data coupled with molecular quantum mechanical calculanons strongi~ suggest that the breaking bond is located at one end of the polymer chain.
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