We study the single chain elasticities of three kinds
of neutral polymers with carbon-carbon (C-C) backbone by AFM-based single
molecule force spectroscopy (SMFS) in a nonpolar solvent (octane), aiming at
measuring the inherent chain elasticity of the very important class of
polymers. The finding that the single chain elasticities of all the three
polymers in octane are virtually identical in the entire force region implies
that the side chains of the polymers have no detectable effects on the single
chain elasticity. By utilizing the single chain elasticity from quantum
mechanics (QM) calculations, the freely rotating chain (FRC) model can provide
the best fitting curve when each C-C bond is set to be the rotating unit. Although
there are some exceptions when the side chain is very huge, our work provides a
general result for the inherent elasticity of single neutral flexible polymer
chains with C-C backbones.
