Low-force single-molecule elasticity of complex polymers

Stretching a polymer with a force f introduces a new length scale, the tensile screening length, equal to kT/f. As the stretching force decreases below a piconewton, the tensile screening length increases above a nanometer. This means that low-force single-molecule stretching measurements can sense chain structure and intra-actions on relatively long length scales. I will discuss application of this method to the structure of complex polymer geometries, including polyelectrolytes dominated by long-range electrostatic interactions, and comb polymers whose structure is determined by side-chain repulsions.