Macromolecular Fractionation of Rod-Like Polymers at Atomically Flat Solid-Liquid Interfaces

Macromolecular fractionation of rod-like polymers at solid–liquid interfaces is monitored by STM imaging of the polymer chains self-assembled on graphite (see Figure). It is concluded that the competition between entropic losses and enthalpic gains favors the adsorption of the longest chains, which are still sufficiently straight. The phenomenon may be used to fractionate stiff polydisperse macromolecules.