Force spectroscopy of self-associating homopolymers

This paper presents a theoretical and simulation investigation into the force-extension behavior of self-associating homopolymers. In particular, we show how long-lasting associations induce a transition in the stretching response of a single polymer from a freely jointed chain behavior (fast kinetics) to a highly dissipative unfolding pathway (slow kinetics). We identify the "shortest chain" through the associating network as the critical coordinate, and use a master equation approach to develop theory that describes the force-extension behavior of any chain. We elaborate on the properties of this theory, and consider two contrasting cases in which it applies, a random self-associating homopolymer and a self-associating helix. The theoretical predictions for both cases are in excellent agreement with the simulation results, demonstrating that the theory captures the essential physics governing the force spectroscopy of self-associating polymers. The disparate behaviors between the two topologies considered suggests their use as "building blocks" for novel materials with tunable mechanical properties.