Fig. 2: Entropic pulling on a macroscopic chain.

a A chain was placed on a vibrating table and monitored by a camera on top. b Experimental snapshot of the chain. A particle was bound to the chain via a spring, and it can hit the chain during vibration. The positions of chain beads were recognized by OpenCV. c Average chain conformation with a bound particle shows a distinct hump at the anchor. The sidechain length is \({l}_{b}=4\) cm. d Comparison of average main-chain conformations with upside binding (y > 0) and downside binding (y < 0). e Comparison of average main-chain conformations with three sidechain lengths: \({l}_{b}=\mathrm{3,4}\) and \(5\) cm. The sidechains are always upward. The solid line is from our simulation. f Time evolution of the anchor position in the y-direction. g Distributions of the anchor and reference-bead positions: \(\Omega ({Y}_{{\rm{anchor}}})\) and \(\Omega ({Y}_{{\rm{ref}}})\). The binding is upside. The reference beads are labeled in (b) and located 5 beads away from the anchor point. The bottom panel shows the corresponding potential-of-mean-force (PMF). h The differences in PMFs between the anchor point and reference beads for \({l}_{b}=\mathrm{3,4}{\rm{and}}5\) cm. The dash lines are linear fits.