Extension of the slide-ring gel, using atomic force microscopy

The slide-ring gel (SR gel) is a new kind of gel in which polymer chains can pass through topological cross-links named figure-of-eight cross-links. Therefore, polymer networks are supposed to be equalized for external stress. In this study our goal is to observe the pulley effect of SR gel at the single-molecular level by atomic force microscopy (AFM). We introduced thiol groups on cross-links and pulled them with Au-coated AFM probe. We focused on the ratio of two characteristic forces F₁ and F₂ appeared in the force curve (F₂ is the first rupture force, and F₁ is the force immediately after the first rupture event.) The histogram of F ₁/F₂ had a symmetrical distribution for swollen SR gel. On the other hands, the ratio F₁/F₂ was plotted at random. This indicates that the pulley effect equalized the stress distribution in swollen SR gel networks.