Normal salts are well behaved and have uniform action (i.e. in the one direction) of the collapse-swelling equilibrium. So the more salt we add, the stronger the effect. However, guanidinium thiocyanate (GndSCN) is special and collapses the polymer at first dose, but but reswells the the polymer at higher salt concentrations.
Our story, which was recently published in JACS was presented at Spring-Meeting of DPG in Dresden 2017 – pdf with presentation.