| Abstract
| - Polymeric chains and cyclodextrins in water produce supramolecular host−guest assemblies calledpolypseudorotaxanes (PPR). The guest polymers thread the host cyclodextrin molecules such as beads on astring. Once formed, these molecular necklaces aggregate into larger assemblies that reveal themselves in asignificant increase of turbidity. This astonishing phenomenon is enthalpically driven and its kinetics dependsstrongly on choice of reactants, concentration, solvent nature, addition of cosolutes, and temperature. Wehave studied the effects on PPR assembly induced by temperature, surface nature, and solute. These studiesprovide some insights into the cooperative mechanisms behind the formation of these organized structures.Hydrophilic surfaces (e.g., glass), low temperatures, and high concentrations of host molecules all favor thethreading process. The addition of sugars to the solution promotes the assembly process in a way that provides strong hints on the nature of aqueous solution structure. The highly specific effects induced bysugars and electrolytes mimic precisely those seen in bubble−bubble coalescence phenomena. Theyreflect the capacity of solutes to modify bulk solvent and solution structure. In agreement with previousobservations, the experimental results can be explained by invoking the formation of pre-assembled, wormlikeaggregates of cyclodextrins in aqueous solutions. Once formed, these worms instantly swallow the polymerchain.
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