Hydrogen Bonding Exchange and Supramolecular Dynamics of Monohydroxy Alcohols

We unravel hydrogen bonding dynamics and their relationship with supramolecular relaxations of monohydroxy alcohols (MAs) at intermediate times. The rheological modulus of MAs exhibits Rouse scaling relaxation of $G\left(t\right)\sim t^{-1/2}$ switching to $G\left(t\right)\sim t^{-1}$ at time ${\tau }_m$ before their terminal time. Meanwhile, dielectric spectroscopy reveals clear signatures of new supramolecular dynamics matching with ${\tau }_m$ from rheology. Interestingly, the characteristic time ${\tau }_m$ follows an Arrhenius-like temperature dependence over exceptionally wide temperatures and agrees well with the hydrogen bonding exchange time from nuclear magnetic resonance measurements. These observations demonstrate the presence of Rouse modes and active chain swapping of MAs at intermediate times. Moreover, detailed theoretical analyses point out explicitly that the hydrogen bonding exchange truncates the Rouse dynamics of the supramolecular chains and triggers the chain-swapping processes, supporting a recently proposed living polymer model.