Enhancement of Proton Ordering in the Hexagonal Ice in Contact with Polyethylene Glycol Crystal

Heat capacities and spontaneous enthalpy-relaxation effects for 20, 30, and 50 wt % polyethylene glycol (PEG) aqueous solutions subjected to a precooling treatment of quenching or annealing were measured precisely by adiabatic calorimetry. Ice and PEG crystals were produced as eutectoids at low temperatures with leaving a part of the glassy solution, and the eutectic temperature was determined to be 264 K. It was found that a small part of ice in the 20 wt % PEG aqueous solution which had been aged in a range of 200–260 K to enhance its crystalline fraction revealed a proton-ordering phase transition between ice Ih and XI. The phase transition is known to be observed in the ice doped with alkali hydroxides but not to be observed in bulk pure ice because of too long relaxation times for the proton rearrangement to occur; the hydroxide ions work as catalysts for accelerating the rearrangement. According to the present results, we proposed a new scheme for introducing Bjerrum’s defects of the L type at the ice interface in contact with a PEG crystal; the introduction enables the rearrangement to be accelerated and the proton ordering to be achieved.