Cationic motions and glass transitions of eutectic mixtures in the (CH3)4NHSO4–H2O and (CH3)4NHSO4–D2O binary systems

Abstract

Differential thermal analysis has been carried out on the (CH₃)₄NHSO₄–H₂O and (CH₃)₄NHSO₄–D₂O binary systems. In both systems the eutectic mixture was vitrified during cooling but the devitrification peak was observed during heating only in the H₂O system. The temperature dependences of the ¹H NMR spin–lattice relaxation time, T₁, and spin–spin relaxation time, T^*₂, were measured for the binary systems. In the eutectic mixture the tetramethylammonium cations are not diffused but the protons (deuterons) in the surrounding water molecules and HSO₄^–(DSO₄^–) ions are still in a mobile state below the eutectic temperature. The effect of water on the appearence of the DTA curve of (CH₃)₄NHSO₄ is discussed.