Possible existence of two amorphous phases of d-mannitol related by a first-order transition

摘要: We report that the common polyalcohol D-mannitol may have two amorphous phases related by a first-order transition. Slightly above its glass transition temperature Tg (284 K), supercooled liquid (SCL) of transforms to low-energy, apparently phase with stronger hydrogen bonds. The enthalpy this so-called Phase X is approximately halfway between those known and crystalline phases, position low for aging high crystal polymorphs. Similar SCL, transparent broad X-ray diffraction Raman scattering; upon cycling, it exhibits glass-transition-like change heat capacity. On fast heating, back SCL near + 50 K, enabling determination their equilibrium temperature. presence D-sorbitol as plasticizer enables observation from entirely in state (liquid-liquid transition). D-mannitol's has intriguing similarities formation glacial triphenyl phosphite (TPP) conversion high-density low-density ice, both studied intensely context polyamorphism. All three processes occur substantial decrease toward phases; water strengthen In contrast TPP, forms more rapidly can transform SCL. These features make valuable new model understanding