Phase behaviour and microstructure of partially-miscible, glass-forming, alcohol-water-maltotriose mixtures

The miscibility, occurrence of glass formation, and microstructure of maltotriose mixtures with water, methanol, ethanol, propan-1-ol and butan-1-ol at 20°C were studied. Maltotriose is fully miscible with water, but in binary mixtures, it is only partially miscible with short-chain alcohols. In methanol mixtures, the maltotriose-rich phase is a highly viscous liquid, but it is glassy in ethanol, propan-1-ol and butan-1-ol mixtures. In ternary alcohol-water-maltotriose mixtures, increasing water content increased miscibility, resulting in the progressive transformation of two phase liquid-glass mixtures into low viscosity single phase solutions. At water contents below about 4% w/w, the state diagram of ethanol-water-maltotriose mixtures includes a region of liquid-glass coexistence. Quenching single phase solutions into this region of the state diagram yielded aggregated dispersions of glassy particles, a process we term “glassy precipitation.”