The miscibility and liquid-liquid phase separation of binary mixtures vary with temperature and composition, often resulting in distinct phase diagram defined as an upper critical solution temperature (UCST), lower critical solution temperature (LCST), or closed-loop miscibility gaps. Recently, it was demonstrated that the molecular aggregation behavior dictates the spatial distribution of constituent molecules and phase behavior in various aqueous mixtures. [1] Some solute molecules tend to form self-associate aggregates by avoiding interaction with water, whereas others form spatially extended network to make significant interaction with water. The growth of self-associate aggregates eventually lead to liquid-liquid phase separation, but the spatially extended aggregates are still compatible with liquid water even at high concentrations. To describe quantitatively morphology of solute and water aggregates, the graph theoretical application was performed with molecular dynamics simulation studies in several binary liquid mixtures, exhibiting UCST, [2] LCST [3] and closed-loop behavior [4] in the phase diagram. It is revealed how topology of solute aggregates vary with the temperature and how the distinct aggregation pattern affects water structure and phase behavior in given aqueous mixture systems. REFERENCES [1] J.-H. Choi, H. Lee, H. R. Choi, and M. Cho, Graph Theory and Ion and Molecular Aggregations in Aqueous Solutions. Annu. Rev. Phys. Chem., Vol. 69, pp. 125-149, 2018. [2] S. Parameswaran, S. Choi and J.-H. Choi, Temperature Effects on Alcohol Aggregation Phenomena and Phase Behavior in n-butanol Aqueous Solution. J. Mol. Liq. Vol. 347, p. 118339, 2022. [3] R. Singh, J. Seo, J. Ryu and J.-H. Choi, Unraveling the interplay of temperature with molecular aggregation and miscibility in TEA–water mixtures. Phys. Chem. Chem. Phys. Vol 26, pp. 18970-18982, 2024. [4] R. Singh, J. Ryu and J.-H. Choi, Temperature-Driven Molecular Aggregation and Phase Behavior in sec-Butyl Alcohol/Water Mixtures. J. Mol. Liq. Vol. 440, p. 128983, 2025.