MODELAGEM DE MISTURAS BINÁRIAS PELA APLICAÇÃO DA EQUAÇÃO DE SCHRÖEDER-van LAAR A UM CONJUNTO DE SUBSTÂNCIAS COM DIVERSIDADE ESTRUTURAL

MODELING OF BINARY MIXTURES BY APPLYING THE SCHRÖEDER-van LAAR EQUATION TO A SET OF SUBSTANCES WITH STRUCTURAL DIVERSITY

The Schröeder-van Laar equation to predict the theoretical eutectic melting temperature values was applied to a set of fourteen binary mixtures (UR1 to UR14). The fourteen binary mixtures belong to a structurally diverse group of organic molecules. They are represented by the 5-membered heterocycles containing N-S and N-O rings, flexible methylene chains (R_H), semi-rigid semi-fluorinated chains (R_F), and hydrogen bonds (HB). A virtual screening totalizing ninety-one possible theoretical combinations was planned. The UR1 to UR14 were prepared by mixing individual components using the calculated mole fractions. The experimental (T_e) and theoretical (T_t) temperatures for the eutectic melting points were determined using polarized optical microscopy (POM) and differential scanning calorimetry (DSC) techniques. Heterogeneous mixtures were formed for components with large structural diversity as seen by POM. During the melting of the mixtures, irregular behavior through the segregation of the components was recorded. The study showed that the similarities in structural diversities favor the formation of homogeneous mixtures, with T_e values approaching T_t, as predicted by the Schröeder-van Laar equation and by the theory of eutectic mixtures. Liquid crystal properties were affected in homogeneous binary mixtures containing one of the individual liquid crystal components.