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Authors
Abstract(s)
Neste trabalho os conceitos de hidrótropos e hidrotropia são revisados com um forte suporte na literatura recente. A ação e o comportamento físico-químico dos hidrótopos são discutidos em relação aos co-solubilizantes e surfactantes. A definição de um hidrótropo é formulada, e demonstrado que o seu comportamento apresenta características específicas e distintivas, que os separam de substâncias co-solubilizantes ou surfactantes regulares, e assim que a agregação é fraca sem um soluto hidrofóbico, mas observando-se uma agregação pronunciada na presença desse soluto hidrofóbico.
Paralelamente a esta análise formal de hidrotropia, neste trabalho pretende-se estudar algumas propriedades, em particular na sua interação com água, como alicerce de interpretações futuras e mais sustentadas do fenómeno. Por esta ordem de razão, foi implementada uma metodologia experimental para a medição da atividade de água, densidade e volumes molares parciais em água de moléculas geralmente utilizadas como hidrótopos, com são os sulfonatos de alquilbenzeno de sódio, que são atualmente os hidrótopos mais utilizados.
A informação experimental aqui compilada mostra que a atividade da água é maior em sistemas contendo os hidrótropos de maior tamanho, havendo uma correlação positiva entre essa propriedade e os volumes molares parciais. Estas informações fundamentais da química-física são os potenciais alicerces para o desenvolvimento e suporte de modelos teóricos da hidrotropia, complementando-a com medições do impacto destes hidrótropos no aumento da solubilidade de moléculas hidrofóbicas em água, e aplicando o modelo de previsão COSMO-RS para testar o modelo de hidrotropia cooperativa que tem vindo a ser desenvolvido recentemente.
In this work, the concepts of hydrotropes and hydrotropy are reviewed with solid support in recent literature. The action and physicochemical behavior of hydrotropes are discussed concerning co-solubilizers and surfactants. The definition of a hydrotrope is formulated, and it is demonstrated that its behavior has specific and distinctive characteristics that separate it from co-solubilizing substances or typical surfactants; and thus, aggregation is weak without a hydrophobic solute, but aggregation is pronounced in the presence of this hydrophobic solute. Parallel to this formal analysis of hydrotropy, this work intends to use some properties, particularly in its interaction with water, as a foundation for future and more sustained interpretations of the phenomenon. For this reason, the water activity, density, and partial molar volumes in the water of molecules commonly used as hydrotropes, such as sodium alkyl benzene sulfonates, which are currently the most used hydrotropes, were measured. The experimental information compiled here shows that water activity is more significant in systems containing the larger hydrotropes, with a positive correlation between this property and the partial molar volumes. This essential information from physical- chemistry is potentially the foundation for developing and supporting theoretical models of hydrotropy, complementing it with measurements on the impact of these hydrotropes on the solubility of hydrophobic molecules in water to test the cooperative hydrotropy model that has been developed recently.
In this work, the concepts of hydrotropes and hydrotropy are reviewed with solid support in recent literature. The action and physicochemical behavior of hydrotropes are discussed concerning co-solubilizers and surfactants. The definition of a hydrotrope is formulated, and it is demonstrated that its behavior has specific and distinctive characteristics that separate it from co-solubilizing substances or typical surfactants; and thus, aggregation is weak without a hydrophobic solute, but aggregation is pronounced in the presence of this hydrophobic solute. Parallel to this formal analysis of hydrotropy, this work intends to use some properties, particularly in its interaction with water, as a foundation for future and more sustained interpretations of the phenomenon. For this reason, the water activity, density, and partial molar volumes in the water of molecules commonly used as hydrotropes, such as sodium alkyl benzene sulfonates, which are currently the most used hydrotropes, were measured. The experimental information compiled here shows that water activity is more significant in systems containing the larger hydrotropes, with a positive correlation between this property and the partial molar volumes. This essential information from physical- chemistry is potentially the foundation for developing and supporting theoretical models of hydrotropy, complementing it with measurements on the impact of these hydrotropes on the solubility of hydrophobic molecules in water to test the cooperative hydrotropy model that has been developed recently.
Description
Mestrado de dupla diplomação com a UNIFACS - Universidade Salvador
Keywords
Hidrótopos Hidrotropia Hidrofobicidade Sulfonatos de alquilbenzeno