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Complex fluids, widely used in many industrial applications, typically include amphiphilic molecules such as surfactants. Most of the surfactants used in products for fabric care, home care, and beauty care, such as detergents, or cosmetics have a complex microstructure and rheological behavior. At high concentrations, surfactant solutions self-assemble into lyotropic mesophases exhibiting complex rheology and viscoelasticity relevant for processing.1, 2 These molecules can rearrange themselves depending on both chemical structure and the process. Furthermore, the microstructure of the system strongly affects the properties of the finished product, which are the determining factors for the specific application. It is, therefore, necessary to identify and study the chemical-physical processes that involve such systems. Industrial processing of surfactant-based materials typically includes a water dissolution step. It is well established that both physicochemical and rheological parameters, such as raw material chemistry, type of solvent, temperature and flow conditions, play a key role in the dissolution process3. However, the mechanisms governing the dissolution process are not well understood. This explains the great interest in the dissolution of complex molecules in flow or in static conditions. As a matter of fact, understanding the dissolution of the concentrated surfactant solutions in different solvents is of fundamental importance for their effective industrial application. In this work video microscopy will be used to investigate dissolution in well-controlled static conditions, and the sample microstructure changes will be observed; a microfluidic device will be rearranged to evaluate the effect of specific flow conditions with the aim to understand which is the controlling factor of the phenomenon and see differences from static results; in order to observe the process in a larger scale, a simple lab scale test will be set up and a Raman tool used to char

Complex fluids, widely used in many industrial applications, typically include amphiphilic molecules such as surfactants. Most of the surfactants used in products for fabric care, home care, and beauty care, such as detergents, or cosmetics have a complex microstructure and rheological behavior. At high concentrations, surfactant solutions self-assemble into lyotropic mesophases exhibiting complex rheology and viscoelasticity relevant for processing.1, 2 These molecules can rearrange themselves depending on both chemical structure and the process. Furthermore, the microstructure of the system strongly affects the properties of the finished product, which are the determining factors for the specific application. It is, therefore, necessary to identify and study the chemical-physical processes that involve such systems. Industrial processing of surfactant-based materials typically includes a water dissolution step. It is well established that both physicochemical and rheological parameters, such as raw material chemistry, type of solvent, temperature and flow conditions, play a key role in the dissolution process3. However, the mechanisms governing the dissolution process are not well understood. This explains the great interest in the dissolution of complex molecules in flow or in static conditions. As a matter of fact, understanding the dissolution of the concentrated surfactant solutions in different solvents is of fundamental importance for their effective industrial application. In this work video microscopy will be used to investigate dissolution in well-controlled static conditions, and the sample microstructure changes will be observed; a microfluidic device will be rearranged to evaluate the effect of specific flow conditions with the aim to understand which is the controlling factor of the phenomenon and see differences from static results; in order to observe the process in a larger scale, a simple lab scale test will be set up and a Raman tool used to char