The behavior of complex multiphase fluids involved in various industrial fields is in large part governed by multi-scale phenomena, coupling interactions at the molecular, meso- and macroscopic scales. Those couplings are still poorly understood and require substantial development in experimental and theoretical knowledge, in order to achieve scientific discoveries that will be transferable to technological applications. Several applications related to energy industries are expected to benefit improvements from molecular and interfacial control of transport phenomena. More generally, any process concerned by the management of complex multiphase fluids and where the mass and heat transfers hindrance causes efficiency loss, will take advantage of extended understanding of multi-scale coupling phenomena. The MUSCOFI project aims at interpreting macroscopic data and predicting macroscopic behaviour by using modelling and experimental tools to elucidate molecular-level phenomena that 1) govern the formation, aggregation, and stability of interfacial and network structures in multi-phase fluids, 2) control their development and effects on macroscopic rheology and transport processes, 3) and finally impact the efficiency of processes in energy technologies. It is a unique opportunity to federate complementary research teams in a new collaborative scheme that will cover the whole scale range, from the molecule to the industrial process. The MUSCOFI project gathers the French partners of an international PIRE project (US NFS program "Partnerships for International Research and Education"), leaded by the City College of New York and that includes 12 research teams from the USA, Germany, Norway, and France. This program includes scientific collaborations, researchers and students exchanges, and symposia organization, on multi-scale investigation of complex fluids of interest to the energy sector. MUSCOFI will thus benefit from synergies at an international level in terms of cooperation, networking and international visibility. The students (2 PhD) and research fellows (2 x 18 months PostDoc) who will be hired during the project will benefit opportunities to spend internships in the partner laboratories abroad, while foreign students will be hosted in the French labs involved. Two systems of particular interest in the field of energy will be investigated within this project: asphaltenes at water/oil interface, and clathrate hydrates in water/oil emulsion. These systems appear in diverse energy applications in oil & gas, heat storage, and environmentally friendly refrigeration. The Tasks of the project are described bellow: 1 The model systems that will be investigated at the different scale levels, as well as the required operating conditions will be validated at the early stage of the project. 2 At the molecular level, the explicit description of the electronic structure will be introduced using an approximate Density Functional based Tight Binding method to retrieve structural, energetic and thermodynamic data. 3 Interactions at the liquid/liquid interfaces in the conditions of solid phase formation will be investigated using microfluidic experiments. 4 The extrapolation of molecular, micro- and meso-scopic results to the macroscopic level will be validated by measuring the influence of the global composition of the systems and the presence of selected additives on flow behaviors, phase change dynamics, and heat and mass transfers. 5 Models will then be developed in an integration and extrapolation approach that will include the local-scale findings to provide macroscopic predictive tools. The project should produce abundent experimental and theoretical new results, promote the development of original methodologies, and offer opportunities for new national and international cooperations. In addition to academic publications, possible patent filling and future industrial partnerships could be valuable outpus of the project.