The advantages of developing models capable of predicting and explaining the link between molecular details and the formation of self-assembled microscopic structures are found not only in the optimisation of molecular structure for current applications and the possibility to design tailor-made molecules for specific purposes, but also in the exploration of new applications. This is particularly relevant in a wide range of nanotechnological applications where self-assembled structures are being used as microreactors in order to form nanoparticles or as templates to form nanomaterials, to mention just two examples. This project proposes to use both Monte Carlo simulation and mean-field theories to study the stability and microstructure of surfactant-polymer-nanoparticle mixtures for technologically relevant systems. Simplified microscopic models will be proposed and compared against experimental results in order to gain a fundamental understanding of these complex mixtures. Particular emphasis will be placed on the phase diagrams of these mixtures in order to study how composition, temperature and molecular details control solubility and the formation of self-assembled microstructures.

This research project will be carried out over a four-year period leading to a PhD degree in the Chemical and Process Engineering graduate program of the University Rovira i Virgili. An ALBAN grant is required for the first three years of this period. The first year of the program will be dedicated mainly to graduate level courses where the applicant will be given advanced formation in the necessary materials for his thesis including mathematical methods, statistical thermodynamics and computer simulation, amongst others. Part of this time will also be employed to carry out a literature review for the research topic of this proposal and to start preliminary projects in order to reproduce results of previous research works related to the project.

The second year will be devoted to carrying out an original piece of work to be used for the Advanced Studies Diploma, a requirement for students to be able to go on to the PhD degree. The third and fourth years will be dedicated to realising the main research work and writing up articles and the PhD thesis that will be defended by the end of the fourth year.

In what follows, a work plan for the research work will be given with respect to years 2 to 4.

After completing the first year of study, the applicant should be in conditions to be able to carry out a first step, where relatively minor changes are done with respect to previous work. In particular, Monte Carlo simulation and the Single Chain mean-field theory will be used to study the behaviour of polymer-micelle mixtures where the dependence on concentration of polymers and surfactant will be studied. These techniques are complementary and, starting from a microscopic model, are able to calculate the corresponding mesoscopic structures that form as well as the macroscopic properties. A highly simplified lattice model will be used which has already been successfully applied to the case of the formation of micelles from non-ionic surfactants. These calculations require intensive computer calculation and parallel computing machine will be used where necessary. The applicant will be required to be familiar in programming and algorithm development. The results of this work will be compared against experimental data from Small Angle Neutron Scattering studies where it is hoped that the theory will be able to offer a microscopic scenario for the experimental data where various regimes are believed to be observed.

The second half of the thesis will be dedicated towards the application of basically the same Monte Carlo simulation and Single Chain mean field theory to the description of an industrially relevant problem. The exact problem to be studied is currently being defined as part of a proposal for a European level STREP project which will be submitted later this year, and will be based on the study of the solubility and phase diagrams of various compounds such as nanoparticles in surfactant polymer mixtures as well as the formation of self-assembled microsctructures. It should be stressed that this project does not depend on the success of the STREP project but rather will use the industrial input from it in order to define the system to be studied. Here it may be necessary to consider more sophisticated models than the one studied during the second year of this project in order to be able to capture the relevant phenomena of interest. In this way it is expected that the basic qualitative features will be well represented and basic insight will be given in order to help optimise and innovate the corresponding industrial processes.