Thesis subject: Time-resolved Small Angle Neutron Scattering to understand kinetics of morphological transitions in Polymerization-Induced Self-Assembly

You will join the LSS group at the ILL (Grenoble, France), and more precisely the small angle neutron scattering (SANS) team. Two out of the four SANS instruments will be mainly used. D11 is designed for the study of large scale structures in soft matter systems, chemistry, biology, solid state physics and materials science. D11 is specialised to access lowest q (VSANS) and therefore very large length scales in real space. D22 was recently equipped with a second detector bank and is ideally suited for kinetic experiments due to its large dynamic range.

The aim of this project is to use Time Resolved Small Angle Neutron Scattering (TR-SANS) to understand the role of reorganization processes in the morphological transitions observed during PISA (Polymerization-Induced Self-Assembly). PISA refers to the simultaneous synthesis and self-assembly of amphiphilic AB diblock copolymers by polymerizing a hydrophobic B block from a hydrophilic A block in water, a selective solvent for A. Conventional strategies for preparation of self-assembled polymer nanostructures involve synthesis of a diblock copolymer in a non-selective organic solvent followed by purification and assembly in water at low concentrations (1 wt%) using a co-solvent. On the contrary, PISA leads to self-assembled nanostructures at high solid contents (10-40 wt%), in one-pot, without organic solvents, making it an environmentally-friendly process. Various nanostructures, mainly spheres, worms, vesicles, can be obtained that are relevant for industrial applications in material and health science. However, the role of the reorganization of the nanostructures (unimer exchange, fusion/fission) during PISA on their morphologies has hardly been studied.

This project will address this issue by using TR-SANS to measure the kinetics of these reorganizations using AB diblock coploymers directly prepared by PISA, a pre-requisite for further industrial development of this sustainable process.