In nature, materials such as wood, bone, and tendon exhibit remarkable mechanical performance thanks to hierarchically organized structures in which nanostructuration and interfaces play a critical role in transferring stress. Inspired by these natural systems, nanocomposites offer a promising route to design sustainable materials with enhanced performances. Among nanoparticles, nanocelluloses (nanofibrils and nanocrystals) are biobased and biodegradable nanoparticles derived from cellulose microfibrils, and are promising reinforcing agents for polymers. The current issues related to the use of nanocelluloses in thermoplastic polymers are a poor dispersion and the quality of the nanocellulose/matrix interface. By controlling the surface chemistry of nanocelluloses, and hence their dispersion and interfacial adhesion with thermoplastic matrices, it is possible to tailor the mechanical properties of the composites. Then, those materials could be used for various applications (transport, packaging, energy…). However, many questions remain: in particular, what are the respective roles of nanostructuration and interfacial adhesion? Understanding and characterizing the polymer/nanoparticle interfacial behavior is thus essential to optimize their performance and achieve the strength and tenacity of natural materials.
PhD project description:
The objective of this thesis is to tailor the interface in a nanocomposite based on functionalized nanocelluloses and a thermoplastic matrix, in order to elucidate the role of nanostructuration and interfacial phenomena on the resulting thermo-mechanical performances of the composites.
To this end, the PhD candidate will be in charge of the following tasks:
- Functionalization of the CNC or CNF by ring opening polymerization strategies in collaboration with Pr Philippe Zinck at UCCS UMR CNRS 8181, Université de Lille.
- Elaboration of nanocomposites using solvent casting and melt processing, characterization of interfacial interactions with multi-scale microscopy observations and rheological analysis, and characterization of the thermo-mechanical properties (tensile, impact) in the Polymers, Composites and Hybrids unit, IMT Mines Alès.