New PhD Project Offers
2012-19-LF Cellulose nanofibres for the production of bionanocomposites (INPG - Rhéologie, IST - Dept. Chemistry)
With the purpose of replacing the materials coming from fossil resources, cellulose nano-fibres and nanocrystals have nowadays drawn a considerable attention in the production of functional biomaterials. As a matter of fact, they may provide many potential applications namely as nano-reinforcement to produce transparent nanocomposites with high mechanical performance. To achieve this objective, the knowledge and control of the physico-chemical properties, at the nanoscale level, are of key rule to build-up bionanocomposites. The first goal of the thesis here proposed is the extraction and the release of nanosized cellulose from cellulose fibers issuing from woody, annual plants and agricultural residues. The emphasis is put on the used of activation methods based on enzymatic, chemical, mechanical or combined routes in order to facilitate the cellulose nanofibres release, and reduce the energy consumption during the high pressure fibrillation of the fibers. Intensified processes based on the application of ultrasonic irradiation will be also investigated. The second goal deals with the surface functionalization of the cellulose nanofibres either by grafting polymer chains or functional monomers. The later is expected to improve their dispersion within the biopolymer matrices such as PLA, starch or polyesters, during the nanocomposite processing using conventional methods such as the extrusion. With this aim, the in situ grafting in aqueous medium seems to be an interesting route to avoid the irreversible nanofibres agglomeration once the water is eliminated.
The project gathers complementary teams with expertises in the fields of the chemistry, physics and the rheology of lignocellulosic materials. Within a main goal aiming to link the macroscopic properties of the materials to its microscopic structure, complementary methods will be used to characterise the nanofibres both from the structural and compositional points of view (XPS, small-angle X-ray scattering (SAXS), TEM, AFM, solid state NMR, Infrared, Raman, rheometry…).
Figure 1 : Field-Emission Scanning Electron Microscopy (FE-SEM) image of nanocomposite dispersions
The image shows a nanocomposite based on cellulose nanocrystals and a polymer (polybutylmethacrylate) that can be used for coatings. This example illustrates how, by modulating the colloidal chemistry, it is possible to produce nanocomposites where the degree of interaction cellulose nanocrystal – polymer particle can be tuned. 
- Departamento de Engenharia Química, IST : this team will be involved in the characterization of the nanofibers and the modified nanofibers using X-ray photoelectron spectroscopy. XPS, will provide a powerful tool for understanding the mechanism and measuring the extent of the polymer grafting process at the cellulose fibrils surface.
- Laboratoire de Rhéologie, INPG : this team will be concerned with the investigation of the rheological properties of the cellulose nanofibers gels, nanocomposite processing and the melt rheological properties of the nanocomposite based on a polymer matrix and nanofibrillated cellulose. It will be involved, also in the analysis of the dispersion degree of the nanofiller within the polymer matrix using small-angle X-ray scattering.
- LGP2, INPG: this team will be mainly concerned with surface functionalization of the cellulose nanofibres and with the characterization of the cellulose nanofiller by AFM observation, solid state NMR, infrared spectroscopy.
- industry partner: ALX develops innovative products from fibers woven textiles for sport, military or industry. ALX is interested in the development of new fibers with high mechanic strength.
It is worth noting that the different teams involved in the project have already worked together as attested by the numerous papers already published, for example the latest :
 A.Ben Mabrouk, M. Rei Vilar, A. Magnin, M.N. Belgacem, S. Boufi, Journal of Colloid and Interface Science 363 (2011) p.129
 A.Ben Mabrouk, H. Kaddami, A. Magnin, M.N. Belgacem, A. Dufresne, S. Boufi, Polym. Eng. Sci. 62 (2011) 62.
 A.Ben Mabrouk, A. Magnin, M.N. Belgacem, S. Boufi, Compos. Sci. Technol. 71 (2011) 818.
 A. M. Ferraria; S. Boufi; N. Battaglini; A. M.Botelho do Rego; M. ReiVilar, Langmuir (2010) 26(3) :1996-2001