Speaker
Description
Being among the first users of D11, I will give during my talk an outlook of the topics I investigated with this SANS camera. My first use of D11 dates back to Mai 1975 for studying the chain conformation in a crystalline polymer, namely isotactic polystyrene (iPS). Unlike polyethylene, that was studied simultaneously by other group of scientists, iPS did not display any isotopic segregation so that the single chain behaviour could be determined. We showed that the chain conformation depends on the crystalline growth rate with respect to the polymer viscosity. The chains fold completely in single crystals grown from dilute solutions while there is an alternation of folded parts and amorphous part in the bulk state. Our studies in polymer thermoreversible gels displaying fibrillar morphology have shown that the chain possesses a persistence length much larger that observed in the usual flexible state. We could show that this is due to helical stabilization through the formation of polymer/solvent molecular compounds. We could further show that a larger persistence length appears as a prerequisite for the formation of polymer thermoreversible gels.
We also investigated hybrid polymer thermoreversible gels/self-assembled systems. We could highlight the encapsulation of a bicopper complex by polymer fibrils, or the sheathing of polymer fibrils by self-assembled nanotubes.
Some references
- J.M. Guenet A neutron scattering study of the chain trajectory in
isotactic polystyrene single crystals. Macromolecules, 1980, 13, 387 - J.M. Guenet A neutron scattering investigation of the chain
trajectory in thermoreversible gels. Macromolecules, 1987, 20 2874 - M. Klein, A. Brulet, J.M. Guenet Molecular structure in isotactic
polystyrene thermoreversible gels. Macromolecules 1990, 23, 540. - J.M. Guenet, A. Brulet, C. Rochas Agarose chain conformation in the sol
state by neutron scattering Int. J. of Biol.Macromol. 1993, 15, 131 - D. Lopez, J.M. Guenet Encapsulation of filaments of a
self-assembling bicopper complex in polymer nanowires. Eur. Phys. J.
B 1999, B12, 405 - S. Malik, C. Rochas, J.M. Guenet Syndiotactic
Polystyrene/Naphthalene intercalates: preparing thermoreversible
fibrillar gels from a solid solvent Macromolecules 2005, 38, 4888 - D. Dasgupta, Z. Kamar, C. Rochas, M. Dahmani, Ph. Mesini, J.M. Guenet
Design of hybrid networks by sheathing polymer fibrils with
self-assembled nanotubules Soft Matter 2010, 6, 3576 - A. Boulaoued, J.-L. Bantignies, R. Le Parc, C. Goze-Bac, P. Mesini, T.-T.-T.
Nguyen, A. Al Ouahabi, P. Lutz, J.-M. Guenet Hybrid fibrillar xerogel
with unusual magnetic properties Langmuir 2016, 32, 13193
