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2014 Des polymères mésomorphes en peigne sont étudiés dans les phases isotrope, nématique et smectique. Les échantillons sont formés de mélanges de polyméthacrylates cristaux liquides dont les squelettes sont deutériés ou hydrogénés. Ils sont étudiés par diffraction et diffusion de neutrons aux petits angles. Les résultats montrent en particulier que dans la phase smectique alignée : i) le squelette présente une forte anisotropie, il est confiné dans une couche smectique. ii) Le marquage du squelette fait apparaitre un ordre local en bicouche. Abstract. 2014 Side chain liquid crystal polymers are studied in the isotropic, nematic and smectic phases. The samples are made from a mixture of liquid crystal polymethacrylate with deuterated or protonated backbones. The samples are studied with neutron diffraction and small angle neutron scattering. The results show in particular that in the aligned smectic phase the backbone is highly anisotropic and confined within a smectic layer. The backbone labelling shows local bilayered order.

Nanoconfinement can profoundly change the bulk characteristics. The question of conformational changes under one-dimensional confinement is recurrent in polymer physics. Very few works addresses this question because of the hard experimental challenge and the complex analysis of the signal. Here, the conformation of polystyrene chains shaped by wetting, in nanotubes or nanorods is for the first time determined at 3 dimensions. Polystyrene chains (molecular weight samples from 38 kDa to 310 kDa) confined in AAO nanopores as large as the size of the pore diameters (from 35 to 180 nm) are probed, revealing the invariance with respect to the bulk-like conformation for polystyrene chains up to 301 kDa confined down to 35 nm diameter nanopores.

Nanochannels and nanowires with diameters ranging from 30 to 400 nm were produced by etching ion tracks in thin polyarylate and polycarbonate foils. The shape and the size distribution of dry and wet nanochannels, as well as of nanowires grown therein, were examined by small-angle x-ray scattering. The x-ray intensity as a function of the scattering vector exhibits pronounced oscillations showing that both the channels and the wires have a highly cylindrical geometry and a very narrow size distribution. UV exposure before chemical etching significantly improves the monodispersity of the nanopores. For fixed etching conditions, the scattering patterns provide evidence that the diameter of dry and water-filled channels as well as for embedded nanowires are identical, demonstrating that the pores in the polymer are completely filled.