References of "Rasmont, A"
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See detailPhase-separated microstructures in "all-acrylic" thermoplastic elastomers
Leclère, Philippe; Rasmont, A.; Brédas, Jean-Luc et al

in Macromolecular Symposia (2001), 167

Atomic Force Microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. Measuring simultaneously the amplitude and the phase of the oscillating ... [more ▼]

Atomic Force Microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. Measuring simultaneously the amplitude and the phase of the oscillating cantilever in tapping-mode operation provides the surface topography along with the cartography of microdomains with different mechanical properties. This in turn allows to characterize the organization of the various components at the surface in terms of well-defined morphologies (e.g., spheres, cylinders, or lamellae). Here this approach is applied to a series of symmetric triblock copolymers made of a central elastomeric segment (polyalkylacrylate) surrounded by two thermoplastic sequences (polymethylmethacrylate). The occurrence of microphase separation in these materials and the resulting microscopic morphology are essential factors for determining their potential applications as a new class of thermoplastic elastomers. This paper describes how the surface morphology can be controlled by the molecular structure of the copolymers (volume ratio between the sequences, molecular weight, length of the alkyl side group) and by the experimental conditions used for the preparation of the films. The molecular structure of the chains is fully determined by the synthesis of the copolymers via living anionic polymerization while the parameters that can be modified when preparing the samples are the nature of the solvent and the thermal annealing of the films. Finally, we report on a systematic comparison between images and approach-retract curve data. We show that this experimental comparison allows the origin of the contrast that produces the image to be straightforwardly evaluated. The method provides an unambiguous quantitative measurement of the contribution of the local mechanical response to the image. We show that most of the contrast in the height and phase images is due to variations in local mechanical properties and not in topography. [less ▲]

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See detailMicrophase separation at the surface of block copolymers, as studied with atomic force microscopy
Rasmont, A.; Leclère, Philippe; Doneux, C. et al

in Colloids and Surfaces B : Biointerfaces (2000), 19(4), 381-395

Atomic force microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. The simultaneous measurement of the amplitude and the phase of the oscillating ... [more ▼]

Atomic force microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. The simultaneous measurement of the amplitude and the phase of the oscillating cantilever in the tapping mode operation provides the surface topography along with the cartography of the microdomains of different mechanical properties. This technique thus allows to characterize the size and shape of those microdomains and their organization at the surface (e.g. cubic lattice spheres, hexagonal lattice of cylinders, or lamellae). In this study, a series of symmetric triblock copolymers made of a inner elastomeric sequence (poly(butadiene) or poly(alkylacrylate)) and two outer thermoplastic sequences (poly(methylmethacrylate)) is analyzed by AFM in the tapping mode. The microphase separation and their morphology are essential factors for the potential of these materials as a new class of thermoplastic elastomers. Special attention is paid to the control of the surface morphology, as observed by AFM, by the molecular structure of the copolymers (volume ratio of the sequences, molecular weight, length of the alkyl side group) and the experimental conditions used for the sample preparation. The molecular structure of the chains is completely controlled by the synthesis, which relies on the sequential living anionic polymerization of the comonomers. The copolymers are analyzed as solvent-cast films, whose characteristics depend on the solvent used and the annealing conditions. The surface arrangement of the phase-separated elastomeric and thermoplastic microdomains observed on the AFM phase images is discussed on the basis of quantitative information provided by the statistical analysis by Fourier transform and grain size distribution calculations. [less ▲]

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See detailMorphology and rheology of poly(methyl methacrylate)-block-poly(isooctyl acrylate)-block-poly(mehtyl methacrylate) triblock copolymers, and potential as thermoplastic elastomers
Tong, Jiang-Dong; Leclère, Philippe; Rasmont, A. et al

in Macromolecular Chemistry and Physics (2000), 201(12), 1250-1258

The phase morphology and rheological properties of a series of poly(methyl methacrylate)-block-poly(isooctyl acrylate)-block-poly(methyl methacrylate) triblock copolymers (MIM) have been studied. These ... [more ▼]

The phase morphology and rheological properties of a series of poly(methyl methacrylate)-block-poly(isooctyl acrylate)-block-poly(methyl methacrylate) triblock copolymers (MIM) have been studied. These copolymers have well-defined molecular structures, with a molecular weight (MW) of poly(methyl methacrylate) (PMMA) in the range of 3 500-50 000 and MW of poly(isooctyl acrylate) (PIOA) ranging from 100 000 to 140 000. Atomic force microscopy with phase detection imaging has shown a two-phase morphology for all the MIM copolymers. The typical spherical, cylindrical, and lamellar phase morphologies have been observed depending on the copolymer composition. MIM consisting of very short PMMA end blocks (MW 3 500-5 000) behave as thermoplastic elastomers (TPEs), with however an upper-service temperature higher than the traditional polystyrene-block-polyisoprene-block-polystyrene TPEs (Kraton D1107). A higher processing temperature is also noted, consistent with the higher viscosity of PMMA compared to PS. [less ▲]

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